Antenna polarization may be one of the least understood properties of a wireless signal. If you are installing many antennas in one location, like on a tower, polarization is an important piece of the puzzle that you’ll need to take into consideration. Here we give you a quick overview on antenna polarization.
Polarization is determined by the way an antenna is mounted, usually horizontally or vertically. To ensure optimal network performance only like-polarized antennas should be used in point-to-point wireless applications. It is possible to establish a wireless link using antennas with different polarities but network performance and connectivity will suffer.
The big advantage of using different antenna polarization schemes is to reduce interference. For example when mounting several antennas on a tower, it is best to stagger vertically and horizontally polarized antennas to reduce interference.
If horizontal or vertical polarization won’t work for your wireless application there are dual-polarized, cross-polarized and circular-polarized antenna options to explore.
Antenna Polarization Options
Dual-polarized antennas feature two antenna elements in a single physical package (radome), one that is vertically polarized and one that is horizontally polarized. When properly installed, dual polarized antennas can communicate with both vertically and horizontally polarized antennas. An advantage of dual polarity antenna is that you get basically two antennas in one package, this saves space and money. These types of antennas are often used with MIMO (multiple-in/multiple-out) wireless access points and CPE devices.
Cross-polarized antennas sometimes referred to as X-Pol antennas, feature two elements in one package. One element is +45° polarized and the other is -45° polarized. The two opposing 45° angle of the elements produces a cross or X orientation. Using a cross polarized antenna with vertically and horizontally polarized antennas further reduces interference.
Circular-polarized antennas have equal response to either horizontal or vertical polarized antennas. These antennas are designed to either support right hand or left hand polarization to suit varied wireless connectivity applications. Using a circular-polarized antenna on a fixed access point can be beneficial if the linear-polarized remote links are constantly moving.
Republished with permission and courtesy of L-com Global Connectivity.
For those of you who were fans of the old “Six Million Dollar Man” TV series you will recall how the show opened every week with the proclamation “We have the technology”. Then, along came Star Trek and the Borg. It was the Six Million Dollar Man mass produced and on steroids.
So with all the technology we now possess in 2017, with the extreme miniaturization of circuits that is now found in everything electronic and with our collective ability to control almost everything with software, why is it two-way radio transceivers do not have something as basic as a VU meter to monitor and display the audio quality of what is being transmitted?
When I first started my broadcasting career it was drilled into my psyche that the VU Meter was not only your friend but the single best tool at your toolbox to monitor the level and quality of your audio. You lived and died by what the VU meter on your console, on your air monitor on anything that enabled you to control the audio quality of your signal told you. Without a VU meter to monitor your audio output, you may as well have been trying to drive a car at night wearing a blindfold. You lived and died by your VU meter if you wanted consistent (and properly modulated) audio levels.
When I ventured into Amateur Radio in 1995, I was absolutely shocked to find few if any Amateur Radio transmitters with some means (other than your ears) of assuring proper modulation and audio quality. And today twenty-two years later, the only devices I have found that are outfitted with something approaching a VU meter are very high-end HF rigs that only a handful of Hams have in their shack. Why is that you might ask? I wish I had the answer.
Just turn on NI4CE any evening during one of the many Nets are conducted each week. You will hear stations that are LOUD, some painfully so. You will hear stations whose audio sounds about right. And you will hear stations (if you turn the speaker volume to the MAX) with low audio, some averaging no more than ten to fifteen percent modulation. It’s all over the road! And with a simple addition of a VU meter or some means of monitoring the transmitted audio volume of the transceiver, these all-over-the-road audio levels are preventable.
Of course, unless someone (FCC) were to require some means of real-time audio level monitoring, it probably won’t happen. Adding an Automatic Gain Control (AGC) circuit to every radio would help. But good luck getting being able to buy any transceiver for thirty dollars after an AGC circuit is added. I am afraid we may have to add this one to the list “obvious problems to fix” (right next to building utility lines through trees).
As we continue to pick up the pieces from this year’s spate of intense and destructive tropical cyclones, there are questions about what worked (and why) and what did not work (and hopefully, why). Were our expectations high enough? Was our vision broad enough? Did we individually and collectively have a realistic view of how to prepare, how to respond and, so to speak, weather the storm? But maybe the most important question that needs to be asked (and answered) is “Can We Make It Better?”.
When the concept of the NI4CE Repeater System was first conceived in 1999, the purpose was to fill a perceived need. Our region did not have a single point, “go to” Amateur Radio communications system where Hams who were SKYWARN spotters could report severe weather information. Before the NI4CE system was built, Net operations were strictly county-based. That meant a Net Control operator located at the National Weather Service in Ruskin spent most of the time “spinning the dial”, going from one repeater to another, trying to collect information. The opportunity for a county-based Net Control operator to have clear visibility of what was coming at them from the next county over was minimal.
When the “Big Stick” repeaters at Verna went on the air, it was the start of connecting a lot of dots. No more “spin the dial”, no more “flying blind”, a network started being built. In 2004, the repeaters at Verna and St Petersburg helps a lot of people “weather the storm” and aided disaster responders like the Salvation Army and Red Cross with their relief efforts.
“Big Stick” was never envisioned as a “Be All, End All” solution. And after the 2004 experience, we were able to expand the system with repeaters at Pebbledale (now Bartow) and Riverview. This accomplished two important improvements: better coverage, particularly for indoor portable radio operation and repeater redundancy. Still, that did not get us where we wanted to be. In 2011, the Holiday site came online to provide better redundancy over the TampaBay Metro area and to expand coverage over counties to the North. And in 2015, a long talked about repeater in Lake Placid was added to cover Highlands County.
Of course, all this has taken a lot of money and a lot of time to build and maintain. Having some great partners, particularly our Broadcast partners Cox Media Group, iHeart Media, ION Networks, Hearst Broadcasting, American Tower Corporation, and Insite Tower has been a big, no, HUGE plus. And the support we receive from the Amateur Radio community has allowed the NI4CE system to serve West Central Florida. To all, we say “Thank You”!
If you have not seen Dave Rockwell’s article titled ‘Disaster Traffic” that was posted on the NI4CE website last week, please take a few minutes to read it and digest it. Disaster response communications don’t just happen. It takes a lot of vision and planning. And, hopefully, our experiences this year will enable us to better plan for the next disaster.
If you live in Florida, anywhere in Florida, the last week has been extraordinary. For many, life is getting back to “normal”, if you define “normal” as electricity from a power utility, air conditioning, a hot shower and most if not all the other conveniences of life prior to Hurricane Irma. For many others, however, “normal” is still an elusive target. And Hurricane Season still has a long way to go.
The last time Florida experienced a storm that ran up the center of the state and affected so many people was Hurricane Donna, exactly sixty-seven years ago. I wasn’t living in Florida at the time. But those who experienced Donna first-hand did not have the satellite imagery, the Tropical Cyclone forecasting, and the other technology now in place to prepare them for what was about to change their lives. A couple Donna survivors I have talked with have told me the impact of Irma was much worse. I wonder if the all the pre-storm anxiety, the long lines at gas stations, food stores, Home Depot, Lowes and other stores wasn’t part of their assessment.
Floridians in 1960 did not have the vast communications resources and networks we have today, either There were no cell phones, Facebook, Twitter and the like to share the experience with others. Heck, Ham Radio and SKYWARN had barely met in 1960 to provide real-time information on the storm, where it was going and who would be impacted the most. Of course, there were a lot fewer people in Florida in 1960 than today. It was a simpler time and place.
We are not going to know the full extent of just how bad Irma was for a few months. For those of us who lost our utilities and were inconvenienced for a few days, the impact will be far more fleeting than those whose homes are flooded or otherwise severely damaged. I can only hope that whatever Irma’s impact was on your neighborhood, you took the opportunity to get to know your neighbors a little better and help them out if you could. And I hope everyone will take this experience and acknowledge what worked, what needs improvement and be better prepared for the next storm that will barge into our lives.
I want to take a moment to acknowledge some extraordinary efforts that helped keep people informed before, during and after the storm. A tip of the hat to Evans Mitchell-KD4EFM and Jason Triolo-KD4ACG for their efforts both collecting and disseminating information about Irma on NI4CE. They kept the SKYWARN Net running under very tough circumstances. Another tip of the hat to our partners at Cox Media Group, iHeart Radio, American Tower Corp. and Polk Co Emergency Management for keeping the generators running, allowing the NI4CE system to remain on the air and available for the Ham Radio community. Downed trees and power lines at the Holiday site made re-fueling the generators there a real exercise in “adapt, improvise and overcome”. And a big thumbs up for the Hams who manned shelters and are aiding in the recovery effort.
Hurricanes like Harvey, Irma and Jose and all those that preceded them serve a necessary purpose, that is, to evacuate an extraordinary amount of heat and energy from the surface of our planet. Hurricanes have been doing this long time, long before all the chatter about climate change. It is part of Mother Nature’s grand schema to keep out eco-system in balance. It is unfortunate so many lives must be disrupted in the process.
I have written before about Digital Two-Way Radio, the several flavors of digital radio that are currently available. I have also discussed what some of the differences between these Common Air Interfaces (CAI) are and why the West Central Florida Group, Inc. made NXDN as its choice for the digital repeaters we operate.
One thing I have not gotten into is WHY digital two-way radio for VHF and UHF is important to the Amateur Radio community here in West Central Florida and for that matter, to Hams everywhere. Once you understand that, I think you will agree it is something we all need to take seriously.
