Amateurs have been sending pictures since the 1950s. Two families of modes are still active.
SSTV — slow-scan television
A single still image encoded as audio tones and sent through an ordinary SSB transmitter. A frame takes roughly 8 seconds to 2 minutes depending on the mode (Robot 36, Scottie 1 and Martin M1 are the common ones).
- Where: 14.230 MHz USB is the worldwide calling frequency; also 7.171, 21.340 and 28.680 MHz,
- What you need: any HF radio, a computer or phone, and software — MMSSTV on Windows, QSSTV on
- Etiquette: listen first, send one image at a time, and keep content family-friendly. Everyone
plus local FM activity on 2 m.
Linux, Robot36 or SSTV Encoder on Android.
on frequency sees what you transmit.
ISS SSTV events
Several times a year the International Space Station transmits SSTV images on 145.800 MHz FM. A handheld with a small yagi — or even a rubber duck outside during a high pass — will decode them, and ARISS issues a certificate for received images. It is the easiest space contact in the hobby and a great club or classroom activity.
Fast-scan amateur television (ATV/DATV)
Full-motion video, essentially broadcast television made by amateurs. Bandwidth means it lives at 70 cm and above: 421–439 MHz, 1.2 GHz and 2.4 GHz are typical.
- Analogue ATV uses vestigial-sideband AM video; digital ATV (DATV) uses DVB-S/S2, the same
- Repeaters exist in many metropolitan areas, often linked into regional networks.
- Common uses: public-service event coverage, damage assessment video for emergency management, and
standard as satellite TV, and gets a usable picture at far lower signal levels.
rocket and balloon downlinks.
Getting started cheaply
Point a receive-only SDR dongle at 14.230 MHz during a weekend and decode what arrives; the software is free and you need no transmitter to learn the modes. Transmitting comes next, once you can hear cleanly what you are about to imitate.