Hands-free system microphone, component description - GF82.70-P-4121RC

MODEL 171 with CODE (523) MB Audio 20 radio Basic telephony

MODEL 171 with CODE (510) Audio 20 with CD changer Basic telephony

MODEL 171 with CODE (525) MB Audio 50 APS radio Basic telephony

MODEL 171 with CODE (511) Audio 50 APS with DVD changer Basic telephony

MODEL 171 with CODE (527) COMAND APS with single DVD drive (with navigation) Basic telephony

MODEL 171 with CODE (512) COMAND APS with DVD changer Basic telephony

MODEL 171 with CODE (386) Mobile phone Comfort telephony

MODEL 171 as of model year 09/YoM 08 model refinement package

B25 Hands-free system microphone group

N70 Overhead control panel control unit

Fig 1: Locating Hands-Free Microphone

Courtesy of MERCEDES-BENZ USA

Location The hands-free system microphone group is installed in the overhead control panel control unit.

Depending on the equipment installed one of the following control units will be installed, hereafter referred to as the "audio unit": Radio (A2), with code (523) MB Audio 20 radio or with code (510) Audio 20 with CD changer - Radio and navigation unit (A2/56), with code (525) MB Audio 50 APS radio or with code (511) Audio 50 APS with DVD changer - COMAND operating, display and controller unit (A40/3), with code (527) COMAND APS with single DVD drive (with navigation) or with code (512) COMAND APS with DVD changer.

Task Receiving signals; Converting signals; Transmitting signals.

Receiving signals Reception of acoustic (audible) signals in the form of sound waves - Circuit 31 from "Audio unit" via discrete line

Converting signals Conversion of acoustic (audible) signals to electrical signals (frequency)

Transmitting signals Discrete lines - Transmission of electrical signals (frequency) to the "Audio unit" over 2 discrete lines

Design The hands-free system microphone group consists of 3 microphones, but only 2 microphones are used.