Differential receiver for direct sequence spread spectrum signals

摘要

The receiver includes a modified IF stage with a number (N) of channels for filtering and amplification in distinct frequency bands. In each channel, a band-pass filter (20) is followed by a variable-gain amplifier (22) and an output level detector (26). The gain in each channel is adjustable so the output delivered to a summing circuit (27) from the different channels follows a predetermined distribution law. The amplification may be divided among two variable-gain and three fixed-gain stages alternating with filtering cells.