XSS

In 2G ALE, the network control uses the ID XSS, most mobile units use 3-letter IDs starting with X, while the AWACS aircraft use 6-character IDs in form of UKE30#. After a link is established, data is exchanged using MIL-STD-188-110.

Each data channel is associated with a single ground station. When the network control (XSS) is actively monitoring a given channel, it broadcasts a 2G ALE sounding every 30 minutes. All frequencies are on the upper sideband.

• 2216 - Inskip, UK
• 2451.5 - St. Eval, UK
• 2784 - Inskip, UK
• 3086 - St. Eval, UK
• 4047.5 - Inskip, UK
• 4239.5 - St. Eval, UK
• 4347.5 - Inskip, UK
• 4510 - Inskip, UK
• 4706 - St. Eval, UK
• 4845 - Inskip, UK
• 5295 - Inskip, UK
• 5466 - Inskip, UK
• 5808 - Inskip, UK
• 6251 - St. Eval, UK
• 6416.5 - Inskip, UK
• 6462 - Inskip, UK
• 6706 - Inskip, UK
• 6845 - Cyprus
• 6873.5 - Inskip, UK
• 6992 - Inskip, UK
• 7535 - St. Eval, UK
• 7567.5 - St. Eval, UK
• 7860 - Inskip, UK
• 8107 - Cyprus
• 8161 - Inskip, UK
• 8167 - Inskip, UK
• 8182 - Inskip, UK
• 8532.5 - St. Eval, UK
• 8773 - Inskip, UK
• 9019 - St. Eval, UK
• 9286 - St. Eval, UK
• 9905 - Inskip, UK
• 10344.5 - Cyprus
• 10351 - Inskip, UK
• 10410 - St. Eval, UK
• 10420 - Falkland Islands
• 10836 - Cyprus
• 10893.5 - Inskip, UK
• 11208 - Cyprus
• 11550 - Inskip, UK
• 12230 - Cyprus
• 12245 - Inskip, UK
• 12313 - St. Eval, UK
• 12752.5 - Inskip, UK
• 13423.5 - St. Eval, UK
• 13552 - Cyprus
• 13877 - St. Eval, UK
• 14485.5 - Cyprus
• 14509 - Inskip, UK
• 14555 - Inskip, UK
• 14875 - Cyprus
• 14968 - St. Eval, UK
• 16148 - Cyprus
• 16321 - St. Eval, UK
• 16357 - Cyprus
• 18210 - Inskip, UK
• 18403.5 - Cyprus
• 18875 - Cyprus
• 20423.5 - Cyprus
• 22571 - Cyprus

Defence High Frequency Communications Service (DHFCS) is the name of HF radio services provided to the UK Ministry of Defence by an external contractor, Babcock International. Their main users are the Royal Navy and the Royal Air Force.^[1]

The DHFCS consists of six pairs of transmitting and receiving sites, all of which are remotely controlled by the Network Control Station at Forest Moor (ALE address: XSS). There is also an Alternate Network Control Station at Kinloss (ALE address: XSA).

Unless noted otherwise, all frequencies mentioned on this page are on the upper sideband.

Royal Air Force^[2]

On the voice channels, the ground control uses the callsign Tazcomm, while most aircraft identify as Ascot ####.

The ALE channels are used primarily for text messaging with the 2G ALE Automatic Message Display (AMD) feature. The addresses heard include:

• XSS: Ground control
• UKE30#: Boeing E-3D Sentry AEW.1; the last digit is between 1 and 7 inclusive
• 2#####: Boeing C-17A Globemaster III; the digits are derived from the tail number
• MEF: Unknown

On each ALE channel, XSS emits a 5-second ALE sounding every 30 minutes.

Royal Navy

The Royal Navy ship-to-shore communications utilize 2G ALE to establish MIL-STD-188-110B links. The vessels use 3-letter addresses in form of XA_, XB_, XC_, XD_, XE_, XF_, XG_, XH_, XJ_, XK_, XL_, XM_, XN_, XP_, and XR_; the 3rd character may be any letter except I, O, and Q. All contacts are made with XSS.

On each active frequency, XSS emits an ALE sounding every 30 minutes. The sounding length is ~14 seconds, except for the UK frequency set 4 where it's ~8 seconds.

Secure broadcasts

The DHFCS carries many continuous STANAG 4285 transmissions. Each 600 bit/s broadcast is a single KW-46 encrypted stream. The 1200 bit/s broadcasts utilize time-division multiplexing to carry up to 12 KW-46 encrypted streams on a single frequency.

Cyprus

• 5553.2 (nighttime)
• 6805.2 (nighttime)
• 7579.2 (nighttime)
• 8312.2 (nighttime)
• 8548
• 12323.2 (14:00-16:00 UTC)
• 14548.2 (daytime)
• 15812.1 (daytime)
• 17398.2 (daytime)
• 19051.7 (daytime)

Ascension

• 8325.5, 10373 (nighttime)
• 14390, 16287 (daytime choice 1)
• 20918, 22186 (daytime choice 2)

Falklands

• 8098.2

References

1. Babcock International 2012, p. 9
2. UK MIL AIP 3.4.1 UNITED KINGDOM DEFENCE GLOBAL HIGH FREQUENCY SYSTEM [accessed January 25, 2020]