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HF & VHF propagations

D is for Digital

D is for Digital


A “Ham Notebook” Look at D-STAR and the “Mini-Industry” of Products It has Inspired
Hams have always been an innovative group, so it comes as no surprise that when Icom introduced its implementation of D-STAR in 2004, early adopters saw something useful in this new digital communications protocol. (Notice I said protocol, and not mode. D-STAR is not a mode, it is a digital protocol.) I am not going to discuss DSTAR pros and cons; instead, let’s take a look at what Icom has brought to the amateur radio community by planting the D-STAR seed.

First, we should begin at the beginning. D-STAR stands for Digital Smart Technologies for Amateur Radio. It is an open standard digital communication protocol for digital voice (DV, 4800 bps) and digital data (DD, 128 kbps) established by the Japan Amateur Radio League (JARL). The JARL is an organization similar to the American Radio Relay League, ARRL, in the USA.

Up until just one year ago or so, Icom was the only radio manufacturer that produced ham radio equipment using this technology, so it may seem like the system is a proprietary offering in Icom radios and repeaters. I think Icom took a brave and risky step in committing the resources and finances to develop and sell off-the-shelf ham radio equipment for D-STAR. I am sure other radio companies are watching the Icom line of D-STAR capable radios from a business perspective, but we can watch those other companies from a consumers’ perspective to see if anyone else will step to the plate and introduce equipment for D-STAR. Some healthy competition will be good for this communication protocol, since it can help drive further innovation and continue to expand the number of users.

Since D-STAR is a digital thing, and digital means computers, it may be something mysterious and scary to analog-and RF-oriented folks. Think of this protocol as a wireless version of a computer network in your office, where various terminals are interconnected and each has access to the internet. In addition, there are levels of network connections, and stations can be configured to include or exclude certain individuals or groups (other D-STAR stations).

Since D-STAR operates on the VHF and higher bands, the radios look like traditional FM mobile and hand-held portable units, and so many may think D-STAR is “FM,” but it is not. In fact, the DSTAR modulation scheme is not compatible with FM. However, repeater and simplex operation does occur with D-STAR. But, because D-STAR is incompatible with standard FM, operations must be coordinated and comply with local band plans (a topic for another day; for a general discussion of repeater coordination and coordinators, see the “Riley’s Ramblings” column in last month’s CQ).

*28181 Rubicon Court, Laguna Niguel, CA 92677


Technically Speaking

Bob Witte, KØNR, “FM” columnist for CQ’s sister publication CQ VHF, published an introductory article on D-STAR in the Winter 2009 issue of CQ VHF magazine. In addition, on his blog site, Bob explains that D-STAR uses Gaussian Minimum Shift Keying (GMSK), the same modulation format that Global System for Mobile communications (more commonly known as GSM or “2G”) cell phones use. Therefore, for those of you who, like me, find it hard not to call D-STAR a mode, its mode is GMSK.

As you look at the products briefly examined in this article, keep in mind what D-STAR is: It is a protocol, or in other words, a specification or definition of how a signal must be configured in order to be understood by the receiving party as it goes from one point to another. In addition, understand that D-STAR consists of two layers—a “transportation” layer (the RF channel) and the “encoding” or “digital” layer. Just like the computer term compatible, we should define what or how much compatibility there may be. If one defines compatible as “it just works,” we must understand how much compatibility there may (or may not) be: Does it work for both voice and data and text, or does it work only for voice? For example, many devices may be called a gateway to a D-STAR system, but only handle the DV portion, and may ignore the DD portion of the D-STAR protocol. Yes, the device may “work,” but there may be some limitations. For example, an e-mail or text message may or may not be received because a routing feature in the digital layer is missing. This is an oversimplified explanation, and the more technical articles mentioned in the References section provide more detail on the D-STAR specifications.

For units that use traditional “analog” FM radios, bear in mind that D-STAR uses a very narrow bandwidth of 6.25 kHz, while a typical FM signal occupies about 16 kHz.

