RS8973 Mindspeed Technologies, RS8973 Datasheet - Page 58

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

3.0 Registers
3.3 Register Description
imp_short[2:0]
rphs[3:0]
enable_dc_tap
adapt_coefficents
zero_coefficients
zero_output
adapt_gain[1,0]
3-12
0x07—Receive Phase Select Register (receive_phase_select)
0x08—Linear Echo Canceller Modes Register (linear_ec_modes)
—
—
7
7
imp_short[2]
Impulse Shortening Filter—Read/write binary field that determines the coefficient of the
impulse shortening filter. It must be set per the software provided by Conexant.
Receive Phase Select—Read/write binary field that defines the relative phase relationship
between QCLK and the sampling point of the ADC. The rising edges of QCLK correspond to
the ADC sampling points when rphs equals 0000. Each binary increment of rphs represents a
one-sixteenth QCLK period delay in the sampling point relative to QCLK.
Enable DC Tap—Read/write control bit which, when set, forces a constant + 1 value into the
last data tap of the LEC. This condition enables cancellation of any residual DC offset present
at the input to the LEC. When cleared, the last data tap operates normally, as the oldest
transmit data sample.
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 that continuously zeros all coefficients when set;
allows normal coefficient updates if enabled, when cleared. This behavior differs slightly from
the similar function (zero_coefficients) of the FFE and EP filters.
Zero Output—Read/write control bit which, when set, zeros the echo replica before
subtraction from the input signal. Achieves the affect of disabling or bypassing the echo
cancellation function. Does not disable coefficient adaptation. When cleared, normal echo
canceller operation is performed.
Adaptation Gain—Read/write binary field which specifies the adaptation gain.
—
6
6
enable_dc_tap
imp_short[1]
adapt_gain[1,0]
5
5
00
01
10
11
imp_short[0]
Preliminary Information
coefficients
adapt_
4
4
Conexant
Normalized Gain
zero_coefficients
512
64
rphs[3]
1
4
3
3
zero_output
rphs[2]
Single-Chip SDSL/HDSL Transceiver
2
2
adapt_gain[1]
rphs[1]
1
1
adapt_gain[0]
N8973DSD
rphs[0]
RS8973
0
0