Hams have not been mandated by the FCC (or any other body yet) to go Narrowband on VHF and UHF. We have been allowed to continue operating with 25 KHz, wideband FM (WBFM) signals on these two important bands, unlike commercial, Land Mobile Radio operators. But don’t believe for a minute that 12.5 KHz Narrowband FM (NBFM) operations will never come. Many newer “Ham” radio products will operate in NBFM mode. It is not a matter of “if” but rather a matter of “when” this will occur.
What is narrowbanding all about? It is simple: Doing More With Less. Narrowband FM operations can enable up to twice as many radio channels for both repeater and simplex operations. But there are some significant drawbacks with Narrowbanding many Ham have yet to discover. One big drawback is the loss of coverage. Narrowband repeaters generally experience a twenty-five percent or more loss of their coverage footprint versus their current WBFM operation. That’s HUGE! This loss of coverage will cause more instances of weak signal reception and loss of reception altogether. Another downside is the impact of more repeaters on the air. More repeaters can increase the probability of Intermod when two or more signals from different sources mix to create a spurious signal.
So WHY is digital so important? And WHY should Hams start paying more attention to DIGITAL? Again it’s all about “doing more with less”.
NI4CE selected NXDN as the digital mode we would support for several reasons. NXDN radios operate with 6.25 KHz channel bandwidth. But instead of suffering a loss of coverage, NXDN actually provides a ten percent or more increase in coverage when compared with a WBFM signal. NXDN voice is clear, no static, no “snap-crackle-pop” even when the received signal strength in analog would be noisy and unreadable. NXDN radios can also be used to deliver text messaging and GPS location data. And the process of connecting NXDN repeaters over IP / Internet to form a repeater network is very simple and straightforward.
End-user NXDN radios are readily available and feature-rich, There is more than one manufacturer producing NXDN radios. And support for the development of applications for the Ham community is also available.
To help Hams in West Central Florida know more about NXDN, we have set up the NI4CE-NXDN email group. You can join the discussion by sending an email to firstname.lastname@example.org. We will be happy to add you to the list. And watch the NI4CE.org website for news about an NXDN Net on the NI4CE NXDN Repeaters coming soon.
As we, once again, celebrate the Fourth of July and the freedoms we enjoy here in the United States, it is easy to be reminded that freedom (and all good things for that matter) is something we cannot become complacent about. Freedom is a precious commodity something we must work at every day. It does not just happen all by itself.
Ham radio and the freedom to communicate freely is the same way. No one, to the best of my knowledge, was born with the knowledge and skills needed to use technology, any technology, to convey ideas, solve problems or just “shoot the breeze”. Using wireless technology, including Ham Radio equipment, is a learned process. If you don’t believe me just tune in to any repeater system and witness the number of key-ups or “kerchunks” followed by dead silence. Those of us who are Volunteer Examiners were called on to administer Morse Code tests to evaluate the ability of Ham Radio license candidates to operate with Morse Code. I sometimes think we need some sort of Phone Proficiency exam as part of the testing process to make sure that operators actually know what to do once they have pressed the Push-To-Talk button.
But back to the topic of “complacency”. It has been thirteen years since those of us on the West Coast of Florida experienced a major disaster. Someone said to me the other day we need a good hurricane or some other type of disaster event to shake everyone out of their complacency and not take everything for granted. By nature, humans, including those of us with an Amateur Radio license, tend to get into a “comfort zone” and stay there because it is the easy thing to do. We avoid taking on challenges or thinking outside the box unless it is something we are really motivated to do.
Unfortunately, we live in a world where the challenges are growing in scope and in number. There are the natural threats (like severe weather and hurricanes) that we can get some prior warning about. And then there are the manmade threats for which we will receive almost no prior warning.
One threat we need to take seriously is EMP – Electro Magnetic Pulse. EMP can occur naturally, the result of sunspot solar flare activity and lightning. EMP can also be manmade on a scale that can range from something very localized to a catastrophic, existential event. The loss of the electric power grid and most electronic communications (including Ham Radio) that we rely on daily could have an enormous impact.
There are several actions you can take to mitigate the threat from EMP. First, protect your radio equipment with EMP-rated devices, like PolyPhasor Lightning Protectors. The West Central Florida Group, Inc. has been using EMP-rated lightning protection for over a decade at our several NI4CE repeater sites. Second, build a Faraday Cage and place one or more radios into it for safe keeping. Third, think about all the things you need electricity for and what you would do if the lights went out. You will find this goes well beyond communications. Finally, raise your voice with your elected representatives and electric power provider about the work that needs to be done to shore up the Electric Power Grid in the United States. Several studies conducted over the last two decades have concluded the electric grid is at significant risk from an EMP event. One of these studies has determined the power grid can be strengthened and made more secure at a cost of around $2 billion. Complacency about this problem and its potential impact, however, has led to inaction. Not good enough!
Take stock of the freedoms we enjoy this Independence Day Week. And if you will be cooking some burgers on the grill, I’ll take mine medium rare!
Lots of hams on NI4CE wanted to help during Hurricanes Harvey, Irma, and Maria. After all, many of us became radio amateurs to become public service operators in the Amateur Radio Emergency Services (ARES). There were questions every night on Eagle Net about how to get health and welfare (H&W) traffic into first Texas, then the Caribbean, and, after Maria, into Puerto Rico. Folks with family in the impacted areas reached out to amateurs here in our coverage area to get messages to friends and loved ones. Many amateurs were frustrated when their H&W traffic requests were turned back. So, let me see if I can put this situation in perspective.
First, let’s look at the situation where we, the local amateurs, are in the impact zone of the hurricane (works for earthquakes, volcanoes, blizzards, and manmade disasters). Depending on the severity of damage, we may only have a small number of radio stations that can operate. Since the power will be out, the stations will likely be on generator or battery power. These operators may have suffered damage and trauma from the storm. Bottom line: If these operators can operate at all, it is for a short period of time. Remember our rule in ARES is “family first”. Make sure you and your family are safe before jumping on the radio.
If the impact area is large, there will be thousands of people displaced by the event. We need an efficient means for folks in the impact zone to pass messages to friends and loved ones. ARES usually works with non-government organizations (NGOs as we call them in Emergency Management) like the Red Cross or Salvation Army (and other faith-based groups). These organizations have proven techniques for collecting health and welfare information. In the impacted area, the NGOs set up reception tables and may have representatives in major shelters and medical facilities. These reps collect names and status of people and destination information for the H&W message. These are assembled into book traffic destined for regions. This makes very efficient use of the scarce radio time.
Now let’s look at what should happen outside the impact area. The natural tendency for most people who know a ham operator is to ask him or her to send a radiogram to the relative or friend. This isn’t bad for a small local event, but the number of such requests soon overwhelms the National Traffic System and the Radio Relay International nets. So, once again, we rely on our partner NGOs, like the Red Cross and Salvation Army to collect requests, assemble them into book traffic, and pass them to affiliated amateur stations.
With our modern, network-based, communications such as the Internet and cellular phone service, amateur radio nets are becoming the last resort channel. If the network infrastructure is partially intact in the impacted areas, the local, state, or regional emergency management team may establish online resources for folks to post H&W queries and reports. Some of the social media services, like Facebook, have services where folks can report their status to friends and loved ones. If the networks are running, these should be the first way. Local governments or NGOs in the impacted areas may establish kiosks where those impacted can post their status. Don’t forget cellphone text messaging. Many times, text messages can make it through the system when voice cannot. The messages take very little bandwidth.
In general, for amateur radio nets during disasters, we give priority to outbound traffic. Inbound H&W queries may be rejected or cached. We want to give precedence to actual H&W traffic, like ARRL ONE (“Everyone safe here. Please don’t worry.”) from a specific person going to a specific destination. Remember, we probably have limited time windows based on the fuel in the generator and propagation, to get that message delivered. Clogging the system with hundreds or thousands of queries doesn’t help. Some of the NGOs set up bulletin boards for incoming queries. These might be online or actual physical signboards. It can be different for each location and disaster.
Now, what do we need to do? First, we need to educate our fellow amateurs in how H&W information is passed. Consider making it a topic at your next ham club meeting. Reach out to your local NGOs and build a working relationship and develop processes to handle H&W traffic. Make sure your agreements and practice sessions with the NGO include the scenarios of being in the disaster zone and serving folks who are outside the zone. Also, tell your family, friends, social groups, and others how the process works. They should know to contact the Red Cross to find out about someone’s status in the impact zone. Ensure everyone knows that it may take days or weeks to get an answer to the query. It’s not unusual for the person in the impacted area to call the relative long before a reply from the amateur radio H&W messages makes it.
In times of emergency like the recent hurricanes, we need to remember that we are communications experts first and radio operators second. We need to advise folks on the most likely channels to get their message through or the query answered. When that channel is amateur radio, then we need to apply our best traffic handling skills and make sure the message gets through as quickly and accurately as possible. Remember, these skills come with practice. If you haven’t sent and received messages in the last six months, you are probably rusty. Join one of the traffic nets and take traffic.
73 de W4PXE
Dave Rockwell-W4PXE is Manager of the Eagle Traffic Net conducted nightly at 8:30 PM. Dave is also a West Central Florida Group Inc. Board Member.
