Differential detection of spread spectrum wakeup codes

A receiving apparatus, comprising:

• a splitter configured to split a received signal into multiple component signals, wherein the multiple component signals are like copies of the received signal and the received signal comprises a plurality of symbols conveying a code sequence, each symbol comprising one or more repetitions of one sub-sequence among a set of sub-sequences of different lengths, and each sub-sequence representing one logic value among a set of logic values used to form code sequences;
• multiple correlation chains, each correlation chain operating on a respective one of the multiple component signals and configured to generate a correlation output, based on autocorrelating the respective component signal using a delay matched to the length of a respective one of the sub-sequences in the set of sub-sequences, such that a corresponding set of correlation outputs is generated for each symbol of the received signal, each correlation result in each corresponding set of correlation results corresponding to a respective one of the sub-sequences in the set of sub-sequences;
• and
• a controller configured to determine the received code sequence from the corresponding set of correlation outputs generated for each symbol, over the plurality of symbols.