Rick and all,
Yes...that's probably correct. I guess what I am really asking (as you are?)
what modulation technique works best on HF. This may be a balance between the
maximum number of bits you can get off of one carrier (tone) vs. how robust it
is.
There will surely be trade offs. But we need to come to some consensus
concerning how robust we want a data mode to be and what user thought we want.
Also, we probably need to divide data modes between keyboard-to-keyboard (chat)
modes, Broadcast modes and messaging modes. I suspect that each classification
will have a different optimum mode and the robustness and throughput desires
will be different.
Here's my "view"...desired specifications:
Mode Robustness * User Throughput
Chat -10 dB SNR 60-200 WPM ASCII
Data -10 dB SNR 800-~ WPM ASCII plus binary equivalent
Messaging -5 dB SNR 800-3000 WPM plus binary equivalent
* on a Poor CCIR Channel
73,
Walt/K5YFW
-----Original Message-----
From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED]
Sent: Wednesday, August 30, 2006 7:12 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] Using 8FSK ARQ in PCALE (Re: ALE QRM is
minimal)
Walt and group,
My understanding is that the 64QAM mode of the DRM programs being used
by SSTV operators does not work well on HF frequencies unless you have
near perfect conditions.
What are the opinions on the how well multipath and difficult
conditions are handled by these different modulation techniques? Also
comparing with QAM and OFDM.
73,
Rick, KV9U
DuBose Walt Civ AETC CONS/LGCA wrote:
>Why not run 64 tones with FSK at 50 baud or 64 tones with OQPSK at 50 baud?
>
>Shucks, for that matter how about 128 tones using QAM64 at 50 baud?
>
>Walt/K5YFW
>
>
>
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