NetModule NB3700, Руководство пользователя

Страница: 133 / 194

NB3700 User Manual 3.8
Based on your equipment, we recommend to adjust the modem’s audio profile for a
better sound experience. The following profiles are available:
Parameter Voice-Over-Mobile Audio Profiles
Handset Provides a mild echo, short delay (less than 16-ms disper-
sion).
This mode is intended for use with a well-designed hand-
set, where the Echo Return Loss (ERL) is generally high.
Full-duplex performance is easiest to achieve in this mode.
Headset Provides a moderate echo, short delay (less than 16-ms dis-
persion).
This mode is intended for use in situations where the echo
may be loud but low in delay. There are a variety of different
headsets available with a wide variety of echo characteris-
tics and noise pickup. Although the echo delay is typically
short (< 16 ms) with all headsets, the echo return loss char-
acteristics can vary significantly and are not well known a
priori to the handset designer. This mode is more robust
and more aggressive at echo cancellation.
Speakerphone Handle situations of loud echo with extreme acoustic distor-
tion.
This mode is intended for use with a car kit or speakerphone
applications with high volume and high distortion. Acoustic
echo in this situation has negative ERL and is impossible
to cancel completely. It operates in a half-duplex manner
and will be very aggressive in muting the entire signal to
prevent any echo blips from being heard.
Bluetooth Provides moderate echo, long delay (up to 64-ms disper-
sion).
This mode is intended for bluetooth headsets and carkits
which may have DSP processing on board and could give
added delay to the system.
133