For those of you who may have missed the Tech Net last Thursday evening on the NI4CE Repeater System, I thought I would share some comments I made concerning an equipment heating issue we recently solved.
The problem first showed its ugly head several months ago when we installed a new RF power amplifier at the Verna Repeater Site. The new amp boosts the output power of the 145.430 MHz VHF repeater there. To achieve the rated power output of the amplifier, we needed to feed it with two watts from the repeater. Sounds simple enough, just dial back the power output and all is good.
Shortly after the amplifier went into service, problems began cropping up. During a Net where both the repeater and the amplifier were in transmit mode for an extended period of time, the output power dropped to almost zero. The symptoms suggested an overheating problem. Was it the repeater or the amplifier? Since the repeater had been in service for an extended period of time and without incident, it was logical to suspect the amp. A fan was placed in front of the heat sink to provide additional heat dissipation. That seemed to work for a while.
But alas after a few weeks, the problem showed up again. And this time, it persisted.
Troubleshooting the repeater got a lot easier with the development of a Windows app and direct IP connectivity that allowed us to monitor the repeater’s core temperature in real time. It did not take long to conclude the repeater, in fact, was where the heat issue resided. The temperature inside the repeater chassis rose quickly during Nets and other periods of extended transmit operations.
To provide better heat dissipation, one of the WCFG Board members (and a retired engineer) Paul Knupke-N4PK, resurrected a desire that has been in place for several years at the NI4CE Riverview site. He modified a rackmount shelf and attached two high volume four inch fans that would blow air across the heat sink and chassis of the VHF and its companion UHF repeater. We tested the impact of the additional air flow in a controlled environment similar to the Verna Communications Room. The data collected confirmed this design worked keeping both repeaters within their published operating temperature. Since this modification has been installed, both repeaters are operating within normal parameters, even during extended transmit periods.
The important take away from this experience is the importance of gathering empirical data to support your troubleshooting hypothesis. In this instance, the problem was excessive heat generation. But the initial culprit, the external power amplifier, was not the culprit. It was the repeater, a piece of equipment that operates within its rated one hundred percent duty cycle power output. Had we not been able to measure the internal core temperature of the repeater, we might still be chasing the problem.
Let us know what you think by sending email to email@example.com or on our Facebook page.
Every year around this time, the great migration of the North American Snowbird starts in earnest. When I first moved to Florida almost twenty years ago, I was fully aware of the migration of Canadian Geese (the ones that fly in V formation) and the elegant, oversized Sand Crane to habitats along the Gulf of Mexico. Being a Wisconsin native, I can’t blame any living being for leaving the Arctic cold and snow in Dodgeville, or Nekoosa or Eagle River (all places I have been in Winter) for Bradenton, Port Charlotte or Lake Placid (FL not NY).
If you have come to West Central Florida to spend some time with us this Winter, we welcome you and hope you enjoy yourself. Our little corner of Paradise has a lot to offer when a CAT 3 or CAT 4 hurricane (also known as a Bad Hair Day) isn’t blowing through. And we have a lot to offer Ham Radio operators who have come to escape the cold.
If you are new to the area or have not previously discovered the NI4CE Repeater Systems before, we have a lot to offer. The five-site Analog repeater system is open to all licensed operators (including our friend from VE-land). You will need to program any or all of our analog repeater frequencies with a PL or CTCSS tone of 100.0 Hz. To find the repeater nearest you, visit the Repeater Page on the NI4CE.org webpage.
The NI4CE Analog System features at least one Net every night at 8:30 with multiple Nets on Monday, Tuesday and Thursday evenings. The NI4CE Digital System will soon have an NXDN Net on Wednesday nights at 8:00 PM where we will be discussing all things digital. One other Net that will pop up as conditions require is the Regional SKYWARN Severe Weather Net. We take severe weather very seriously!
Just in time for Snowbird Season, we have just added a third NXDN Digital Repeater to our network to complement the Riverview (444.425) and Verna (444.3125) repeaters. NXDN is now loud and clear in Northern Pinellas, Northwest Hillsborough, Pasco and Western Hernando Counties on 442.650. All three repeaters use RAN 1 and support Talkgroups 1200 (Local) and 65000 (NXDN-Worldwide). If you are from New England, you may also want to use TG 9000.
Of course, both NI4CE systems are available for friendly QSOs anytime there isn’t a Net scheduled. You will find a pretty diverse group to rag chew with. Please try to limit your use of four-letter words like COLD, SNOW and WORK. We try to be “family friendly”. We also ask that you keep any kerchunking to a minimum We ask that of everyone, although a couple people think squeezing their PTT button is good hand exercise and a stress reliever.
So, welcome, snowbirds, to West Central Florida and NI4CE-land. Ham Radio Lives Here!
During a recent discussion on Facebook, I was asked for some tips on NXDN radios. The person asking was a fellow Ham I know who wants to become active on the NXDN digital repeaters here in the Tampa Bay area.
After giving it some thought and knowing a little bit about what this Ham was interested in, I posted my thoughts for him to consider. Shortly thereafter, another person posted a comment which I thought was somewhat telling. The comment stated in part, “But you can’t buy any of those radios at a Ham Radio store.” At face value, that is a true statement. NXDN radios are considered Land Mobile Radio products by both ICOM and Kenwood. As such, you will need to visit a local Land Mobile Radio dealer in person or on the web if you want to purchase a new NXDN radio.
However, let’s look at this statement in a slightly broader sense. There are a lot of Hams, rightly or wrongly, who believe equipment used in Ham Radio MUST be purchased from a Ham Radio vendor or it just isn’t “Ham Radio”. Let me give you a couple examples.
Many vendors produce ANTENNAS that are cut to work specifically in the VHF, 222 MHZ and UHF “Ham” bands. You will generally find these products sold at Ham Radio stores. But you will also find a wealth of omnidirectional antennas, Yagis, mobile antennas and replacement portable antennas on websites and at retail locations that are not “Ham Stores”. Many repeaters use commercial grade antennas because Ham-grade antennas would not hold up to the environmental conditions several hundred feet off the ground. Commercial grade antennas are generally built to withstand more punishment.
Ham Radio has always been a haven for equipment built for Land Mobile Radio. Many WBFM analog repeaters are refurbished Motorola and General Electric radios that started their service with Public Safety agencies or other commercial users. Now that digital two-way radio is here, NXDN, DMR, and P25 repeaters and end-user gear come almost exclusively from the Land Mobile Radio marketplace. D-Star and Fusion are the exceptions. That should not be a surprise since repeaters, whether they are operating on “Ham Radio” or Land Mobile Radio frequencies, must be able to co-exist with each other in high RF environments. That means tighter filtering and better adjacent channel and harmonic rejection.
Ham Radio RF equipment must pass the technical standards established by the FCC for Part 97 operation. Land Mobile Radio equipped must navigate a tighter, more strenuous set of technical standards to be Type Accepted for Part 90 Land Mobile Radio. When you are talking RF, the better the specs, the better the radio. That does not necessarily make these radios more expensive!
Hams who want to use Land Mobile Radio equipment for their Ham Radio activities do face one challenge. Most Part 90 radios cannot be programmed on the fly. You must use software to put a frequency, a PL tone or RAN code into the radio or activate other features. “Ham Radio” equipment does allow you the freedom to put a new frequency or parameter in from the front panel. Many “Ham Radio” portables and mobiles will also allow you to operate on more than one band. There are some newer Part 90 radios that operate on more than a single band. But you have to have really, really deep pockets to afford them.
My advice to all my fellow Ham operators is simple: Don’t be afraid to expand your horizons. And don’t discount a radio, an antenna or any other equipment just because it doesn’t say “Ham Radio” on it.
I am sure I am going to take some flak for what I am about to say. And I am sure some people are going to think I am just an “old fuddy-duddy”. But I need to get this off my chest!
Ham Radio has been something special, something worth taking the time to earn an FCC license for. It has enabled license holders to experiment, communicate with other Hams, even help out during emergencies on RF spectrum reserved for us. All we needed to do was come up with the necessary radio equipment and the time.
But there has been an increasing trend by Hams to abandon our Ham Radio roots and spectrum in favor of unlicensed Part 15 frequencies (which anybody can use), piggybacking on licensed, pay-to-play spectrum and the Internet. What gives?
Digital two-way radio is not exactly a new technology. And there are lots of flavors to choose from NXDN, DMR, P25, TETRA, not to mention Vo IP and LTE just to name a few. These commercial modes are finally starting to attract some attention in the Ham world but not in a way that you might expect. In the analog world, you either operated simplex (radio-to-radio) or through a repeater. Hams today seem fixated on using “Hot Spots” to connect with non-Ham Radio spectrum and the Internet. Yes, Hams are putting digital mode repeaters on the air. But the inability of the Ham community to embrace any single digital operating mode coupled with the desire to operate “everywhere” has caused the “hot spot” to become the new “gotta have” device in Ham Radio.
I am excited that Hams want to learn more about digital communications. Since the Ham community is somewhat dependent these days on the commercial marketplace, there will come a time when today’s aging analog repeaters and radios will disappear. But the use of “hot spots” and dependence on the several commercial cellular networks as a transport is, I believe, a train wreck waiting to happen. We have already seen numerous examples of what happens when major disasters or terrorism events occur. Without robust, digital repeater systems, Amateur Radio communications efforts will be negatively impacted. And your digital Ham Radio transceiver will become a useless appliance, just like your cell phone.
