| 摘要 |
<p>A rake receiver comprises a plurality of fingers (31 to 36), each finger having an output; and a combiner (38), which is connected to receive signals provided on the outputs of the fingers and to provide a combined output signal in response thereto. Each finger (31 to 36) includes a respective mixer (51) arranged to mix a received signal with a locally generated pseudo-random noise code, which is provided by a further mixer (56). At least one finger (31) of the receiver includes a first detector (46) which detects a first parameter (the SIR) of a signal downstream of the mixer (56) over a first period of time and provides an output signal in response thereto; first control means (47), which is arranged to control the finger (31) to track a component of the received signal on the basis of the first detector output signal; a second detector (48), which detects a second parameter of the signal downstream of the mixer over a second period of time which is shorter than the first period of time, and provides a second detector output signal in response thereto; and second control means (49), which is arranged to control a switch (39) in response to the second detector output signal. In effect, a finger continues to track a component of the received signal on the basis of a parameter, for example its average power, but varies the contribution the finger makes to the output of the rake receiver on the basis of this or another parameter of the signal over a shorter period of time than that used as the basis for the tracking decision.</p> |
