Frequency scan and lock circuit for mobile radio channel selection
AssigneeBell Telephone Laboratories, Incorporated
InventorsReed Edward Fisher, Robert William Humes
Life of this patent
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Abstract
Sequentially received frequency channel samples in a mobile radio telecommunication system are compared by pairs. The name of the channel providing the larger sample in any comparison is overwritten into a storage register if that larger sample is also the newest sequential sample of the pair. The next sample of the sequence is compared to only the larger sample determined in the previous comparison operation. At the end of the sampling sequence the channel name remaining in the register is utilized to tune the mobile unit receiver to the named channel.
Claims5
A mobile radio telecommunication unit having a tunable receiver and a circuit for ascertaining which one of predetermined receivable frequency channels is strongest, said circuit comprising
- first and second analog signal sample and hold circuits,
- controllable means for steering an output, which is indicative of received signal strength in one of said channels, of said receiver to one or the other of said sample and hold circuits,
- means for comparing outputs of said sample and hold circuits,
- means, responsive to an output of said comparing means, for producing a signal pulse state when a new channel sample is the larger of two compared samples and a signal no-pulse state when the new sample is the smaller of the two compared samples, and
- control means comprising
- means for sequentially tuning said receiver to each of said channels,
- means, responsive to said pulse state, for storing the name in said sequence of said channel having said larger sample, and
- means for controlling said steering means to steer each sequential channel sample from said receiving means to the one of said sample and hold circuits that held said smaller sample of two previously compared samples.
Dependencies are inferred from the claim text.