[Linux-ham] Fwd: Questions about D-STAR

Thu Oct 25 00:11:52 EDT 2007

Gary's reply forwarded... (with permission)

---------- Forwarded message ----------
From: Gary Pearce KN4AQ <kn4aq at arrl.net>
Date: Oct 25, 2007 12:00 AM
Subject: Re: Questions about D-STAR
To: Tanner Lovelace <kb4tye at arrl.net>
Cc: rars-l at rtpnet.org

 Hi, Tanner

 I'll snip and thread my reply.... (I'm also copying this to the RARS
mailing list, since they are "hosting" the D-STAR repeater in town
temporarily. Tanner's complete e-mail is copied at the end of this
message).

 >...in response to a letter in QST ..KN4AQ wrote:

...The AMBE vocoder, licensed by Digital Voice Systems, is the only
 proprietary component, and anybody can buy one.

Yet, as another friend of mine points out... For small-scale use and
 prototyping, the only option is to purchase a dedicated hardware IC from
 DVSI."
 As I said, anyone can buy one. Yes, if you want to license the
software and roll your own, it's either prohibitive or not available.

 There are vocoders and codecs available for free. WinDRM uses one.
It's not as good. You couldn't skinny the signal down to the ~8 kHz
wide channel and have voice, FEC and data.

What, exactly, does installing a D-STAR system gain us as amateurs?
 We gain experience with digital voice systems. My article pointed out
the advantages (and disadvantages) of digital. In this case, some of
the advantages are noise-free operation down to a signal threshold
equivalent to a very noisy analog signal; elegant callsign-based
network routing; a 1200 bps data stream that is an integral part of
the signal, and routes with the voice signal anywhere through the
network; and several user/radio features such as "callsign squelch"
that allow selective calling based on your callsign.

Does it let us advance the state of the art in learning and implementing
 communication technologies?
 Hams know nothing about digital voice technology today - 10 years or
more behind the state of the art. D-STAR may or may not become THE DV
technology for ham radio, but it is a huge jump-start.

Does it bring hams together by giving them a common platform that
 people can use without having to spend lots of money on new equipment?
 A common platform? If hams and other manufacturers choose to
implement D-STAR, then yes. In today's world of splintered format
technology, that's not a given. There are a handful of P-25 based
digital ham repeaters (they were on the air before D-STAR arrived)
that are incompatible. I pointed out in my article that other DV
formats may compete. Anyone jumping on the D-STAR bandwagon is taking
a risk, though the radios are all good analog radios, too.

 Inexpensive? Not today. One ham is experimenting with the Icom D-STAR
plug-in board (about $150) to see if he can make it work with other
radios. It's not ready yet, but he's had some success.  Several hams
are working on implementing D-STAR on existing analog repeaters. New
ICOM radios are expensive now, but over time I think we can assume
that the "average" radio will be DV capable, just as the "average" HF
rig became SSB capable, the "average" FM rig gained CTCSS
encode/decode, etc. Once that occurs, hams who operate only legacy
radios may not be able to use DV unless adapter projects are
successful.

Does it help us in the mission of emergency communications?
 The ARES leadership in Alabama and other areas think so. But it will
be a long time before there is a critical mass of D-STAR (or any other
digital voice/data format) operators to truly supply a DV emergency
communications team. Analog voice will be the "least common
denominator" for a long time, but specialized use/teams will take
advantage of D-STAR's DV and DD (the 128 kbps "ethernet" 1200 MHz
connection).

Can I as a software engineer code up a program that will implement
 D-STAR as a software defined radio and fully interoperate with installed
 systems?
 With an AMBE vocoder chip, yes. The specs are published.

As it is now, my understanding is that the answers to all of those questions
 are no, but I would love to hear your side of the story?  I don't mean to
 rain on your parade, but it just seems to me like we're getting further
 away from our original beginnings and much closer to "black box radio"
 where no one knows anything except how to push the power button.
 Ham radio's original beginnings, of course, are spark, and I don't
think you want to take us back there. But where would you draw the
line, and what would the trade-off be in giving up advanced
technology?

 I've been a ham since 1965, and most people consider me fairly
technically competent - as a ham (I have no formal technical training
or education beyond some electronics courses in high school). I am not
capable of nor interested in designing or building my own radios. I do
want to know how they work, and how to use them to maximum
effectiveness, especially in ways the designers may not have
predicted.

