A great copy of the manual, and the only one I could find anywhere on the net! The circuit diagrams are easily readable, all component values marked and easy to see. A highly appreciated download!
Text excerpt from page 28 (click to view)
3. TECHNICAL BRIEF
3.13 Microphone
The microphone is placed to the front cover and contacted to main PCB. The audio signal is passed to VINNORP (#J10) and VINNORN (#K10) pins of AD6525. The voltage supply 2V55_VAN is output from ADP3522, and is a bias voltage for the VINNORP. The VINNOR or VINAUX signal is then A/D converted by the Voiceband ADC part of AD6521. The digitized speech is then passed to the DSP section of AD6525 for processing (coding, interleaving etc.).
