Direct-conversion, low-rate FSK radiofrequency signal receiver

摘要

The receiver (1) has a low noise amplifier (3) to amplify frequency shift keying (FSK) radiofrequency signals captured by an antenna (2). A phase shifter circuit (16) operates phase shift of 0 to 90 degrees and vice versa of oscillating signals (LO) or radiofrequency signals in half-period of phase switching cycle so as to alternatively generate in phase and quadrature oscillating or FSK signals. The circuit is switched by a phase selection signal (SEL) at frequency of the cycle less than frequency deviation of modulated data in the radiofrequency signals and greater than data flow.