Method and system for determining the integrity of a received signal

摘要

A method for determining the integrity of a received signal in a frequency tracking environment so that a determination can be made whether Automatic Frequency Control (AFC) can be utilized. Several samples of the frequency are taken (205). At least one statistic based on these frequency samples is calculated for use in determining whether the received signal may be used for AFC operation. These statistics may include, for example, the mean, the mean deviation, the standard deviation, and the variance of the measured frequency. A strong signal limit and a weak signal limit are used to determine whether AFC operation should be disabled. If the calculated statistic is less than the strong signal limit (210) then AFC operation is enabled. If the calculated statistic is also greater than the weak signal limit (220) then AFC operation is disabled (225). This allows the receiver to continue AFC operation until the signal level is so weak as to cause erroneous frequency measurements. If the calculated statistic is between the strong signal limit (210) and the weak signal limit (220) then the signal strength is tested (230). If the signal strength is below a minimum value then AFC operation is enabled but if the signal strength is above this minimum value then AFC operation is disabled because a strong interfering signal may be present.