The Cacophony of Digital Voice Continues (Part 2)

Digital transmissionThis post is a continuation of The Cacophony of Digital Voice Continues (Part 1), so you probably should read that one first.

All of the popular amateur digital voice (DV) systems (D-STAR, DMR and YSF) use the AMBE vocoder (voice codec) technology. This technology was developed by Digital Voice Systems, Inc. and is proprietary technology covered by various patents. The use of proprietary technology on the ham bands causes some folks to get worked up about it, especially proponents of an open source world. See my blog posting: Digital Voice at Pacificon and this presentation by Bruce Parens K6BP: AMBE Exposed. Codec2 is an alternative open voice codec developed by David Rowe, VK5DGR. David is doing some excellent work in this space, which has already produced an open codec that is being used on the ham bands. FreeDV is an umbrella term for this open codec work. Here’s a recent video of a presentation on FreeDV by VK5DGR.

It will be interesting to see if and how Codec2 gets adopted in a DV world already dominated by AMBE. After all, a new codec is another contributor to the digital cacophony. On the HF bands, it is easier to adopt a new mode if it can be implemented via a soundcard interface (which FreeDV can do). Any two hams can load up the right software and start having a QSO. The same is true for weak-signal VHF/UHF via simplex. (Note that Flexradio also supports FreeDV, showing how Software Defined Radio (SDR) has an advantage with adopting new technology.)  VHF/UHF repeaters are trickier because you must have a solution for both the infrastructure (repeaters and networks) as well as the user radios.

The vast majority of digital repeaters support just one digital format. For example, a D-STAR repeater does not usually repeat DMR or YSF transmissions. Interestingly, DMR and YSF repeaters often support analog FM via mixed mode operation for backward compatibility. It is definitely possible to support multiple digital formats in one repeater, but the question is will large numbers of repeater owners/operators choose to do that? With existing DV systems, the networking of repeaters is unique to each format which represents another barrier to interchangeability. In particular, most of the DMR infrastructure in the US is MOTOTRBO, which won’t ever support D-STAR or YSF.

In the case of a new vocoder, we can think of that as just a new format of bits being transported by the existing DV protocol. DMR, for example, does not actually specify a particular vocoder, it’s just that the manufacturers developing DMR equipment have chosen to use AMBE technology. So from a technical viewpoint, it is easy to imagine dropping in a new vocoder into the user radio and having it work with other identical radios. Of course, these radios would be incompatible with the existing installed base. Or would they? Perhaps we’d have a backwards compatibility mode that supports communication with the older radios. This is another example of putting more flexibility into the user radio to compensate for DV incompatibilities.

One objection to AMBE is the cost of the technology, especially when compared to free. When D-STAR radios first started using AMBE codec chips, the chip cost was rumored to be $25 to $50, but I don’t have a solid source on that. Now, I see that Tytera is selling a DMR handheld at around $100, including AMBE technology inside, so the codec can’t be very expensive. If a free codec starts to be a credible threat, it will put additional pricing pressure on the AMBE solution.

A potential advantage of Codec2 is superior performance at very low signal-to-noise ratio. We’ve all experienced the not-too-graceful breakup of existing DV transmissions when signals get weak. Some of the Codec2 implementations have shown significant improvement over AMBE at low signal levels.


Repeating a key conclusion from Part 1:

  • For the foreseeable future, we will have D-STAR, DMR and YSF technologies being used in amateur radio. I don’t see one of them dominating or any of them disappearing any time soon.

Adding in these conclusions for Part 2:

  • Codec2 will struggle to displace the proprietary AMBE vocoder, which is well-established and works. The open source folks will promote codec2 but it will take more than that to get it into widespread use. Perhaps superior performance at low signal levels will make the difference.
  • Repeater owner/operators will continue to deploy single-DV-format repeaters. This will make multiformat radios such as the DV4mobile be very attractive. In other words, we will deal with the digital cacophony by having more flexible user radios. This will come at a higher price initially but should drop over time.

Repeating this one from Part 1:

  • A wild card here is DMR. It benefits from being a commercial land mobile standard, so high quality infrastructure equipment is available (both new and used gear). And DMR is being embraced by both land mobile providers (i.e., Motorola, Hytera) and suppliers of low cost radios (i.e., Tytera, Connect Systems). This combination may prove to be very powerful.

Well, those are my thoughts on the topic. I wish the DV world was less fragmented but I don’t see that changing any time soon. What do you think is going to happen?

