Scanner Tapping

    Audio from a scanner to be fed to a data slicer for digital translation, can not come directly from the audio out of the ear phone speaker plug. This is because the band width of the audio has been reduced through filtering. It is therefore necessary to tap the base band audio, before it is filtered for human speech. The photo in the adjacent column is of a hand held scanner that has had the audio base band tapped and presented externally via a mono female phone plug. As long as the tapped audio is presented to a properly made data slicer or sound card, the tap will not interfere with the function of the scanner.

    This photo is an internal look at the tap within the scanner above. The connections are very simple. An audio tap is taken from from a capacitor off of the IC shown and the ground connection is made to a RF shield on the board. Be sure to use solder flux for the ground connection.

    As it seems two connections must be made within the scanner. A ground and a tap of the audio. Exactly where to tap the audio from however is the topic of the next page. It will discuss how to build a simple tool that will let you easily find the correct point and where to look for it in a scanner.