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Title: Synchron timing of signals in spaced transmitters and in a receiver for a phase comparison navigation system using time sequential transmissions
Claims: I claim: 1. Sychronizing means for a phase comparison radio navigation system having a prime and one or more secondary spaced transmitting stations radiating phase-locked signals in a time-shared sequence, the prime station also radiating a timing identification signal, and one or more receivers for comparing the phase of the signals; which synchronizing means comprise, at the prime station, a signal source of a frequency related to the radiated frequency, digital counting means for deriving timing signals by counting signals from said signal source and means controlling the timing of the prime station transmissions in response to the output of the counter and wherein, in a receiver, there are provided means for receiving the radiated signals, means for deriving, from the received signals of said radiated frequency, a repetitive pulse counter input signal of a frequency related thereto, and a counter arranged for counting pulses from said counter input signal to derive a timing cycle corresponding to that at the prime station, and wherein the transmissions from said prime station include a timing identification signal and wherein, at the receiver, means are provided for detecting said timing identification signal and for applying the detected signal as a synchronizing signal to the counter to synchronize the counter timing at the receiver with the timing of the counting means at the prime station. 2. Synchronising means for a radio navigation system as claimed in claim 1 wherein a secondary station has a receiver for controlling the timing of the transmissions therefrom. 3. A radio navigation system as claimed in claim 1 wherein, at the receiver, a switch is provided operable to disconnect the feed of the synchronising signal to the counter. 4. A radio navigation system as claimed in claim 3 wherein the switch is arranged so that the switch when operated is effective to interrupt the feed after the next snychronising signal. 5. A radio navigation system as claimed in claim 1 wherein, at said receiver, said means for deriving the pulse counter input signal comprises an oscillator phase-locked to the received signals. 6. Synchronizing means for a phase comparison radio navigation system having a prime and at least one secondary spaced transmitting stations radiating phase-locked signals in a time-shared sequence, the prime station also radiating a timing identification signal, which synchronizing means comprise, at the prime station, a signal source of a frequency related to the radiated frequency, digital counting means for deriving timing signals by counting signals from said signal source, and means controlling the timing of the prime station transmissions in response to predetermined counts for said counter and wherein, at the secondary station there are provided a receiver for receiving signals from the prime station, means for deriving, from the received signals of said radiated frequency, a repetitive pulse counter input signal of a frequency related thereto, and a counter arranged for counting pulses from said counter input signal to derive a timing cycle corresponding to that at the prime station, and wherein the transmissions from said prime station include a timing identification signal and wherein, at the receiver, means are provided for detecting said timing identification signal and for applying the detected signal as a synchronizing signal to the counter to synchronize the counter timing at the receiver with the timing of the counting means at the prime station. 7. A radio navigation system as claimed in claim 6 wherein, at the secondary station, said means for deriving a pulse counter input comprises an oscillator phase-locked to the received signals. Other info: Inventors: Phipps, Derek John (London, EN) Application Number: 524199 Filing Date: 1974-11-15 Publication_date: 1976-08-03 Assignee: Decca Limited (London, EN) Primary Class(es): 342/397 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Wilbur, Maynard R. Assistant Examiner: Berger, Richard E. Attorney: Connors; Edward F. |
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