73, Bob KØNR

The Cacophony of Digital Voice Continues (Part 1)

Digital transmission

It wasn’t that long ago that I commented on the state of digital voice on the VHF/UHF ham bands: Digital Voice Balkanization. We have three main competing (incompatible) standards in the running: D-STAR, DMR and Yaesu System Fusion (YSF). At a high level, these three formats all do the same thing but there are significant differences in implementation (See Comparison of Amateur Radio DV by Roland Kraatz W9HPX.) All three of these are (arguably) open standards, allowing anyone to implement equipment that supports the standard. However, the reality is that D-STAR is still largely an ICOM system (with Kenwood joining the party), YSF is mostly a Yaesu system and DMR is…well, DMR is not deeply embraced by any large amateur radio equipment supplier. Instead, DMR is promoted heavily by Motorola for the commercial market via their MOTOTRBO product line. Another big factor is the availability of DMR radios from some of the low cost providers in the ham market: Connect Systems, Tytera MD-380. Baofeng has also announced a DMR radio but it has some potential shortcomings.

D-STAR has a clear head start versus the other DV standards and is well-entrenched across the US and around the world. DMR and YSF are the late comers that are quickly catching up. To put some numbers on the adoption of DV technology, I took at the digital repeater listings in the August issue of the SERA Repeater Journal. SERA is the coordinating body for Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia and West Virginia. This is a large region that includes rural and large urban areas, so perhaps it is a good proxy for the rest of the country. I just considered the listings for D-STAR, DMR and YSF repeaters, some of which are set up as mixed-mode analog and digital repeaters.

D-STAR   161    39%
DMR      136    33%
YSF      121    29%
Total:   418   100%
SERA Repeater Journal - August 2016

I was definitely surprised at how the DMR and YSF numbers are in the ballpark with D-STAR. Of course, we don’t know for sure how many of these repeaters are actually on the air or how many users are active on each one. Still, pretty impressive numbers. (And I did not bother to count the analog FM repeaters but those numbers are way higher, of course.)

It is the repeater clubs and repeater owners that drive the deployment of infrastructure for new technology. To some extent, they are driven by what their users want but also by their own technical interests and biases. One of the positive factors for DMR is that most of these systems are Motorola MOTOTRBO. Hams involved in commercial land mobile radio are exposed to that technology and naturally port it into the amateur radio world. MOTOTRBO is actually not that expensive and it’s built for commercial use. YSF received a big boost when Yaesu offered their repeater for $500 to clubs and owners that would put them on the air. By using Yaesu’s mixed analog/digital mode, it was an easy and attractive upgrade for aging repeater equipment.

Disruption From New Players

Early on in the world of D-STAR, the DV Dongle and DV Access Point by Robin AA4RC allowed hams to access the D-STAR network without needing a local repeater. This basic idea has continued and evolved in several different directions. For example, the DV4Mini is a cute little USB stick that implements a hot spot for…wait for it…D-STAR, DMR and YSF. This is very affordable technology (darn right cheap) that lets any ham develop his or her own local infrastructure. We don’t need no stinkin’ repeater. DV MEGA is another hot spot, supporting D-STAR, DMR and YSF. Oh, and then there’s openSPOT…don’t want to leave them out. I guess somebody forgot to tell these guys they have to choose one format and religiously support only that one.

DV4 Mobile Transceiver as shown in Dayton 2016

OK, so that’s one way to solve the babel fish problem…support all three formats in one device. And that’s what the DV4 mobile radio promises to do as well: “This DV4mobile is a tri-band VHF/UHF transceiver (2m, 1.25m and 70cm) that supports DMR, D-STAR and C4FM ( or “fusion”) all in one box.” Heck, let’s throw in LTE while we are at it, it’s only software. This site says the radio will be available Q4 2016. Well, it’s Q4, so maybe it will be here soon.


So let’s wrap up Part 1 of this story. What can we conclude?

  • For the foreseeable future, we will have D-STAR, DMR and YSF technologies being used in amateur radio. I don’t see one of them dominating or any of them disappearing any time soon.
  • Equipment that handles all three of those DV modes will be highly desirable. It is the most obvious way to deal with the multiple formats. Software-defined radios will play a key role here.
  • A wild card here is DMR. It benefits from being a commercial land mobile standard, so high quality infrastructure equipment is available (both new and used gear). And DMR is being embraced by both land mobile providers (i.e., Motorola, Hytera) and suppliers of low cost radios (i.e., Tytera, Connect Systems). This combination may prove to be very powerful.

Digital Voice at Pacificon

Last weekend, I had the privilege of attending the Pacificon amateur radio convention in Santa Clara, something I have been trying to do for several years now. It is a great event, with good technical programs and a super venue.

