Multi-Tech Systems MMCModem GPRS (MTMMC-G) - Manual (Page 28)

Chapter 5 – Call Control Commands
Multi-Tech Systems, Inc. Wireless GSM/GPRS AT Commands (Document Number S000293I) 28
♦ Convergence time in quiet condition:
This parameter expresses duration as the number of GSM speech frames (20 ms each)
containing far end speech, upon which the switch only mechanism must run in quiet
conditions. The allowed range is [162 - 32767].
The default is
200.
♦ Convergence time in noise condition:
This parameter is the same as ConvergenceTime1 but for the noise condition. The
allowed range is [162 - 32767].
The default is
550.
Important Note: must be greater than or equal to
♦ Upper bound of the noise floor estimate:
This parameter is expressed as an integer of 16 bits and corresponds to the rounded
value of the noise floor estimate expressed in dB (log2). The allowed range is
[NOISE_LEVEL_MIN+1 - 31] with NOISE_LEVEL_MIN being a constant
(NOISE_LEVEL_MIN=4 in the current implementation).
The default is
15.
♦ Far-end speech detection threshold:
In order to detect far end speech on the loudspeaker's signal, the SNR is computed
regarding the far end signal power and the far end signal noise floor level. This parameter
specifies a threshold on the SNR above which the switch mechanism will be activated.
This parameter is expressed as an integer of 16 bits and must be in the range [0 - 32767].
The default is
32767.
♦ Comfort noise volume gain:
Although the comfort noise volume will self adjust to the estimated ambient noise level, it
is possible to artificially reduce its level. This parameter is expressed in fixed point as a
signed Q15, meaning that 32767 stands for 1.0, and 0 for 0.0. It ranges fro 0 to 32767.
Setting this value to 0 means no comfort noise.
The default is 32767.
♦ , : 16 bits comfort noise AR2 coefficients:
The user will set the AR2 coefficients for a specific car. Their value will be estimated on a
recorded noise sequence by means of a tool provided by Wavecom (C or Matlab source
code) The recorded sequence shall be made in the noisy conditions and contain noise
only.
The allowed range is [0 - 65535].
The default for
CNGParam1 is 27484.
The default for CNGParam2 is 38697.
♦ : 16 bits comfort noise AR2 gain coefficients:
This specifies the gain of the AR2 filter used for comfort noise generation. It will be
estimated by the same tools use to estimate
and .
It is represented as a Q15 of 16 bits. The allowed range is [0 - 32767].
The default is
7311.
♦ : Switch attenuation value at the beginning of the call:
This parameter will range from 1 to 16 and set the depth of the attenuation of the transmit
audio signal when speech is detected on the distant side.
The default is
4.
♦ : Value of the noise floor estimate written by the DSP (only in case
of active communication):
The allowed range is [0 - 32] when a communication is active. Otherwise, the returned
value is 65535.
Notes:
• The field is present only for Algold 6 and only in the response to
AT+ECHO?
• When a new algoid is selected, AT+ECHO? returns 3 for the mode. The changes will
be taken into account after a reset.