It says on the very first paragraph of the Wiki Page...mpdonala said:give me the info I need that a discriminator tap will give.
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, and UniTrunker. 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.