The most interesting presentation I saw was the one on digital voice (DV) technology by Bruce Perens K6BP. The presentation was mostly about the digital voice known as FreeDV,  an open source approach to DV that uses the Codec 2 voice codec for digitally processing/compressing speech.

K6BP photo
Bruce Perens K6BP talking about FreeDV

I won’t cover all of the technical details here but you can follow the links above to go deeper on the topic. The initial FreeDV efforts are focused on the HF bands, using the sound card plus computer approach to implementing DV. This is a good approach since it is a relatively easy way to adopt this technology. (Compare this to VHF/UHF where you need to solve the repeater infrastructure problem to make progress.) FreeDV operates with a bandwidth of  1.25 kHz, narrower that the standard 3 kHz or so SSB signal. FreeDV also has the benefit of degrading gracefully as the  signal-to-noise ratio is decreased, with less of a digital dropoff that we see with D-STAR and other DV technologies.

Like many hams, Bruce pointed out the concerns and limitations of the proprietary AMBE chip used in D-STAR, DMR and now the new Yaesu DV system. I totally get this point and support the idea of a an open source codec. On the other hand, this work is coming more than a decade later than the creation of D-STAR. I like to refer to this phenomenon as “our ideas are better than their products.”

Bruce introduced Chris Testa KB2BMH to talk about the “HT of the Future”. This is a handheld transceiver implemented using Software Defined Radio (SDR) and inspirations from the world of smartphones. As Bruce said, “Why isn’t your HT as smart as your smart phone?” This is similar to the Android HT idea that I blogged about a while back. See Chris’s blog and this HamRadioNow video for more information.

Another presentation that I attended was about D-STAR with several speakers, including Robin AA4RC. The innovation continues to happen in the D-STAR world with a strong theme of using Raspberry Pi computers to create D-STAR hotspots and repeaters. Robin described the “DV Pi” being developed…a DVAP-like daughter board that plugs into a Raspberry Pi. Jim Moen K6JM talked about the many ways you can implement a D-STAR Hotspot. For more info on that see his D-STAR Hotspot page.

There’s much innovation happening in the area of Digital Voice. It got me thinking about it again so I dug out my ICOM D-STAR HT and put my DVAP back on the air.

73, Bob K0NR

The Android HT

I’ve been watching all of the innovative work going on in the smartphone and tablet arena and wondering how we could get more of that going in ham radio. To be sure, there are always radio amateurs developing creative technology. Some examples are adaptations of D-STAR, IRLP, improvements on APRS and sound card modulation modes. However, amateur radio is missing a standardized platform for handheld communications. Such a radio platform could open up lots of software innovation in this space.

What I have in mind is a dualband (2M/70cm) handheld transceiver that is built on top of the Android operating system. (Sorry Apple Fan Boys, iOS is a non-starter based on Apple’s walled garden philosophy.) This radio would have some of the hardware features we now take for granted in smartphones: GPS, WiFi, USB, maybe even a camera. I’d also include APRS hardware built-in, similar to the Yaesu VX-8GR or the Kenwood TH-D72A. I’ve hacked together a concept photo shown on the left of this post (click to enlarge). We would probably want to maintain some of the most important direct hardware controls such as PTT, volume and channel select. The rest of the user interface would be done via a touchscreen display, where the power of the Android OS comes into play.

While this hardware configuration is exciting, the real power comes from having a software developers kit (SDK) with a stable Application Programming Interface (API). This would unleash the creativity of all those software-oriented hams out there and a plethora of apps would emerge. There are plenty of ham radio apps available on the Apple and Android platforms…it’s just they are missing the radio as part of the package. An obvious area for innovation would initially be in APRS or maybe D-STAR. We could actually have the equivalent of SMS text messaging on ham radio, backed up via the WiFi connection. (Yeah, this kind of exists already but it is really cumbersome to use due to the braindead menu-driven user interfaces of current radios.) Just think how easy programming the radio would be with a touchscreen approach.

This is the type of product development that requires significant investment, but the technology is readily available. I suppose a garage shop operation could get this done but one of the big radio manufacturers could easily pull this off. Maybe one of those upstarts from China might want to take this on. Whoever does it, just send me $5 per unit and I’ll be happy :-).

That’s my best idea for this morning. What do you think?

73, Bob K0NR

New Transceiver from ICOM: IC-7100

ICOM has shown the new IC-7100 at the JARL show in Tokyo. The interwebz is buzzing with information, including a preliminary data sheet.

