John's Meanderings

Is AMBE/D-STAR the only way?

Every few months, the various D-STAR forums have someone come on and say that AMBE was a bad choice for D-STAR and that it should be replaced by CODEC2 or some other open source CODEC.  Side note: AMBE is not a codec, its a vocoder.

Here is my latest response.

I don’t think anyone is saying that AMBE/D-STAR is the only way to do digital voice on Amateur Radio.

I think what people that do the work, understand the system, and have been at this for awhile get tired of are just a few key points:
  1. Beating up D-STAR over the use of AMBE
    • It’s just a part, like a microprocessor, DSP, etc.
    • It is the best commercially available, off the shelf, component to provide digital human voice over the radio
    • It’s price is reasonable (how it is packaged by some vendors for sale is pretty high for their BOM)
    • It is used in other Amateur Radio products (AOR ARD  digital voice, Alinco digital voice, NXDN, MotoTRBO, next generation P25) without the same vitriol.
  2. People saying we can just modify D-STAR to use Codec-2 or some other Codec
    • Those of us who work with interoperability and implementation standards understand the issues with making non-standard changes to a protocol.
    • Standards are controlled through a process (that the JARL doesn’t execute well), which is where changes should be vetted, voted, and documented.
    • We shouldn’t confuse consumers of a protocol by implementing something different and give it the same (or very similar) name.
    • Introduction of incompatible systems into a working and established network or protocol framework creates unneeded issues.
  3. People taking a narrow view of what the protocol means
    • If you only look at Digital Voice you are leaving out much of the D-STAR protocol
    • Not considering side effects
    • Not understanding how one interconnects incompatible protocols  (through the use of bridges, protocol gateways, etc.)
  4. Market, social, investment, and cultural aspects
    • Acknowledging that most operators want a self-contained radio whether a handheld, mobile, or base.
      • Interconnect issues to external devices creating more points of failure
      • Aesthetics – lost on the experimenter, but for the larger community there is value in an attractive package.
      • They want to buy something off the shelf that is ready to use. (USTrust registration is problematic for this)
    • People who have made investments in infrastructure (repeaters, gateways, etc.) don’t want them “broken” by non-compliant systems
    • Some people like the clarity of AMBEs vocoder and don’t want it mixed with analog or even other systems that don’t fit the same profile.
I, and I venture many others, look forward to additional digital voice and data options.  Maybe something will come of Codec-2, maybe not.  If it proves to be a better technical (not religious) solution and a manufacturer picks it up to create the self-contained radios to build out an entire network like D-STAR, great, the market will decide.  I believe digital is the future and it will evolve, but basically I think the plea is basically, bluntly, “put up or shut up” — in other words, do the work to build something and put it out, in the meantime use what is available without this continued babble about how evil AMBE/D-STAR is and if “somebody” would just make “this change” it would be so much …
Let’s use the D-STAR and related forums and groups to work on D-STAR.  If one wants to do something different create your own community/forum/group and have at it.


  1. I realize this is old, but a Google search of Codec 2 D-STAR puts this page near the top. It is now almost 2 years later, and things have stabilized a bit. ICOM’s great ID-51a truly sets the bar for other D-STAR HT’s.

    You make a great point about repeaters and other infrastructure, and the fact that the digital voice codec is only a part of the discovery, linking, texting and all the other features that make D-STAR so popular. I also understand the ‘standards’ argument, and its a very valid argument.

    BUT… (you knew it was coming..) The ‘breaking stuff’ argument is bull-hockey. The AMBE part of D-STAR may be a black box, but the rest is upgradeable firmware. Any decent programmer could modify the D-STAR standard to include other codecs, add a codec-specifier to the digital handshake, and gracefully revert to AMBE if that handshake fails for a radio that doesn’t have the new firmware yet.

    What is very true (and kinda sad..) is that D-STAR marks the first time ANY proprietary encoding scheme has been embraced as a standard by Amateur Radio. The fact that I cannot even try to reverse-engineer this codec, forget write my own version, without breaking the law is anathema to everything Amateur Radio has stood for during its many decades of existence. We can’t LEARN from it. We can’t experiment with changes to it. We can’t improve upon it. Kinda sad indeed.

    Granted, Codec 2 may not be the answer, but all tests point to it being a Very Good option. Does Codec 2 need to be standardized? Sure, but so would any other codec. Standardization requires a lot of time, effort, and money – hard to come by with little support. Current tests on HF seem to indicate robustness and graceful degredation in noisy and/or fading RF paths. Bandwidth is a quarter of AMBE’s 3600 bps codec (current D-STAR), which does mean more power to get the bits down the airwaves.

    I’m not saying D-STAR sucks – its obviously a very good and well implemented effort at digital voice communications. But the bandwidth (6 KHz) is huge for HF voice. Lets drop our polarized glasses and think digital for a minute. This stuff is all bits, and we can make them all work together. If we want to.

    • K7VE

      20 June 2013 at 23:32

      Chris – I respect your views, however AMBE is not the first proprietary (patented / IP) ‘encoding’ to be used in Amateur Radio. To name a few: AM, FM, SSB, RTTY, Pactor

      D-STAR isn’t the first or only Amateur system to use AMBE (Alinco, AOR, …) also if you use NXDN, DMR/MotoTRBO, P25 Phase II, etc. on amateur radio, you are using AMBE.

      Codec2 is interesting. I run it on HF, I also wrote and run (Codec 2 QSO Finder)

      It’s really not about one is better than the other — it’s one isn’t the other and existing D-STAR radios/infrastructure is not easily modifiable. Some folks are working on bridging systems so that one can talk to the other.

  2. I am progressing with a CODEC2 variant of DSTAR, currently .
    I’ll be using the full 3600 bps available- no FEC because codec2 is fairly resilient and the improvement of voice quality is worth the extra bits.

    I actually do this sort of thing for a living.

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