 Some hams DO want to design and build their own equipment. I think
there will always be an important place for them, from the most basic
level as someone gets started with a QRP CW transmitter in an Altoids
can, to modifying a GE MSTR-II repeater to work with D-STAR, to
designing advanced analog and digital equipment.

 And that is great! What's stopping them? The AMBE vocoder?

 Is this a practical discussion or a purely hypothetical one?

 By the way, I see you copied the Linux user group. I didn't, since
I'm not a member and my e-mail would probably bounce. But feel free to
forward my reply. And I'll note that the D-STAR gateway requires a
Linux computer.

 Speaking of which, hams are busy writing software aps to take
advantage of the data signal, re-writing the gateway software that we
inherited from Japan that doesn't work that well for us here, and
understanding the in's and out's of networking these systems. I've
seen literally hundreds in one room, learning, discussing, arguing,
and having a great time with this new (to us) technology. It reminded
me of the excitement hams felt about packet radio when that was new.

 73,
 Gary KN4AQ

 ==============

 Tanner's full, original question:

 From: "Tanner Lovelace" <kb4tye at arrl.net>
 Sender: clubjuggler at gmail.com
 To: kn4aq at arrl.net
 Subject: Re: Fwd: [KD4RAA-K4JDR Rptrs] RARS Testing UHF D-STAR Repeater
 Cc: "Amateur Radio meets Linux" <linux-ham at trilug.org>
 Hi Gary,

 I have a few questions about D-STAR. If you don't mind spending a
 few moments on them, I'd really appreciate it.

 One of my friends notes that in response to a letter in QST that
 was critical of D-STAR (and was a response to your article there)
 you wrote:

 "I appreciate the compliment!  There has been a furious debate on
 Internet message boards about whether or not D-STAR is proprietary.  It
 isn't.  The AMBE vocoder, licensed by Digital Voice Systems, is the only
 proprietary component, and anybody can buy one.  I wrote the article to
 give the average ham an idea of what was coming down the road, and so
 far, only ICOM has taken the gamble on VHF/UHF digital technology with a
 full system that makes the radios more than a novelty.  If it find a
 market, others will follow.  Right now some hams are building their own
 D-STAR radios and repeaters with non-ICOM components."

 Yet, as another friend of mine points out from
 http://en.wikipedia.org/wiki/Advanced_Multi-Band_Excitation

 "AMBE is controversial in that the licensing terms are very restrictive.
 While a licensing fee is due for most codecs, DVSI does not disclose
 software licensing terms. Anecdotal evidence suggests a minimum fee from
 $100,000 to $1 Million. PC implementations are not allowed. For the purposes
 of comparison, MP3's licensing starts at $15,000. For small-scale use and
 prototyping, the only option is to purchase a dedicated hardware IC from
 DVSI."

 So, I'm trying to reconcile both your statement where you contradict
 yourself by saying D-STAR isn't proprietary yet then go on to say
 that it is (because AMBE is) and the other statement about AMBE
 wherein licensing is outrageously expensive with prohibitive restrictions
 on it.  What, exactly, does installing a D-STAR system gain us as
 amateurs?

 Does it let us advance the state of the art in learning and implementing
 communication technologies?

 Does it bring hams together by giving them a common platform that
 people can use without having to spend lots of money on new equipment?

 Does it help us in the mission of emergency communications?

 Can I as a software engineer code up a program that will implement
 D-STAR as a software defined radio and fully interoperate with installed
 systems?

 As it is now, my understanding is that the answers to all of those questions
 are no, but I would love to hear your side of the story?  I don't mean to
 rain on your parade, but it just seems to me like we're getting further
 away from our original beginnings and much closer to "black box radio"
 where no one knows anything except how to push the power button.

 Thanks very much for your time.  I eagerly await your response.

 Cheers,
 Tanner Lovelace
 KB4TYE

 --
 Tanner Lovelace
 clubjuggler at gmail dot com
 http://wtl.wayfarer.org/

 ARVN: Amateur Radio//Video News
 Gary Pearce KN4AQ
 508 Spencer Crest Ct.
 Cary, NC 27513
 kn4aq at arvidnews.com
 919-380-9944
 www.ARVidNews.com

-- 
Tanner Lovelace
clubjuggler at gmail dot com
http://wtl.wayfarer.org/
(fieldless) In fess two roundels in pale, a billet fesswise and an
increscent, all sable.