Methods and apparatus for reducing a sampling rate during a sampling phase determination process
View Patent ↗Techniques for use in sampling a signal of a receiver are described. In a sampling determination mode, a signal is sampled at a first sampling period for producing a sample set for each phase of the sampled signal. For each sample set, a correlation process is performed for producing a correlation result. One of the phases associated with an optimal correlation result is identified from the correlation results. In a communication mode, a received signal is sampled at a second sampling period at the phase associated with the optimal correlation result, for recovering user or signaling information from the received signal. The second sampling period is less than the first sampling period.
1. A method for use in sampling a signal of a receiver, the method comprising:
in a sampling determination mode:
sampling, in the receiver, a signal at a first sampling period producing a sample set for each phase of the sampled signal;
for each sample set, performing a correlation process producing a correlation result;
identifying, from the correlation results, one of the phases associated with an optimal correlation result; and
in a communication mode:
sampling, in the receiver, a received signal at a second sampling period at the phase associated with the optimal correlation result, to recover user or signaling information from the received signal, the second sampling period being less than or greater than the first sampling period, wherein the first sampling period is T±T/n, where T is a symbol or chip period of the signal and n is a number of phases of the sampled signal, where n≧4.
2. The method of claim 1 , wherein the second sampling period is T.
3. The method of claim 1 , wherein performing the correlation process further comprises performing a correlation process between the sample set and a pseudorandom noise (PN) sequence.
4. The method of claim 1 , wherein the receiver comprises a direct sequence spread spectrum (DSSS) receiver and the received signal comprises a DSSS signal.
5. The method of claim 1 , further comprising:
wherein sampling the signal at the first sampling period further comprises sampling the received signal during a first time period; and
wherein the act of sampling the received signal at the second sampling period further comprises sampling during a second time period following the first time period.
6. The method of claim 1 , further comprising:
wherein sampling the signal at the first sampling period comprises sampling with a first analog-to-digital converter; and
wherein sampling the received signal at the second sampling period comprises sampling with use of a second analog-to-digital converter.
7. An electronic circuit comprising:
control circuitry;
an analog-to-digital converter which includes a sampler;
the control circuitry being configured to control the sampler, in a sampling determination mode, to sample a signal at a first sampling period, outputting a sample set for each phase of the sampled signal;
a pseudorandom noise (PN) generator configured to produce a PN signal;
a plurality of correlators, each correlator having:
a first input configured to receive one of the sample sets associated with a corresponding phase of the sampled signal;
a second input configured to receive the PN signal;
an output which provides a correlation result from a correlation process between the sample set and the PN signal; and
the control circuitry being further configured to identify, from the correlation results, one of the phases associated with an optimal correlation result; and
the control circuitry being further configured to control the sampler, in a communication mode, to sample a received signal at a second sampling period at the phase associated with the optimal correlation result, to recover user or signaling information from the received signal, the second sampling period being less than or greater than the first sampling period, wherein the first sampling period is T±T/n, where T is a symbol or chip period of the signal and n is a number of phases of the sampled signal, where n≧4.
8. The electronic circuit of claim 7 , wherein the second sampling period is T.
9. The electronic circuit of claim 7 , which is part of a receiver comprising a direct sequence spread spectrum (DSSS) receiver.
10. A communication device, comprising:
a wireless receiver;
a frequency synthesizer of the wireless receiver;
control circuitry coupled to the frequency synthesizer;
an analog-to-digital converter which includes:
a sampler;
a clock input coupled to a clock output of the frequency synthesizer;
the control circuitry being configured to set the frequency synthesizer, in a sampling determination mode, to produce a clock signal at the clock output so that the sampler samples a signal at a first sampling period, outputting a sample set for each one of n phases of the sampled signal;
a pseudorandom noise (PN) generator configured to produce a PN signal;
a plurality of correlators, each correlator having:
a first input configured to receive one of the sample sets associated with a corresponding phase of the sampled signal;
a second input configured to receive the PN signal;
an output which provides a correlation result from a correlation process between the sample set and the PN signal;
the control circuitry being further configured to identify, from the correlation results, one of the phases associated with an optimal correlation result; and
the control circuitry being further configured to set the frequency synthesizer, in a communication mode, to produce a clock signal at the clock output so that the sampler samples a received signal at a second sampling period at the phase associated with the optimal correlation result, to recover user or signaling information from the received signal, the second sampling period being less than or greater than the first sampling period, wherein the first sampling period is T±T/n, where T is a symbol or chip period of the signal and n is a number of phases of the sampled signal, where n≧4.
11. The communication device of claim 10 , wherein the received signal comprises a direct sequence spread spectrum (DSSS) signal.
12. The communication device of claim 10 , wherein the sampler is set to sample the signal at the first sampling period during a first time period and set to sample the received signal at the second sampling period during a second time period following the first time period.
13. The communication device of claim 10 , forth comprising:
a first plurality of downsamplers coupled to the output of the analog-to-digital converter to produce the sample set for each phase of the sampled signal; and
a second plurality of downsamplers to produce the PN signal for each one of the plurality of correlators.
14. The communication device of claim 10 , wherein the wireless receiver is configured for communications in a wireless communication network and the received signal is a signal from the wireless communication network.
15. The communication device of claim 10 , wherein the second sampling period is T.