The present disclosure relates to a method for demodulating a radio frequency (RF) signal comprising the steps of determining the nearest harmonic of a clock signal from a central frequency (Frx) of a received frequency band; and, if said nearest harmonic is in said frequency band, setting an intermediate frequency (IF) of a Near Zero Intermediate Frequency (NZIF) receiver to the difference (SpurOffset) between said central frequency (Frx) and said nearest harmonic.

A 4 frequency-shift keying (4FSK) transceiver is provided. The 4FSK transceiver includes both a 4FSK transmitter and a 4FSK receiver. The 4FSK transmitter includes a voltage-controlled oscillator (VCO) and two data links coupled to the VCO for delivering two parallel streams of input data bits to the VCO. For each pair of parallel input data bits received from the two data links, the VCO outputs a modulated signal having one of four operating frequencies via 4FSK modulation. Separately, the 4FSK receiver includes a power divider, for dividing the multi-frequency modulated signal into two paths of two binary bit streams, and a pair of low-noise amplifiers (LNAs) separately coupled to the two paths and configured as a pair of band-pass filters for filtering two different subsets of the four operating frequencies from the two binary bit streams into two filtered binary bit streams.