Quick Decision Preamble Detector with Hierarchical Processing

1) A preamble detector operative during repeating preamble detection intervals, the preamble detector receiving an in-phase baseband channel signal and a quadrature baseband channel signal and generating a packet detect output, the preamble detector forming an array of values for accumulation, the array of values comprising the individual results of summing a squared in-phase correlation and a squared quadrature correlation, the in-phase correlation formed by cross correlating the in-phase baseband channel signal with a template PLCP, the quadrature correlation formed by cross correlating the quadrature baseband channel signal with the template PLCP, the length of the template PLCP being equal to the length of a preamble PLCP on either the in-phase baseband channel or the quadrature baseband channel;

• at the start of each preamble detection interval, resetting an accumulation register, thereafter accumulating each array of values into the accumulation register, the accumulation register having a peak value greater than other accumulation register values, the peak value compared with a first interval threshold during a first interval;
• if the peak value does not exceed the first interval threshold, powering down the preamble detector, and if the peak value exceeds the first interval threshold, continuing to accumulate each array of cross correlation values into the accumulation register for a second interval, thereafter comparing the peak value of the correlation register with a threshold;
• if the peak value exceeds the threshold, powering down the preamble detector until a subsequent preamble detection cycle, otherwise accumulating each array of values into the accumulation register for a third interval, thereafter comparing the peak value of the correlation register with a threshold;
• if the peak value exceeds the threshold, asserting a preamble detect output.