User Guide

RM-11

System Module CC Technical Documentation

Internal Audio

Internal Microphone

The internal microphone capsule is mounted to in the UI frame. The microphone is

omni-directional and is connected to the UEM microphone input (MIC1P/N). The micro-

phone input is asymmetric and the UEM (MICB1) provides bias voltage. The microphone

input on the UEM is ESD protected. Spring contacts are used to connect the microphone

to the main PWB.

Figure 9: Internal microphone connection

Internal Speaker

The internal earpiece is a dynamic earpiece with an impedance of 32 ohms. The earpiece

is low impedance because the sound pressure is to be generated using current and not

voltage as the supply voltage is restricted to 2.7 V. The earpiece is driven directly by the

UEM and the earpiece driver (EARP and EARN outputs) is a fully differential bridge

amplifier with 6 dB gain. In RM-11, an 8 mm leak tolerant PICO earpiece is used.

Figure 10: Speaker connection

IHF Speaker and Stereo Audio Amplifier

The Integrated Hands Free (IHF) speaker (16 mm MALT) is used to generate speech audio,

ringing and warning tones. The audio amplifier is controlled by the UPP. The speaker

capsule is mounted in the C-cover. Spring contacts are used to connect the IHF speaker

contacts to the main PWB.

UEM

MIC1N

MIC1P

EMC

Microphone

Charge

Common mode

choke

EARP

EARN

UEM