Specifications

AirPrime Embedded Module Hardware Integration Guide
52 Proprietary and Confidential 2130114
Gain distribution
For Handset and Headset mode, the threshold of pain (+120 dBSPL) must not be
exceeded at the maximum volume setting. A good target for the medium volume
setting is +94 dBSPL, as this is a typical level for conversational speech.
Most audio gain should be added to the host audio front end (within the PDA style
codec gain blocks or amplifiers between the host codec and transducers). Refer
to the appropriate Product Specification Document for reference levels on the
modem receive and transmit side.
Echo cancellation support
AirPrime embedded modules offer four modes of echo cancellation to support
unique end-unit audio capabilities (echo cancellation can also be turned off
completely). All echo cancellation is near-end (mobile TX) cancellation only. The
network provides some level of far-end echo cancellation.
Table 4-3: System gain values
a
a. Typical system gains are estimates only and vary from system to system depending upon
transducer sensitivity.
Mode Modem TX
gain (dB)
Modem RX
gain (dB)
Typical system
TX gain (dB)
Typical system
RX gain (dB)
Handset +8 +8 +28 +32
Headset +8 +8 +28 +24
Car Kit +16 +8 +36 +32
Speakerphone +16 +8 +36 +32
Table 4-4: Echo cancellation details
Mode Details
Handset • Short echo path (<16 ms travel time from speaker to micro-
phone)
• Handset design requires good isolation between speaker and
microphone
• Echo canceller allows full-duplex conversation with absolute
minimum echo
Headset • Short echo path (<16 ms travel time from speaker to micro-
phone)
• Headset design may allow higher echo than handset mode—
microphone and speaker are physically closer
• More aggressive echo canceller algorithm allows full-duplex
conversation on headsets with good isolation