Frequency management system for use in multistation h.f. communication

Abstract

A frequency management scheme for a multistation H.F. communication network establishes communication channels among network stations over respective ones of K frequencies, so that network stations may communicate with one another. Any station desiring to communicate with another station, repeatedly transmits, on each of plural ones of the K communication frequencies in sequence, a probe message comprised of three successive symbols, each of which is defined in accordance with a prescribed pseudo random M-ary code, in the form of multi-chip sequence, that represents the address of the station to whom the communication is directed. The first symbol is effectively unmodulated to permit monitoring equipment of a receiving station of the network to settle out. The second symbol represents the address of the transmitting station. The third symbol identifies the number of times that the frequency which carries the probe message has been transmitted. Each idle station monitors the level of activity of each of the K communication frequencies by successively dwelling on each frequency for the length of time required for any message-transmitting station to step through all K frequencies of the network. During each dwell time, the idle station looks for its address. If a probe message is directed to that monitoring station, the addressed station transmits back to the probing station a prescribed three symbol response message.