We can lament how Ham Radio is virtually invisible to most Americans. But we have done it to ourselves. Instead of building a robust and independent communications capability using Ham Radio spectrum and resources, we have copped out, instead of throwing our $$$$ at Verizon, AT&T, T-Mobile and the dozens of Internet Service Providers that dot the landscape. Instead of a fifty-watt mobile/base station radio, we are content settling for a four or five-watt portable radio and a “hot spot”, kidding ourselves into believing they are all we will ever need. Sorry, but that’s not the Ham Radio I signed up for.
Every profession, every hobby seems to come with its own set of litmus tests as a means of measuring a person’s commitment to and competence with the endeavor. Ham Radio has had a number of these “qualifiers” over the years, some which newly licensed Hams probably never experienced.
There was a time when you could not earn a U.S. Amateur Radio license without passing a Morse Code test. Even an entry-level Technician Class licensee had to pass a five word per minute proficiency test to get on the air. If you wanted to upgrade to a General Class license, the requirement was thea success with a thirteen word Morse Code exam. And Amateur Extra candidates had to score a passing grade on a twenty word per minute code test to earn the top ticket.
Some old time Hams maintained these Morse Code requirements kept CBers from getting into the ranks of Ham Radio and trashing up the airwaves with their use of “10 codes” and “Roger Good Buddy” lingo. I have heard worse language, much worse, from Hams who passed the Morse Code litmus test, once again demonstrating the fallacy of that filter as a benchmark.
Another litmus test was a Ham’s ability to build a radio from scratch, or at least from a kit you could purchase from the local Ham Radio Store. There are some radio kits still available if you want to make the effort. But it is less of a litmus test and/or rite of passage in today’s microprocessor-based world.
I would suggest a better measure of a Ham Radio operator is their command of the radio(s) they are using, their technical ability to construct a station that operates efficiently and enables clear communication and their grasp of written and verbal communications skills. Unfortunately, none of these qualities are incorporated into any of the FCC exams. And unlike Marshall McLuhan, who put forth the position “the medium is the message”, I would maintain it is how you use your Ham Radio technology that is much more important. “The message IS the message” even if all it is is “You’re 5-9, West Central Florida. Good luck in the contest”.
Know the basics. You wouldn’t use #18 wire for a twenty amp electrical circuit in your shack. Check the specs on your coax and use an appropriately sized cable when building your antenna system. Check your forward and reflected power. If the SWR is greater than 2:1, some adjustments are required.
If all you have is a portable radio (particularly one of the “cheap” portables), don’t expect to hit a repeater forty miles away with a clear signal, not even NI4CE. Concrete, metal, and distance attenuate radio signals.
Know what you want to say before you press the PTT button on your mic or radio. The goal is to convey information, clearly, concisely and conversationally. Find a mentor to help you. At the very least, take the advice of an Air Force MARS Training Officer I know, “Listen, listen and learn”.
Well, I figured there would be some reaction to my last article on the use of HotSpots to support Amateur Radio Digital Communications activity. But by some of the reaction I received, you would have thought I was suggesting the abolition of Amateur Radio.
“How dare you criticize my use of a HotSpot?” wrote one commenter. Another commented “If I want to build and use a HotSpot, I am going to do it. After all, this is Ham Radio where experimentation is perfectly OK.”
As a short-term “means to an end” solution, using a HotSpot will enable operators to use their NXDN, DMR, and P25 radios almost everywhere. Aside from a reliance on “commercial, pay-to-play” network services, both wired and wireless, it is a way to allow Hams to use these modes. But to grow the digital modes, to really make them part of the mainstream rather than just another Ham Radio sideshow, the Ham community needs to make a commitment, a long-term commitment to building out the digital repeater infrastructure needed in their area. Relying on commercial cellular carriers for the transport of a Ham Radio signal is not in the hobby’s best interest.
The FCC holds the future of analog VHF and UHF radio in its hand. We are still waiting for the other shoe to drop as the Commission moves towards its quest to squeeze more use out of the existing VHF and UHF spectrum. Their stated goal is to enable four “conversations” in the same bandwidth that used to support one conversation. The 2013 implementation of Narrowbanding-Part One has achieved half that goal. The other half remains in abeyance in part, because the Commission allowed Public Safety to use P25 Phase One emissions on VHF and UHF channels. P25 Phase One uses a 12.5 KHz emission making the “Ultra-Narrowbanding” of these bands to the stated goal of 6.25 KHz channels, at least on some level, impossible. But when analog emissions are finally phased out, Hams will be hard-pressed to continue analog operations for very long.
That is why it is in Ham Radio’s long-term interest to build and operate a digital infrastructure. Yes, the food fight going on in the industry between NXDN, DMR, Fusion, and D-Star make that more difficult. But remember, the FCC has already stated the ultimate goal is 6.25 KHz channelization for Land Mobile Radio. Ham Radio would do well to take its lead from that pronouncement and embrace the technology that gets us there.
Of course, HotSpots enable the use of low power, digital portable radios almost everywhere. But that’s because the cellular industry can afford to build out its massive infrastructure. Ham Radio, collectively, does not have that kind of money. Ham operators will better serve their interests by mixing portable radios with higher output mobile/base radios. This will reduce the cost of the infrastructure needed and reduce the dependence on non-Ham Radio infrastructure to have fun and serve the community.
One of the things that does not get a lot of discussion or visibility in Amateur Radio is the cost of this hobby. While most Hams eventually find out what new radios, coax cable, antennas and other components cost, most have little or no idea what the costs are associated with putting a repeater on the air and maintaining one (or more). Well, let’s shed a little sunlight on this topic.
But first, an analogy. When you first got your license and could start using your privileges on VHF and UHF, you quickly learned about how to operate and communicate with your fellow Hams on a repeater. Most QSOs were like talking on a telephone, except only one of you could talk at a time. If your QSO was with a group of people, you quickly learned that if two or more in your group tried talking at the same time, there was this annoying and ear piercing racket that came through your radio’s speaker.
When you graduated to a license that allowed you to operate on HF, you quickly realized you had to learn a whole new set of skills, technical and otherwise. Operating here was in a completely different realm that didn’t seem to have a lot in common with VHF/UHF.
Most Hams get over whatever “Mic Fright” they may have and quickly become proficient operating through a repeater with their portable or mobile radio. But few really get to know much about the repeater itself. If it is a Club repeater they are using, they just know that Joe or Tom or Larry is the “repeater guy”. They are usually shielded from the details of what this magic box is, how it works and how much it costs. It is time to change that because every repeater “user” needs to know these details.
First, repeaters are NOT like your ordinary Ham Radio transceiver. They are usually “commercial grade” devices you will not find at your favorite Ham Radio store or website. While most Ham radios have a Twenty Percent Duty Cycle, that is, for every minute the radio is transmitting, it is receiving (and cooling off) four more minutes. Repeaters, on the other hand, need to have a One Hundred Percent Duty Cycle, that is, they need to be built to withstand continuous duty, no time outs. That means better components, better construction, and better cooling,
Most repeaters usually require a “Controller”, another piece of electronics that controls how the repeater operates, including the transmission of its FCC ID every ten minutes. Most repeaters also require a “Duplexer”, a filtering device that must be tuned to the frequencies (input and output) the repeater operates on. Many repeaters also use an external Power Amplifier and an external Receiver Pre-amp to enable the use of low power end user portable radios. There is also the Power Supply, the coax cable (usually not the LMR400 most Hams use at their Home station), a commercial grade antenna built to withstand the rigors of the environment they operate it and of course, a high-quality Lightning Arrestor to keep Mother Nature from blowing everything up.
Whoa! That’s a lot of stuff. It is! And the cost of all that stuff can be, collectively, ten or twenty times (or more) the cost of your Home station!
But that is just the starting point. Most repeaters are located on tall buildings or commercial towers. While many repeater owners have been successful in getting a monthly tower or building space fee waived, the cost of Liability Insurance, tower climbing fees, electricity and Internet service adds up quickly. For example, one trip up a commercial tower to mount an antenna or install coax cable can cost thousands of dollars. Many tower owners and building owners now require insurance that goes well beyond your homeowner’s or vehicle insurance coverage.
In my next article, we are going to discuss why every Ham has a stake in keeping your local repeater(s) on the air and what you can do to ensure your favorite repeater is there when you want to use it.
In my last post, I mentioned that most Hams have little or no knowledge about all the things that go into the operation of a Ham Radio repeater. They just know if they want to use one, they
need to program the transmit and receive frequencies into their radio (along with the Offset, CTCSS tone or RAN code) and press the Push-To-Talk button.
No matter WHO owns and operates the repeater, every USER of that repeater has a financial stake in keeping it on the air. REPEATERS ARE NOT FREE!!!
Here in Florida (and most places), there are three groups of repeater owners. The first group is the LOCAL Repeater Club. Depending on where the club is located (rural versus urban) and how many members are in the Club, the repeater system may be a single VHF or UHF repeater, a VHF and a UHF repeater at a single site or a multi-site repeater system that may include multiple repeaters. Most Club repeaters cover a very specific (and limited) geographic area. Most Clubs charge an Annual Membership Dues or fee, much of which is used to cover the costs I talked about in my last post. If a repeater, antenna or some other component needs to be replaced, the Treasurer may need to “pass the hat” to cover the costs involved.
