RCVDL56DPFL/SP, RCV56DPFL/SP, and RCV336DPFL/SP Designer’s Guide
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10-1
10. V.8bis
10.1 V.8bis TRANSMITTER
V.8bis tones can be transmitted from tone mode (CONF = 8Xh), speakerphone mode (CONF = ACh), or V.21 mode (CONF
= A0h). CEQ should be 0. The V8bis tones are sent in the same manner as DTMF tones, i.e., write the codeword into
TBUFFER when TDBE=1.
The codewords for V.8bis are described in Table 10-1.
Table 10-1. V.8 bis Codewords
V.8bis Codeword
(Hex)
V.8bis
Signal
Segment 1
Dual Tones
(Hz)
Segment 1
Power level
(dBm)
Segment 2
Single Tones
(Hz)
Segment 2
Power level
(dBm)
20
MRe
1375 + 2002
-23.5
650
-23.5
21
MRd
1375 + 2002
-10
1150
-10
22
CRe
1375 + 2002
-23.5
400
-23.5
23
CRd
1375 + 2002
-10
900
-10
24
ESi
1375 + 2002
-10
980 *
-10
28
MRe
1375 + 2002
-10
650
-10
2A
CRe
1375 + 2002
-10
400
-10
30
**
1529 + 2225
-23.5
650
-23.5
31
MRd
1529 + 2225
-10
1150
-10
32
**
1529 + 2225
-23.5
400
-23.5
33
CRd
1529 + 2225
-10
1900
-10
34
ESr
1529 + 2225
-10
1650 *
-10
38
**
1529 + 2225
-10
650
-10
3A
**
1529 + 2225
-10
400
-10
Notes:
*
The 1650 Hz and 980 Hz single tones are V.21 MARK frequencies for the high and low channels, respectively. Therefore, it would
be generated by setting DTR immediately after writing 34h or 24h into TBUFFER. If in answer mode, set NV25 =1 to prevent answer
tone from being sent instead of MARK.
**
These signals are available, but are currently undefined by V.8bis.
10.2 V.8bis RECEIVER
The V.8bis detector is enabled by setting bit 439h:0 = 1 and setting NEWC from dial modes (CONF = 8xh), V.21 mode
(CONF = A0h), or speakerphone mode (CONF = ACh). (When in tone mode, the “talk-mode tone detectors” are unavailable
when running the V.8bis receiver.)
When a valid V.8bis signal is received, the corresponding codeword appears in the V.8bis RX buffer (16h). Also, bit 7 of the
V.8bis Rx buffer (16h:7) indicates that a dual tone has been detected. A value of E0h means that a valid Segment 1 (dual
tone) has been received and a single tone is being detected.
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