Scandata faq q1

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Q1: What is a 'Discriminator Output' and 'baseband audio'?

There is a growing interest in tapping the baseband audio
out of various scanners for decoding of a variety of
esoteric signals, including CTCSS, SCA, FSK, RTTY, FAX,
Pager data, and trunked system control data, etc.

By and large, such signals cannot be taken from TAPE REC
jacks, headphone jacks, and EXT SPEAKER jacks because of the
voice-band filters that are between the signal source and
these output jacks.

Therefore, it is necessary to tap the wider "baseband audio"
directly at the output of the NFM discriminator chip in your
scanner. This is the first step to successful data decoding
from the airwaves.

Also see article on Discriminator output.

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