Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

404 FREQUENCY MODULATION, Volume IIt had a response characteristic down 14 db at 100 kc each side of thecenter and down 37 db at 200 kc each side of the center.The detector characteristic was more linear than is usually thecase, having very small departure from a straight line up to 100 kcon each side of the center.It was found necessary to separate the sound and facsimile programsimmediately following the detector, as passing both througha single common amplifier stage, even a fully degenerated stage,resulted in excessive cross modulation. The de-emphasis filter in theoutput of the detector attenuated the facsimile frequencies sufficientlyso that cross-modulation did not occur in the succeeding stage. Anadditional low-pass filter was used following the first audio-frequencywFM RECEIVERAND DISCRIMINATOR