Digital paging system having bit rate switching means and digital paging receiver therefor
First Claim
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1. A paging receiver comprising:
- receiving means for receiving a carrier wave which is modulated with a paging signal including first coded pulse sequences of a first transmission rate and second coded pulse sequences of a second transmission rate, said first and second transmission rates differing from each other, said first and second coded pulse sequences including first and second predetermined bits, respectively, said second pulse sequences bring comprised of a first codeword and n codewords following said first codeword, n being zero or a positive integer, said second pulse sequence further including third predetermined bits which follow said second predetermined bits and represent the number of said n codewords;
demodulating means for demodulating the received carrier wave;
low-pass filter means coupled to the output of said demodulating means for switching the first cut-off frequency thereof to the second one to pass said second coded pulse sequences when said first means receives a first control signal and switching said second cut-off frequency to said first one to pass said first coded pulse sequences when said filter means receives a second control signal; and
data processing section means coupled to the output of said low-pass filter means for generating said first control signal at the end of said first coded pulse sequences when said first coded pulse sequences coincide with a third coded pulse sequence unique to said paging receiver, generating said second control signal at the end of said second coded pulse sequences in response to the reception of said second predetermined bits and in accordance with the content of said third predetermined bits, and decoding the passed first and second coded pulse sequences.
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Abstract
A paging system in which an address code is transmitted at a lower transmission rate than message code and a discrimination code defines the boundary between the address and the message. The receiver includes a low pass filter with a cut-off frequency switchable between the reception rate for the address and the reception rate for the message in response to the discrimination code.
40 Citations
10 Claims
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1. A paging receiver comprising:
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receiving means for receiving a carrier wave which is modulated with a paging signal including first coded pulse sequences of a first transmission rate and second coded pulse sequences of a second transmission rate, said first and second transmission rates differing from each other, said first and second coded pulse sequences including first and second predetermined bits, respectively, said second pulse sequences bring comprised of a first codeword and n codewords following said first codeword, n being zero or a positive integer, said second pulse sequence further including third predetermined bits which follow said second predetermined bits and represent the number of said n codewords; demodulating means for demodulating the received carrier wave; low-pass filter means coupled to the output of said demodulating means for switching the first cut-off frequency thereof to the second one to pass said second coded pulse sequences when said first means receives a first control signal and switching said second cut-off frequency to said first one to pass said first coded pulse sequences when said filter means receives a second control signal; and data processing section means coupled to the output of said low-pass filter means for generating said first control signal at the end of said first coded pulse sequences when said first coded pulse sequences coincide with a third coded pulse sequence unique to said paging receiver, generating said second control signal at the end of said second coded pulse sequences in response to the reception of said second predetermined bits and in accordance with the content of said third predetermined bits, and decoding the passed first and second coded pulse sequences. - View Dependent Claims (2, 3, 4, 5)
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6. A method for receiving a paging signal at a paging receiver, comprising the steps of:
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receiving a carrier wave which is modulated with said paging signal including first coded pulse sequences of a first transmission rate and second coded pulse sequences of a second transmission rate, said first and second transmission rates differing from each other, said first and second coded pulse sequences including first and second predetermined bits, respectively, said second pulse sequences being comprised of a first codeword and n codewords following said first codeword, n being zero or a positive integer, said second pulse sequences further including third predetermined bits which follow said second predetermined bits and represent the number of said n codewords; demodulating the received carrier wave to provide demodulated first and second coded pulse sequences; receiving first and second control signals, selectively passing said demodulated first and second coded pulse sequences by switching the cut-off frequency of a low-pass filter included in said paging receiver dependent upon receiving said first and second control signals; generating said first control signal when said first coded pulse sequences coincide with third coded pulse sequences unique to said paging receiver; generating said second control signal in response to the reception of said second predetermined bits and in accordance with the content of said third predetermined bits; and decoding said demodulated first and second coded pulse sequences which have been passed. - View Dependent Claims (7, 8)
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9. A paging method comprising the steps of:
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modulating a carrier wave with a paging signal including first coded pulse sequences of a first transmission rate and second coded pulse sequences of a second transmission rate, said first and second transmission rates differing from each other, said first and second coded pulse sequences including first and second predetermined bits, respectively, said second pulse sequences being comprised of a first codeword and n codewords following said first codeword, n being zero or a positive integer, said second pulse sequences further including third predetermined bits which follow said second predetermined bits and represent the number of said n codewords; transmitting the modulated carrier wave to a paging receiver; receiver and demodulating the transmitted, modulated carrier wave to provide demodulated first and second coded pulse sequences; selectively passing said demodulated first and second code pulse sequences by switching the cut-off frequency of a low-pass filter included in said paging receiver in accordance with the demodulated first, second and third predetermined bits; and decoding said demodulated first and second coded pulse sequences which have been passed. - View Dependent Claims (10)
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Specification