Amateur radio is a radio service among radio amateurs who can use it experimentally and technically-scientifically for social contacts, for auxiliary and emergency purposes. For the classical amateur radio the short wave was available. Since the transmission conditions in this frequency band have deteriorated, further frequency bands in the HF range and in the VHF band have been reserved for amateur radio.
The other frequency bands are the 6-m band with the frequency range between 50 MHz and 54 MHz, which is amplitude modulated in single sideband( SSB) operation in Germany. The sideband used is the lower sideband. Another frequency band is the 2- meter band between 144 MHz and 146 MHz. In this band, frequency modulation( FM) is predominantly used, but single-sideband modulation is also possible. In addition, the 70-cm band between 430 MHz and 440 MHz is available, also with frequency modulation, and the 23-cm band between 1,240 MHz and 1,300 MHz. The transmit power depends on the amateur radio license class and can be up to 750 W.
Amateur radio supports several telecommunication modes. These include phonics, which is voice radio, telegraphy using Morse code, known among amateur radio operators as continuous wave( CW), radio teletype( RTTY), facsimile ( FAX), slow scan television ( SSTV) for image transmission, amateur television (ATV) for photos, packet radio ( PR) for data transmission, relay radio with small handheld radios, satellite radio, and earth-moon- Earth ( EME) and meteor scatter for range extension. In the first case, the moon serves as a reflector; in the second, the atmosphere ionized by meteor impact is used to reflect radio waves.