How does the crest factor relate to the mean power vs the peak power? It doesn't seem correct to add 3 to that figure to come up with the crest factor.
Patrick has the peak and mean power for the various modes listed in the documentation for Multipsk, but I am not clear how to convert them to crest factor. My understanding is that the peak power and average power of a rectangular wave is 1. It can't be correct to add 3 to that value to come up with 4, can it? And MT-63 which has a peak to average of 10 times has a crest factor of 13? If you want to "broadcast" a message from one to many, then the only practical alternative is to use a non-ARQ mode, typically with a large amount of FEC. While this is done on amateur frequencies for sending a bulletin, calling CQ, and having a roundtable, if your goal is to have accurate messaging, then I don't see any option other than a good ARQ system. If Clover II would have worked better, I would have considered keeping my HAL P-38 board. But it was not that good with weak signals. Also, the P-38 had serious problems with Pactor back then. I remember someone later criticizing me for not using a 386 computer for the card. But at that time the 386 was barely even invented and 286 machines were state of the art. 73, Rick, KV9U Mark Miller wrote: >At 10:33 PM 8/23/2006, you wrote: > > >>I am not very knowledgeable on CRF (Crest Factors). Can you give us an >>idea of converting peak power/average power into CRF? >> >> > > >Using powers, crest factor = Peak Instantaneous Power / Average Power. A >more piratical way of measuring crest factor is (PEP/Average Power) + 3dB. > >I agree that ARQ has its benefits, but we still have to rely on the modem >scheme. This was my point earlier, that we reach a limit because we are >power and bandwidth limited. Because we are using HF frequencies, we pay a >coding penalty. Also if we look at the broadcast nature of non-ARQ modes, >it is apparent that they are much more efficient than ARQ modes. This does >not mean that ARQ does not have its place, it certainly does. The more >tools in the tool box the better. > >BTW I am an AMTOR OT myself. I remember when APLINK was used before >unattended operation was allowed on HF. I miss keyboarding with >AMTOR/PACTOR and CLOVER. > >73, > >Mark N5RFX > > > > >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/ <*> 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/
