| 摘要 |
Signal delay and combining techniques are used with multipath signals to provide signal diversity gain within CDMA over-the-air repeater and low noise amplifier systems. An incoming signal from a remote user is typically processed through two processing paths, wherein a differential delay is provided between the two processing paths, such as by one or more delay elements and/or filters, and is applied to the processed signal. The two signal paths are then combined and filtered through a sharp band pass filter, preferably a SAW filter. The gain of the two processing paths is typically balanced, to preserve the signal quality of the combined diversity signal. In an over the air repeater, the filtered signal is retransmitted towards a CDMA rake receiver at a base station, which can process the multipath signal to produce a clean signal representation. In a low noise amplifier, the filtered signal is transferred directly into a base station or repeater. The use of SAW filters protect the latter stages of the low noise amplifier, and also protect the base station from out-of-band signal interference. A quadruple diversity low noise amplification system for base stations embodiment is also disclosed, which provides quadruple diversity and improved sensitivity for CDMA base stations. Preferred embodiments of the delay combiner system provide adaptive gain balancing. |
