Hotspots: Gateway to Digital Radio

By Dale L. Puckett, KØHYD

Digital radios – DMR, D-Star, YSF, P25, NXDN – pick your protocol poison. These new radios populate the amateur radio landscape. They make worldwide contacts possible to amateurs everywhere.

Repeaters worldwide communicate using the Internet, making this new medium possible. Unfortunately, few repeaters exist to support these new communication protocols.

In Kansas we seem to be stuck in an analog morass, tolerating the noise and excessive bandwidth. Where repeaters do exist, they are most often not connected to the Internet. This limits communication to a local area.

No worries! There is a solution.

Ingenious hams invented hotspots to solve this very problem. With a hotspot you can have your own personal “repeater” that connects you to hams around the world.

The first hotspots were either “sticks” or dongles that you plugged into your computer. The sticks used your computer’s microphone and speakers to communicate.

The dongles were digital access points that were miniature radios. You talked to them with your digital handheld or mobile radio.

The access points used software in your computer to connect the small radio to the Internet. This was often problematic because the computer often went to sleep. This caused the software to quit and disabled communication.

Hotspots today use their own dedicated computer to connect you to the Internet. Most use a Raspberry Pi computer and a “hat.” The hat is a small circuit board holding a miniature digital radio. These radios usually have a range of several hundred yards.

Hotspots have two components, hardware and software. I use a ZumSpot which contains a small hat riding on a Raspberry Pi Zero W. The W stands for wireless. This board gives you a way to talk to your LAN and the Internet. Both boards together fit in a small compact case. The combination is highly recommended.

Jim McLaughlin, KI6ZUM, designed the ZumSpot hardware. José “Andy” Uribe, CA6JAU, wrote its firmware. ZumSpot descends from the Multi-Mode Digital Voice Modem (MMDVM), created by Jonathan Naylor, G4KLX.

The software of choice today is Pi-Star. It delivers access to your mode of choice when paired with a hotspot like the ZumSpot.

The ZumSpot/Pi-Star combination can link to DV repeaters, DMR talk-groups and reflectors. It also links to D-Star reflectors, YSF rooms, and QuadNet Smart Groups. This will keep you busy for hours, if not days on end.

You’re sold! OK! Where to start?

The best source for the official ZumSpot hardware is Ham Radio Outlet. You can buy either a bare board or a kit.

I recommend the kit. If you are a true hardware guru with tiny hands, go for the bare board. The kit includes a Raspberry Pi Zero W and a microSD card preloaded with Pi-Star. For a compact and very neat installation I recommend a C4Lab case.

When you complete the assembly of the kit, it’s time to install the Pi-Star software. It sounds scary, but actually it’s very straightforward. First you flash the Pi-Star software into a microSD card. You’ll need a card with at least 8 GB.

Then, you boot up the Raspberry Pi and create a WiFi connection using the Pi-Star software. You do this by connecting to Pi-Star.setup on your web browser.

Once you have the WiFi connection you reboot the hotspot and login to Pi-Star.local with your web browser. Pi-Star then gives you all the web forms you need to configure every mode you want to operate.

It sounds complicated. It’s the exact opposite. You’ll find two excellent sources of step-by-step instructions. The best source depends on your learning style. If you would like to follow someone else going through the steps, go to YouTube and search for Pi-Star setup. If you prefer written step-by-step instructions, point your web browser to pi-star.hamnotes.com.

I was able to configure my ZumSpot for both D-Star and DMR in less than an hour. It was a blast!

A DMR repeater is coming to WARC sometime in the future. In the meantime, why wait? Get your own hotspot, an inexpensive DMR handheld and get on the air now.

It’s opportunities like these that get me excited about amateur radio.

Let me know what you would like to see next in an email to kØhyd@arrl.net. Until next month! 73 de KØHYD.

Digital Ham Radio: What to Do?

By Dale L. Puckett, KØHYD

During the birth of the personal computer, clubs popped up across the nation. Many clubs were large. Several SIGs operated in each club. SIG stood for Special Interest Group.

Members using microcomputers based on Motorola’s processor architecture discussed projects in one room. Those owning machines based on other architectures met in other rooms. Then, they all got together and defined personal computing as we know it.

Fast forward now to the second decade of the 21st century. Can we apply parallels in amateur radio clubs like the Wichita Amateur Radio Club today? I’m pretty sure we can.

The microprocessors born in the 1970s became the personal computers of the future. These personal computers revolutionized almost everyone’s life.

These same microprocessors redefined amateur radio. They made efficient and effective operating techniques available to all. Logging software made it possible to maintain accurate records during contests. They also made it easy to chase awards. The evolution of cloud-based databases like Logbook of the World simplified the process even more.

Microprocessors gave us better control of things like our bandwidth and audio quality. They let us automate antenna tuning and any number of other processes.

Today microprocessors are making digital radio not only possible, but practical. WARC already maintains a Fusion repeater at Wesley Hospital. The board of directors and technical staff are busy investigating a digital mobile repeater.

