Walt, Maybe someone can clear this up, but what is the difference between the differential modes such as DBPSK, DQPSK, 8DPSK, and 16DPSK such as used with Pactor 2 and modes such as 8QPSK, 16QPSK?
With the former, it is my understanding that with a single tone, the binary form (DBPSK) gives you one bit/second, DQPSK two, 8DPSK three and 16DPSK four. With the previous discussions on baud rate for the STANAG and MIL modems, can we still say that HF should use baud rates below 45? The claim is that these modems appear to be able to use extremely high baud rates, well above even 300 baud on HF and still work well under difficult conditions. In fact, the ALE folks believe that amateur radio is being held back on HF because we can not transmit in excess of 300 baud on most HF frequencies. Even Pactor does not exceed 200 baud and that is only under the best of conditions and even at 100 baud, the claim by Dr. Rink was that "The short term time jitter has a magnitude of up to 5 msec. Larger time smearing can only be observed under very special conditions of the ionosphere. A baud rate of 100 symbols per second has proven to be low enough for almost all possible propagation conditions, especially if powerful error control coding is applied. Is there anyone here who can further explain this? 73, Rick, KV9U DuBose Walt Civ AETC CONS/LGCA wrote: >Greeings All, > >How hard is it to demodulate a 16QPSK as compaired to a 8QPSK signal. > >And I have forgotten but does a 16QPSK signal will allow for 6 bites per cycle? > >Looking back at some very old hand written notes I took at an HF conference at >Scott AFB, IL where Collins-Rockwell, Magnavox and Harris Comm Gp were making >presentations, they said that they all agreeded that 45 baud (maybe 45.5) >should be the highest baud rate for the low end of the HF band and even though >you could go higher closer to the MUF, if you needed a fixed buad rate, chose >the one that was the lowest. > >Thus, if you have a single tone/carrier with 16QPSK, modulates at 45 baud, 1) >what would its bandwidth be and 2) what is the total bit rate for the signal? >(I would give you my answer; but think I might be really wrong and you will >question my math. Hi Hi.) > >Until tomorrow...Thanks and 73, > >Walt/K5YFW > > > >Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org > >Other areas of interest: > >The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ >DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) > > >Yahoo! Groups Links > > > > > > > > > > > > > > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
