RCVDL56DPFL/SP, RCV56DPFL/SP, and RCV336DPFL/SP Designer’s Guide
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Function 52:
ITU-T CRC 32 Select
Acc. Method: 1
Addr.: 0B3h(0)
The type of cyclic redundancy check (CRC) generation and detection can be selected by writing to bit 0B3h:0
[0 = ITU-T CRC 32; 1 = ITU-T CRC 16 (default)].
Function 53:
Secondary Channel Transmitter Speed Select (V.32 bis/V.32)
Acc. Method: 1
Addr.: 28Eh
Secondary Channel Receiver Speed Select (V.32 bis/V.32)
Acc. Method: 1
Addr.: 28Bh
The default data rate for the secondary channel is 150 bps. The rate can be changed by modifying a divide factor in two
addresses: 28Eh for the transmitter and 28Bh for the receiver. The following table lists the possible secondary channel
speeds for the various main channel speeds and the corresponding RAM value. Reset will clear locations 28Eh and 28Bh.
Secondary Channel Speed (bps)
Transmitter and Receiver RAM Divide Constant Values (Hex)
Main Channel Speed (bps)
75
150
300
600
1200
2400
14400
8
10
12000
8
10
9600 TCM
4
8
10
9600 QAM
2
4
8
10
7200
2
4
8
10
Functions 54 - 59: Not Applicable.
Function 60:
V.34 Symbol Rate Value
Acc. Method: 1 (RO)
Addr.: 2E3h
Function 61:
V.34 Baud Rate Mask (BRM)
Acc. Method: 1
Addr.: 101h
During the start-up handshake, the MDP probes the communication channel and determines the available bandwidth. This
information helps establish the common symbol rate between the modems. The following data rate ranges are available for a
selected symbol rate:
Symbol Rate
(baud)
Highest Possible V.34
Data Rate (bps)
2400
21600
2800
26400
3000
28800
3200
31200
3429
33600
If line conditions cannot support the higher symbol rates, the MDP automatically reduces the data rate to match the
allowable symbol rate.
The host can control the symbol rate negotiation process via the Baud Mask Register (BMR), located at address 101h. By
either setting or resetting one or more of five bits in the BMR, the host can specify if a particular symbol rate is to be
supported. In Loop 3 (L3ACT = 1), the baud rate may be selected by writing the desired symbol rate value (0, 2, 3, 4, or 5)
to address 2E3h anytime prior to establishing the loopback. The default value is 4 for 3200 baud. The symbol rates and the
corresponding bit positions are:
Symbol Rate
(baud)
Symbol Rate Value
(Addr. 2E3h)
Baud Mask Register (BRM) Enable
Bit Position (Addr. 101h)
2400
0
0
Reserved
1
1*
2800
2
2
3000
3
3
3200
4
4**
3429
5
5
* Bit 1 must always be a 1.
** Bit 4 (3200 symbol rate) must be set for K56flex operation.
Summary of Contents for RC336DPFL
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