DStar - Digital Smart Technologies for Amateur Radio
No Longer a Nay-sayer
I will be the first one to admit that I dismissed D-Star from the day I first saw it introduced at the Dayton Hamvention. Every year after its introduction I completely ignored the various Icom D-Star displays. My thinking was FM was just fine, audio quality was usually good, and there were plenty of FM repeaters all across the country. So how was digital audio going to really improve the situation?There were hardly any repeaters available for many years. Sure I read where you could access other D-Star users with a DV Dongle, but that was through a computer and the Internet. Hardly amateur radio to me.
During a business trip to Florida in early 2010, on the return trip home, I made a 28 hour stop in Atlanta to visit my daughter who currently lives there. While she and her husband were at work the next afternoon, I decide to make a trip to the Ham Radio Outlet store in North Atlanta. After a few minutes to wandering the store, I was asked if I needed help. I said "sure, I'd like to speak to someone about D-Star." I was directed to the store manager, Mark KJ4VO who I was told was their local D-Star expert.
Mark proceeded to explain just how D-Star works. How most of the repeaters are linked. The fact that you can carry on QSOs with hams throughout the world on just a handheld, or by using the DV Dongle. I was shown a D-Star repeater system which is installed in the store. Mark demonstrated linking and unlinking the repeater to various "reflectors" to which various repeaters are connected to throughout the world. We even made a few QSOs with three of his fellow ham friends in different states.
All I can say is after an hour, I was hooked. My first purchase while there was an Icom IC-80AD dual-band handheld. I had it shipped since I did not want to carry it back on the plane. Within a week of receiving it and playing with it, I ordered an Icom ID-880H for use as a base radio in the shack. Yes, I am totally and completely hooked on D-Star.
What is D-Star?
D-Star offers digital voice and slow and high-speed data communications. Slow-speed digital voice and data are transported at 4800 bps, of which 3600 bps is used for voice transmission and the remaining 1200 bps is used for syncronization and general use. Of that 1200 bps, around 900 bps is available for the transmission of data.High-Speed digital data communication is transported at 128kpbs and is capable of supporting Ethernet packets and also is fast enough to use for Internet applications such as displaying web pages.
D-Star is capable of connecting repeater sites using the Internet and forms a world-wide radio network. This state-of-the-art system has a tremendous amount of functionality not available with less sophisticated linking system like IRLP and Echolink.
D-Star refers to voice communication as "DV Mode" for Digital Voice Mode. Voice is converted to a digital format using a bit of computer code referred to as a CODEC. The CODEC code is embedded on a microchip which encodes and decodes the audio signals into and out of the AMBE (Advanced Multi-Band Excitation format). The CODEC that D-Star users is the only proprietary portion of the D-Star design. All other parts of D-Star are open which has allowed U.S. hams to create many new developments with D-Star that will be discussed later.
The quality of the D-Star voice signal is very similar to that of FM voice. Some say it sounds slightly inferior, but I think it is equivalent and definitely has less noise - in fact no noise like you will find with FM at times. The signal either makes it to the repeater or receiver perfectly, or not at all. There is no in-between signal quality that is found with traditional analog voice modes and no squelch tail at the end of every transmission and the repeaters usually do not have a courtesy beep. However, Icom has an ability to provide that courtesy beep from within the radio to let you know when the other party has turned the conversation over to you.
Unlike analog voice modes like FM, DV mode has the ability to transmit 1200 bps data simultaneously with the voice signal since they are both digital signals and the "voice" and "data" portions of the signals do not interfere with each other. While the data portion of this signal is referred to as "slow-speed" data, it still is much faster than other digital modes like PSK31. It is plenty fast for keyboard to keyboard conversations, but not suitable to sending large files.
For the sending and receiving of greater volumes of data and large files, D-Star has the "DD Mode" or Digital Data Mode. The DD mode is only supported on the 1.2Ghz amateur band and is capable of sending a receiving data at a 128kbps rate.
To send slow-speed data on D-Star, all that is required is connecting a home-made serial cable or low cost commercially made serial cable from your PC to the data port on the back of the radio. No special or additional data modem is required. To send and receive high-speed data on D-Star on a 1.2Ghz D-Star radio, all that is required is a standard Ethernet cable connection.
The Practical Usage of D-Star
The above are just some of the basics on D-Star. But now I will review the value of D-Star and why every amateur should consider adopting this new voice and data mode for the VHF and UHF bands (2M, 440Mhz, and 1.2Ghz).One of the biggest benefits are that most repeaters are connected to D-Star Reflectors. These are basically network servers. Once a ham is registered with a repeater gateway, they can connect to D-Star users beyond the local repeaters. You do not have to be registered with a gateway to use a local repeater, only if you want to make use of the D-Star network. If you do register with your local gateway, you only have to register with one gateway as your registration information is propagated to all other gateways and reflectors in the D-Star network.
This allows retired and older hams who have had to move into apartments and retirement homes to still talk to their ham friends around the world using only a D-Star capable handheld radio! No large special antennas are required. If the ham does not have a D-Star capable handheld, or does not have a local D-Star repeater yet, no worry, several U.S. amateurs developed and manufacturer a little device known as a DV Dongle. The DV-Dongle connects to a Personal Computer which needs to be connected to the Internet with a high-speed DSL or Cable Modem connection. Dial-up just does not cut it. Then with a standard computer audio headset with microphone and headphones, the DV Dongle allows the user to connect to any of the D-Star reflectors on the network and carry on conversations with other DV Dongle users or radio users through the repeaters connected to the various reflectors! This allows every ham, no matter how they are housing and antenna restricted, to again communicate with hams around the world.
