[clue-talk] Vintage Voltage Expo

[Nate Duehr]

On 3/20/07, Sean LeBlanc <seanleblanc at comcast.net> wrote:
> I'm lurking on the Denver Mad Scientists' list, and someone mentioned this:
>
> http://www.danacain.com/about5.html
>
> Seems pretty interesting, though I'm not really going to buy anything.
>
> The Tesla Tech thing sounds interesting.

Yeah, that's a new gathering this year, should be interesting.  I'm
still deciding if I can make it to that one or not...

There's also four Front Range area HamFests listed so far on the ARRL calendar:

http://www.arrl.org/hamfests.html
(You can search by State - that's the easiest...)

For those who haven't heard, all Morse Code requirements have been
dropped from all three Amateur Radio license class tests by the FCC as
of late February 2007.  This is causing a renewal of interest in the
hobby overall, and of course, the usual controversy people are prone
to manufacture...

http://www.arrl.org/?artid=7300

All sorts of interesting digital work going on on the HF bands these
days... the ARRL is even petitioning folks to submit their best ideas
for an open-source standard for digital audio in narrow (2.5 KHz)
audio bandwidths seen on HF.

Right now a couple of competing protocols are out there, both using
(wait for it...) Coded Orthogonal Frequency Division Multiplexing
(COFDM) and Quadrature Amplitude Modulation (QAM) as the on-air
modulation method.

http://www.arrl.org/news/stories/2007/02/22/102/?nc=1b

Sadly, the brainiac coders who would know how to do this with the
Linux audio chain don't seem to be as interested as the Windows
coders, so far...

I've also lamented that our FM repeater club would like to try out
some digital (versus FM analog) modulation on our systems, but that
there are really only two good options (user radios are available)...
one being the APCO Project 25 digital standard which uses a
proprietary ($$$) CODEC made by DVSI, and the other being Yaesu
Corp.'s "D-Star" system, which is an open standard but not being
really adopted by anyone other than Yaesu.  (It's CODEC also sounds
horrible, from what I've been told by those who jumped in with both
feet.).  DVSI's CODEC is too expensive for personal/educational
coding, sadly, since P25 is a decent standard otherwise.

Other stuff of note:

WSJT -- a specialized digital mode for EXTREMELY weak signal work,
originally conceived to handle radio contacts via the ionized trails
left behind meteors, but since used for bouncing signals off the moon,
etc...

http://www.vhfdx.de/wsjt/
Debian even has a WSJT package!  :-)
http://packages.debian.org/unstable/hamradio/wsjt

PSK31: Low speed text over very narrow bandwidths
http://www.psk31.com/
(This one's kinda the "grand-daddy of the newest wave of digital RF
modes, and is almost "old" at this point, but lots of activity...)

It's been interesting the last few years to watch all of this digital
stuff start to take over radio... even to have a voice chat.  Nothing
beats the "DSP filter between your ears" for weak-signal work, but
some of these digital software packages may truly change all that.

Linux and OSX are making a "showing" in all of these modes, but the
vast majority of the good software for this stuff is done on Windows.
I like to blame it on the convoluted mess known as "Linux Audio" --
not many good DSP coders really want to jump into the mess Linux has
made of it's audio interfaces, etc... Plus hams are generally cheap,
but they know when they should pay for software they can't write...
and lots of this stuff is $10-$20 US and/or shareware... the free
stuff on any OS, Windows, Linux, OSX is pretty poor quality or arcane
in its user interface(s).

Nate (WY0X)