The second group of repeater owners is Government. Many local Emergency Management agencies operate one or more repeaters for use by their local RACES, ARES or ACS groups. When there is no emergency in progress, the repeater(s) are usually available for all Hams to use. In this case, your property taxes are paying for the repeater(s).
Finally, the third group consists of private individuals or non-Club operators. The repeater(s) may or may not be OPEN for all to use or may cater to a specific group of operators.
The West Central Florida Group, Inc. falls into this third category. The NI4CE system was conceived in 2000 as an OPEN repeater system to enable Hams in a multi-county region to communicate with each other using portable and mobile VHF and UHF equipment. NI4CE is a one-stop point of contact during major severe weather events. It enables a daily regional NTS Traffic Net, a regional Technical Net and provides regional Ham Radio support for organizations and events that would otherwise require a “spin the dial” approach to communicate.
It costs around $3,600.00 a year to operate and maintain NI4CE. That’s around $300.00 per month. If we had to cover the cost of tower space in real dollars, multiply that figure by 10! We don’t talk about this on the air because Part 97 of the FCC rules prohibits us from doing so.
By comparison, some commercial SMR repeater systems with similar coverage charge $35.00 to $50.00 per month to use their repeaters. But NI4CE is Ham Radio and, by law, we are prohibited from doing that, too.
What we can do is ASK (NI4CEly) here for your support. If we all pitch in just a little bit every month to underwrite the cost of this one of a kind community and regional Ham Radio resource, we, the NI4CE users, can continue to enjoy something most areas of the country do not have on the air and available 24/7/365. Do your part. Click on one of the PayPal buttons you will find on the NI4CE Home Page right now.
Most Hams, particularly those operators new to Ham Radio, use one or more VHF or UHF repeaters to communicate with their local Ham Radio friends. The repeater is that magic box that enables you to communicate more than a mile or two, particularly if you are using a portable radio.
So what is a repeater? How does it work? Why do some repeaters cover more territory than others?
First, let’s talk about the radio side of the repeater. Most portable and mobile radios operate in half-duplex mode. That is, they transmit and receive but not simultaneously. That’s called Half Duplex mode operation and is the “norm” for two-way radio. Repeaters, on the other hand, receive an incoming signal (uplink) and then immediately re-transmit that signal (downlink) on a different frequency. In the VHF band, the uplink signal is usually 600 KHz above or below the downlink signal. In the UHF band, there is usually a 5 MHz difference between the uplink (mobile and portable user) and the downlink (repeater output).
A repeater can use one antenna to receive the uplink signal and a separate antenna to transmit the downlink (repeater output). The antennas usually require some amount of vertical separation, usually 20 feet for UHF, 30 feet or more for VHF. If that vertical separation cannot be achieved, a single antenna can be used to receive the uplink signal and transmit the downlink repeater output. In order to keep the local transmit signal from causing interference and feedback into the repeater’s receiver, a set of RF filters, called a duplexer, is now part of the repeater system.
Duplexers come in various shapes sizes and configurations. The filters are tuned to pass the specific frequency that is being received or transmitted, nothing more, nothing less. Most duplexers consist of four filters, two for receive and two for transmit. As you increase the power output of the transmitted signal, more RF filtering is usually required on both the receive and transmit side of the equation.
A repeater system can incorporate a receive Pre-amp. This boosts the strength of the incoming uplink signal by 15 dB or more. To boost the strength of the repeater’s output (downlink), an external Power Amplifier can be used.
Many Ham repeaters use an external Repeater Controller to enable Station IDs, announcements and connections with link radios or other audio sources like a Weather Alert radio.
All of the active components (e.g. repeater, controller, receiver pre-amp, RF power amplifier) all require electrical power to operate. That’s where a 13.8 VDC Power Supply (sometimes with a Battery Backup) comes into the picture.
Finally, there is the transmission line and Lightning Protection. If the repeater is on a building top, like an apartment or condo building, a hospital or a tall office building, your cable can be relatively short. However, if your antenna is mounted in a tower, your cable can be quite long and lose a lot of signal along the way.
We’ll discuss the challenges of operating a repeater in our next post.
Go to facebook.com/NI4CE now and tell us what you think. Or send an email to info@NI4CE.org
In our last post, we detailed the several different components that make up a typical Ham Radio repeater. If you were not aware of how many working parts there are in most repeaters, don’t feel bad. Most Hams just think of a repeater as a “black box” and never get into the intimate details to appreciate the complexity.
One of the questions we posed in our last post was what determines the geographic area a repeater covers. The downlink transmit power of a repeater is one determining factor. Another factor is the efficiency of the coax cable and antenna. What determines the Effective Radiated Power (ERP) or a repeater is a complex equation: Transmitter Power Output – (Duplexer Loss + Coax Cable Loss) + Antenna Gain. For example, if your repeater output is 50 watts, Duplexer Loss=3 dB plus Coax Loss=3 dB, with an Antenna Gain of 3dBd, your Effective Radiated Power will be 25 watts.
The biggest determining factor of just how far a repeater will be able to receive and transmit is Antenna Height. An antenna located one hundred feet above ground level (AGL) will have a line-of-sight horizon line of 11.89 miles. By comparison, a repeater antenna located at 1,000 feet (AGL) will have a line-of-sight horizon line of 37.60 miles, quite a difference. The formula for determining the horizon line for a repeater is SQRT(1.414*Ant Ht (in feet)). Because radio waves can go beyond the line-of-sight horizon, the formula for determining the Radio Horizon is SQRT(1.414*Ant HT)*1.333.
The NI4CE system is much more than a collection of stand-alone repeaters. Our five sites are strategically located and constructed to optimize coverage. But more importantly, by linking the five sites together, many parts of West Central Florida’s most densely populated counties enjoy overlapping coverage from two or more sites. This design is not by accident and affords many operators the ability to access the system from more than one site.
Building and maintaining a repeater system, whether it is a one site system or the five site system that is NI4CE, is a challenging and costly endeavor. But without repeaters, like NI4CE, Ham Radio’s ability to use of the 2 meter (VHF) and 70 cm (UHF) bands would be severely limited. Now that you know what goes into a repeater system, we think you will have a much better appreciation of all the repeaters that are on the air here in West Central Florida and the role they play in your Ham Radio life.
I was reminded of just how far we have come when a note from a Ham Radio friend of mine. He sent me a quick email commemorating the 71st anniversary of the first photo of our planet taken from outer space. That first image was from a camera onboard a V-2 rocket launched in October 1946. WOW!
Today, we would be hard-pressed to predict major storms like Hurricanes Harvey, Irma, and Maria. Our manned space program (when we had one) enabled the astronauts to maintain constant contact with flight controllers through the TDRS satellites that hovered thousands of miles above them. That dish antenna at your neighborhood gas station connects that card reader you just swiped your credit card through with a satellite to a processing center. And despite their name, CNN (Cable News Network) would likely be nowhere without the satellites they use to distribute their product. Let’s face it; life in the 21st Century would be a lot different without all the satellites that now orbit our planet.
I guess that is why I found another recent announcement fascinating. This week, the several MARS organizations that still function will be working with the Departments of Defense and Homeland Security on a terrestrial-based communications readiness exercise. According to an Information Release from the ARRL, this drill will be used to gather information from official and unofficial sources in the wake of a “Very Bad Day”. Ham Radio operators who are not affiliated with MARS can participate through reports offered up on local VHF and UHF repeaters. The information that is gathered will then is relayed via HF radio to Command Posts on the East Coast and in Arizona. By the way, if you were around on 9/11/2001, all this may sound eerily familiar.
If you have an HF radio or shortwave receiver in your shack, this Interoperability Exercise will kick off Tuesday, October 31 at 0300 UTC with a high power broadcast on 5330.5 KHz (Channel 1 in the 60-meter band). MARS operators will be looking for signal reports to find out just how many locales were able to hear the voice transmission.
Now, “why is this so important?” you might ask. This almost seems like one of those “busy work”, Back to the Future drills to justify your existence. After all, everyone has a cell phone. What do we need with 60-meter voice broadcasts, Ham Radio and MARS? The answer can be found in Newton’s Third Law (for those of you who remember High School Physics): “For every action, there is an equal and opposite reaction.”
Imagine, if you will, what life would be like without cell phones, satellites, the Internet and all the other communications devices and services we now rely on daily. I think that would likely qualify as a “very bad day”. And just as Newton told us centuries ago, there is a counter-balance we cannot and should not ignore. It could be an event, like the devastation Puerto Rico is now experiencing from Hurricane Maria or something much worse that will isolate us and turn our world upside down. The inconvenience of a few days without power could pale by comparison.
Take advantage of this Interoperability Exercise this week. And let’s hope we never have to experience a “very bad day” for real.
Ham Radio is sometimes more about the technology than applying available technology to solve a problem or a need. It has also been, over the years, a proving ground for many of the communications technologies we now use in everyday life. This article is about a Ham Radio technology that is a very practical solution that benefits everyone.
We know this technology by its four-letter acronym, APRS. That’s short for Automatic Position Reporting System. APRS is a mix of GPS technology, mapping software, and Ham Radio. Its roots date back to the early 1990s at the U.S. Naval Academy in Annapolis MD where Professor Bob Bruninga was looking for a low-cost method for tracking Midshipmen as they conducted maneuvers on the water.
Today, in the commercial world, the practical application of APRS allows transportation companies to track their fleets, provides firefighters and other in Public Safety situational awareness at events large and small and pizza drivers the needed information to get you your pie while it is still hot.
