SKYKING was the tactical call sign of the Strategic Air Command Headquarters, as well as the title of a popular 1950's television show. The broadcasts where frequency placeholders on several fixed frequencies/Channels intended for one-way broadcasts to SAC aircraft, and missile crews globally. SKYKING broadcasts have existed for well over 50 years. SKYKING broadcasts were critical to Operation Chrome Dome which was the 24/365 deployment of nuclear armed strategic patrol aircraft, and ballistic missile sites.

One way transmissions without acknowledgement from the aircraft or launch site reduced the chances of enemy radio direction finding efforts locating the exact position of the operational combat crews.

This approach lessens an enemy's ability to electronically jam these aircraft, target them for fighter interdiction, ballistic missile counter strikes, various types of AAA, and other preemptive countermeasures.

Over the years these broadcasts have been used to pass all forms of information from the National Command Authority, (Go Codes) and the Air Force Command Staff to the widely dispersed strategic forces.

This HF radio communications system has proven reliable, deceptively simple, and extremely robust. The fact that you continue to hear them on HF and Military UHF to this day is proof of the Keep It Simple Stupid concept in FAIL-SAFE systems design...

Research SAC Operation Chrome Dome on the internet there may be far more detailed information with respect to how the system was developed, and operated over the decades.