Discriminator output

From The RadioReference Wiki

Revision as of 17:15, 15 January 2018 by Darunimal (talk | contribs) (Needs current scanners)

The Discriminator output from a scanner is the raw, unfiltered signal that a scanner produces before it is sent to the audio stage for output through the speaker -- also called the "baseband audio." This discriminator source is required for applications such as Trunker, T4Win, UniTrunker, and DSD. Most scanners must have a simple modification made to them to feed the discriminator output to Data Slicers, or in the case of UniTrunker, a soundcard.

Note that for providing a signal for ACARS decoding, a connection from an earphone or speaker output is all that's required. This is because ACARS runs at a much lower speed, and the discriminator is not involved in AM reception.


Also see the Scandata faq q2 article for a list of older scanners' tap points. This is from an original article written by the original scanner hacker and guru the late Bill Cheek.


Radio Shack

Other Radios

Scanners not needing a tap to output discriminator based info

These scanner's listed below need no internal modification to allow discriminator info to be extracted. This would be though a Menu setting, that may need to be set to output data. Those setting would need to be reverted to default setting for programming and/or firmware updating.

Why use a resistor and/or capacitor ?

See #6 through 8 of this URL: FAQ

Wikipedia Page showing Circuit and calculations for Discriminator Tap.

Related Pages

These pages or links contain more information on discriminator taps for many brands and models of scanners, including older models