Spread spectrum receiver

A receiver for a spread spectrum signal, said receiver comprising:

• means for receiving a spread spectrum signal and for producing an analogue chip sequence;
• means for digitizing the analogue chip sequence to produce a digitally sampled chip sequencer;
• a digital matched filter having an input for the digitally sampled chip sequence;
• means coupled to an output of the matched filter for obtaining a running average of the output of the matched filter over successive bit periods;
• means for noting which of the matched output samples corresponds to a maximum value in the running average in successive bit periods;
• and
• decision means for noting a sign of the signal in the filter stage synchronized with the maximum value and assigning a data bit value in accordance with said sign.

A method of recovering data bits from a spread spectrum signal, the method comprising:

• deriving a digitally sampled chip sequence from a received spread spectrum signal;
• filtering the digitally sampled chip sequence in a matched filter;
• and
• obtaining a running average in accordance with the equation:
• {circumflex over (X)}in=α*{circumflex over (X)}in−1+(1−α)*Xin
• where is Xin an absolute value of an i th matched filter output sample in an n th data bit period,
• {circumflex over (X)}in−1 is a corresponding i th sample running average at an end of an n−1 th data bit period, and
• α is an averaging gain and has a value between 0≦α≦1.