RFX144V24-S23 and RFX96V24-S23 Modem Designer’s Guide
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7. The timer expires. The IIA input is switched to the Line IN, control bit RMM is reset, and voice or audio codec
configuration selected. Go to step 2 or go to step 4 with timer reinitialized to same Room Monitor period.
8.5 TONE DETECTION
The tone detectors operate with either 8000 Hz or 4000 Hz sample rate (see control bit TND8K in Table 3-1). All tone
detector filters need to be designed with the 8000 Hz or 4000 Hz sample rate (see Section 6). The 4000 Hz sample rate is
required only when the voice encoder is enabled during Room Monitor operation.
When using the 4000 Hz sample rate, tones appearing in the 2 kHz to 4 kHz frequency band will be folded back into the 0
Hz to 2 kHz frequency band. Therefore the tone detector filter center frequencies must also be folded into this lower band by
subtracting the filter center frequency from the 4000 Hz sample rate. For example, to detect a tone transmitted at 2100 Hz,
program the tone detector filter using a center frequency 1900 Hz.
Содержание RFX144V24-S23
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