OVERVIEW: iDEN Digital Modulation Technology
Table 1-1: Audio Amplifier Outputs and Acoustic Transducers
Outputs Acoustic Transducer
A1 (RR) Earpiece speaker output
A2 (RR) Unused
A3 (RR) Internal microphone input
A4 (RR) Audio jack output
A5 (RR) External microphone input
AL (Ext.)
Left channel output to left channel high audio speaker (stereo) or earpiece speaker (mono)
AR (Ext.)
Right channel output to left channel high audio speaker (stereo) or earpiece speaker
(mono)
1.5.3 Audio Modes
The i897 audio circuitry has two basic modes of audio communication operation: interconnect and
dispatch. It also has digital audio and digital video with digital audio multimedia playback modes.
In standard interconnect mode, the i897 uses Roadrunner's internal amplifiers to directly drive the
dynamic earpiece speaker. It can also drive the two high audio speakers in mono if the
speakerphone feature is enabled.
In standard dispatch mode, the i897 uses Roadrunner's internal amplifiers to directly drive the two
high audio speakers in mono. It can also drive the dynamic earpiece speaker.
1.5.4 Audio Paths
The i897 can accept audio from the internal or external microphones. Interconnect voice, dispatch
voice, dispatch tones, and ringer tones are also generated during audio communication operation. These
received audio signals can be transmitted or routed to the earpiece speaker, high audio speakers, output
depending on the audio mode of operation and state of the High/Low Speaker key and audio USB
device detect circuit.
The High/Low Speaker key toggles the audio output from the high audio speakers to the earpiece
speaker. The functionality of the High/Low Speaker key is disabled when there is an audio USB
connect detected.
The microphone input can also be muted and unmuted at any time during an interconnect call.
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