| 摘要 |
A signal detecting circuit detects the presence in an input signal of a component of a predetermined frequency fp. The circuit includes a sampling arrangement for sampling the input signal at predetermined times separated by a sampling period 1/fs and providing first, second, and third signal samples. An adding circuit provides a sum signal A+C from the first and third signal samples, and a calculating circuit provides a calculated signal 2B cos theta from the second signal sample, where theta is the phase relation of the signal samples 2 pi fs/fp. A comparator provides an output signal when the values of the sum signal A+B and the calculated signal 2B cos theta are substantially equal, indicating the presence of the component of interest.
|
