Abstract :
The MSF standard frequency transmissions take place on 60kc/s, and on 2.5, 5, and 10Mc/s and include modulation frequencies of 1kc/s and 1c/s. The transmissions are controlled by one of three highly stable oscillator-clock chains, which are checked daily in terms of a frequency standard, and are continuously intercompared in order that instability may be quickly detected. Automatic shut-down features are incorporated to reduce the risk of broadcasting incorrect frequencies under fault conditions. The vital parts of the equipment are protected against mains failure. The transmitted frequencies are normally kept within 1 part in 108 of the currently-assessed nominal frequency, based on predicted clock performance, so as to keep within a tolerance of ±2 parts in 108 in terms of finally-corrected time determinations. Day-to-day frequency variations are usually less than ±2 parts in 109.