But APRS has turned into much more. In 1997, twin identical brothers, Keith (WU2Z) and Mark (KB2ICI) Sproul, teamed up with another Ham Radio operator who was heavily involved with the National Weather Service SKYWARN program in New Jersey to expand APRS’ mission. They were the first to bring the transmission of live weather telemetry to APRS as a practical transport. Hundreds of Amateur Radio weather stations beacon temperature, wind, barometric pressure and rainfall data in real time to enhance the SKYWARN program. The data from these weather stations also supplement data from NOAA sensors to help forecasters plot tomorrow’s forecast.
APRS weather station data can provide accurate, real-time information on rainfall and wind speed and direction to trigger severe weather warnings. That data is also used to tell forecasters whether radar estimates of precipitation are accurate. And sometimes, that data can be used to track a storm. Such was the case in 2004 when APRS weather stations here in West Central Florida provided a means of tracking Hurricane Francis when other instrument data was offline because of the storm.
The West Central Florida Group operates a number of APRS Weather Stations and Digipeaters to support the network here. Other Hams, including Dave-KG4YZY in Pasco County, Polk County Emergency Management and Highlands Co. Emergency Management have joined the effort. And so can you. All you need is a weather instrument sensor package (some of the most popular are from Peet Brothers in St. Cloud, FL and Davis Instruments), a two-meter radio to operate on 144.390 MHz, a TNC, like the Kantronics KPC-3+ or the new WX3in! controller and an antenna system. Once your station is on the air, you will want to register it with the National Weather Service’s Community Weather Observer Program (CWOP). You can do so online at www.wxqa.com/SIGN-UP.html
If you are a licensed Ham and are operating a weather station on the Internet only, exercise your operating privileges and put your station on the air.
The 2017 Hurricane Season officially begins this week. Unofficially, it got underway several weeks ago with a bona fide Tropical Storm that spun for several days in the Central Atlantic. And if the forecasters at the National Hurricane Center are to be believed, we may be in for an above average season, possibly the most active since 2005.
A few weeks ago, I was re-discovering a portable radio I purchased about ten years ago. When I acquired my Kenwood TH-F6A, my motivation was to have a Ham Radio transceiver that could transmit and receive on 2 meters (VHF), the 222 MHz band and 70 cm (UHF). At the time, I knew a couple other Hams who had purchased the radio and were happy with how it operated. So, I took the plunge.
While re-discovering the radio and what it could do, I was pleasantly reminded the F6A had a really cool feature that every Ham operator needs to have at their fingertips, particularly during large-scale emergencies. That feature is the ability to receive Broadcast AM and Broadcast FM stations. The F6A also tunes the three domestic Broadcast Television bands, too, although the migration of TV stations to digital now makes this capability a moot point.
Why is the ability to receive AM and FM broadcast stations so important? In a large-scale emergency, broadcast stations, particularly those who are the designated EAS LP1 and LP2 stations, are an authoritative resource for information vital to the community. These broadcasters have direct links to local and State Emergency Managers and other authorities whose job it is to mitigate the disaster, whatever it is. This includes information on road closures, power outages, emergency ice and water resources and much more, including the weather forecast. These broadcast stations can operate for as long as necessary on generator-based backup power.
After the Hurricane Charley disaster thirteen years ago, I spent a day serving as a liaison between Charlotte Co. Emergency Management and the local AM-FM broadcast station in Charlotte County. My task was to convey information transmitted to me via Ham Radio to the radio station so they could then relay it to the general public and those most severely impacted by the storm. It didn’t hurt that I am an ex-broadcast journalist and could take raw information and turn it into an easy to read script.
As our society has become more cellular and wireless data-centric, we need to be reminded these resources will be the first one to go down in a large scale disaster. That’s why having a battery-powered radio capable of receiving local AM and FM broadcast stations is vitally important. Much to my delight, that capability is part of my multi-band Ham Radio transceiver that is always close by.
Should a tropical weather system threaten West Central Florida, the NI4CE Repeater System also stands ready as a communications and information resource you can count on.
Go to facebook.com/NI4CE now and tell us what you think. Or send an email to info@NI4CE.org
Even though Ham Radio is all about “wireless communications”, getting the RF signal from the radio to the antenna efficiently and effectively requires using the right cable. That sounds easy and it is. But it requires a bit of education and some calculation to come up with the numbers and the right cable selection.
First, let’s shine a little light on your cable options. There are many different kinds of coaxial cable on the market. Two-way radio for Ham and commercial use is designed to use fifty-ohm cable. That will provide your radio with the best impedance match, lowest power loss, and lowest reflected power.
There are lots of different fifty-ohm cables to choose from. Let’s focus on some of the more popular cables. They include RG-58U, RG-8X, RG8U, RG-213, LMR-400, Belden 9913 and LMR-600.
Most mobile installations require a cable that is relatively thin, flexibility and something that will not break easily. RG-58U and RG-8X are most often used because they use a stranded center conducted. These two cable types work because the length of cable required is usually short, less than twenty feet. Even at that length, the loss you can expect from RG-58 is typically 2 dB. Using RG-8X nets a loss of 1.6 dB. If you are using a quarter wave antenna with a gain of 3 dBbi or 0 dBd, you will experience a NET LOSS.
RG-58 and RG-8X are not the most efficient cables to use for a Base Station application. Here, you want something beefier. A fifty foot run of RG-8 will net you a loss of 1.2 db at 146 MHz, 2.2 db at 446 MHz. RG-213 has similar loss numbers. Time Mirror LMR-400 lowers the loss at 146 MHz to 0.8 db, at 446 MHz to 1.3 db. Belden 9913’s numbers are similar. If you are looking for even lower loss, LMR-600 reduces the loss at 146 MH to 0.6 db and at 446 MHz to 0.9 db.
What makes one cable type better than another? The most dramatic feature is the gauge of the center conductor. RG-58 is a stranded, 20 AWG (0.033”) wire. By comparison, LMR-400 and Belden 9913 uses a solid core center conductor that is 0.108” in diameter, 10 AWG or what is used for most 20A electrical circuits in your home.
Times Mirror has an easy to use Cable Performance Calculator on their website that makes it easy to determine which cable type is best for your application. Go to: http://www.timesmicrowave.com/calculator/?productId=121&frequency=445&runLength=100&mode=calculate
Go to facebook.com/NI4CE now and tell us what you think. Or send an email to info@NI4CE.org
When I was first licensed over twenty years ago, I was faced with the same daunting challenge that every new Amateur Radio operator faces: “What should new FIRST Amateur Radio purchase be?” Should my first radio be a Portable I can take everywhere? Should it be a Mobile radio that I can use as a Base Station (with a power supply) or in the car? Decisions, decisions, decisions. Well, here is what I decided.
My first radio was (wait for it) a MOBILE radio. A curious choice you are thinking. But in retrospect, if I had to do it again, I would make the same choice. Here’s why.
Portable radios, no matter the brand or model, are limited in their power output. Now, if the repeater you are trying to talk through has an output of fifty watts and the portable radio you have chosen transmits at five watts, you will be operating at a distinct disadvantage. That difference in power output is 10 dB. That may not sound like a big difference. But believe me, it is. Now, let’s compare Antenna Gain. The repeater is probably using a high gain antenna to boost the Effective Radiated Power by 6 dBd to 10 dBd, maybe even more. But comparison, most portable radios are outfitted with antennas that have a negative gain maybe as much as -4.0 dBd. Now, add up the differential and, as you can see, that portable radio you are trying to use has a -20 dBd or more disadvantage. And just got good measure, let’s say you are trying to use your portable radio inside a vehicle or a well built structure. You can tack on -15 dBd to the RF hole you are in.
By comparison, most VHF mobile radios transmit at up to 50 watts. UHF radios can transmit at up to 45 watts maximum output. Most mobile antennas will offer a gain factor that will offset any losses introduced by the coax cable needed to connect the antenna to the radio. And because your mobile antenna is located on the exterior of your vehicle and the radio is powered by the vehicle’s alternator, you will not be added to the losses described above with a portable radio. Base Station antennas may actually offer you enough gain to increase your Effective Radio Power (ERP) by a factor of two or more. And a Base Station antenna will likely be mounted at some elevation that will allow you to eliminate losses from trees, buildings and other vertical obstructions.
Why is all this important for a new Ham? You have heard the saying “Success begets success!” A successful first radio experience will encourage and motivate a new Ham (and, for that matter, any Ham) to want to do more. Ham Radio is not a spectator hobby. You learn by doing. And the more you do, the better you will be.
More on your First Radio in my next post.
In my first post on this subject, I discussed my rationale for selecting a MOBILE radio as my first Ham Radio. When I added up the numbers including Transmit Power Output and Antennas Gain and factored in other losses I could expect using a Portable radio, it just made more sense to make that first radio a MOBILE radio.
But there were other important criteria I took into consideration for that first purchase. Many new Hams will purchase a VHF, single band radio. It is less expensive than many VHF+UHF dual band models. And, in many parts of the country, there is more activity on the VHF (Two Meter) band or so many people believe. But even though a dual band, VHF-UHF radio was going to cost more, I thought going that direction was worth the every investment. And that decision turned out to be a good one.