Grounded Grid Editor Randy Fisher, KEØJYU, asked me to tackle the topic of digital radio in monthly installments. This first column is as much a survey of our readers as anything else. Where would you like to see us go in a column about digital radio? How detailed would you like it to be?

Would you like to see a SIG within WARC dedicated to digital radio? How granular should it be? Would you like one generic group that discusses and experiments with digital radio? Or, specific groups dedicated to D-Star, DMR and Fusion? Where does digital TV fit in the big picture?

We now stand on the threshold of exciting possibilities for all hams. To get a feel for the question “Why digital radio?” you only need to think about an earlier transition.

A mere decade ago broadcasters transitioned from analog to digital television. Before the transition if the analog signal was strong you got a good picture. If it was weak, you could see the picture but a field of snow almost hid the picture. With the new digital television you either received a perfect picture or no picture.

Likewise you can hear the difference between analog and digital radios. On our current analog repeaters if you drive into a valley, your signal weakens. Repeater listeners then begin to hear a lot of noise with your voice. On our digital Fusion repeater you will either hear a perfect audio signal or hear nothing.

There are many other reasons to champion digital radio. Take bandwidth for example. DMR repeaters allow two conversations on a single 12.5-KHz channel. Analog repeaters meanwhile deliver only one conversation on a 25-KHz channel.

The good news is that you don’t have to wait to start experimenting with digital radio. Even if there are no repeaters in your area you can communicate with hams around the world. To do this, you set up a hotspot that communicates over the Internet to a gateway that connects you to any repeater. Your digital radio, usually a handheld, talks to your hotspot and bingo – you’re on the air anywhere in the world.

I’ve been experimenting with a hotspot for several months now and it is a lot of fun. Working in this medium is different but it’s not hard. Once you understand the big picture about the various modes it becomes a simple question. What do you want to do?

So, what do you want to read here or in the Grounded Grid? Do you want to know how to configure your hotspot? Do you want to know how to create a code plug for your DMR radio? Do you want to know how to connect to a reflector on D-Star? Please let me know and I’ll do my best to give you an easy to follow path for success in digital radio.

Email your requests and ideas to me at kØhyd@arrl.net within the next few weeks. I’ll do my best to deliver results for you beginning with the next Grounded Grid.

An Introduction to Digital Ham Radio

By Dale L. Puckett, KØHYD

On most months the Wichita area ham luncheon on the second Saturday doesn’t feature a program.

September 8th was different.

Like in the movie, “Build it and they will come.” And on this Saturday afternoon, they did! Hams from Garden City, Great Bend, Arkansas City, Emporia and Topeka came. A special presentation about DMR was the dessert.

Chuck Kraly, KØXM, a leader in the Kansas City area’s Backyard Repeater Group (BYRG), and the technical support manager at BridgeCom Systems in Kansas City, spoke.

A ham since 1979, Kraly’s background allowed him to explain the what, why and when about DMR to the excited crowd. BYRG is deep into DMR deployment and Chuck has spearheaded the move.

Much like single sideband in the early 1960s, digital radio is the future of amateur radio in the 21st century. Today it takes many forms including DMR, D-Star and System Fusion. BYRG leadership believes DMR is best suited for amateur radio.

What is DMR?

So what is DMR? For one thing, it’s an acronym for Digital Mobile Radio. Developed by the European Telecommunications Standards Institute, it’s used worldwide.

DMR has three tiers. Amateurs today use the Tier II, which is a twoslot, 12.5-kHz wide peer-to-peer specification. The two slots give it a spectrum efficiency of 6.25 kHz per channel. Amateur repeaters talk to each other using the Internet. The IP Site Connect (IPSC) specification makes communications possible.

Amateurs encode the analog voice from their microphone using the DSVI AMBE+2™ vocoder. Most DMR radio manufactures have implemented licensed copies of this vocoder. The newer version delivers an improved voice quality over earlier versions. D-Star, for example, uses the earlier version.

There are three types of users working with DMR today. They are the individual ham, the repeater operator, and the network operator. It takes all three to make DMR function worldwide.

Another type of amateur DMR user implements a small device called a hotspot. Hotspots deliver worldwide connectivity when there is no DMR repeater in the area. Your DMR radio talks to the hotspot which in turn talks to the Internet. Amateurs use their personal LAN at their home QTH. On the road, they often connect their hotspot to the Internet using their cell phone.

The Future

In the next column, originally written for Grounded Grid, we’ll look at DMR and other digital modes in more depth. With DMR you can get your hands dirty and learn how it works as you program your radio, which is a great mode for DIY fans. It’s a great sport.

If computer programming scares you, never fear. BridgeCom is preparing a preprogrammed Anytone ATD868UV radio. This radio, declared the “must have” DMR radio by many amateurs, is dual band. KØXM will program the radio before it ships.

One last thing! Chuck made an exciting announcement near the end of his presentation. BYRG has received several dozen DMR repeaters from a donor. They are making them available to ham clubs in Kansas at no cost providing the club meets a simple set of criteria. With the blessing of the Wichita Amateur Radio Club membership and board we may soon see a DMR repeater in Wichita. We may even see a robust amateur DMR network spanning Kansas. I’m excited!

Talk to you on DMR!