Bit synchronization circuit and method capable of correct bit synchronization for both 2-value and 4-value FSK transmission signals
First Claim
1. A bit synchronization method comprising the steps of:
- receiving a polarity-judged output signal obtained by detecting polarity variations of a demodulation signal obtained by demodulating a transmission signal that is modulated according to 2-value FSK or 4-value FSK and a level-judged output signal obtained by detecting level variations of the demodulating signal;
generating a first sampling output by sampling and delaying a state variation of the polarity-judged output signal with a sampling signal;
generating a phase signal indicating a period during which a count of a counter circuit needs to be corrected;
generating, when levels of the first sampling output and the phase signal satisfy a given relationship, a correction signal indicating that the count of the counter circuit should be corrected; and
in response to the correction signal, adding to or subtracting from the count of the counter circuit a number corresponding to an integral multiple of a reference clock period so that a clock signal that is output from the counter circuit has a rate equal to a transmission rate of the transmission signal.
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Accused Products
Abstract
A bit synchronization circuit receives polarity-judged output signal and a level-judged output signal that are produced through demodulation of a 2-value FSK or 4-value FSK transmission signal. Flip-flop circuits and an exclusive-OR circuit generate a second sampling output by sampling and delaying the polarity-judged output signal. Flip-flop circuits and an exclusive-NOR circuit generate a third sampling signal having a given temporal relationship with the second sampling output by sampling and delaying the level-judged output signal. AND circuits supply a correction signal to a counter circuit when levels of the second and third sampling outputs and a phase signal indicating a correction period of the counter circuit satisfy a given relationship. In response to the correction signal, the counter circuit corrects its count so as to produce a clock signal having a rate that is equal to a transmission rate of the transmission signal.
8 Citations
14 Claims
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1. A bit synchronization method comprising the steps of:
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receiving a polarity-judged output signal obtained by detecting polarity variations of a demodulation signal obtained by demodulating a transmission signal that is modulated according to 2-value FSK or 4-value FSK and a level-judged output signal obtained by detecting level variations of the demodulating signal; generating a first sampling output by sampling and delaying a state variation of the polarity-judged output signal with a sampling signal; generating a phase signal indicating a period during which a count of a counter circuit needs to be corrected; generating, when levels of the first sampling output and the phase signal satisfy a given relationship, a correction signal indicating that the count of the counter circuit should be corrected; and in response to the correction signal, adding to or subtracting from the count of the counter circuit a number corresponding to an integral multiple of a reference clock period so that a clock signal that is output from the counter circuit has a rate equal to a transmission rate of the transmission signal.
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2. A bit synchronization method comprising the steps of:
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receiving a polarity-judged output signal obtained by detecting polarity variations of a demodulation signal obtained by demodulating a transmission signal that is modulated according to 2-value FSK or 4-value FSK and a level-judged output signal obtained by detecting level variations of the demodulating signal; generating a first sampling output by sampling and delaying a state variation of the polarity-judged output signal; generating a phase signal indicating a period during which a count of a counter circuit needs to be corrected; generating, when levels of the first sampling output and the phase signal satisfy a given relationship, a correction signal indicating that the count of the counter circuit should be corrected; and in response to the correction signal, adding to or subtracting from the count of the counter circuit a number corresponding to an integral multiple of a reference clock period so that a clock signal that is output from the counter circuit has a rate equal to a transmission rate of the transmission signal; wherein the phase signal includes an on-period during which the count of the counter circuit needs to be increased and an off-period during which the count of the counter circuit needs to be decreased, and wherein an addition correction signal is generated when the first sampling output turns on in the on-period of the phase signal, and a substraction correction signal is generated when the first sampling output turns on in the off-period of the phase signal.
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3. A bit synchronization method comprising the steps of:
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receiving a polarity-judged output signal obtained by detecting polarity variations of a demodulation signal obtained by demodulating a transmission signal that is modulated according to 2-value FSK or 4-value FSK and a level-judged output signal obtained by detecting level variations of the demodulation signal; generating a second sampling output by sampling and delaying a state variation of the polarity-judged output signal; generating a third sampling output having a given temporal relationship with the second sampling output by sampling and delaying a state variation of the level-judged output signal; generating a phase signal indicating a period during which a count of a counter circuit needs to be corrected; generating, when levels of the second sampling output, the third sampling output, and the phase signal satisfy a given relationship, a correction signal indicating that the count of the counter circuit should be corrected; and in response to the correction signal, adding to or subtracting from the count of the counter circuit a number corresponding to an integral multiple of a reference clock period so that a clock signal that is output from the counter circuit has a rate equal to a transmission rate of the transmission signal. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. A bit synchronization circuit which receives a polarity-judged output signal obtained by detecting polarity variations of a demodulation signal obtained by demodulating a transmission signal that is modulated according to 2-value FSK or 4-value FSK and a level-judged output signal obtained by detecting level variations of the demodulation signal, said bit synchronization circuit comprising:
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means for generating a second sampling output by sampling and delaying a state variation of the polarity-judged output signal; means for generating a third sampling output having a given temporal relationship with the second sampling output by sampling and delaying a state variation of the level-judged output signal; a counter circuit for counting reference clocks to produce a clock signal; means for generating a phase signal indicating a period during which a count of the counter circuit needs to be corrected; means for generating, when levels of the second sampling output, the third sampling output, and the phase signal satisfy a given relationship, a correction signal indicating that the count of the counter circuit should be corrected; and means, responsive to the correction signal, for adding to or subtracting from the count of the counter circuit a number corresponding to an integral multiple of a period of the reference clocks so that the clock signal has a rate equal to a transmission rate of the transmission signal. - View Dependent Claims (11, 12, 13, 14)
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Specification