| 摘要 |
An automatic gain control system for a packet-based radio receiver (10, fig.2) comprises signal level detectors (18, 19, 20, fig.2) for monitoring analogue signals at points in the receiver chain. The signal level detectors comprise a binary memory cell such as a flip-flop 22, 24 and a monitoring system. The monitoring system comprises a comparator 21, 23 which receives the analogue signal and a reference voltage. The system continuously monitors the voltage of the analogue signal, detects when the signal exceeds the reference voltage, and stores a logic value in the memory cell 22, 24 in response to such a detection. The AGC system controls the gain of a variable-gain component (LNA 12, mixer 13, filter 14, fig.2) of the radio receiver in dependence on the contents of the binary memory cell 22, 24. The system ensures that subsequent demodulation and decoding of a received packet can be carried out effectively, while reducing the chance of any of the receivers components saturating if a strong interfering signal appears on an adjacent channel. |
