Synchronization method and frequency hopping communication system

A transceiver for a frequency hopping radio communication system comprising:

• a first frequency hopping program of predetermined length consisting of M discrete frequencies changing at N rate;
• a second frequency hopping program of predetermined length consisting of P discrete frequencies changing at Q rate, P being greater than M and Q being greater than N;
• a third frequency hopping program of predetermined length consisting of M discrete frequencies changing at O rate where O is greater than N;
• means for generating a predetermined sync acquisition signal and a predetermined sync maintenance signal;
• means for recognizing the receipt of said predetermined sync signals;
• switch keyed transmitter means;
• and
• receiver means,
• said receiver means being normally tuned by said first frequency hopping program, being disabled responsively to the keying of said transmitter means for the duration of the transmission, and being tuned by said second frequency hopping program in response to said sync signal recognizing means,
• said transmitter means being tuned to said third frequency hopping program by the keying thereof to transmit responsively to said sync signal generating means, being tuned to said second frequency program responsively to the completion of the transmission of said sync signal, and being tuned to said second frequency hopping program if keyed within a predetermined time interval following receipt of a signal in said second frequency hopping program.

A transceiver for a frequency hopping radio communication system comprising:

• transmitter means;
• receiver means;
• means responsive to said transmitter means for disabling said receiver means;
• and
• tuning means,
• said tuning means being responsive to a predetermined first condition of said transmitter means to initiate the transmission of a sync signal in accordance with a first predetermined discrete frequency hopping program,
• said tuning means being responsive to the termination of said first frequency hopping program to initiate a second predetermined discrete frequency hopping program,
• said tuning means being responsive to receipt of a sync acquisition signal at a plurality of discrete frequencies in a third frequency program for initiating a second predetermined discrete frequency hopping program at a time dependent upon the frequencies at which said sync signal is received,
• said tuning means being responsive to receipt of a sync maintenance signal at a plurality of discrete frequencies in said second frequency hopping program to adjust the time of frequency shift in said second frequency hopping program.

Apparatus for synchronizing a receiver to a remote transmitter for frequency hopping radio communications comprising:

• means for tuning the receiver to receive signals at M successive discrete frequencies at a rate N;
• means for detecting a predetermined sync acquisition signal at not less than two of the M discrete frequencies within a predetermined time interval initiated responsively by first detection of the sync acquisition signal;
• means for tuning the receiver to receive signals at P successive discrete frequencies at a rate Q responsively to said sync acquisition signal detecting means, P being at least twice M and Q being at least twice N, to thereby initially synchronize the receiver for frequency hopping communications with a remote transmitter;
• means for detecting a sync maintenance signal at not less than two of the P discrete frequencies within a predetermined time period initiated responsively to the first detection;
• and
• means for adjusting the time of shifting of the P discrete frequencies responsively to said sync maintenance signal detecting means to thereby maintain synchronization between the receiver and the remote transmitter.

A transceiver for a frequency hopping radio communication system comprising:

• means for providing a sync acquisition signal, a sync maintenance signal, an "end of message" signal, a slow frequency hopping program of M discrete frequencies at a rate N, a fast frequency hopping program of P discrete frequencies at a rate Q, and a sync frequency hopping program of R frequencies at a rate S;
• a keyed transmitter;
• means (a) for tuning said transmitter to transmit said sync acquisition signal at said sync frequency hopping program upon keying of said transmitter, and (b) for tuning said transmitter to transmit audio frequency signals at said fast frequency hopping program upon completion of said sync frequency hopping program;
• a receiver;
• means for detecting said sync acquisition signal, said sync maintenance signal and said "end of message" signal;
• means for tuning said receiver (a) to receive normally at said slow frequency hopping program, (b) to receive at said fast frequency hopping program in response to detection of said sync acquisition signal, (c) to receive at said slow frequency hopping program in response to detection of said "end of message" signal, and (d) to shift in time said fast frequency hopping program in response to detection of said sync maintenance signal.

A method of synchronizing a receiver to a transmitter for frequency hopping radio communications comprising the steps of:

• (a) tuning the receiver the receive signals at M successive discrete frequencies at a rate N;
• (b) detecting a predetermined sync acquisition signal;
• (c) tuning the receiver to receive signals at P successive discrete frequencies at a rate Q responsively to the detection of the sync acquisition signal, P being at least twice M and Q being at least twice N, to thereby initially synchronize the receiver for frequency hopping communications with a remote transmitter;
• (d) detecting a sync maintenance signal;
• and
• (e) adjusting the time of shifting of the P discrete frequencies responsively to the detection of the sync maintenance signal to thereby maintain synchronization between the receiver and the remote transmitter.

Apparatus for synchronizing a receiver to a remote transmitter for frequency hopping radio communications comprising:

• means for tuning the receiver to receive signals at M successive discrete frequencies at a rate N;
• means for detecting a predetermined sync acquisition signal;
• means for tuning the receiver to receive signals at P successive discrete frequencies at a rate Q responsively to said sync acquisition signal detecting means, P being at least twice M and Q being at least twice N, to thereby initially synchronize the receiver for frequency hopping communications with a remote transmitter;
• means for detecting a sync maintenance signal;
• and
• means for adjusting the time of shifting of the P discrete frequencies responsively to said sync maintenance signal detecting means to thereby maintain synchronization between the receiver and the remote transmitter.