RFX144V24-S23 and RFX96V24-S23 Modem Designer’s Guide
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12-3
Bit 5:
TONEXE (XIA Tone Enable).
When set, tone is generated through the XIA codec DAC.
Bit 6:
TONEIE (IIA Tone Enable).
When set, tone is generated through the IIA codec DAC.
Bit 7:
N/A (Reserved).
Before switching out of Speakerphone Mode, set both MUTEX and MUTEI bits for at least 10 ms. This will allow the modem
to clear out any left-over samples in the analog codec interface processing.
12.3.2 FDX Speakerphone Mode
After the CONF control bits (06:0-7) are loaded with 91h and the SETUP bit (1F:0) is set, the speakerphone defaults to the
following:
SP/HS = 1;
FDX Speakerphone Mode.
MICLVL = 01;
Microphone volume level = +6 dB.
MUTEX = 1;
Microphone muted for dial-tone passing through unswitched.
MUTEI = 0;
Speaker voice channel activated.
VOLDWN = 0;
No speaker volume decrement. Speaker gain setting defaults to -10 dB
VOLUP = 0;
No speaker volume increment.
AGCXE = 1;
Microphone AGC enabled.
AGCIE = 1;
Speaker AGC enabled.
TTONEE = 0;
Tone transmit mode disabled.
Setting SP/HS control bit to a 1 configures the FDX Speakerphone Mode. In this mode, the microphone volume is controlled
by the MICLVL bits; the speaker volume is controlled by the VOLUP and VOLDWN bits; the speaker and microphone
channels can be muted by setting the MUTEI and MUTEX bits to a 1, respectively; and their AGC functions can be enabled
by setting the AGCIE and AGCXE bits to a 1, respectively. The TTONEE bit should remain at a 0 in this mode.
As soon as the speakerphone connects through to the dialed party for FDX speakerphone operation, the MUTEX bit must be
reset to a 0 to activate the microphone voice channel.
12.3.3 Tone Transmit Mode
While operating in the Speakerphone Mode, tone transmission is available to either the line and/or speaker at the same time.
There are two completely separate tone transmitters, one for the line, and one for the speaker. Different tones can be played
on each channel and each channel tone can be a single-tone, dual-tone, or melody ring-tone. Frequency and output level
information for each desired tone from the IIA or XIA must be programmed prior to activation.
First, the TTONEE control bit must be set to a 1 to inform the modem that speakerphone tone transmit mode is engaged.
The modem will freeze the adaptation of the echo cancellers and start to check the TONEIE and TONEXE bits. Tone is
transmitted to the line and/or speaker as long as the respective TONEIE and/or TONEXE bit stays at a 1. Keeping the
TTONEE bit to a 1 and toggling the TONEIE and/or TONEXE bit will generate the make and break periods of the tone.
Setting any of these two bits to a 1 will silence the corresponding voice channel until the TTONEE bit is reset to a 0.
For example, if you select the TONEIE bit first, then turn on the TONEXE bit, the microphone and speaker voice will be both
disabled. When you finish transmitting tones, you must reset the TTONEE bit to enable both microphone and speaker
voices, or reset-then-set the TTONEE bit to enable one voice and continue tone transmit on the other channel depending on
the status of the TONEIE and TONEXE bits.
The two separate dual-tone transmitters should be programmed to their desired frequencies and levels. Each transmitter has
four parameters: tone 1 frequency, tone 1 transmit output level, tone 2 frequency, and tone 2 transmit output level (see
Table 4-1).
12.3.4 Handset
Mode
The Handset Mode provides a private means of conversation which may be necessary in some occasions. Resetting SP/HS
control bit to a 0 configures the Handset Mode. In this mode, a regular handset in place of the microphone and speaker
arrangement is assumed. All the AGC adaptation processes are frozen at their previous gain factors and the microphone
AGC is bypassed. If the speaker AGC is enabled, it will keep using the latest gain factor determined in the FDX
Speakerphone Mode, otherwise the AGC gain will be forced to unity. Muting, tone generation, and volume level controls for
both microphone and speaker channels are available, just as in the FDX Speakerphone Mode.
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