Only one comment from me... "...What is the fastest individual tones that you are recommending for HF use?"
Much research on this subject was done during and after WWII by Stanford Research Institute (SRI) and later confirmed by Collins, Harris RF Comm Gp, Magnavox, ARINC, etc. They found out that the optimum baud rate for any single tone/carrier was between 40-50 baud. This is I believe the major reason that the MIL-STD-188-110 tones are modulated at 45.5 baud and why the original RTTY baud rate was 45.5 baud...well the exact baud rate was also for ease in timing I am told. Most of the above I learned while being on the Pacer Bounce (AN/ARC-119) evaluation team and looking at HF data transmissions for TRANSCOM following Operation Just Cause. I actually had a copy of the original "blue book" from SRI on the baud rate study...and I'll be darned if I haven't lost it...or misplaced it. Some of you OTs from the military may know about the "blue books". The latest unclassified "blue books" in the news have been about the aliens landing in New Mexico and about the early nuclear test in the Pacific. The RTTY blue book used to be available from the Air Force MARS Library at Scott AFB. Walt/K5YFW -----Original Message----- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] Sent: Thursday, August 31, 2006 11:25 AM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] USA; Baud Limit = 300 Symbols Per Second (HF Digital Data) Bonnie, If MT-63 is legal on the ham bands, since each tone runs at 10 or 20 baud depending upon the commonly used versions of this mode, but has 64 tones, it would seem that it is running well over 300 baud when you consider the entire waveform. The question that I need to be clear on is how many tones are running at the *same* time. This seems to be the key issue. Some modes only have one tone operational at any one time, even if they have multiple tones. Clover is a good example of this but I am not sure about many of the others. If all the current sound card modes are not running many tones simultaneously, and they have low baud rates, then I can see where they would be under the 300 baud limit even if you take into consideration the entire spread of the mode and not one given tone. The bps rate of course will vary depending upon the modulation technique used and doesn't enter into this at all. If the image sending operators are using QAM 64 (even if it doesn't work very well), I ask what is the baud rate of the individual tones and what is the total baud rate of the signal? Do the rules exempt voice and digital image from the 300 baud limit? If it does then my position would be that the FCC would welcome data modes with a total that exceeds 300 baud as long as individual tones do not. What is the fastest individual tones that you are recommending for HF use? I still don't see any possible use for anything faster than 300 baud because 300 is too fast for almost all conditions. You have been a big proponent of changing the rules so that we can run higher baud rates. You also have seemed to back the ARRL proposal. Now you are suggesting very wide BW data modes which would be contrary to the ARRL proposal that is going to restrict us to the new "technology jail" of 3.5 KHz, is it not? Can you explain this seeming conflict? Sincerely, Rick, KV9U expeditionradio wrote: >It appears that USA hams are the only ones in the world operating >under the thumb of such an obsolete "300 baud" limit for digital data >on HF! As far as I have been able to research, the rest of the world's >hams have no such 300 baud limitation placed upon them. > >The USA FCC rule is "300 baud" maximum for digital data on HF, meaning >"300 symbols per second" or "symbol rate". > >Symbol Rate (or Baud as used in radio), is not the same as the >commonly used digital bit rate or commonly used digital kb/s baud rate >in telephone modems and digital logic. > >Under the present USA FCC rule, hams can transmit digital data on HF >with 6kHz bandwidth (or more), as long as 300 symbols per second is >not exceeded! Would anyone like to design a fast 300 baud HF digital >mode for USA hams that is 10kHz wide? How about a good bit rate of >10kb/s? Certainly possible, and "street legal". > >Oddly, under the quirky mode-based FCC rules, the 300 baud limitation >does not apply to transmitting images or voice on HF. Go figure... > >Hopefully, new FCC bandwidth-based rules will throw out the antiquated >300 baud rule and release USA hams from the technology jail. > >Bonnie KQ6XA > > > > > >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 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! 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