Maxim Integrated Teridian V.22 bis Linux Softmodem for 73M1822/73M1922 MicroDAA - Manual (Page 26)

V.22 bis Linux Softmodem for 73M1x22 MicroDAA User Guide UG_1x22_043
26 Rev. 1.5
S13 DTMF-Data / Transmit Attenuation

16 0dB nominal for call progress and data, +2dB nominal for DTMF
Attenuation level can go from +4.0 dB to –11.0 dB from nominal.
DTMF gain increments have to be a minimum of 1dB, while for CP/Data the minimum is
2dB gain increments.
DTMF CP / Data Level
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Gain/Atten
0 0 1 0 X 0 1 0 +4.0 dB
1 0 1 0 X 0 1 0 +3.0 dB
DTMF 0 0 0 1 X 0 0 1 +2.0 dB
1 0 0 1 X 0 0 1 +1.0 dB
CP/Data 0 0 0 0 X 0 0 0 0.0 dB
1 0 0 0 X 0 0 0 -1.0 dB
0 1 1 1 X 1 1 1 -2.0 dB
1 1 1 1 X 1 1 1 -3.0 dB
0 1 1 0 X 1 1 0 -4.0 dB
1 1 1 0 X 1 1 0 -5.0 dB
0 1 0 1 X 1 0 1 -6.0 dB
1 1 0 1 X 1 0 1 -7.0 dB
0 1 0 0 X 1 0 0 -8.0 dB
1 1 0 0 X 1 0 0 -9.0 dB
0 0 1 1 X 0 1 1 -10.0 dB
1 0 1 1 X 0 1 1 -11.0 dB
S85 DTMF- DAC transmit level coefficient
n 60 – 127
 60 Default value.
This coefficient affect the transmit value, thus the overall transmit level of the DTMF tones,
sent to the DAC. A higher value, yet increasing the DTMF level transmitted, also increases
the level of signal distortion. This coefficient only affects DTMF transmission.
Refer to the “Transmit levels at 3.3V operations” application note for further details.