| 摘要 |
In a transceiver (1) forming part of a digital communications system, there is described a system for data recovery from the demodulated analogue signal, said system comprising a slicer circuit (6) for extracting the digital data from the analogue signal and a low pass filter (9) for generating, from the input analogue signal (5), a threshold signal for use in the operation of said slicer circuit (6). The low pass filter (9) has a variable time constant, selected by a switch (5), to alter the rate of change of the threshold level in accordance with the position of the switch. The switch is itself controlled by a composite control signal (16) output from a gate (10) and indicative of two properties of the received R.F. signal, namely the received signal strength (RSSI) and the state of synchronisation. The arrangement is such that a high rate of change of threshold level is permitted only if the transceiver is not synchronised and the received signal strength is above a predetermined level. <IMAGE> |
