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Component Product Manual
11/6/2003
6
RX_DESCRAMBLER_DISABLE_BIT
7
RX_V26_ALT_A_BIT
FAX_DEMOD_DISABLE_BIT
8
915
RX_EC_DISABLE_BIT
0=disabled, 1=enabled (v26, v32, v32bis). This bit disables the
descrambler during the message state for STU-III compatible
operation. Requires V32_STU_III symbol definition at compile
or assembly-time.
0=v26 ALT-B, 1=v26 ALT-A. This bit is used to configure the
v26 modem for ALT-A or ALT-B operation.
0=Fax demod initialization enabled, 1=fax demod initialization
disabled. This bit is used in GenDet Fax modem (v.17, v.21
channel 2, v.27, and v.29) detectors to selectively disable the
call to start the demodulator upon detection. If this bit is reset,
then the demodulator’s Rx_init_vxx function is called upon
detection of the corresponding signal in GenDet, and Rx->state
switches to that demodulator. If disabled, then GenDet Rx>state_ID reflects the modulation type detected and the state
switches to Rx_tone_undetector. This mode would be used for
GenDet operating only as a detector and discriminator.
0=echo canceller will be enabled by the
enable_echo_canceller() function, 1=all echo canceller
parameters will be initialized by enable_echo_canceller()
function but EC_2mu will remain DISABLED. This allows the
user to externally disable the echo canceller without removing it,
and would be used for 4-wire applications where the canceller
might not be needed.
Undefined
Table xx. Rx->mode bit field definitions
threshold - Specifies the minimum power level for gendet and data modem signal detections. It is
initialized in Rx_block_init() to the default value of -48 dB. The minimum value is -48 dB below which the
demod will produce errors.
detector_mask - Enables various detectors for execution in “gendet”. Mask definitions for
Rx_detector_mask are provided in “gendet.h”. The user can selectively enable or disable the tone and
demodulator detectors in “gendet” by setting Rx->detector_mask with the appropriate mask value. The
“set_detector_mask()” and “Rx_init_detector()” functions examine the Rx->detector_mask and enable the
required filters. If the AUTO_DETECT_MASK bit is not set, then the filters will execute but no detectors
will post-process the filtered results. The user must ensure that the AUTO_DETECT_MASK is ORed in
with Rx->detector_mask to enable detection and subsequent demodulator startup. It is initialized in
Rx_block_init() to 0 (no detectors enabled).
digit_CP_mask - Enables various digit and call progress detectors for execution in “gendet”. Mask
definitions for Rx_digit_CP_mask are provided in “gendet.h”. It is initialized in Rx_block_init() to 0 (no
detectors enabled).
temp0 - scratch memory.
temp1 - scratch memory.
Nbits – Number of bits per symbol for the current demodulator. This value is related to Rx->rate by the
modulation format. For example, v.17 at 14,400 is 128 QAM TCM so there are 64 points per symbol period
and Nbits=6. As another example, v.27 at 2,400 bits/sec. is QAM so there are 4 points per symbol and
Nbits=2.
Nmask – Bit mask corresponding to Nbits2 – 1. Can be used to mask for valid bits when converting
symbols from Rx_data[]. For example, , v.17 at 14,400 has Nbits=6 so Nmask=0x3f. V.27 at 2,400 bits/sec.
has Nbits=2 so Nmask=3.
bit_register – upper 16 bits of a 32-bit register used to implement a symbol-to-byte data conversion for
various modems.
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