| 摘要 |
A signal processor identifies a burst frequency in a communication channel. Buried in a multitude of RF transmitted incoming data is a sinusoidal burst frequency. The incoming data is stored, and the mean and variance of zero crossings of the incoming data is determined and an indicator is calculated. The indicator is compared to a threshold. When the indicator becomes greater than the threshold, then the burst frequency is identified. Next, the start of the burst frequency must be located. The mean and variance of the frequency of the burst signal is determined. The minimum variance is the start of the burst frequency. Other tests are performed to validate the burst frequency and minimize the probability of falsely identifying the burst frequency. The burst frequency is used to calibrate a crystal oscillator that controls the downconversion of the incoming data.
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