Ok Jose and everyone...let's take a poll or have some SWAGs. So what do YOU (plural) think is the best modulation technique to use for a NEW and BETTER HF data mode?
PSK QPSK DBPSK DQPSK (Dairy Queen PSK...Dairy Queen is an ice cream franchise) 8DPSK DQPSK 8QPSK 16QPSK And by the way, the Russians have a 96 tone HF data mode that is suppose to have great throughput, is very robust and is wider than 4 KHz. Concerning baud... If the MUF is 32 MHz, then I believe that it is reasonable to think that 300 or 400 baud might work well on 10M...but on 40M and 80M it flat won't work. So at 40 and 80M we will probably find that 45.5 baud works rather well. Some might suggest that 31 baud is better. I don't know how we can really find out what baud is best for each band and even if we want to. Maybe we want to take a SWAG and have a different baud for every band? That's probably a bad idea. But what about 31 or 45 baud for 80-20M, 90 baud for 30M-15M and 200 baud for higher bands...we can make the baud rate manual or automatically selectable. For a basic or start, I would recommend manually selecting baud rates. My gut feeling is to start slow...play it safe to start with...31 or 45 baud all bands. Choose a good modulation technique...one that where you can manage the detection. Choose a method of FEC and add ARQ. You can see if you get better quality (error free copy) with or without ARQ, with or with FEC, etc. Choose a standard test text for testing and of course make sure that the chat mode works because after all, we DO (at least most hams) like to chat at bit. The KEY to any adventure is to have a goal and the flexibility to make changes as you go and work with as many as you can to evaluate what you create. Once a mode have shown what it can do, i.e. established its capability, then change to some other configuration. AND REMEMBER, IT NOT A BAD THING TO FAST FAIL A BAD IDEA. If something doesn't work as good as you have, deep six it...don't carry on with a bad idea. Its not a bad thing to say that you idea didn't work. Those who are very technically astute, you will have to being things such as throughput, and robustness, etc. down to terms that everyone can relate to. How about it? Are we (hams), as a group, up to creating a better communications mode? I know we can. 73, Walt/K5YFW -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] Sent: Monday, September 18, 2006 8:28 AM To: [email protected] Subject: Re: [digitalradio] 16QPSK Modulation and Baud --- KV9U <[EMAIL PROTECTED]> wrote: > 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? Even when theory says that differential modes have a worse BER, seemingly they work better on ionospheric paths, as with a moving ionosphere, is difficult to maintain an absolute phase reference. > 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. Still holds true... > 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? Depending on multipath, which is worse on lower frequencies. > 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. The game is using many slow channels in parallel. Already in 1991 there was a 41 parallel tone modem being tested in transatlantic paths...it was capable of running 4800 bit per second and sometimes, up to 9600. > 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. Signalling rate....the speed at which every tone is wiggled. Actually, the ionosphere imposes a much lower rate for succesful transmission on the lower 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? Once again....Pactor can adaptively switch from 100 to 200 baud and back...be either Pactor I, II or III. Additionally, it can adaptively switch in and out constellation complexity and quantity of tones. Using compression, FEC and the whole boxful of coding tricks, it can go up to 5200 bits per second. I have seen it on Pactor III ocassionally running up to 3600 bps on 40 meters, and more often, 2800 and 1400 bps. 73 de Jose, CO2JA __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com 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/