My scan of the preliminary datasheet indicates that this radio is in the class of the IC-7000 or even the IC-706. It covers all modes on HF plus 6 Meters, 2 Meters and 70 cm. (It also has the 70 MHz band which is a nice add for the European countries that have that band.) The radio includes DV (D-STAR) modulation capability and has a new touchscreen user interface. The slanted control panel is meant to make the touchscreen more accessible.

A new HF plus VHF/UHF radio always gets my attention (see my plea for an FT-950 with 2 Meters).  I am starting to think that the real benefit of this rig is the addition of D-STAR capability, which would a good but not essential feature to have.

What do you think?

73, Bob K0NR

Update (30 Aug 2012): Universal Radio has the radio on its website.
There’s a good video look at the radio here.

A New Digital VHF/UHF Radio from Yaesu

A while back, Yaesu published a white paper/brochure on VHF/UHF digital technology that slammed D-STAR for using GMSK modulation and stated that C4FM (4-Level FSK) is the way to go. See my previous posting on that topic. The paper also talked about DMR and APCO 25 as standards that use C4FM.
Page 14 of the document says:
At this point in time Vertex Standard believes the C4FM (4-level FSK) FDMA or TDMA are the most suitable selections for Amateur radio applications. In early 2012, we will release a C4FM (4-level FSK) FDMA Handy-Talky and a Mobile transceiver into the Amateur radio market. After our initial introduction, we plan to introduce a C4FM (4-level FSK) TDMA (2 slots) or TDMA Handy and Mobile transceiver into the Amateur market.
This led to speculation that we would see a Yaesu DMR or APCO 25 radio at the Dayton Hamvention. The topic was hotly debated in various online forums, with the prevailing theory being that it would be a DMR radio to play and compete with Motorola’s MOTOTRBO™ radios. It now seems that the initial introduction is the FT-1D, a dualband handheld that just does analog FM and a plain C4FM digital format (no DMR or APCO 25 protocol).  This blog has the product brochure for the FT-1D.  (Click on “Page 1” and “Page 2” links.)
The general reaction from the ham radio community is WTF, over? I don’t know why anyone would buy a radio to use with digital C4FM modulation. This digital mode is incompatible with D-STAR, DMR and APCO 25…the most common digital formats on the VHF/UHF ham bands. The quote listed above indicates that there will be more coming from Yaesu later in the year, that includes TDMA. This could be DMR but who knows?
– 73, Bob K0NR

Mixed Signals from Yaesu

This just in from the Things That Make You Go Hmmm Department: the amateur radio portion of Yaesu splits from Mother Motorola while the land mobile portion stays. This is right on top of an announcement that Yaesu will pursue a digital amateur radio offering based on land mobile technology (i.e., definitely not D-STAR).

The K0KDS blog has a post about the split, so go there for the full story. The ARRL has this news item about the organizational change. Here’s the paper that Yaesu published about their move into digital technology for amateur radio.

73, Bob K0NR

Completing the 2010 Trip Around the Sun

As the year 2010 comes to an end, I feel compelled to write something really insightful and meaningful as we log another trip around the sun. Perhaps some brilliant insights for the coming year? Or predictions of future technology breakthroughs?

Instead, I am writing this.

This is a mishmash of my thoughts about amateur radio at the start of 2011:

  • Tech License Class: One of the most fun and rewarding ham radio things I did this year was help teach a couple of Technician License Classes. There is nothing like engaging with newbies to the hobby to give you a new perspective on how cool amateur radio really is! I have a great set of teammates that made this class fun and successful: Stu W0STU, Paul AA0K and Joyce K0JJW.
  • Next Challenge: The challenge we see right now is helping these newly licensed Techs get engaged with amateur radio, so they don’t drop out. My belief is that the Technician License is a beginners permit that only enables a person to get started in the hobby. We are cooking up some fun activities to keep them going.
  • Public Service: We have a good thing going with the local fire district and the RACES group in our county in terms of real engagement on emergency communications. This is fun, rewarding and a good thing for our local community.
  • Dayton Hamvention: I am going to skip Dayton (again) this year. Instead, I’ll attend the International Wireless Communications Expo (IWCE), a trade show centered on land mobile and mobile wireless communications. For me, it has an interesting mix of emergency communications, land mobile, data/voice convergence and test & measurement topics. Oh, did I mention that it is in Las Vegas?  I suspect that it will be a better venue than Hara Arena 🙂
  • ICOM IC-9100: I have been patiently waiting for this rig to move from vaporware status to reality. Maybe it will happen this year?
  • Keep On Writing: I find that writing is good therapy, so I will keep that on the list for 2011. Mostly it will be this blog and the FM column for CQ VHF magazine.
  • Operating: It seems I don’t actually get on the air as often as I’d like, certainly not for the casual ragchewing QSO. Operating events seem to be a good way for me to get some air time: VHF Contests, Colorado 14er event, Colorado QSO Party, maybe an HF contest or two.
  • D-STAR: I haven’t been spending much time with D-STAR lately and I want to increase the focus on it. D-STAR falls into that dorking around with new technology category where experimenting with it and learning about it is the main activity.  The technology continues to grow in adoption…arguably slow in real terms as the analog modes have such a huge installed base.
  • APRS: Oddly enough, I have been messing around with APRS again, mostly thinking of it as a tracking tool for hiking and other outdoor activities. Maybe we need to look at bridging APRS with D-STAR location data?