Another factor was audio quality. Once again, the MOBILE radios I had been exposed to before making that first purchase just sounded cleaner and more full bodied than their Portable Radio counterparts. That still holds true today for most ANALOG radios. Digital Mobiles and Portables (e.g. NXDN, DMR, P25, Fusion, etc.) tend to have virtually identical audio quality. There are other factors, including the Speaker/Mic you may be using and the digital format itself, that make once format better than another. More on this topic in another post.
Perhaps the most important item I factored into my first radio purchase was how I wanted to use the radio. Did I want to talk with other Hams going to and from work? YES! Did I want to participate in Nets? YES! Did I want to get involved with emergency/public service activities, like SKYWARN and ARES? YES! How about Club activities? YES! With those criteria in mind, a MOBILE radio made the most sense.
Now, in all fairness and in full disclosure, it became pretty clear within three months that a VHF-UHF dual band Portable radio was going to be in my immediate future. Ultimately, an active, energized, engaged Ham is going to have at least one MOBILE and one PORTABLE radio.
More on DIGITAL Ham Radio in my next post.
A new Ham in the 1990s had some important choices to make when selecting his/her first radio. Was it going to be an ICOM, Kenwood, Yaseu, Alinco or one from a handful of lesser known brands, like Standard or Azden. Or maybe, you knew someone who could convert an old Motorola or GE mobile or portable that had been used by a commercial user.
Twenty years later, the choices are a lot more numerous. Yes, the Big Four in Ham Radio are still around and still innovating with radios that include color LCD screens, PL+CTCSS+DTCS tone control, voice compression and more. Many of the lesser known brands have been replaced by radios from Chinese manufacturers who have flooded the market with low cost (and, in some cases, dubious quality product).
While most ANALOG Amateur Radio repeaters still operate Wide Band FM, that is with a 25 KHz channel bandwidth, the Narrowband Mandate (12.5 KHz bandwidth) imposed on commercial and government users in 2013 has dried up the availability of commercial radios capable of 25 KHz operation. We are also seeing older WBFM repeaters now being replaced by new models that must operate at 12.5 KHz NBFM.
The FCC mandate for commercial radio has also brought with it new DIGITAL operating modes that some Hams are experimenting with. P25, NXDN, DMR, Fusion, TERTA and D-Star are just some of the DIGITAL modes out there. All but D-Star and Fusion (which are Ham Radio only) are gaining prominence in commercial and government use. All of these DIGITAL modes are feature rich. Some allow multiple VHF and UHF repeaters to be connected via IP. Interoperability, one mode to another and one manufacturer to another, is still a problem (just as computer networking was twenty years ago). And each mode has its strengths and weaknesses. No two modes are created equally.
I personally like NXDN, created by ICOM and Kenwood jointly in 2005. Each manufacturer’s radios are interoperable. The repeaters can be networked easily. And equipment is readily available from dealers and on the Internet. I also happen to like the range and clarity of NXDN radios, which rivals WBFM despite the fact they use one quarter the bandwidth of WBFM.
DMR offers two talk paths per RF carrier, a feature some Hams find desirable and fascinating, although you can only talk on one at a time. DMR repeaters tend not to cover the same amount of real estate as NXDN repeater do. And there have been some interoperability issues between Type 2 and Type 3 formats. Yet, DMR is popular in many areas, in part because of the availability of product.
P25 has two versions, the older Phase 1 mode and the newer Phase 2 mode. Both are designed for the Public Safety market and, as a result, P25 radios are a lot more expensive than most other Digital radios.
More on the Ham Radio only DIGITAL modes in my next post…..
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In my last post, we started talking about DIGITAL two-way radio, why it exists and why you should seriously consider a DIGITAL radio. Let’s expand on that with a look at the several DIGITAL radio protocols and radios that are available.
First, no two digital modes are created alike. Each of the several CAI (Common Air Interface) has their strengths and weaknesses. NXDN is the only mode that meets all of the FCC’s 2004 engineering mandates for Ultra Narrow Band Digital. In a Report and Order issued in December, 2004, the FCC told the radio manufacturers they wanted to see radios that used 6.25 KHz bandwidth, FDMA modulation and a data rate of 4800 baud. That is what NXDN, jointly created by ICOM and Kenwood, is.
In that same R&O, however, the FCC gave manufacturers like Motorola some wiggle room allowing their two channel TDMA mode to operate. DMR radios, the generic term for TDMA, uses 12.5 KHz bandwidth with two simultaneous voice paths. Some early DMR offerings are not compatible with the newer Type 3 radios that include products from Hytera, Tait and others.
P25, the modes (there are two) adopted by APCO for Public Safety are also 12.5 KHz. P25 Phase 1 uses a FDMA modulation schema while the new P25 Phase 2 mode is a two voice path TDMA offering that uses one modulation type for the uplink (radio to the repeater) and a different modulation schema for the downlink (repeater to radio).
Radios using all these operating modes have been created primarily for commercial and government use. But they are also is use on Amateur Radio bands. Why? What are the benefits of DIGITAL?
ANALOG transmissions are subject to all kinds of noise and disruption. Weak signal analog voice transmissions are often difficult to copy because of the inherent noise that is part of the signal. Then, add to that “snap, crackle pop” from atmospherics in the area, disruptions caused by multipath, trees and other vertical obstacles. In short, analog transmissions have drawbacks that can make communications difficult.
DIGITAL transmissions are usually much cleaner, clearer and easier to comprehend. That’s because the transmitting radio turns your voice into a stream of “zeroes and ones”, sends them over the air to the receiving radio that decodes the stream and re-creates the voice communications. With some exceptions, digital voice is far more stable than analog voice. Digital voice transmissions are generally usable at RF signal strengths up to 20 dBm weaker than analog signals. Most digital radios also feature ambient noise reduction to eliminate or substantially reduce road noise.
One drawback with most of the commercially available digital radios: they are single band only.
More on DIGITAL radio in our next post….
Some of you have heard me state that “Amateur Radio was the FIRST Social Media”. That is a rather bold statement given all the other Social Media offerings that now grace the digital landscape. The fact that Ham Radio, in Analog or Digital mode, is still a relevant Social Media, is pretty remarkable.
Let’s close the loop on DIGITAL radio before we get too far off topic. Here are some thoughts on the several DIGITAL modes available to all Hams.
I personally like NXDN, created by ICOM and Kenwood jointly in 2005. The radios from both manufacturers are interoperable. The repeaters can be networked over IP easily. And equipment is readily available from commercial dealers and on the Internet. I also happen to like the range and clarity of NXDN radios, which rivals WBFM despite the fact they use one-quarter the bandwidth of WBFM. NXDN radios also support Text Messaging and GPS.
DMR offers two talk paths per RF carrier, a feature some Hams find desirable and fascinating, although you can only talk on one at a time. DMR repeaters tend to come up short on coverage compared to NXDN and P25 Phase 1, a product of their modulation schema. And there have been some interoperability issues between Type 2 and Type 3 formats. Yet, DMR is popular in many areas, in part because of product availability and local dealer support. There is also the Motorola name recognition that has helped popularize DMR.
P25 has two versions, the older Phase 1 mode and the newer Phase 2 mode. Both are designed for the Public Safety market and, as a result, P25 radios are a lot more expensive than most other Digital radios.
There are two digital products that are “Ham Only”: ICOM’s D-Star and Yaesu’s Fusion. D-Star remains ICOM’s prominent Ham Radio offering, even though its GMSK modulation schema is hardly state of the art. The end user D-Star radios will do both analog and digital modes. D-Star repeaters are digital only. D-Star has become less of a “proprietary” mode thanks to the proliferation of D-Star dongles that turn your computer into a virtual radio. Still, if you want to operate wirelessly, ICOM is your radio source.
Fusion, from Yaesu, is a ‘proprietary’ created only for Ham Radio product. Its C4FM modulation schema has some P25 Phase 1 characteristics. Fusion radios support both analog and digital mode operations. And Fusion repeaters can be programmed to automatically convert analog to digital and vice versa. Fusion has gained a foothold with some Ham Radio Clubs, in part, because of an early marketing campaign that made Fusion repeaters available at Fire Sale prices. Yaesu’s success with Fusion may also be based on a belief that the majority of Hams will only buy Ham-class radios.
The West Central Florida Group, Inc. currently has two NXDN repeaters in operation at our Riverview and Verna repeater sites. Like our analog repeaters, the NXDN repeaters are linked full time to create a large coverage footprint along Florida’s West Coast.
If you have forty dollars or so invested in a radio, you probably consider it a “disposable appliance”. In the accounting world, it would be considered an “expense item” rather than a more expensive “capital investment”. Nevertheless, you are going to want to continue reading because what I am about to share with you is important. Now, if you have made a more substantial investment into your radio, you want to do everything you can to protect and optimize your investment. So, you will want to continue reading.
PM is short for Preventive Maintenance. It is a process and series of procedures that many radio owners, commercial and Amateur Radio, undertake on an annual basis. PM looks at key metrics of a radio that determine just how well the radio performs, no matter what bands it operates on. PM can also provide valuable clues about key components in your radio and whether your radio is working well or may be getting ready to fail.
Most radio Preventive Maintenance procedures examine several key metrics. For example, how far off the center frequency is your radio operating. Very few devices will ever be exactly “on frequency”. The question is just how far off the center frequency has your radio deviated. If your center frequency is plus or minus fifty Hertz, your radio is considered to have an acceptable error. If your radio is a couple hundred Hertz high or low from the assigned center frequency, the radio needs some tweaking or adjustment. And if your radio is, let’s say, a kilohertz off frequency, your audio is probably sounding a bit fuzzy and your radio has likely lost some of its sensitivity or so it seems. Your radio’s best friend is a qualified radio technician equipped with a frequency counter or more appropriately a Service Monitor.
