Tahoe 671, Руководство пользователя

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3.2. Modem type
After pressing Enter the modem type may be selected - either
Master (HTU-C) or Slave (HTU-R). After selecting the type and pressing
Enter again the connection will be reset and renegotiated with new
settings.
NOTE: Always one modem has to be set as a Master and the
other one as a Slave.
3.3. Line coding
After pressing Enter the G.shdsl line coding (signal modulation)
may be chosen. The number (32 in the example above) means the
number of values encoded in one symbol (32 - 5 bits per symbol). The
higher this number is, the lower is the signal frequency, which gives
better immunity for signal attenuation and higher reach.
The second part - PAM or TCPAM - means either the Pulse
Amplitude Modulation or Trellis Coded Pulse Amplitude Modulation.
The latter is more efficient.
It is recommended to use the 32-TCPAM modulation, which
provides the best results. The remaining line codings are available to
provide compatibility with others’ manufacturers equipment. The 32-
TCPAM allows throughputs from 256 kbps to 2048 kbps, while 16-
TCPAM - from 128 kbps to 2048 kbps.
The “Auto” setting forces use of 32-TCPAM for speeds higher
than or equal to 256 kbps per line and 16-TCPAM for lower rates.
3.4. CRC4 checksum
After pressing “Enter” the CRC4 transmission and checking may
be either enabled or disabled.
3.5. G.703 coding
The G.703 port may use one of two available codings - HDB3 and
AMI. The first one is used in most cases, the second one is provided for
compatibility only.
3.6. G.703 receiver sensitivity and range
The G.703 port’s receiver sensitivity (thus port range) may be
changed - either -12dB (50m) or -43 dB (2000m)
3.7. Test loopbacks
The test loopback are useful to diagnose the network problems.
Two kinds of loopback are available:
¡
towards DSL - packets received from the G.shdsl line are sent back
to it
¡
towards PCM - packets received from the G.703 port are sent back
to it
3.8. Console throughput
Different console port throughputs may be chosen - 9600,
19200 or 38400 bps. Be sure to set the same throughput on the modem
and the PC.
7
Line coding:
32-TCPAM
3.2
3.3
Modem type:
Master / HTU-C
3.5
3.7
3.4
CRC4:
on
G.703 line code:
HDB3
G.703 port range
2000m
Loopback:
disabled
Console port:
9600 bps
3.6
3.8