Amateur radio is clearly my #1 hobby interest, and by a wide margin. But it is primarily a hobby (yes, with a public service hook to it…at least for me). It is important to keep it in perspective and not let it turn into another job. I already have one of those.

What are you going to be doing in 2011?

73, Bob K0NR

This Spewed Out of the Internet #15

It’s time to do one of those miscellaneous collections of drivel that spews forth from the interwebnet pipes. Some of this might even be important!

Some upcoming events: ARRL June VHF QSO Party and the Colorado FM Sprint, on the weekend of June 12th. The FM Sprint runs concurrently with the ARRL contest but only on Sunday afternoon. This is a good chance to get on the air with very basic equipment and have some fun.

The ARRL Field Day is coming up on June 26th and 27th. This is arguably the biggest on-the-air amateur radio event in North America.

I was playing around with setting up an SMS text messaging system for callsign lookup. The idea is that you send a text message (containing an amateur call sign) with your mobile phone and get the FCC or QRZ info back. In the meantime, I found that this problem has been solved by Callsign By Text. Very nice, check it out.

Female radio amateurs should check out Chick Factor International. It looks like a fun group.

I picked up a DV Access Point (DVAP) for D-STAR. This is a neat little device that provides flea-powered D-STAR access on 2 Meters by plugging it into a PC with internet connection. The South Yorkshire Repeater Group has a good description of the product. So far, this thing works really well.

By the way, the South Yorkshire group has a really good web site…interesting and timely information. Although they are in the UK, I find it relevant to US ham radio activity, too.

The Technician Class License question pool will be updated as of July 1, 2010. Our next Tech Class in Monument will be in October, so we’ll be updating the classroom material before teaching that class. It is clear that more technical content is being added to the question pool, which I think is a good thing. See KB6NU’s posting on the topic.

From The Complete Waste of Time Department, the FCC once again dismissed a petition from K9STH to change the amateur radio station identification requirements. Look, the FCC doesn’t see a problem here (and neither do I) so save yourself the trouble.

The FCC is seeking comments on the proposed new rules concerning emergency communications.  I took the time to file a short comment, basically saying that the FCC is on the right track but they should remove the reference to “government-sponsored drills”. Any legitimate emergency communications drill should be included, regardless of who sponsors it. The ARRL made similar but more detailed comments.

– 73, Bob K0NR

Update on the IC-9100

Ham radio VHF enthusiasts have been patiently waiting for the ICOM IC-9100. This HF/VHF/UHF/Satellites covers most or all of the popular amateur bands. Recently, ICOM has posted the specs and brochure on its web site.

The rig has dual receivers that allow monitoring two bands at once and it is set up for full-duplex on satellites. The built-in antenna tuner covers HF and 50 MHz. Operating on 1.2 GHz requires an optional module.

There is an optional DV (D-STAR) option that works on 10M, 6M, 2M, 70 cm and 1.2 GHz. This is the first combo HF+VHF+UHF rig that has DV available.

The 100 Watt output power all the way up to 50 MHz and 144 MHz is a real plus and 75 Watts on 430 MHz is not bad either. The 1.2 GHz option would be nice, too. This would be a great radio for portable VHF contesting. Oh, and I guess it works HF, too. 🙂

So everyone was expecting a big ICOM announcement at the Dayton Hamvention. Based on the reports I heard via the D-STAR system in Dayton, one unit was shown “under glass” so attendees could look but not touch. Also, a number of people have reported that the ICOM booth staff are saying that the 9100 will be available later this year (fall timeframe?) at a price of ~$US 4000.

Ouch. Most observers see that as a bit too expensive. I’ll withhold judgment until it is really in stock at a dealer with a real price.

