bt8970 Mindspeed Technologies, bt8970 Datasheet - Page 52

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

4.0 Register
0x0B—Transmitter Modes Register (transmitter_modes)
isolated_pulse[1,0]
transmitter_off
htur_lfsr
data_source[2:0]
4-8
data_source
7
–
[2:0]
000
001
010
011
100
101
110
111
isolated_pulse[1] isolated_pulse[0]
Isolated Pulse Level Select—Read/write binary field that selects one of four output pulse
levels while in the isolated pulse transmitter mode.
Transmitter Off—Read/write control bit that zeros the output of the transmitter when set;
allows normal transmitter operation (as defined by data_source[2:0]) when cleared.
Remote Unit (HTU-R/NTU) Polynomial Select—Read/write control bit selects one of two
feedback polynomials for the transmit scrambler. When set, this bit selects the remote unit
transmit polynomial (x
polynomial (x
Data Source—Read/write binary field that selects the data source and mode of the transmitter
output. The transmitter must be enabled (transmitter_off = 0) for these modes to be active.
Isolated pulse. Level selected by isolated_pulse[1:0]. The meter timer must be enabled and in the continuous
mode. The pulse repetition interval is determined by the meter timer countdown interval.
Four-level scrambled detector loopback. Sign and magnitude bits from the receiver detector are scrambled
and looped back to the transmitter. Feedback polynomial determined by the htur_lfsr control bit.
Four-level unscrambled data. Transmits the four-level (2B1Q) sign and magnitude bits from the channel unit
transmit interface without scrambling.
Four-level scrambled ones. Transmits a scrambled, constant high-logic level as a four-level (2B1Q) signal.
Feedback polynomial determined by the htur_lfsr control bit.
Reserved.
Four-level scrambled data. Scrambles and transmits the four-level (2B1Q) sign and magnitude bits from the
channel unit transmit interface. Feedback polynomial determined by the htur_lfsr control bit.
Two-level unscrambled data. Constantly forces the magnitude bit from the channel unit transmit interface to
a logic zero and transmits the resulting two-level signal (as determined by the sign bit) without scrambling.
Valid output levels limited to +3, –3.
Two-level scrambled ones. Transmits a scrambled, constant high-logic level as a two-level signal. Feedback
polynomial determined by the htur_lfsr control bit. Scrambler is run at the symbol rate (half-bit rate) to
produce the sign bit of the transmitted signal while the magnitude bit is sourced with a constant logic zero.
Valid output levels limited to +3, –3.
6
Preliminary Information/Conexant Proprietary and Confidential
isolated_pulse[1,0]
–23
5
+ x
–5
00
01
10
11
–23
+ 1).
transmitter_off
+ x
–18
4
Conexant
+ 1); when cleared, it selects the local unit (HTU-C/LTU)
Transmitter Mode
htur_lfsr
3
data_source[2]
2
Output Pulse Level
Single-Chip HDSL Transceiver
data_source[1]
–3
–1
+3
+1
1
data_source[0]
100101B
Bt8970
0