1. A frequency shift keying (FSK) demodulator for demodulating symbols comprising: a plurality of correlation circuits, each configured to output a correlation metric that indicates a likelihood of whether a frequency of a buffered portion of an input signal matches a respective target frequency behavior pattern, as the input signal is continuously received by the FSK demodulator; a result combining stage coupled to the plurality of correlation circuits, the result combining stage configured to output a set of first correlation results based on correlation metrics generated for a first portion of the input signal that encodes a current symbol and a past symbol, the current symbol received at the FSK demodulator after the past symbol, and output a set of second correlation results based on correlation metrics generated for a second portion of the input signal that encodes the current symbol and a next symbol, the next symbol received at the FSK demodulator after the current symbol; and a time combining stage coupled to the result combining stage, the time combining stage configured to delay the set of first correlation results until the set of second correlation results are generated to produce a set of delayed first correlation results, and combine the set of delayed first correlation results and the set of second correlation results to produce a demodulation decision that returns a most likely symbol value for the current symbol.