Also, Technician licensees can experience international communication with D-Star. Sure it is possible for Techicians to experience the thrill of DX on 6 Meters and even some of the higher bands, or with meteor scatter or moon bounce, that is not practical and available all the time for the average Techician Class licensee. But with D-Star, hams can talk to other hams around the world all the time. It's not unusual for hams on the west coast getting ready for bed to talk with hams in the United Kingdom who are on their daily commutes to work.
One of the features I really like is the ability to call another ham without knowing his current location or what D-Star repeater he or she is currently using. For example, I am in Cincinnati and a good friend of mine WI0T, is usually in St. Charles, Missouri. If WI0T recently used the K0MDG repeater in St. Louis, the D-Star network knows where he is and what repeater is recently used. I program my radio to access my local repeater, K8BIG C (the "C" means that it is the K8BIG 2 Meter repeater). In the "URCALL" position, I enter "WI0T" which is Rod's call. When I make a call to Rod on the K8BIG C repeater, the D-Star network knows to route that transmission to the K0MDG repeater and Rod will hear my call!
But let's say several days later, Rod goes on a business trip to Los Angles and takes his D-Star capable radio with him and chats with some of the local hams in Los Angeles on one of their D-Star repeaters. When I use the same method to call Rod as before, this time the D-Star network knows that WI0T is now in Los Angeles and routes my call automatically to the Los Angeles area repeater that WI0T last used. All this is accomplished automatically!
One of the best guides to providing an overview of D-Star, how to program radios, using the repeaters, linking to reflectors, using the DV Dongle, overview of third-party software programs to use with D-Star such as D-RATS (RATS is STAR spelled backwards) and D-Chat, and how the D-PRS capability of D-Star integrates into the APRS network, can be found in a book by Bernie Lafreniere, N6FN called the Nifty E-Z Guide to D-STAR Operation. This book can be order from www.niftyaccessories.com or from amazon.com.
If you would like to see if there are any D-Star repeaters in your area, you can check this constantly updated list here:
http://www.dstarusers.org/repeaters.php
This list only lists the U.S. based D-Star repeaters and not those repeaters listed in other countries. Currently there are over 2,000 D-Star repeaters throughout the world with more being added each month. There are also over 50,000 users of DStar so there are always plenty of people to talk to on DStar unlike some of the other digital methods being promoted.
This listing does not show the hundreds and hundreds of D-Star Hotspots and DV Access Points in operation. What are Hotspots and Access Points? They are yet another way users can access the D-Star Network using D-Star capable radios.
The latest device to assist hams in connecting to the D-Star world-wide network is the DV Access Point Dongle or "DVAP" for short. The DVAP was introduced in January 2010 by Internet Labs the same people who created the DV Dongle.
DVAP Dongle
The DVAP can do two things. First, if you have a D-Star radio but no local repeaters, it allows you to use your radio to connect to any reflector in the D-Star network. How? The DVAP is actually a D-Star voice encoder/decoder coupled with a micro two-meter transceiver that can be set to any frequency in the two-meter amateur band. Let's say in your area no one typically uses the 146.46 simplex frequency. So you set the DVAP frequency to 146.46. You then connect the DVAP to the D-Star network and desired reflector with the provided software. Now you set your D-Star transceiver or handheld to 146.46 simplex using the Digital Voice or DV setting. Now start talking! You control the DVAP with the same commands that you would use for D-Star repeaters. This allows you to unlink and link different reflectors from your radio.
Since this particular device only has output power of around 10 mws, its range is rather limited at about 100 yards. But that is perfect for someone wanting to use their D-Star handheld around the house and yard. You can also connect an external antenna to increase the range to maybe around your neighborhood.
Hotspots
Hotspots are very similar to the DVAP outlined above. In fact the Hotspots came long before the DVAP was developed and sold. The DVAP's low power limits its use to around the house, or maybe a few blocks if connected to an outside antenna.A Hotspot on the other hand is usually connected to a higher power standard analog VHF or UHF radio (with a 9600 baud packet port) and therefore has a lot more flexibility and range. With a sufficiently high antenna connected to a radio with a Hotspot interface, you can actually create what some might call a simplex repeater.
Similar to the DVAP, the Hotspot in connected to an Internet enabled computer and the radio via the 9600 baud packet port. The radio is set to a D*Star simplex frequency and you and your friends can talk all around the world from another hand-held or mobile radio.
Hotspots are very reasonable and there are two quality sources that you can buy kits and/or pre-built units. Following are the two Hotspot vendors I am most familiar with in purchasing the Hotspot and the required firmware. The circuit board on this page is an actual Hotspot from MoenComm and represents their latest version. The firmware is already installed and this board is only offered pre-assembled (you will still need to find an enclosure for the board). The firmware was developed by Dutch*Star who also offers a Hotspot in kit form.
If you would like to hear the quality of DStar audio, following are a sample files of actual DStar QSOs recorded on an Icom ID-51A. Remember, on newer generation DStar radios, the user can adjust the audio fidelity by varying the high and low response.
DStar Sample Audio 1
DStar Sample Audio 2
DStar Sample Audio 3
DStar Sample Audio 4
DStar Sample Audio 5
DStar Sample Audio 6