–   73, Bob K0NR

Hacking Away at D-STAR Hardware

dstarWe’ve been looking at optimizing the performance of the D-STAR repeater here in Monument (W0TLM, 446.8875 MHz), so I’ve been searching the web for information on what other groups have uncovered. Not surprisingly, there has been some creative reverse-engineering and re-engineering of the ICOM D-STAR repeaters.

Here’s a summary of some Good Stuff that I found:

1. NU5D paper on DSTAR Repeater Modifications & Interference Testing

2. A good overview of the ICOM D-STAR repeater block diagram and a few modifications to the ICOM repeaters on the web site

3. The N5EBW LED Board – a drop in board to add transmit/receive LEDs to the ICOM D-STAR repeaters

4. The Utah VHF Society D-STAR page — some of the best technical information and practical evaluation of D-STAR technology

5. A Look Inside D-STAR Modulation – an article I wrote for CQ VHF magazine that explains the vocoder and modulation scheme in D-STAR.

If you come across other D-STAR resources, please let me know.

73, Bob K0NR

This Spewed Out of the Internet #9

0511-0701-3118-0930I have been traveling quite a bit lately for work, so here’s a catch up on a number of things spewing forth from the interwebnet.

I’ve recently re-discovered High Frequency Electronics Magazine, edited by Gary Breed, K9AY. This is a top quality trade pub that targets RF design engineers. In Gary’s September editorial, he highlighted the environment that the college class of 2013 grew up in….such as “text has always been hyper.”

I came across this summary of Top Ham Radio Blogs. They clearly have excellent judgment, since my blog is listed.  🙂

Computer World published this article,  Want to bone up on wireless tech? Try ham radio, a good read on the experimentation side of amateur radio written by John Edwards, W6JE.

Google’s Eric Schmidt talks about the future of the web…some interesting thoughts.  I hope his prediction of 100MB broadband comes true…but I am not expecting it to come down my road any time soon.

KB9MWR posted an interesting article about the radio range of D-STAR.

Ham radio saves the world (again)…. hams assist rescue on Catalina Island. This reminds me of when  I was out climbing Uncompahgre Peak and radio’d in a fallen hiker report.

Last weekend was the CQ Worldwide DX Contest (SSB version), so I did get on the air for a few hours. Mostly, I got clobbered on 20 Meters with my 100-Watts-to-a-dipole station being overrun by the Big Gun Stations. I did manage to work some DX on both 15M and 20M.

The FCC actions concerning EmComm and Part 97.113 have exposed different views on the role of amateur radio in emergency communications. See the comments on my blog posting, this article by Steve K9ZW and N5FDL’s blog. There seems to be some pent up frustration with ham radio EmComm folks coming from some corners of the ham community.

I encourage everyone to go back and read Part 97.1, the Basis and Purpose of the Amateur Radio Service. It lists five different items as the purpose of amateur radio, all of which are relevant and important. I’d also suggest that everyone lighten up just a bit (and be sure to stay on your meds).

73, Bob K0NR

D-STAR Presentation at MARC

dstarThe interest in D-STAR continues to grow in Colorado. I have responded to a request to talk about D-STAR at the Mountain Amateur Radio Club (MARC) meeting on Wednesday night. It will be a basic introduction to the mode/technology along with a demo of D-RATS. I don’t think I am an expert on the topic so I asked Elliot KB0RFC to assist. Between the two of us, we have enough experience with D-STAR to handle the topic well.

The MARC club is a fun group, so stop by if you get a chance!

Bob Witte (KØNR) and Elliot Linke (KBØRFC) will be presenting a program and demonstrating the basics of D-Star, the new amateur radio digital mode that can be used for both voice and data, at our MARC Meeting at 7 pm this Wednesday, Sept. 16th, at the Woodland Park Library. I hope you will make plans to attend!

See you then!!!

73 Wes KØHBZ

This Spewed Out of the Internet #8

0511-0701-3118-0930I am trying out a new twitter ap called DestroyTwitter. There are many to choose from, so as I reloaded my PC I decided to give this one a try. So far it seems to be good, which means compact, not too fancy and easy-to-use.

John C. Dvorak wrote that Twitter is the New CB Radio. I think he is right. My enthusiasm for twitter drops about 1 dB per week.

The VHF/UHF crowd is excited about the new ICOM IC-9100 that was shown recently at a Japanese ham radio show. This is basically an HF + 6 Meters + 2 Meters + 70 cm transceiver set up for satellite and (optional) D-STAR. Kind of does everything.

I am very much in favor of a Cash for Clunkers program for amateur radio gear and computer gear more than 5 years old. It seems like the gubment is handing out money to everyone else (without much logic applied), so why can’t we get a piece of that?

