Hello everybody and welcome back to Everything Hamradio! If you didn’t read my Happy New Year post, today we are starting on the topic of digital communications. This month we will be covering the digital voice aspect of it, like DStar, Yaesu System Fusion, Project.25 and Digital Mode Radio. Let me start out by prefacing that I am not an expert in this area by no stretch of the imagination, nor have I been able to personally use any of these modes, with the exception of Project.25(P.25) through my work, so if anyone reads this and sees a mistake that I made, please leave a comment below so that not only I can know, but also all of yall can as well.
What is DStar?
So what is DStar? First off, DStar stands for Digital Smart Technologies for Amateur radio. It is a digital voice and data protocol specification for amateur radio. Some people, myself included, believed that DStar was a digital mode that was developed by and used solely by Icom. While it is true that, Icom was the first and the biggest Amateur Radio company that uses the DStar system, it was actually developed by the Japan Amateur Radio League and funded by a ministry of the Japanese Government then call the Ministry of Posts and Telecommunications. It was developed in the late 1990’s and uses frequency-division multiple access and minimum shift keying in its packet-based standard(wow, that’s a mouthful!)
This is a video produced by Icom about what DStar is, it’s about 8 mins long. Go ahead and watch it and then continue on with this post…
Digital vs Analog
Being that it is a digital system, it has many pros and cons when put up against a traditional analog system. Probably one of the most noticeable differences is the voice quality. The sound of a digital signal is often times much clearer and crisper than that of an analog system. It has about the same range as an analog system, but rather than like with an analog system, where you get more and more noise in your transmission the farther away from the repeater you are, with digital signals like DStar, you are either there or you’re not and your voice quality is pretty much the same the entire range.
One of the pros of digital voice is that there is more than just voice that is being transmitted when you key up your radio. Your radio is programmed with your call sign, and that information is sent every time you key up, so arguably that could meet the identifying requirements laid out for amateur radio, however, it is a good idea to always identify the traditional way just to CYA.
Another bit of information that can go out with your transmission is your location. DStar radios have a built-in GPS receiver in them. There is a digital version of APRS on DStar and it is called DPRS. I have read that there is a module or piece of software in the works that will join these two systems together. I don’t know if this has already been done or not. The GPS information is used for more than just position reporting though. There is a feature built into the radio where you can download a database of repeaters from radioreference.com and you can do a search of nearby repeaters both DStar and analog. This feature would be really nice to have during trips rather than having to plan your route and then manually find repeaters along your route.
So what about the cons? I think the biggest con of the DStar system is how hard it is to use, at least from the perspective of someone who has never used one before. There seems to be a fairly steep learning curve involved, and more programming than a typical analog radio. Each repeater can have multiple modules on different frequencies or for different functions. Each memory channel of your radio has five fields that you have to fill out in order to use the repeater. You have to put your call sign(not sure if this has to be done per memory channel or just once per radio), RPT1, RPT2, the repeater frequency and the offset. Unlike analog repeaters, not all DStar repeaters use the standard offset of the bad. You either will need to have someone who knows what they are doing, or do a lot of searching for information. You can goto http://www.dstarinfo.com and they have a “calculator” on their page where you select the repeater you want to talk to and the module you want to use and the repeater and module you will be talking on and it will tell you what each field needs to be.
Even though there are a lot of other things that you have to set when using a DStar repeater, it doesn’t have to mean that it is harder. If you are just talking on your local repeater, there is a quick and easy way to get on the air fast that is automatic. If you are wanting to talk to someone in another area on a different repeater, then you have to manually set up the RPT1 and RPT2 fields. Check out the video below to see how easy it can be to just talk on your local area repeater and not go through the internet for you QSO.
Something else that you have to do before you can talk on the DStar system is to register your call sign with the DStar system. This can be and is normally done by your local area administrator. Until your call sign is registered, no matter what you do with your radio, you will not be able to access a DStar repeater. Sometimes this process doesn’t take very long and other times it can take forever. Back in October, I was listening to an episode of the FoTime Podcast where they were talking about the Dstar system. One of the people who were doing the episode was from the Bay-net group in San Francisco, I believe, and he was talking about how their group is the regional administrators for the DStar system and how they had registered people from other areas of the country because their local administrators were taking forever.
Below is a tutorial video produced by Icom on how to register you call sign on the DStar network:
As far as using a DStar radio on an analog repeater or on simplex, I don’t think that it is much different from an analog radio. I’m not sure if there is a difference in audio quality when using an analog repeater, however I have heard good reports from the ICOM ID-51 Anniversary Edition and the ID-51A have very good sound quality both on the receive and transmit sides of it.
One of the nice functions of DStar or digital radios in general is the ability to easily link two or more repeaters together, thus allowing all the users on both repeaters to communicate with each other. This can be a big help when you are working in a large area where one repeater doesn’t cover the entire area. The major drawback to this though is that DStar, unlike traditional over-the-air linking, is that it requires an internet connection. If the internet connection goes down, the link won’t work. Also the more repeaters that are linked together, the higher the internet bandwidth that is required. There is, however, a fall back to internet connection. there is an interlinking radio system that can be used to create links on the 10 GHz band in the local area. I would think, though, that the distance between repeaters would have to be fairly close in order to use this option, but if properly planned in an area, it is possible.
One of the major draw backs to the DStar system, at least as it go off the ground, was the price. Up until recently, like within the past year or so, DStar radios could cost as much as double as their analog counter parts. This lead to a slow expansion in usage and a steep entry fee for the average user. Prices of DStar radios have come down considerably in the past year or so and are only slightly higher than their analog counter parts. Whether this drop in price was because the research cost had finally been absolved or the per unit license price was dropped or if it was just because there was finally a digital competition, is better left to smarter minds than myself. I, personally, think that it played, at least, a part in the drop in price.
Yaesu recently launched their own digital voice system called System Fusion. When they released their repeaters, they offered them at about half or a third of the price of the retail price but limited it to clubs. This caused their system to explode! We will talk more about the Yaesu System Fusion next Sunday.
Basically, like most everything in life, DStar has it’s pros and cons and it all depends on you, the end-user, to decide what is best for you. It may be that you live in a big city and there are a lot of DStar repeaters in your area, if so then it would probably be a good idea to get a DStar radio to take full advantage of what is being offered in your area. However, you may, like me, live our in the sticks and the closest DStar radio is over 50 miles or more away from you. If this is the case, it probably wouldn’t be feasible to fork out the extra money for a digital radio. Like with any decision in your life, the choice is up to you, or at least your XYL(wife)’s. On Thursday, we will be talking about DStar radios and accessories for the DStar system, so make sure you come back to check that out.
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Until next time…
73 de Curtis, K5CLM
- Wikipedia: https://en.wikipedia.org/wiki/D-STAR
- DStar Info: http://www.dstarinfo.com/
- Icom: http://www.icomamerica.com/en/products/amateur/dstar/dstar/