bt8970 Mindspeed Technologies, bt8970 Datasheet - Page 51

• Manufacturer Part Number: bt8970
• Description: Single-chip Hdsl Transceiver
• Manufacturer: Mindspeed Technologies

Bt8970
Single-Chip HDSL Transceiver
0x09—Nonlinear Echo Canceller Modes Register (nonlinear_ec_modes)
negate_symbol
symbol_delay[2:0]
adapt_coefficients
zero_coefficients
zero_output
adapt_gain
0x0A—Decision Feedback Equalizer Modes Register (dfe_modes)
adapt_coefficents
zero_coefficients
zero_output
adapt_gain
100101B
negate_symbol symbol_delay[2] symbol_delay[1] symbol_delay[0]
7
7
–
Negate Symbol—Read/write control bit which, when set, inverts (2’s complement) the receive
signal path at the output of the nonlinear echo canceller. When cleared, the signal path is
unaffected. This function is independent of all other NEC mode settings.
Symbol Delay—Read/write binary field which specifies the number of symbol delays inserted
in the transmit symbol input path.
Adapt Coefficients—Same function as LEC Modes Register [linear_ec_modes; 0x08].
Zero Coefficients—Same function as LEC Modes Register.
Zero Output—Same function as LEC Modes Register.
Adaptation Gain—Read/write control bit which specifies the adaptation gain. When set, the
adaptation gain is 8 times higher than when cleared.
Adapt Coefficients—Read/write control bit which enables coefficient adaptation when set;
disables/freezes adaptation when cleared. Coefficient values are preserved when adaptation is
disabled.
Zero Coefficients—Read/write control bit which continuously zeros all coefficients when set;
allows normal coefficient updates, if enabled, when cleared.
Zero Output—Read/write control bit which, when set, zeros the equalizer correction signal
before subtraction from the input signal. Achieves the affect of disabling or bypassing the
equalization function. Does not disable coefficient adaptation. When cleared, normal equalizer
operation is performed.
Adaptation Gain—Read/write control bit which specifies the adaptation gain. When set, the
adaptation gain is 8 times higher than when cleared.
6
6
–
Preliminary Information/Conexant Proprietary and Confidential
5
5
–
4
4
–
Conexant
coefficients
coefficients
adapt_
adapt_
3
3
zero_coefficients
zero_coefficients
2
2
zero_output
zero_output
1
1
4.0 Register
adapt_gain
adapt_gain
0
0
4-7