Who’s Using This Stuff and Where are They?

Now that we basically know what D-STAR is, the next question is: Where are all these D-STAR stations located? A quick Google search finds sever-al pockets of D-STAR activity, and there is an interesting DSTAR repeater location map to see where these folks are. See the screen capture, fig. 1.

I asked my good friend and digital radio expert George Zafiropolous, KJ6VU, what he knew about D-STAR. He pointed me to his local radio club and its library of presentations. The Bay-Net radio club has been pretty busy with D-STAR projects. Take a look at its presentations, saved on its website, for some introductory information and interesting club project ideas.

Hot Spots

Meanwhile, those inquisitive and creative hams have been busy developing accessories and other items to supplement D-STAR activity. One example of the more popular gadgets is the D-STAR hot spot. Hot spots are a great way to get started with D-STAR, since they create a “gateway” into a D-STAR network without having to buy a complete radio.

Generally speaking, if you can gather and properly interface an analog FM rig with a 9600-baud data port (or access to the FM discriminator and modulator; this connection is usually used for a packet radio TNC or some other digital mode), a mini hot spot adapter (or node adapter), and a Windows® PC, you can put a D-STAR hot spot into operation. Later, this hot spot, plus a few more items, can become a full-duplex DSTAR repeater.

D-STAR Programming Helpers

Remember what I said about digital modes and computers? Continuing along this path, computers often mean something has to be configured or programmed. Some people understand programming, and some do not. (I fall somewhere inbetween these groups.) Also, once again, the creative hams out there have developed plenty of D-STAR programming aids for the rest of us.

Speaking of programming, Icom has a D-STAR UHF handheld radio called the ID-31A that comes factory-programmed with a D-STAR repeater database, thus minimizing or eliminating the need to program the radio. The little HT also includes a GPS capability as well as traditional FM mode.

Dongles and Other Doo-Dads

Dongles are little computer gadgets that dangle from the end of a USB port cable, or sometimes look like a connector with complex, tiny integrated circuits inside. In the D-STAR world there are two popular dongles, both made by Internet Labs.

The DV Access Point (DVAP) is a red dongle that plugs into a computer (PC or Mac) USB port via a cable, as shown in fig. 2. It is basically a GMSK modem with a small 2-meter radio inside that enables access to D-STAR gateways and repeaters with your D-STAR radio. It is not a gateway or a converter for a traditional FM rig to access D-STAR systems. A typical application of the DVAP is to extend the range of your D-STAR handie-talkie to increase its coverage area. For example, if you are in your cubicle office at work, and cannot access the repeater, you can mount the DVAP near a window and gain coverage from your HT on low power.

To use the DVAP, you will need DVAPTool software (a free download), DVAP drivers to match your computer operating system, an audio headset with a microphone, and an internet connection.

The second Internet Labs product is called the DV Dongle (fig. 3). It is a small blue unit that connects to your PC or Mac via a USB port and provides encoding and decoding of DSTAR signals so you can access the D-STAR network. Software, of course, is needed to run the DV Dongle, and you also need an Internet connection as well as speakers and a microphone. But here is the interesting part: While the DVAP requires a D-STAR radio to gain access to the D-STAR network, the DV Dongle requires no radio at all.

More details, including how to register your system for DSTAR gateway access, can be found on the DVAP and DV Dongle web pages mentioned in the References section.


Many hams are using APRS, the mixture of GPS positioning data and amateur radio, and know how useful this can be. There is a D-STAR variant that includes GPS data for position reporting, and it is called D-PRS. D-PRS is a “converter” that takes D-STAR information and translates it into normal TNC2-formatted APRS strings. From a user standpoint, nothing extra is needed to enable a D-STAR radio to report GPS position data to normal APRS tracking sites.

