Patent ID: 6546237
Filing Date: 2003-04-08
Classification: H03D,H04L

Abstract:
A. differential FM detector for use in a receiver in which in-phase (I) and quadrature phase (Q) signal components of a received signal in a prescribed modulation format are available comprising:a first limiter for limiting the amplitude of said I signal component to yield a limited version of said I signal component; a second limiter for limiting the amplitude of said Q signal component to yield a limited Q signal component; a first sampler for sampling at a prescribed sampling rate the limited I signal component to obtain a limited and sampled version of said I signal component; a second sampler for sampling at said prescribed sampling rate the limited Q signal component to obtain a limited and sampled version of said Q signal component; a first filter having a prescribed characteristic for filtering said limited and sampled version of said I signal component to yield a filtered version of said limited and sampled I signal component; a second filter having said prescribed characteristic for filtering said limited and sampled version of said Q signal component to yield a filtered version of said and sampled Q signal component; a first delay unit for delaying said fillered version of said limited and sampled I signal component by a prescribed interval; a second delay unit for delaying said filtered version of said limited and sampled Q signal component by said prescribed interval; a first multiplier supplied with said filtered version of said limited and sampled I signal component and an output from said second delay unit for generating a first product signal; a second multiplier supplied with said filtered version of said limited and sampled Q signal component and an output from said first delay unit for generating a second product signal; and an algebraic difference unit supplied with said first and second product signals for generating an output data signal representative of the algebraic difference of said second product signal and said first product signal, whereby harmonics and interference caused by said first and second limiters and said first and second samplers is significantly reduced and thereby reducing the detector bit error rate.