VHF and HF radio system basics
Aeronautical voice systems (TC AIM COM 1.1):
| System | Band | Role |
|---|---|---|
| VHF-AM | 118 to 137 MHz |
Canada's primary voice system |
| HF-SSB | 2.8 to 22 MHz |
Extends range in northern areas and over the North Atlantic |
VHF channel spacing (TC AIM COM 1.4):
- Standard in Canada:
25 kHz, needs a 760-channel transceiver. - 50-kHz radio can be locked out of airspace and airports using 25-kHz spacing for ATC.
VHF air-to-ground (TP 1102 Ex.2):
- Two-way but not simultaneous (half-duplex), unlike a telephone.
- Keying mic jams all other transmitters and receivers on the frequency.
- Release button to hear a reply.
- Transmissions must be short and to the point.
Trap: a 50-kHz radio can be locked out of 25-kHz airspace; keying the mic blocks all other stations on the frequency.
References
- TC AIM COM 1.1
- TC AIM COM 1.4
- TP 1102 Ex.2 (Communications System)