Low Pass Filter (for FSK) (Digital Demod)

FSK measurements often require spans which are much larger than the symbol rate because of large deviations inherent in many FSK signals. The wide span may result in a noisy demodulated signal. The low pass filter is a type of narrow, Gaussian filter (Gaussian shape in the frequency domain) with a cutoff frequency greater than the symbol rate. The filter has a 3 dB point of approximately 2/3 of the symbol rate and is down by 40 dB at about 2x the symbol rate. Applying the low pass filter to the measured signal may smooth the result.