Patent ID: 6563887
Filing Date: 2003-05-13
Classification: H04L

Abstract:
A direct conversion receiver for frequency shift keying modulated signals, said receiver including:an antenna able to receive a frequency shift keying modulated signal; conversion means able to receive said modulated signal and to provide in response first and second analog signals in phase quadrature, these signals being representative of the real and imaginary parts of a complex signal having at least a first negative frequency or a second positive frequency demodulation means able to receive said first and second signals and to provide in response a third signal representative of the data contained in said modulated signal, wherein said demodulation means include: a complex filter arranged to receive said first and second signals, and to provide in response fourth and fifth analog signals so that, when the frequency of said first and second signals is equal to said first frequency, respectively to said second frequency, the gain of the transfer function is equal to a first gain value, respectively to a second gain value which is different to said first gain value; first and second normalisation means arranged to receive respectively said fourth and fifth signals, and to provide in response a sixth analog signal respectively a seventh analog signal representing a standard of said fourth signal, respectively of said fifth signal; and a first adder arranged to receive said sixth and seventh signals and to provide in response said third analog signal representing the sum of said sixth and seventh signals.