Sigrand SG-16G, Руководство пользователя

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1. Modem description
The Sigrand SG-16G modem is a SНDSL-modem. It features an E1 system
interface (ITU-T G.703/G.704, 2048 kbps) and is intended to be used as a
line termination unit of TDM-based communication equipment. The modem
allows to make connections between devices equipped with E1 interfaces
such as telco equipment, routers and access servers.
The SHDSL interface of the modem conforms to ITU-T G.991.2.bis standard
and uses ТСРАМ (Trellis-Coded Pulse Amplitude Modulation) line coding.
Features of the ТСРАМ line coding:
The ТСРАМ line coding used by G.991.2 (G.SHDSL) compatible modems
has a few modes. The modes differ in complexity of coding algorithm. The
modes with larger number of modulation positions (ТСРАМ16, ТСРАМ32)
are applicable for higher rates, the modes with less number of modulation
positions (ТСРАМ4, ТСРАМ8) are applied for lower rates. Respectively, the
more complicated the coding algorithm the worse the channel noise
immunity and vice versa.
So take special attention to the ТСРАМ line coding algorithm selection while
configuring the line rate. It may be necessary to change the line coding to
achieve the best result.
Table 1 shows the line coding options and respective data rate ranges.
Table 1
Line coding Data rate range (kbps)
TCPAM32 256 – 2048
TCPAM16 192 – 2048
TCPAM8 192 – 1216
TCPAM4 64 – 704
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Manual line coding selection is available only in the console
management mode – see chapter 3 of this Guide
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