Ham College episode 136 is now available for download.
Technician Exam Questions Part 23.
T8A – Basic characteristics of FM and SSB: Bandwidth of various modulation modes: CW, SSB, FM, fast-scan TV, Choice of emission type: selection of USB vs LSB, use of SSB for weak signal work, use of FM for VHF.
T8B – Amateur satellite operation: Doppler shift, basic orbits, operating protocols, modulation mode selection, transmitter power considerations, telemetry and telecommand, satellite tracking programs, beacons, uplink and downlink mode definitions, spin fading, definition of “LEO”, setting uplink power.
This episode of Ham College (0:00) covers essential topics from the Amateur Radio Technician Exam Question Pool, focusing on FM and SSB modulation characteristics, bandwidth, and amateur satellite operations.
The hosts discuss the technical aspects of different modes. Modulation Modes and Bandwidth (4:02 – 24:50)
CW (Continuous Wave): Provides the narrowest bandwidth (10:55, 23:52). SSB
(Single Sideband): Typically has a bandwidth of 3 kHz (18:00) and is preferred for weak signal work on VHF/UHF (7:42).
FM(Frequency Modulation): Commonly used for repeaters with a bandwidth between 10 and 15 kHz (18:22, 19:00).
Fast-scan TV: Requires a very wide bandwidth, approximately 6 MHz (19:47, 20:47).
Amateur Satellite Operations (28:15 – 45:26)
Satellites and Beacons: Satellites use beacons to transmit telemetry and status information (28:19, 35:22).
Tracking and Doppler: Tracking programs calculate the satellite’s position and
the Doppler shift of frequencies (32:01, 33:05).
Operating Protocols: Excessive power on the uplink can block other users (30:10).
Spin fading is caused by the rotation of the satellite and its antennas (41:56).
Modes: UV mode indicates a 70 cm (UHF) uplink and a 2 meter (VHF) downlink (40:46).
LEO stands for Low Earth Orbit (43:02).