Interesting piece from the ARRL about power line companies and their responsibilities concerning radiated interference. Despite all of the concern about Broadband Over Powerline messing up the ham bands, there are far more incidents of good old power line noise causing trouble for ham radio operators. I have been involved in several of these cases and it is generally a real mess….especially if the utility is incompetent.

AMSAT has rejiggered its Suitsat program to fly without the spacesuit. I always wondered why they needed a spacesuit to make this work anyway. It turns out they don’t. The new suitless name is ARISSat-1.

There has been plenty of bickering on the AMSAT-bb email list as various people have complained about this project or that project AMSAT is pursuing. For some reason Suitsat-2 has become a target for complaints. My philosophy? Anything that involves amateur radio in space that works is OK by me.

I continue to play around with D-STAR now that the repeater is up and running in Monument. I was sitting there last night fiddling with the radio when VK2LOB from Sydney, Australia comes on the frequency looking to demonstrate D-STAR. We had a nice, short chat — what a pleasant surprise!

73, Bob K0NR

D-STAR is On Line in Monument

One of our local radio groups has put a 70 cm D-STAR repeater on the air here in Monument. Here’s the announcement from Elliot KB0RFC:

The W0TLM B repeater and gateway are on the air in their new PERMANENT home in monument near hwy 105 and I 25, coverage reports are needed. All gateway functions are operating please feel free to link to the repeater, or just call around.

The repeater is a joint effort between the Tri-Lakes Monument Fire radio association, the Tri-Lakes Monument Fire Department Communications Auxilary, And the Tri-Lakes Monument Fire Protection District. The purpose of this repeater is  to support emergency communications in northern El-Paso County. we will do what we can to create an environment conducive to training and support for actual emergency events.

We run a net on 447.725- 100.0hz tone every Monday night except the last Monday of the month where we have our monthly meeting at Tri-Lakes Fire station 1. All are welcome We hope to be participating in the CO-D-STAR net soon. W0TLM++B and W0TLM++G are on 446.8875- please check it out!

Please email any questions to
Elliot Linke

I got a chance to try D-STAR out from a remote perspective when I was out in the San Francisco Bay area. I got on the W6YYY repeater in Oakland on 440.03750MHz and chatted with Elliot KB0RFC back in Monument. This is way  cool!

OK, you may be thinking “I can do that with EchoLink or IRLP”, which is true (and that is also way cool). The benefits of D-STAR are still emerging, but one big difference is that each transmitted packet has callsign routing. One feature that I see as useful is the callsign squelch mode. I can keep my radio squelched expect for people specifically calling me. Other advantages of the “all digital” network are starting to surface, so stay tuned on that.

There are several D-STAR repeaters popping up in Colorado. The group leading the way is the Colorado D-STAR Association in the Denver area. The Cheyenne Mountain Repeater Group has a system on the air in Colorado Springs, currently in a test phase (limited coverage) on 446.9125 MHz (KC0CVU B). A group in Boulder is also working on a system but I am not sure of the status of that effort.

New technology, new learning, new fun.

73, Bob K0NR

Investigating the D-STAR Modulation Format

The D-STAR buzz continues to build in Colorado with a few repeaters on the air and more to come. For an overview of D-STAR, take a look at the article I wrote for CQ VHF magazine. I decided to dig into the digital modulation format that is used in D-STAR so I could understand it better. (Moving Forward!) At first, I figured that this newfangled digital modulation had nothing to do with FM but later realized that this is not completely true. (No, FM and D-STAR do not interoperate.)

It turns out that D-STAR uses Gaussian Minimum Shift Keying (GMSK), the same modulation format that GSM mobile phones use. What is that, you say? Let’s start with Frequency Shift Keying (FSK)…when the digital signal is a logical one, a particular frequency is generated. When the digital signal changes to a logical zero, a different frequency is generated. On the receive end, we just keep an eye on the frequency and decode the digital signal accordingly. In concept, we could generate this FSK signal by hosing the digital signal into an FM modulator. Minimum Shift Keying is a special case of FSK where the frequency shift (and the phase changes) are carefully controlled (modulation index of 0.5) to keep the phase discontinuities low and the bandwidth minimal. Add a Gaussian filter on the front end of this and you have GMSK. (The gaussian filter smooths out the digital transitions and gives an even narrower bandwidth.) I found this GMSK tutorial to be very helpful.

On the air, a GMSK signal has a constant amplitude, just like FM. It will switch back and forth between two frequencies as the digital signal goes high and low. The digital signal can be recovered using an FM detector but the output of the detector is the digital format.

