Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
126 words
A frequency-hopping radio communication system comprising a plurality of radio transmitter/receiver sets (Fig. 1) characterised in that the radio sets have means (2, 3) for changing their operating frequencies periodically, in synchronism, and according to a common main-line pseudo-random channel sequence, each radio set having means (4, 6) for modifying its operating channel sequence to a side-track sequence dependent upon the point in said main line sequence at which the modification is initiated and means for transmitting a signal to a selected other radio set to initiate said side-track sequence in the receiving radio set at the same instant as in the transmitting radio set, both radio sets being arranged (6, 8, 16, 18) to revert to the main-line channel! sequence on termination of the transmission.
Claim 2
Dependent Claim
126 words
A frequency-hopping radio communication system comprising a plurality of radio transmitter/receiver sets (Fig. 1) characterised in that the radio sets have means (2, 3) for changing their operating frequencies periodically, in synchronism, and according to a common main-line pseudo-random channel sequence, each radio set having means (4, 6) for modifying its operating channel sequence to a side-track sequence dependent upon the point in said main line sequence at which the modification is initiated and means for transmitting a signal to a selected other radio set to initiate said side-track sequence in the receiving radio set at the same instant as in the transmitting radio set, both radio sets being arranged (6, 8, 16, 18) to revert to the main-line channel! sequence on termination of the transmission.
Claim 3
Dependent Claim
79 words
A system according to Claim 1, characterised in that each radio set (Fig. 1) incorporates a pseudo random number generator (2) and a channel frequency identifying store (3), each number generated by the pseudo random number generator (2) determining a respective operating channel frequency for the radio set, and wherein the pseudo random number generator (8) incorporates a controllable two-state feedback path (4) which, in one state causes the pseudo random number generator to produce a said side-track sequence.
Claim 4
Dependent Claim
33 words
A system according to Claim 2, characterised by transmit-key means (2) whereby, before transmission, operation of said transmit key means causes said feedback path (4) to adopt the other of the two states.
Claim 5
Independent Claim
91 words
A system according to any preceding claim characterised by a relay station which comprises two radio sets (B,C) each as aforesaid, one (B) of said two radio sets being adapted to accept transmissions irrespective of addressee and the other (C) of said two radio sets being coupled to said one radio set (B) to re-transmit all signals received thereby, the difference in time between reception by said one set (B) and retransmission by said other (C) causing the two links to operate on different side-track sequences and thus provide frequency isolation.