IF RESPONSE with modified filters

The filter modifications shown above will cause severe distortion of the received audio, at least for high modulation levels, and of course will cause reduction of the stereo image. The effect on the audio quality from a strong local signal without QRM is shown in these clips

For loud modulation

TIMINGS: 0 - 6s WIDE, 6 - 11s NORMAL, 11 - 16s NARROW

For quiet music and speech,

TIMINGS: 0 - 5s WIDE, 5 - 9s NORMAL, 9 - 13s NARROW, 14 - 19s WIDE, 19 - 25s NORMAL, 25 - 30s NARROW

For a weak signal with high modulation and without QRM


The ability to separate weaker signals is demonstrated in this clip of adjacent-channel QRM where the weak station (on 96.1) playing Annie Lennox is subject to strong QRM from an adjacent station playing Gwen Stefani (on 96.2)

TIMINGS: 0 - 16s NARROW, 16 - 26s WIDE, 26 - 35s NORMAL, then back to NARROW

Similarly in this clip of QRM from both sides where the weak Radio Wales is subject to strong QRM from adjacent stations

TIMINGS: 0 - 3s WIDE, 3 - 11s NORMAL, 11-16s NARROW

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Last updated Oct.2008

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