Hello Sholto, MFSK SSTV is an analogical SSTV mode with the originality that it is a narrow band SSTV mode (the same as MFSK) and the format of the picture is free (small or big as you want).
It would be possible to put some RS prefix (with more bits available than for RS ID) to define the center frequency, format and color. But I'm not sure that the gain would be important as this type of SSTV is an "old" technology. Better would be a Digital SSTV within 500 Hz and as fast as standard SSTV. 73 Patrick For information the specifications of SSTV in MFSK16 SSTV in MFSK16 Created by : Nick Fedoseev (UT2UZ) and Denis Nechitailov (UU9JDR) in 2003 Description : It is a SSTV mode without transmission of a synchronization ray, in color or in black and white mode, where the picture may be transmitted among MFSK16 text. The picture format is not fixed as in classical SSTV but variable (limited to small pictures). Multipsk proposes to use the standard "320x256" to take advantage of the SSTV "workshop" and the stored SSTV pictures. The band of frequencies used is 234,375 Hz (15 x 15,625 Hz), which is the width between extreme peaks of a MFSK16 transmission. The duration of a pixel is exactly 1 ms. In color mode, the colors are transmitted in the following order: Red, Green, Blue. In black and white mode, the black color corresponds to the lower frequency and the white color to the higher frequency. To be recognized, the picture must be MFSK16 prefixed by: * "Pic:320x256C;" for example for a color picture of 320x256 dimension whose transmission will last 320x256x3x0,001=246 sec, * "Pic:320x256;" for example for a black and white picture of 320x256 dimension whose transmission will last 320x256x1x0,001=82 sec. ----- Original Message ----- From: Sholto Fisher To: digitalradio@yahoogroups.com Sent: Sunday, January 20, 2008 4:45 AM Subject: Re: [digitalradio] Re: Redefining SSTV operations Yes I never quite understood why it only appeared as an MFSK thing. I guess it was because it shares a similar bandwidth with it. I think using a transmitted header (similar to Patrick's Reed Solomon sequence) at the start would be a better way to define picture size & colors and it provides an automatic tuning reference - which will be important because unlike regular SSTV you don't really know in advance where the tones are going to be in the narrow digital areas of the bands. 73, Sholto KE7HPV. ----- Original Message ----- From: "Leigh L Klotz, Jr." <[EMAIL PROTECTED]> To: <digitalradio@yahoogroups.com> Sent: Saturday, January 19, 2008 7:37 PM Subject: Re: [digitalradio] Re: Redefining SSTV operations > The MFSK picture mode isn't tied to MFSK in any logical way, only in the > programs. It doesn't use MFSK modulation for the picture, for example. > > I think your plan is good and intend to put it into place, but others > with production digimode programs are better situated to do it now. > > 73, > Leigh/WA5ZNI > On Sat, 19 Jan 2008 7:34 pm, Sholto Fisher wrote: > > Andy, > > > > I agree with you - it would be nice to have a general purpose narrow > > bandwidth image mode which could be used in a stand alone fashion. > > > > The problem with MFSK16 SSTV is that it is tied to MFSK16 and you can't > > receive it if you didn't catch the MFSK "Pic:" command. > > > > Perhaps one of the programmers who frequent this group could invent an > > analog 500Hz SSTV mode that allows someone listening to start receiving > > even > > if they missed the initial "Pic:" command plus some form of automatic > > header > > (like SSTV has now) or Patrick's RS-ID for easy tuning and correct > > submode > > selection? > > > > 73, Sholto KE7HPV. > > > > > > > > > > Announce your digital presence via our Interactive Sked Page at > > http://www.obriensweb.com/sked > > > > > > DRCC contest info : http://www.obriensweb.com/drcc.htm > > > > Yahoo! Groups Links > > > > > > >