D-RATS: An Emergency Responders’ Toolkit for D-STAR

D-RATS uses the slow speed digital channel in the D-STAR protocol for text messaging, file transfers, e-mail, chat, and position reporting via a simplex D-STAR channel. It was created to enhance the d*Chat function to accommodate emergency response forms and other documents needed by emergency responders. D-RATS was created by Dan Smith, KK7DS, for the Washington County ARES/RACES group in Oregon.

Not Just Another Radio

A new company called Northwest Digital Radio is creating something called the UDR56K-4, a universal digital radio (see fig. 4). As this is being written (March 2013) John Hays, Director of Marketing for NW Digital Radio, said, “The UDR56K-4 has been in active development for approximately two years. It was announced at Hamvention® 2012. At that time, NW Digital Radio had built the integrated, Linux/ARMprocessor based, computer module which runs various protocols including AX.25 and D-STAR (both voice and data).

“In the weeks following the Hamvention®, tests of the original radio and included modem did not meet the high expectations of NW Digital’s engineering team,” says Hays. “In Q3, it was determined that a new radio design was necessary. The original design was dependent upon a high integration RF radio integrated circuit which included predefined modems. After analysis, the design evolved to a new architecture which uses DSP and I/Q modulation techniques to provide modem performance and flexibility that would not be available in the previous design.

“After 6 months of re-design and development, the new RF module is in internal beta with boards entering fabrication. The goal is to have demonstration units at Hamvention 2013 with customer shipments shortly thereafter.

“The final product includes an integrated Linux server that has open source software for the operating system, drivers, protocols, and applications and is tightly integrated to a high performance and extensible radio platform.

“The command and control structure of the radio is exported using web socket technology that facilitates real time web pages, or custom applications to configure and operate the radio. NW Digital Radio will provide market specific user interfaces to defined segments, such as EMCOMM, APRS, and D-STAR. Furthermore, this approach permits independent developers to create new and customized user interfaces according to the needs of different user communities, whether emergency communications, experimenters, network integrators, visually or otherwise impaired users, and more.

“NW Digital Radio wants to put amateurs back into amateur radio and is actively encouraging amateurs to develop new software, protocols, and hardware to integrate with the UDR56K-4 platform radio.”

This radio is not yet ready as this article goes to press, so check their Yahoo Group (see References) for the latest news.

Looking at the global D-STAR users map and the growing number of products—including several low-cost options—it looks like D-STAR is here to stay. DV or DD mode, partially-or fully-compatible, homebrew or commercial, the D-STAR seed, planted by Icom, is finally beginning to sprout new offshoots.

73, Wayne, KH6WZ


Here are some great websites on D-STAR and D-STAR projects, separated by topic:

Introduction to D-STAR

Bay-Net Amateur Radio Club and Repeater Network, WW6BAY

D-STAR for the Rest of Us!

Map of D-STAR World Wide Activity, by Peter Loveall AE5PL

Investigating the D-STAR Modulation Format by KØNR


Technical Topics

“A Look Inside D-STAR Modulation,” by Bob Witte, KØNR, CQ VHF, Winter 2009

GMSK Tutorial by MX Com, Inc

D-PRS by Peter Loveall AE5PL

D-STAR Uncovered, by Peter Loveall, AE5PL

Construction Projects

Building a D-STAR Compatible Hotspot, by James M. Moen, K6JM

D-STAR Hot Spot, Current Version is 2.56 by The W9ARP D-STAR Repeater Group

DIY Homebrew Non-ICOM D-STAR Repeater, by Randy Nelson, WB0VHB

MoenCom board

Non-Icom Commercially Available Products

DV Access Point Dongle (DVAP) by Internet Labs

DV Dongle

ProHam D-STAR Repeater Controller by Newfield Design

UDR56K-4 Universal Digital Radio, by Northwest Digital Radio

Software and Programming

D-RATS, A Communications Tool for D-STAR

Nifty E-Z Guide to D-STAR Operation, a Comprehensive D-STAR Operating Reference

Available from the CQ Bookstore or from

List of D-STAR software programs

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