bt8970 Mindspeed Technologies, bt8970 Datasheet - Page 59

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

Bt8970
Single-Chip HDSL Transceiver
0x29—Transmitter Gain Register (tx_gain)
tx_gain[3:0]
0x2A, 0x2B—Noise-Level Histogram Threshold Register (noise_histogram_th_low,
noise_histogram_th_high)
Two-byte read/write register interpreted as a 16-bit, 2’s-complement number. The range of meaningful values is
limited to positive integers between 0x0000 and 0x7FFF. The value of this register is compared to the absolute
value of the slicer error signal produced by the detector. A count of error samples that exceeds this threshold
(greater than) is accumulated in the noise-level histogram meter.
100101B
7
–
Transmit Gain—A 4-bit, 2’s-complement, read/write field controlling the transmitter gain.
Upon initialization, the value in the Transmitter Calibration Register [tx_calibrate; 0x28] may
be written into this register by software to set the transmitter gain to the nominal value, or the
user may set it to another desired value.
6
–
Preliminary Information/Conexant Proprietary and Confidential
tx_gain[3]
tx_gain[3:0]
5
1000
1001
1010
1011
1100
1101
1110
1111
0000
0001
0010
0011
0100
0101
0110
0111
tx_gain[2]
4
Conexant
tx_gain[1]
3
tx_gain[0]
Relative Transmitter Gain (dB)
2
–1.60
–1.36
–1.13
–0.91
–0.69
–0.48
–0.27
–0.07
0.13
0.32
0.51
0.70
0.88
1.05
1.23
1.40
1
–
4.0 Register
0
–
4-15