Of course, GMSK is only part of the D-STAR modulation system. The other key component is the vocoder, which is the AMBE-2020™ Vocoder from Digital Voice Systems, Inc (DVSI). This chip performs the magic of smooshing the digitized voice signal into a reasonable number of bits per second so that when they are turned into GMSK they fit within the rather narrow bandwidth (6 kHz nominal). Since this vocoder chip is proprietary, it has caused some hams to grumble about the lack of an “open” vocoder algorithm. I think they have a point but it does get overblown. I have heard statements that this proprietary algorithm adds $100s to $1000s of dollars to the price of a D-STAR radio. My sources tell me the chip sells for about $20, a very reasonable price for this functionality.

I’m in the process of turning this investigation into my FM column for the Winter issue of CQ VHF, so there will be more detail there. I hope this short note gets your brain thinking.

73, Bob K0NR

My First D-STAR Repeater Contact

Here is another milestone in my D-STAR experience….my first repeater contact using the technology. (I had previously been using D-STAR on simplex.) There are no D-STAR machines within range of my house, but there is one west of Denver (the Colorado D-STAR Association, W0CDS).

I was headed to the Denver airport for a business trip to the west coast and I realized I would be within the W0CDS repeater coverage. I had previously programmed my IC-91AD with the right info to access the W0CDS UHF repeater on 446.9625 MHz. (If you think getting the right CTCSS tone plugged in is difficult, wait until you deal with the callsign routing for D-STAR.) I tossed the HT in the car and gave a call when I got close enough to Denver. Barry KA0BBQ came back to my call and we chatted for a few minutes.

As widely reported, the D-STAR audio is fine but you have to get used to how it cuts out under weak signal conditions. You don’t have the gradual fade of increasing FM noise…it just starts cutting out, similar to a digital mobile phone. I just had the HT rubber duck antenna inside the vehicle, so the signals were a bit on the weak side.

Watch to see D-STAR activity.

73, Bob K0NR

My First D-STAR Contact

At Dayton, I picked up an ICOM IC-91AD handheld radio, with D-STAR capability. The thing is, there are no D-STAR repeaters within range of my house. Fortunately, Elliott KB0RFC also picked up a D-STAR handheld and we arranged a sked on 2M simplex. The de facto calling frequency for D-STAR is shaping up to be 145.67 MHz, so that is what we used.

I have to admit that the audio quality was better than I expected. When the radio is not dropping bits, the audio is quite clean and clear. When the Signal-to-Noise Ratio degrades, you do start to hear that digital twang as the vocoder does its best to recover the audio in the face of digital errors. Overall, I was favorably impressed.

Tonight, we did some additional testing with DV mode and were surprised at the range of the handheld on 2M. The 70 cm band seemed even better, apparently due to the improved efficiency of the handheld antennas on that band.

There is lots more stuff to play around with, so stay tuned.

Digital voice on the ham bands? Must be the 21st Century!

For more info on D-STAR, see my article from CQ VHF.

73, Bob K0NR

D-STAR Equipment Grant in Colorado

The Colorado Council of Amateur Radio Clubs (CCARC) and Ham Radio Outlet (HRO) teamed up to encourage the adoption of D-STAR technology in Colorado. To date, there are no D-STAR machines on the air in the state so HRO offered to provide equipment to a suitable ham radio group to help get things started. The CCARC, the repeater coordinating body for the state, agreed to assist in the selection process. According to the letter from the CCARC and HRO, the equipment grant was awarded to the Colorado D-STAR Association, a newly-formed group of radio amateurs in Colorado. The donated gear is a “full stack” of ICOM D-STAR repeaters: 2M, 70 cm and 1.2 GHz.

This is a very creative way to get the ball rolling on a new technology for ham radio. Yes, HRO has a vested interest in having a D-STAR machine on the air in the Denver area….they will sell more D-STAR radios. But it is good to see that they coughed up some equipment to help get this going.

The ICOM web page on D-STAR is here. For an overview of D-STAR technology, see my CQ VHF article.

73, Bob K0NR

Jay Maynard K5ZC on D-STAR Repeaters

The Radio Amateur Information Network (RAIN) Report has an interview with Jay Maynard, K5ZC, from the National Frequency Coordinators Council concerning the use of digital repeaters. Jay discusses the issues around the alledged FCC statement that “D-STAR systems are not repeaters” and gives a good overview of the challenges of adopting digital repeater technology.

The interview exists in two parts:

Part 2:

If you are interested in the future of amateur radio repeaters, this is worth a listen.

73, Bob K0NR