Hold those thoughts for the ARRL Prize.
But yes there is lots of thought about narrow moodes, 500 Hz and less and wider
modes...3.5 KHz and perhaps 5-6 KHz.
The ARRL has proposed a 3.5 KHz bandwidth limit for wide bandwidth modes but I
think the FCC wants to limit it to less than 3 KHz (maybe
I did some more research and found out that according to the Wikipedia
(which I find to be the most incredible resource on the internet for
general encyclopedic information), PSK (Phase Shift Keying) can be
considered to be a subset of QAM (Quadrature Amplitude Modulation). That
rather
KV9U wrote:
I did some more research and found out that according to the
Wikipedia (which I find to be the most incredible resource on the
internet for general encyclopedic information),
I can agree on that8-)
PSK (Phase Shift Keying) can be considered to be a subset of QAM
Please allow me to make some comments based on research done here in San
Antonio.
As some may know, SouthWest Research Institute is located here in San Antonio
and has done work on high baud rate modes with very poor SNRs. Also they are
part of the current project that is flying a space craft
Nino,
That was kind of my thought...interesting about the Chip64 decoder...I will
have
to study the mode more.
In my post I did day that it was a 100 mile path but did not stipulate that is
was all over land. Also, unless you live in an area where the ground
conductivity changes a large
If I understand it correctly, the raised cosine pulses tend to be more
efficient with power, reduce the crest factor (Pactor 2 is under 1.5),
and perhaps make it easier to have a cleaner signal.
Just for clarification I have a question: Is QAM modulation a form of
ASK? It would seem so to me
wa5rop
- Original Message -
From: KV9U [EMAIL PROTECTED]
To: digitalradio@yahoogroups.com
Sent: Tuesday, January 23, 2007 9:55 AM
Subject: Re: [digitalradio] PSK Modes
If I understand it correctly, the raised cosine pulses tend to be more
efficient with power, reduce the crest factor
Why do some modems use more rectangular waveforms instead of what
appears to be the optimum waveform for HF modems? Or are there downsides
to raised cosine waveforms?
In terms of bandwidth, it seems to me that for most uses, a 500 Hz
bandwidth is a wise choice. This seems to be a good tradeoff
KV9U wrote:
If I understand it correctly, the raised cosine pulses tend to be
more efficient with power, reduce the crest factor (Pactor 2 is under
1.5), and perhaps make it easier to have a cleaner signal.
Raised cosine is, above all, less bandwidth greedy.
Just for clarification I
Walt/K5YFW wrote:
if you may be receiving 1, 2 and 3 hop signals. How does this affect BPSK
and QPSK signals from for example PSK31/63/125?
the 3 different signals will sum at the receiver, but, having each one a
different phase, the sum is destructive with the result that they tend to
Nino:
I have not had luck with Chip...not a single QSO so far.
On 40 meters local NVIS test it did not work.
Maybe the 300 baud chip rate was too fast for it to work.
Would it be prefarable to use it on a close to the MUF, single ray link?? I
would like to try it on the air.
How has been
Some of us did try Chip modes when Nino first came out with them, but
they did not seem to perform as well as existing modes.
I really implore to our treasured programmers to see if they can come up
with some modes that can compete with Pactor modes. Especially some ARQ
modes that can work on
-- Original Message --
From: KV9U [EMAIL PROTECTED]
Reply-To: digitalradio@yahoogroups.com
Date: Mon, 22 Jan 2007 14:47:12 -0600
Some of us did try Chip modes when Nino first came out with them, but
they did not seem to perform as well as existing
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