[DSP-10] Last Month's DCC

[Courtney Duncan]

I attended the Saturday afternoon sessions of the ARRL/TAPR Digital 
Communications Conference September 24.  Though I couldn't make it to 
the Friday or Sunday portions, it was still well worth the drive down to 
Santa Ana.

I attended three sessions and the membership meeting:

Software Defined Radio, Gerald K5SDR

These are the SDR-1000 people and they have an impressive product.  The 
presentation was clearly geared to folks who know the sights and sounds 
of HF contesting and DXing operation and the demos were clearly and 
convincingly aimed at selling those folks on the direct-conversion, 
software intensive approach.  No-ring filters, unbelievable noise 
control, the list of things that the large open source group wants to do 
with this platform is huge, the amount that is already supported already 
surpasses most commercial rigs, and the near-term items on the todo list 
are enticing.  Like, connections to existing sound card software, all 
internal, no wires.  I'll have to have one of these one of these days 
... I kept trying not to think.

The USRP and GNU Radio, Matt N2MJI

On the heals of the SDR-1000 talk I was thinking, "How can anything 
follow that?" but Matt's approach and goals are so different that it was 
really an orthogonal presentation.  Hardware towards RF is nearly an 
afterthought, and this is broadband in ways that "conventional" amateurs 
are not used to thinking about.  Among live demonstrations was tuning in 
a local FM stations and watching the spectrum (including stereo 
subcarrier) while listening, and showing simultaneous transmission on 
multiple 440 FM channels of different audios.  The ultimate "regional 
jammer" technology.  Of course, that particular application is not the 
point, but the possibilities that this technology would open up are a 
new frontier.

This isn't for HF contesting and DXing, this is for big bandwidth 
applications.  Their demo table in the "toys" room was interesting too. 
  One of their PCB antennas looked like a 900 to 2400 MHz log periodic 
in about five elements.

Passive Radar, Eric K7GNU

The idea here is to us other people's high power transmitters (like FM 
broadcast) and process the reflections from objects like airplanes or 
the aurora to determine range and range rate in a bi-static radar mode 
(transmitter and receiver at separate locations).  Eric hasn't actually 
done anything yet except seriously interesting research about the 
history and mathematics of radar.  (Did you know that bi-static radar 
was first used by the Germans in WWII?  When the English were using 
their brand new mono-static radars to navigate their bombers attacking 
over the channel, the Germans listened clandestinely on the radar 
frequency and when they heard something, knew that an attack was on the 
way.)  He thinks he can see airplanes from his house on a $2000 budget, 
and I don't doubt it (having strongly suspected fortuitous airplane 
reflections on VHF packet tests I've been involved in.)

The most fun was a description of some amateur-budget aurora research 
being done at the University of Washington.  They use a rock-n-roll 
broadcast station in Seattle and receive reflections from the aurora, 
ionosphere e-layer, and, yes, airplanes, to the north on the other side 
of a mountain range.  In terms of correlation properties of the signal 
they have a saying, "hard rock is better than talk".  Hi!

TAPR Membership Meeting

This is most memorable from the discussion of TAPRs name.  After all, 
they are no longer based in Tucson and no longer exclusively packet or 
radio.  Indeed, the quintessential discussion of the problems of the 
hobby being thought of as "amateur" came up.  I don't think they are 
going to change anything.  Recognition always trumps accuracy.

Also in the "toys" room, I got a good look at N7HPR's DSP-10.  It looks 
a lot like mine, but the internal wiring harness is a lot cleaner (looks 
like it was put together by someone who knew what they were doing), the 
jack placement is more logical (user stuff on one side, antennas, power, 
and jumpers on the other), and, it uses PowerPoles.

Between this and some of Byon, N6BG's products (byonics.com, APRS and 
related gear), I became sold on PowerPoles and have spent the last weeks 
since the conference converting all of my old and new equipment, and 
vehicle harnesses, over to them.

Had a first eyeball visit with John W2FS who had, years ago, written an 
online article about an AMSAT speech I had given in the late 80s.  ( 
http://www2.compcenter.com/%7Etcarc/w2fs-article.html )  What was neat 
about this was that I had just discovered this piece and referred to it 
in my own online ham autobiography ( 
http://home.earthlink.net/%7Ejccool3/hambio.html ).  The point of my 
speech, as an AMSAT leader at the time, was that there are hams who are 
operators and hams who are builders and we have to manage our 
institutions to utilize and meet the needs of both groups.

I told him, "When I discovered that I was a builder, I resigned from 
AMSAT administration and vowed I'd come back as a builder."  That's 
where we are right now!

Finished up the day with a long chat with Paul KB5MU about AMSAT gossip, 
MacIntosh ports of everything we'd seen today, and nearly limitess other 
topics of mutual interest.

I'm glad I took the Saturday to go see this show and, browsing over the 
proceedings now, wish I'd been able to go to the Friday sessions as 
well.  Lesseeee, where is this going to be next year?

Courtney, n5bf at amsat.org