n_sstv_logoThe idea behind recent exper­i­ments with nar­row band ana­logue SSTV trans­mis­sions is sim­ply an attempt to rede­fine some com­mon prac­tices among SSTV ama­teurs. The rede­fined prac­tices attempt to “fit” SSTV QSOs into the nor­mal oper­a­tions of the dig­i­tal radio enthu­si­asts. PSKers, MFSK oper­a­tors, and Olivia users are used to nav­i­gat­ing a spe­cif­ic sec­tion of the bands, and are used to dig­i­tal rag-chews that exchange sig­nal reports, sta­tion info and gen­er­al oper­a­tor info (e.g. “been a ham 100 years”). In North Amer­i­ca the SSTV enthu­si­asts have tend­ed to con­gre­gate on a cou­ple of fre­quen­cies and par­tic­i­pate in voice con­ver­sa­tions between the send­ing of pic­tures. Typ­i­cal PSKers enjoy QSOs with­out hav­ing to use a micro­phone. At times, QSOs can be had with­out dis­turb­ing oth­ers in the house­hold late at night.
In order for the SSTV sig­nals to be locat­ed in the typ­i­cal PSK31/Olivia/MFSK por­tions of a band, the SSTV sig­nal must be less than 500 Hz in width. Most com­mon SSTV modes are much wider than this, but lo-and-behold, sev­er­al hams have recent­ly remind­ed us that nar­row band SSTV has been added to MMSSTV. So now dig­i­tal radio folks can have SSTV QSOs in the same fre­quen­cy ranges as their oth­er QSOs. This has a spe­cial appeal if you like to use the 30M band. This band, for USA hams, is assigned to CW and Data modes. 30 meter enthu­si­asts can use nar­row SSTV and user “text over­lays” to com­mu­ni­cate recep­tion reports, QTH, sta­tion infor­ma­tion, etc.
How these QSOs should be con­duct­ed has yet to be firm­ly estab­lished. Some have sug­gest­ed hav­ing the usu­al PSK/MFSK/DominoEX type QSOs and switch­ing to MMSSTV when a pic­ture needs to be sent. MMSSTV has some inter­est­ing abil­i­ties where one can actu­al­ly “key­board” with­in the pic­ture. With the con­cept of “a pic­ture is worth a thou­sand words” in mind, here is how MMSSTV might be used in nar­row mode.

 


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