A technical term for SSTV is narrowband television. Broadcast
television requires huge 5, 6 or 8 MHz wide channels, because it
transmits 25 or 30 pictures per second (in the NTSC, PAL or SECAM
systems), but SSTV usually takes up to only 3 kHz of bandwidth. It is a
much slower method of still picture transmission, usually lasting from
about eight seconds to a couple of minutes.
Since SSTV systems operate on voice frequencies, amateurs use it on
shortwave (also known as HF by amateur radio operators), VHF and UHF
radio..