In the United Kingdom, the HF systems of all military branches are unified into a single Defence High Frequency Communications Service (DHFCS).
The system employs six pairs of ground stations, three of which are in the UK, and three are overseas. All ground stations are remotely controlled from either Forest Moor (the main site), or Kinloss (the alternate site).
|UK (South)||St. Eval||Transmitter|
|Ascension Island||Donkey Plain||Transmitter|
|East Falkland||Bush Rincon||Transmitter|
The air-to-ground, ship-to-shore, and ground-to-ground services of the DHFCS are known as Terrestrial Air Sea Communications, or TASCOMM.
The voice activity takes place on the following channels, all on the upper sideband:
- 3146 kHz
- 4742 kHz
- 6733 kHz
- 9031 kHz
- 11205 kHz
- 13257 kHz
- 15031 kHz
- 18018 kHz
The network control station uses the callsign "Tascomm."
The digital modes used are 2G ALE (MIL-STD-188-141A) and MIL-STD-188-110. The network control station uses the ID XSS, the mobile units use 3-letter IDs beginning in "X," while the AWACS aircraft use 6-character IDs in form of "UKE30#."
Each digital channel is associated with a single ground station. When a channel is active, it carries 2G ALE soundings from XSS every 30 minutes. Around 10-20 channels are active for each station at any given time.
Sporadic KG84-encrypted RATT broadcasts conformant with STANAG 4481 (50 Bd or 75 Bd, 850 Hz shift, +2000 Hz offset) are made simultaneously on the following channels, all on the upper sideband:
- 2813 kHz
- 4730 kHz
- 6757 kHz
- 8986 kHz
- 11211 kHz