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Amateur television (ATV) is the hobby of transmitting broadcast-quality video and audio over radio waves allocated for amateur radio using the broadcast standards of NTSC in North America and Japan, and PAL or SECAM in Europe and elsewhere, using the full refresh rates of those standards. It also includes the study of building of such transmitters and receivers and the propagation between these two. ATV is an extension of amateur radio. It is also called HAM TV or Fast Scan TV (FSTV). Ham operators are also allowed to transmit Slow Scan TV (SSTV) which is similar to video facsimile. SSTV may be transmitted on any ham radio frequency band.

Contents 1 North American context 2 European context 3 Transmission standards 4 Permissible content 5 See also

In North America, transmissions are typically sent from repeaters on four UHF channels below the UHF TV broadcast band (air channels 14 to 69). These can be received on a cable-ready NTSC-format TV or set-top box tuned to cable channels 57 to 60 (420-444 MHz). Individual channels (with center frequency for video and audio) are:

• 57: 420-426 MHz (421.25 video, 425.75 audio)
• 58: 426-432 MHz (427.25 video, 431.75 audio)
• 59: 432-438 MHz (433.25 video, 437.75 audio) - offset to 434.0 and 438.5 to clear the satellite sub-band (435-438).
• 60: 438-444 MHz (439.25 video, 443.75 audio)

In Europe, which generally has a narrower UHF allocation than the USA, the majority of amateur television operation is currently FM on 1.2GHz and above. The frequencies in use depend on national permissions. In most of mainland Europe, the most common frequency is 1255MHz. Other bands commonly used for ATV are the 13cm (~2.3-2.45GHz) and 3cm (~10GHz) bands, although ATV is used on most of the microwave bands.

In several countries crossband repeaters are used, with AM inputs on 430 MHz and FM outputs on 1255 MHz, others have FM-ATV inputs on 13 cm and outputs on 3 cm.

In the United Kingdom, much activity occurs using in-band repeaters. These generally have an input of 1248, 1249 or 1255MHz and typically output at 1308, 1312 or 1316 MHz, although other frequencies are also used. Simplex operation ocurs on these or other frequencies chosen to avoid interference with other users of the band, e.g. 1285MHz.

Recent experiments have been done with digital modes following widely-adopted DVB-S and DVB-T standards. Several repeaters, e.g. GB3HV have had digital TV input and output capabilities for years, also in Germany, see [1]. Technical details of one development by a combined radio amateur/university branch effort at [2]

Currently, digital ATV modes have not been approved by the FCC in the U.S. ^{[dubious — see talk page]}

Typically frequency modulated TV is used on frequencies above 1200 MHz (1.2 GHz), where there is enough bandwidth for such wideband transmissions. This is often used as a repeater's input frequency, with output being standard VSB on the four channels listed above.

In a nutshell

• below 1.2 GHz: Vestigial Sideband
• above 1.2 GHz: FM, PSK etc...

From 1968 to about 2004 amateur TV provided behind-the-scenes co-ordination for the annual New Year's Day Tournament of Roses Parade in Pasadena CA.

HAM TV - as it is also called - provides video co-ordination of many public service events and, along with traditional amateur radio, provides much needed "eyes" in natural disasters.

A HAM TV repeater may also broadcast a noncommercial TV network which does not include music (a U.S. requirement also part of amateur radio). ^{[dubious — see talk page]} U.S. stations often retransmit NASA TV while they are not in use, especially if there is currently a Space Shuttle mission.

• SSTV
• DVB-T
• ATSC
• NTSC
• SECAM