RS8973 Mindspeed Technologies, RS8973 Datasheet - Page 71

• Manufacturer Part Number: RS8973
• Description: Single-chip Sdsl/hdsl Transceiver
• Manufacturer: Mindspeed Technologies

RS8973
Single-Chip SDSL/HDSL Transceiver
eq_error_
adaptation
adapt_coefficients
adapt_gain
adapt_last_coeff
zero_coefficients
adapt_coefficents
adapt_gain
N8973DSD
0x3C—Digital AGC Modes Register (dagc_modes)
0x3D—Feed Forward Equalizer Modes Register (ffe_modes)
—
—
7
7
Equalizer Error Adaptation—Read/write control bit that selects between the equalizer-error
adaptation mode when set, and the self-adaptation mode when cleared. Equalizer error
adaptation uses the equalizer error signal produced by the slicer as the DAGC error input
signal. In self-adaptation, the value of the DAGC Target Register [dagc_target_low,
dagc_target_high; 0x38–0x39] is subtracted from the absolute value of the receive signal at the
output of the DAGC, and this difference is used as the error input signal.
Adapt Coefficients—Read/write control bit that enables coefficient adaptation when set;
disables/freezes adaptation when cleared. Coefficient values are preserved when adaptation is
disabled.
Adaptation Gain—Read/write control bit that specifies the adaptation gain. When this bit is
set, the adaptation gain is eight times higher than when cleared.
Adapt Last Coefficient—Read/write control bit that enables adaptation of the last (oldest)
coefficient only when set; allows all coefficient adaptation when cleared. Overall coefficient
adaptation must be enabled (adapt_coefficients = 1) for this behavior to occur. If coefficient
adaptation is disabled (adapt_coefficients = 0), the value of this control bit is not used.
Zero Coefficients—Read/write control bit that, with coefficient adaptation enabled
(adapt_coefficients = 1), continuously zeros all coefficients when set; allows normal
coefficient updates when cleared. If coefficient adaptation is disabled (adapt_coefficients = 0),
this control bit has no affect. This behavior differs slightly from the similar function
(zero_coefficients) of the LEC, NEC, and DFE filters. Whenever this bit is set, it must be
accompanied by adapt_coefficients (set) for a 2-symbol time period.
Adapt Coefficients—Read/write control bit that enables coefficient adaptation when set;
disables/freezes adaptation when cleared. Coefficient values are preserved when adaptation is
disabled. This overall coefficient adaptation must be enabled for adapt_last_coeff to have an
affect.
Adaptation Gain—Read/write control bit that specifies the adaptation gain. When set, the
adaptation gain is four times higher than when cleared.
—
—
6
6
—
—
5
5
Preliminary Information
—
—
4
4
Conexant
adapt_last_coeff zero_coefficents
—
3
3
adaptation
eq_error_
2
2
adapt_coefficients
coefficients
adapt_
1
3.3 Register Description
1
3.0 Registers
adapt_gain
adapt_gain
0
0
3-25