| 摘要 |
A rake receiver comprises a plurality of fingers e.g. 31, 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 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. Each finger includes a first detector (46 fig 3) which detects a parameter such as the signal to interference ratio (SIR) of the signal downstream of the mixer 56 over a first relatively long period of time and provides an output signal in response thereto. A control means (47), controls the finger 31 to track a multipath component of the received signal on the basis of the first detector output signal. A second detector 48 detects the SIR over a second relatively short period of time, and provides an output to a second control means 49, which switches 39 the output to the combiner 38 off, if any sample falls below a threshold 59 SIR. The receiver may have a second set of fingers which receive a code-multiplexed pilot signal such as a CPICH channel in the UMTS system and switch the output of the data signal in dependence on variations in the CPICH channel. |
