Timing synchronization for M-DPSK channels
First Claim
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1. A differential phase shift signal receiver comprising:
- a demodulator comprising a first input to receive a differential phase shift signal, and an output to provide a differential phase shift base-band signal;
an analog to digital sampling module comprising an input coupled to the output of the demodulator, and an output to provide a sampled differential phase shift base-band signal; and
a synchronization detection module comprising;
an input coupled to the output of the analog to digital sampling module;
a first output to provide a symbol center sample index that identifies a sample of the sampled differential phase shift base-band signal having a predefined relationship to a center of a received symbol;
a second output to provide a sample interval fraction that identifies a fractional portion of a sample period from the sample identified by the symbol center sample index to an estimated center of the received symbol;
a phase differential detection module to receive the sampled differential phase shift base-band signal and to produce a sequence of phase differential samples;
a signal correlation module responsive to the phase differential detection module, the signal correlation module including a sample correlation module, the sample correlation module having a first input to receive the sequence of phase differential samples and a second input to receive a predetermined synchronization symbol pattern, pattern associated with predetermined synchronization bit pattern, the sample correlation module to produce symbol correlation values; and
a timing detection module responsive to the signal correlation module to generate the symbol center sample index and the sample interval fraction.
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Abstract
The present invention discloses an improved method of timing synchronization with transmitted data packets in a receiver on a communication channel using differential phase shift keying (DPSK) modulation—especially an RF wireless communication channel. The invention reduces the complexity of the circuits, especially the multipliers, required for digital signal processing. The invention also increases performance compared to previously known methods.
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Citations
23 Claims
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1. A differential phase shift signal receiver comprising:
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a demodulator comprising a first input to receive a differential phase shift signal, and an output to provide a differential phase shift base-band signal; an analog to digital sampling module comprising an input coupled to the output of the demodulator, and an output to provide a sampled differential phase shift base-band signal; and a synchronization detection module comprising; an input coupled to the output of the analog to digital sampling module; a first output to provide a symbol center sample index that identifies a sample of the sampled differential phase shift base-band signal having a predefined relationship to a center of a received symbol; a second output to provide a sample interval fraction that identifies a fractional portion of a sample period from the sample identified by the symbol center sample index to an estimated center of the received symbol; a phase differential detection module to receive the sampled differential phase shift base-band signal and to produce a sequence of phase differential samples; a signal correlation module responsive to the phase differential detection module, the signal correlation module including a sample correlation module, the sample correlation module having a first input to receive the sequence of phase differential samples and a second input to receive a predetermined synchronization symbol pattern, pattern associated with predetermined synchronization bit pattern, the sample correlation module to produce symbol correlation values; and a timing detection module responsive to the signal correlation module to generate the symbol center sample index and the sample interval fraction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A differential phase shift signal receiver comprising:
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a phase differential detection module to receive a differential phase shift keying signal and to produce a sequence of phase differential samples; a bit correlation module responsive to the phase differential detection module, the bit correlation module including a bit recovery module responsive to the sequence of phase differential samples and producing a recovered candidate bit stream, the bit correlation module including a binary correlation module, the binary correlation module having a first input to receive the recovered candidate bit stream and a second input to receive a predetermined synchronization bit pattern, the binary correlation module to produce bit correlation values; a signal correlation module responsive to the phase differential detection module, the signal correlation module including a sample correlation module, the sample correlation module having a first input to receive the sequence of phase differential samples and a second input to receive a predetermined synchronization symbol pattern wherein the sample correlation module performs a correlation on a selected subset of the phase differential samples, the signal correlation module to produce signal correlation values; and a timing detection logic module responsive to the bit correlation module and responsive to the signal correlation module, the timing detection logic module generating a synchronization indicator based on the bit correlation values and the signal correlation values.
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16. A method of synchronizing a received differential phase shift signal, the method comprising:
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receiving a differential phase shift keying signal; demodulating the differential phase shift keying signal to produce a baseband differential phase shift keying signal; determining a sequence of phase differential samples derived from the baseband differential phase shift keying signal; recovering a candidate bit stream from the sequence of phase differential samples; correlating the candidate bit stream with a predetermined synchronization bit pattern to produce bit stream correlation values; correlating the sequence of phase differential samples at a symbol separation with a predetermined synchronization symbol pattern to produce signal correlation values; comparing the bit stream correlation values with a threshold to detect a data packet; performing peak tuning of the detected data packet to determine a sample interval fraction based on the signal correlation values; and determining synchronization timing with respect to a start time of the detected data packet based on the detected data packet and the sample interval fraction. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification