significant performance degradation the magnitudes of the inphase and quadrature filters 50 are squared 60 and added to generate energy values u03b5 2 jk for each of the possible symbols jk 00 01 10 11 the output signal of the detector 20 is sampled 70 at a rate of 3200 samples per second the decoder 30 receives the output energy measurement from the detector 20 and generates bit metrics for use in determining the least reliable bits generally the larger the detected value u03b5 2 jk the more likely the supposition that the associated symbol was transmitted the decoder 30 converts the symbol soft value to a bit metric for each phase let m be an upper bound on the value of u03b5 jk for a given received word the decoder 30 generates the 2 binary sequences corresponding to the hard decision for each phase by selecting the symbols with the largest energy measurement u03b5 jk the decoder 30 then computes the bit metrics for each bit based on the above formulas the p bits of each word having the largest metric values represent the p least reliable bits in a second embodiment of the present invention the detector 20 is a discriminator detector as shown in greater detail in fig3 discrimination detection may be implemented using commercially available analog fm demodulators the construct and operation of a discriminator detector are well known to those of ordinary skill in the art hence for clarity and to prevent unnecessarily obscuring the instant invention only a high level discussion is provided the detector 20 includes a demodulator 100 a filter 110 a numerical discriminator 120 and a post detection filter 130 in the illustrated embodiment the filter 110 includes a first stage 2 nd order.