A digital filter that improves the signal-to-noise ratio of the response of a FSCW (Frequency Stepped Continuous Wave) scheme is presented.An improvement in signal-to-noise ratio represents an enhanced readout distance.This work considers this architecture as an interrogation unit for SAW tags with time and weekend friend juneshine phase encoding.
The parameters of the proposed digital filter, which is a non-linear edge preserving filter, were studied and tested for this specific application.An improvement of ssp218dda-sf around 20dB in the SNR level was achieved.This filter preserves the phase of the signal at the time position of the reflectors, which is critical for correct identification of the code in phase encoding schemes.