Schmid Watson Przewodnik Instalacji Strona 20

  • Pobierz
  • Dodaj do moich podręczników
  • Drukuj
  • Strona
    / 129
  • Spis treści
  • BOOKMARKI
  • Oceniono. / 5. Na podstawie oceny klientów
Przeglądanie stron 19
SZ-DOC-W5-1.pdf LTU/NTU
Version: 1.5 Operating Manual
11 Revision: 2002-09-10
3.1.3 Power Back-off
In order to reduce ingress on other transmission systems operating on adjacent pairs bundled in
the same cable, the transmit power of LTU and NTU can be decreased by activating the power
back-off mode.
3.1.4 Symmetric and Asymmetric PSD Mask
For payload bit rates of 2048 kbit/s and 2304 kbit/s the Power Spectral Density (PSD) masks of
LTU and NTU can be switched into symmetric or asymmetric mode. Activating asymmetrical
PSD masks will increase transmit power of LTU and NTU and by this the possible loop length.
The PSD masks of LTU and NTU will have different (asymmetric) shapes in this operation mode.
3.2 E1 Interface (2 Mbit/s G.703 / G.704)
3.2.1 Framing
3.2.1.1 Transparent Mode
In transparent mode, the E1 data will be transmitted without any changes, whereas in framed
mode, the frame / multiframe alignment words and CRC4 bits are regenerated by the E1 framer.
The “CRC4 “ and “E-bit Insertion” options are not relevant in transparent mode.
3.2.1.2 Framed Mode ITU-T G.704
In framed mode (framing according to ITU-T G.704), the incoming E1 data stream passes
through an E1 framer before entering the DSL section. From the other side, the same process
happens in reverse; the E1 data stream received from the DSL section first passes through the
E1 framer before being transmitted to the E1 network.
The E1 framer operates in Common Channel Signaling (CCS) mode. Time slot 16 and all national
bits are fully transparent.
Consider the “CRC4” and “E-bit Insertion” options when operating in framed mode.
3.2.1.2.1 CRC4
If operating in framed mode, the “CRC4” option can be used to adapt to specific E1 network
requirements:
If enabled, the E1 framer will synchronize on CRC4 multiframes and CRC4 errors will be
reported. In the outgoing E1 signal the framer regenerates the CRC4 multiframe alignment
and checksum words. The A-Bit and the Sa-Bits pass transparently.
If disabled, the international bits are set to ‘1’ in the outgoing E1 signal. All national bits are
fully transparent. On the receive side, the E1 framer will synchronize on basic frames only
and no CRC4 errors will be reported.
Przeglądanie stron 19
1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 128 129

Komentarze do niniejszej Instrukcji

Brak uwag