This is a Skymaster transmission on the Us Air Force operated, all service US military used, HF-GCS (High Frequency Global Communications System) radio network. Common HF-GCS frequencies are 4724 kHz, 8992 kHz, 11175 kHz, and 15016 kHz, all transmissions in USB mode. Most transmissions are simulcast on all frequencies at the same time. In this case the recording is of 11175 kHz, USB mode.
Some Skymaster transmissions appear to be one-way, with no responses heard or. seemingly, anticipated. Others, as this one, do have responses.
Skymaster transmissions are not uncommon, but often not a daily event either. Sometimes you might hear several a day, other times none for extended periods. Skymaster transmissions, while common in the 1980's and before, have been less used in recent years, however, they appear to have become more frequent (or at least more commonly reported / recorded) since around early 2023.
Skymaster transmissions seem to increase in tempo during large scale exercises or some real world notable events. There is much speculation as to the meaning of such transmission, but little about them is actually confirmed.
The HF-GCS is maintained and operated by the US Air Force, however all US forces have access to the system.
Recorded at my location in the Mojave Desert, of California, USA, on 11 January, 2024, 0024 UTC.
Disclaimer: Many of the radio reception recordings on this Youtube channel pertain to unusual, uncommon, unknown, or mystery signals that might be found on radio, both shortwave and VHF/UHF. Among the subjects covered are numbers stations, utility stations, military transmissions (both in the clear and encrypted / encoded), aviation, maritime, ham radio, CB radio, radars, ionosodes, propagation beacons, ditters, dashers, whistlers, and just about anything else that might transmit, in any mode, USB, LSB, CW, Morse Code, FM, AM,FMCW, LFMCW, etc. Think of it as SIGINT (signals intelligence) / COMINT (communications intelligence) / ELINT (electronic intelligence) lite, the hobby version. All the recordings are made by me, most often at my home. Although there are a few mysterious things to be found here, you will not find anything paranormal, extraterrestrial, spiritual, or mystic. However, everyone can have their own interpretations of the sounds heard, make of it what you will.
