Frequency hopping radio communications apparatus having pseudo-random _channel selection
First Claim
1. Frequency hopping radio communications apparatus having selection circuitry for providing in psuedo-random order a sequence of multi-digit signals identifying n channels selected from N possible channels comprising a first counter responsive to clock signals to provide a series of multi-digit signals identifying each of the N possible channels, electronic latching means the input of which receives the multi-digit signals from said first counter and which is arranged to provide a multi-digit signal at its output corresponding to the multi-digit signal present at its input each time the latching means is enabled, a store which is addressed by said multi-digit signals from said first counter and which is arranged to provide a first signal whenever said multi-digit signals from said first counter identify one of the n channels, and a second counter which is responsive to the first enabling signals to count the clock pulses supplied to said first counter and which is arranged on reaching a predetermined value of the count to provide a second enabling signal to the latching means to latch its output to the multi-digit signal then present at its input.
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Accused Products
Abstract
Channel selection in a frequency hopping radio set is controlled by a pseudo-random number generator, the pseudo-random number being used to address an N bit memory (3) which is used to identify each of n available channels from N equipped channels. When a preselected number of the n channels have been identified by the psuedo-random number generator a latch (4) is enabled to store the channel number for selection purposes. Various scrambling methods are employed so that the channels on which one network of radio sets is operating is not readily identifiable from the channels on which another network of radio sets is operating.
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Citations
9 Claims
- 1. Frequency hopping radio communications apparatus having selection circuitry for providing in psuedo-random order a sequence of multi-digit signals identifying n channels selected from N possible channels comprising a first counter responsive to clock signals to provide a series of multi-digit signals identifying each of the N possible channels, electronic latching means the input of which receives the multi-digit signals from said first counter and which is arranged to provide a multi-digit signal at its output corresponding to the multi-digit signal present at its input each time the latching means is enabled, a store which is addressed by said multi-digit signals from said first counter and which is arranged to provide a first signal whenever said multi-digit signals from said first counter identify one of the n channels, and a second counter which is responsive to the first enabling signals to count the clock pulses supplied to said first counter and which is arranged on reaching a predetermined value of the count to provide a second enabling signal to the latching means to latch its output to the multi-digit signal then present at its input.
Specification