| 摘要 |
A method and apparatus for determining received signal strength of a radio frequency signal of a frequency dependent device to determine errors in automatic frequency control calculations. The method includes the steps of: 1 ) receiving the radio frequency signal; 2) providing at least two artificial thresholds based upon the signal during a first portion (45) of a signal block (32), wherein the artificial thresholds lie outside the peak and valley amplitudes of a demodulated intermediate signal (225) of the radio frequency signal; 3) providing automatic frequency control to determine a frequency error value (250) during a second portion (46) of the signal block (32); 4) determining a correction factor based upon the position of the demodulated signal in relation to the artificial thresholds during the second portion (46) of the signal block (32); and 5) varying the frequency of an adjustable crystal (220) in accordance with the correction factor applied to the frequency error value (250). The adjustable crystal (220) controls the frequency of a transmitter (112) of the frequency dependent device and the frequency of the local oscillator (210), the signal of which is mixed with the radio frequency signal to produce the intermediate signal (215). The apparatus comprises the circuitry for determining received signal strength of a radio frequency signal according to the above described method.
|