Once you have your radio back on frequency, it will likely perform a lot better and sound a lot better on the air, too. But a Frequency Check is only the first metric to test. Another key metric is the TX Power Output of your radio. With age, the components in your radio change value. This can cause your radio’s power output to degrade. A portable radio rated at five watts may now only be putting out four watts. Optimizing the transmit power output of your radio is your best chance for getting the most out of your radio and cleanly getting into your favorite repeater. While your radio is on the bench, make sure any “fixed” power settings are also optimized. I recently discovered a Medium fixed power setting on one of my radios was only registering a nineteen-watt output. This setting is rated at a twenty-five-watt output.
Digital radios have another metric that must be measured, Modulation Fidelity. This metric is an indicator of how accurately the Zeroes and Ones are being transmitted. A Mod Fidelity error of three percent or less will result in a low Bit Error Rate and optimal reception of the stream of Zeroes and Ones you are sending.
One other very important metric to maintain clear, concise voice communications is your audio output. In Wide Band FM mode (WBFM), your radio should be transmitting a 3 KHz deviation. Anything less and your modulation is not optimal. If your deviation is 5 KHz (or more), you are over-modulating and likely have a hard time holding a repeater.
An annual PM will help you operate by the numbers. And that’s a good thing because the quality of your on-the-air signal is your radio personality.
Amateur Radio was the great proving ground for many of the communications devices that ultimately ended up in the hands of the masses. In fact, the whole concept of portable, go anywhere two-way radios was a staple in Amateur Radio long before the cell phone came along.
But in the mid-1980s, cellular communications devices and infrastructure made their way to the marketplace. Early cell devices were big, bulky and heavy. Let’s not forget about heavy. My first cell phone was a three watt “bag phone”. I recall dragging that thing over my shoulder on business through airports, hotel elevators and the like. I also remember having to drag it into Disneyland with me on vacation (I was supporting a very high profile computer imaging product at the time).
Cell phones in late 2017 are a lot less like portable telephones and more like a portable, hand-held computer that is a one size fits all. Sure, you can still make a phone call. But you can also send text messages, read email, navigate using the internal GPS receiver and any number of apps. In fact, the term “smartphone” really is an inaccurate descriptor for the personal communications devices used by most people.
Now, by comparison, two-way radio and Amateur Radio devices could be compared to the forgotten “red headed” stepchild that nobody wants to talk about. Land Mobile Radio and Amateur Radio, in many ways, are tied at the hip. While many of the radios have gotten physically smaller, their functionality remains limited, in fact, almost primitive, when compared to personal cellular devices. Most LMR and Amateur portable radios do one thing, one to many voice communications, something cellular has tried several times to do unsuccessfully. Digital LMR and Amateur Radio devices are now capable of Talkgroup and Individual calling. Some recent product releases now have a built-in GPS receiver (not necessarily for navigating) and Bluetooth support for wireless headsets. But LMR and Amateur Radio devices in 2017 are still much like their predecessors from the 1970s and 1980s. Any color displays are too small to support a touch screen keypad. There are virtually no apps available. What apps that do exist require a separate computer or tablet in tow. And only really high end Public Safety class radios are equipped with some form of WiFi. It’s hard to attract new people into the Amateur Radio realm when the technology seems like something from Jurassic Park!
I would love to have an Amateur Radio transceiver that could support operations on VHF, UHF, WiFi (both bands), a touch screen interactive color display, USB connectivity, built-in GPS and apps to support navigation as well as APRS, and apps for text messaging, NTS messaging, even email. Yes, I might have to sacrifice some range (i.e. antenna size and lower power output, maybe 2 watts instead of four or five watts). Battery technology has gotten so much better that such a device should be able to be made without weighing twenty pounds. No, such a device is going to cost more than your typical Bao-feng. But if Apple and Samsung can build their latest smartphones for around a grand, LMR and Amateur Radio manufacturers should be able to do so, too.
When the first NI4CE repeater went on the air in 2001, it was a Wide Band FM Analog repeater. Fast forward almost eighteen years. The actual repeater is a different make and model. But it still operates in WBFM analog mode as do the other five NI4CE analog repeaters.
But in the eighteen years that NI4CE has been on the air a lot of other things have changed and changed dramatically. For example, cell phones are now digital. The major cellular providers all operate high speed LTE-based wireless data networks that allow you to take a hand held computing device (your cell phone or tablet) to surf the Internet, send and receive email, shop online and much more.
Land Mobile Radio, the commercial “Big Brother” to Amateur Radio VHF and UHF repeater systems, no longer allows WBFM operations. In 2013, LMR users were forced to migrate to Narrow Band FM Analog or a Digital operating mode.
Broadcast Television went all digital in 2010 and is about to embark on ATSC 3.0, a new digital TV standard with improved screen resolution and throughput.
In case you did not realize it, NI4CE does not just play in the WBFM sandbox. We have been operating parallel NXDN digital repeaters at our Riverview and Verna sites for many years. We also are working cooperatively with Dave-KG4YZY on the operation of an NXDN repeater in Pasco County. These repeaters are IP linked and connect to a master server in Orlando that allows NXDN-equipped Hams to talk with other NXDN Hams in the USA, Canada and a number of other parts of the world including Europe and Australia
So, why did we choose NXDN? There are other digital operating modes including DMR and P25 as well as Amateur Radio only D-Star and Fusion. Simple! NXDN was jointly created in 2005 by ICOM and Kenwood (two familiar names) to meet the FCC’s ultimate Ultra Narrow Band standard, 6.25 KHz bandwidth operation. It uses very efficient FDMA modulation. It natively supports digital voice, digital messaging, GPS Tracking and allows linking multiple repeaters via IP or RF. NXDN radios are readily available. And new portable and mobile NXDN radios are on the way.
Another important attribute of NXDN is repeater coverage. Commercial LMR users discovered a substantial loss of coverage when they made the migration to Narrow Band FM in 2013. But those that went from WBFM to NXDN actually realized about a ten percent increase in coverage in many cases. NXDN provides clear voice and data signaling at lower signal strengths because of its efficient modulation schema.
WBFM repeaters and radio are still pre-dominant in Amateur Radio after all these years. But that will change. If you want to get out ahead of the curve, NXDN Ham Radio is here in West Central Florida NOW! Turn it on, tune it in and discover the power and effective communications possibilities. And if you need help getting started, there are local Hams and local resources readily available like the NI4CE-NXDN-Users group on Google.
When the NI4CE Repeater was first conceived sixteen years ago, it had two primary objectives: Provide a VHF-UHF platform that ALL Hams in West Central Florida could communicate through. This included support for the several Nets the ARRL West Central Florida Section conducts each week. The second objective was to provide a VHF-UHF communications platform to support the National Weather Service’s SKYWARN severe weather spotter program.
Ham Radio has played an integral and vital role since the SKYWARN program first started in the late 1950’s in “Tornado Alley”. Trained Ham operators were the eye and ears of the NWS during severe weather outbreaks in Kansas, Oklahoma and Texas using their radio communications privileges to report severe weather directly to NWS meteorologist. It wasn’t until the 1970s when the program was rolled out nationwide. In the 1990s, when the Weather Service was downsized and re-organized into the 118 offices it now operates from, SKYWARN took on an even more important role.
The technology used by the National Weather Service has changed dramatically since the early days of the SKYWARN program. Forecasters now have geo-synchronous satellites and 3D Doppler radar to help predict severe weather and issue warnings to keep all of us safe. Spotters who were limited to telephone and Ham Radio now have a plethora of social media and email to send in reports, including still images and video.
So, why is Ham Radio still relevant to the SKYWARN program and to the general public? The answer is simple. Ham radio does not require the Internet, a working telephone or any other technology (other than a portable or mobile radio) to get severe weather reports from spotters to the NWS forecasters. Moreover, that same Ham Radio link can also be used by the forecasters to push out severe weather warnings and other guidance to all the SKYWARN Hams as needed in a timely manner.
Let’s turn the question around. Is SKYWARN still relevant to Ham Radio? Absolutely!!! SKYWARN is a year-round opportunity for Ham Radio operators to demonstrate our importance at a time when society is cell phone and Internet centric, so much so that many people think Ham Radio, the original “social media”, is a thing of the past. And SKYWARN participation is a great opportunity to fulfill one of the prime justifications for the Amateur Radio Service’s existence.
2017 has the potential to be a very active Hurricane and Severe Weather year, maybe the most active since the 2004 and 2005 seasons. Now is the time to get ready. Attend an upcoming SKYWARN Training session scheduled for your area or take the online SKYWARN training offered by the National Weather Service. Participate in the SKYWARN Information Net every Tuesday night at 9:00 PM on NI4CE. Be ready to be part of the solution when severe weather threatens your county, your neighborhood. And when you finish reading this article and feel so motivated, find the PayPal “Contribute” buttons on our main NI4CE.org webpage to help keep NI4CE on the air and ready for whatever Mother Nature will throw at us this year.
A correction to my comment about ICOM being the sole source for D-Star radios in my last column. Kenwood’s TH-D74 portable now provides Hams with a second source for operating in D-Star mode wirelessly.