Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
135 words
A radio communication system having a plurality of transmitters which each transmit on a different one of a plurality of channels and a receiver including tuner means for tuning said receiver to any one of said plurality of channels and scanner means for causing said tuner means to scan said plurality of channels wherein each said transmitter includes means for periodically transmitting a channel signal on its transmitter's channel, and said receiver further includes timer means for activating said scanner means when a channel signal has not been received on the channel to which said receiver is tuned for a predetermined time which is not less than the time period of said channel signals, and for de-activating said scanner means when a channel signal is received on the channel to which said receiver is tuned.
Claim 2
Dependent Claim
135 words
A radio communication system having a plurality of transmitters which each transmit on a different one of a plurality of channels and a receiver including tuner means for tuning said receiver to any one of said plurality of channels and scanner means for causing said tuner means to scan said plurality of channels wherein each said transmitter includes means for periodically transmitting a channel signal on its transmitter's channel, and said receiver further includes timer means for activating said scanner means when a channel signal has not been received on the channel to which said receiver is tuned for a predetermined time which is not less than the time period of said channel signals, and for de-activating said scanner means when a channel signal is received on the channel to which said receiver is tuned.
Claim 3
Dependent Claim
14 words
A system according to claim 1 wherein said channel signals are unmodulated carrier signals.
Claim 4
Dependent Claim
76 words
A system according to claim 1 or 2 further comprising channel signal threshold detector means for producing an output signal when a channel signal having a value greater than a predetermined value is received on the channel to which the receiver is tuned, the output of said channel signal threshold detector means being connected to said timer means so that said timer means is responsive only to channel signals having values greater than said predetermined value.
Claim 5
Dependent Claim
57 words
A system according to claim 3 wherein said timer means comprises a resettable timer arranged to be reset by said channel signal threshold detector means output signal so as to produce an output signal after said predetermined time unless and until reset, and said scanner means is arranged to be activated by said timer means output signal.
Claim 6
Dependent Claim
40 words
A system according to claim 1, 2, 3 or 4 wherein said predetermined time is substantially thirty seconds, said time period of said channel signals is substantially twenty seconds and the duration of said channel signals is substantially one second.
Claim 7
Independent Claim
68 words
A system according to any preceding claim wherein each said transmitter includes receiving means for receiving signals on a reception frequency different from that on which the transmitter transmits and the receiver includes transmitter means for transmitting signals on the reception frequency of the transmitter to whose channel the receiver is tuned, said timer means being arranged to de-activate said scanner means when said transmitter means is active.
Claim 8
Dependent Claim
26 words
A transmitter for use in a radio communication system according to any preceding claim including means for periodically transmitting a channel signal on the transmitter's channel.
Claim 9
Dependent Claim
15 words
A transmitter according to claim 7 wherein said channel signal is an unmodulated carrier signal.
Claim 10
Dependent Claim
27 words
A transmitter according to claim 7 or 8 wherein the channel signal time period is substantially twenty seconds and the channel signal duration is substantially one second.
Claim 11
Dependent Claim
27 words
A transmitter according to claim 7, 8 or 9 including receiver means for receiving signals on a reception frequency different from that on which the transmitter transmits.