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All I've ever used is CW, and a some SSB; even then always replying; haven't seen much difference there in the manner of the QSO. But there are other modes which I have not used, and some that are superseded/not available in VU land.

Apart from the obvious differences in equipment & perception, what differences in protocol are applicable to a QSO over A3F (double sideband full carrier amplitude modulation with video) as compared to J3E (single sideband telephony with suppressed carrier)?

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    $\begingroup$ A3F = double sideband video, J3E = single sideband telephony, so that no one else has to google it. You probably should spell that out in the question. $\endgroup$ – Dan KD2EE Oct 25 '13 at 21:03
  • $\begingroup$ Related: What do the three-letter modulation codes (emission designators) stand for? $\endgroup$ – a CVn Oct 26 '13 at 15:44
  • $\begingroup$ I'm not sure I understand the question - are you asking how does a video QSO (I assume one of the SSTV modes?, although I haven't read of using AM for those) differ from a SSB audio QSO (a pretty standard activity)? $\endgroup$ – Chris Wiegand K0DEN Oct 28 '13 at 5:29
  • $\begingroup$ @ChrisWiegand Asking about how the operating practice differs. On SSB/CW I'd seek an open spot, and give a call. How does it work on SSTV? $\endgroup$ – VU2NHW Oct 28 '13 at 5:33
  • $\begingroup$ I'm not familiar with SSTV operating, but it strikes me as quite odd that it would be common to use double sideband full carrier (especially as this gives you only 25% of nominal output for carrying useful information; 50% is consumed by the carrier, and the remaining 50% is distributed across the two sidebands). Are you sure it shouldn't be J3F rather than A3F? That said, if you're asking about how to make SSTV contacts, it might be better to put that in the title. $\endgroup$ – a CVn Oct 28 '13 at 12:25
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With SSTV you'd typically do the same thing as with SSB/CW: You'll seek an unused frequency, and transmit your CQ call image, and then listen for a response.

With SSTV you normally use an SSB transceiver and you'll be able to listen to the audible representation of the image transmission, or any other communications on that frequency using any other mode. You shouldn't transmit SSTV images on top of someone's voice QSO, either. Most SSTV software packages have a frequency scope or a waterfall display to aid tuning, too.

When doing ATV on UHF (regular analog or digital TV, not SSTV) you'll typically use specially allocated ATV frequencies, and possibly repeaters, which should not have any voice traffic on them. The presence of traffic should be obvious from the presence of audio (instead of FM "no carrier" noise) and video (instead of "snow").

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