Circuits and methods for frequency offset estimation in fsk communications
AssigneeTexas Instruments Incorporated
InventorsWenxun QIU, Timothy Mark SCHMIDL
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Abstract
Disclosed embodiments include a receiver having an input that receives a frequency shift key (FSK) signal having a preamble comprising preamble symbols, a phase compensator that applies a compensation vector to one of first and second samples of a first preamble symbol, wherein applying the compensation vector to the one of the first and second samples produces a compensated sample, a demodulator that determines a phase offset between the compensated sample and the other one of the first and second samples of the first preamble symbol, and a frequency offset mapper that determines a frequency offset based at least upon the phase offset. The receiver applies the frequency offset to the FSK signal.
Claims20
A receiver comprising:
- an input that receives a frequency shift key (FSK) signal having a preamble comprising preamble symbols;
- a phase compensator that applies a compensation vector to one of first and second samples of a first preamble symbol, wherein applying the compensation vector to the one of the first and second samples produces a compensated sample;
- a demodulator that determines a phase offset between the compensated sample and the other one of the first and second samples of the first preamble symbol;
- and
- a frequency offset mapper that determines a frequency offset based at least upon the phase offset;
- wherein the receiver applies the frequency offset to the FSK signal.
A method comprising:
- receiving a frequency shift key (FSK) signal including a preamble having bits, wherein, for each preamble bit, at least a first sample and a second sample of the preamble bit are received;
- for each preamble bit:
- applying a compensation vector to one of the first and second samples that at least partly compensates for phase change between the first and second samples, wherein applying the compensation vector to the one of the first and second samples produces a compensated sample and the other of the first and second samples is an uncompensated sample;
- and
- demodulating the first and second samples to determine a phase offset between the compensated sample and the uncompensated sample;
- determining a frequency offset based on a mean phase offset that is the average of determined phase offsets for a predetermined number of the preamble bits;
- and
- applying the determined frequency offset to the FSK signal.
A integrated circuit device comprising:
- a receiver circuit that receives a frequency shift key (FSK) signal having a preamble, compensates a first sample of a preamble bit of the preamble, determines a phase offset between the compensated first sample and a second sample of the preamble bit, estimates a frequency offset based at least partially on the phase offset, and applies the frequency offset to the FSK signal.
Dependencies are inferred from the claim text.