T2006

T8[edit]

SUBELEMENT T8 – Modulation modes, amateur satellite operation, operating activities, non-voice communications – [4 Exam Questions - 4 Groups]

Operations

T8A – Modulation modes; bandwidth of various signals

AM: used on HF mostly; typically 6khz; sometimes called "double sideband" as it contains both the LSB and USB signals (and possibly the carrier too)
FM: generally used on vhf and higher, especially with repeaters; can be 5khz, 15khz (vhf) , 25khz (uhf) 100khz (commercial, not amateur)
spread spectrum
packet radio: digital mode, usually FM modulated on VHF, uses a channel as wide as a VHF voice channel
APRS: a protocol that uses packet radio to transmit telemetry, including instant messaging, GPS, weather data, and more
single side band (SSB USB LSB): 3mhz voice mode for HF; sometimes used on VHF/UHF for weak signal and long distance
digital modes: cw, phase shift keying (psk), psk31, frequency shift keying, RTTY
CW: "continuous wave" or morse code; only digital mode that can be encoded and decoded by humans without computers; typically 150hz max bandwidth
slow scan tv (SSTV): pictures transmitted digitally using the bandwidth of a SSB voice channel; typically uses SSB modulation with either a FAX mode or digitally transmitting a jpeg
fast scan tv: (XX) also called Amateur television (ATV); a modulation method for transmitting live motion video; typically uses 6mhz wide NTSC encoding in the UHF band and can be demodulated with a regular TV (corresponds with cable channels 57-61)