[amsat-bb] Re: Icom D-Star
greggwon at gmail.com
Sat Apr 23 08:42:53 PDT 2011
In the end, digital compression of spectrum space is going to happen more and
more. AM style broadcast is hugely inefficient even though it is painfully
simple to do. I don't really believe that D-Star is the right choice for
"everything" because it is single source. But, so is Microsoft windows,
MacOS-X, and many other software based systems. If you are an FPGA programmer,
perhaps you can build an FPGA based CODEC for amateur radio that would do voice
compression etc. But in the end, you also have to have an transmitter with the
appropriate bandwidth output to reduce the spectrum used.
It's by no means a simple task. Everything in a radio system has to change to
do spectrum conservation or provide high speed digital data transmission.
The simple fact is that HAM radio emission standards (simple voice modulated
with some simple emission standard) are now more than a century old. As
capable as they are, the abilities they present seem minimal to some. I think
that there are great things about them because they do allow long distance
communications which the HAM community regularly uses to support distant
operations which provide aid to areas struck by natural disaster.
But, we all have to understand that it costs money to do anything "new and
different". People experimenting with stuff is great, but it minimizes who can
participate if you have to "build it" or "pay a lot". That's just life in
general. You can't participate in everything unless you have the resources to
In the US, any digital communications that is coded in some way only needs to
have a publicly visible document detailing how it works for the FCC regulations
to be met. Other places in the world may have different requirements and
that's nothing new is it?
On 4/23/2011 5:37 AM, Gordon JC Pearce wrote:
> On Sat, 2011-04-23 at 20:00 +1000, Tony Langdon wrote:
>> At 07:33 PM 4/23/2011, you wrote:
>>> The chips are "readily available" at a few hundred dollars apiece, and
>>> if you attempt to implement your own AMBE codec then you're going to
>>> have DVSI's lawyers jumping on you.
>> More like $20 apiece in small (possible 1 off) quantities.
> I'd love to know where you're seeing them for that much in onesy-twoesy
>>> Proprietary software has no place in Amateur Radio.
>> It's hardware with firmware. So let's throw out all the other
>> proprietary bits (processors with embedded code, etc) and go back to
>> soldering valves?
> Yes, throw out the proprietary bits. Write your own, it's easy.
>> The simple fact of the matter was back around 2000 when the D-STAR
>> spec was developed, there weren't a lot of choices for how to
>> compress speech into 2.4kbps and have FEC. AND have it available in
>> a suitable form for implementation into mobile and handheld
>> radios. While the proprietary codec is a minor inconvenience in some
>> situations, it's proved to be no impediment to home brew enhancements
>> to D-STAR. The number of ham developed D-STAR projects is
>> significant, so that one chip hasn't proved to be an impediment to
>> ham experimentation in practice.
> Yes, "back around 2000". It's over ten years old. We have better
> codecs and better modulation schemes now. Why are we crippling digital
> comms with a single-source proprietary codec that sounds like an angry
> duck in a tin outhouse?
> The commercial world is no better - just look at DMR, which uses the
> same awful AMBE codec!
> Gordon MM0YEQ
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