Dplc (B) Or Mixed Aplc/Dplc (C) Operation In Etl600 Erect Mode - ABB ETL600 Instruction Manual

ABB Switzerland Ltd
•
Digital data interfaces for lower speed data avoiding intermediate
modems.
The ETL600 system supports both APLC and DPLC mode of
operation. As explained in Cigré publication TB164, a digital PLC
consists of 3 main building blocks:
•
the RF front end,
•
Signal converter,
•
Digital time division multiplexer.
These building blocks can be found also in ETL600. However, as
shown in Fig. 3-1, with an additional external multi service multiplexer /
router, the strengths of digital PLC can be exploited even more.
Fig. 3-3a, b and c show the use of the nominal frequency band in case
of pure APLC, pure DPLC or mixed APLC/DPLC mode of operation.
The APLC band - if present - comprises 1 to 3 AF channels of 4 kHz
bandwidth each. Therefore the width of the APLC band is 4, 8 or
12 kHz for 1, 2 or 3 AF channels, respectively. There is one exception
to this rule: A special mode of operation offers three AF channels with
bandwidths of 3.2, 2.4 and 2.4 kHz, resulting in an APLC bandwidth of
8 kHz.
a
b
c
Fig. 3-3
By default, the APLC band is located below the DPLC band on the
frequency scale as shown in Fig. 3-3c. This placement is referred to as
erect ETL600 overall mode. It is possible to operate the link in inverted
overall mode if desired, with the effect that the signal spectra of Fig.
3-3 are mirrored with respect to the center frequency as shown in Fig.
3-4. In erect mode, the nominal frequency f
3-4
1KHW001489-EN
APLC
Ch 1 Ch 2
Fn
Bn
DPLC
Fn
APLC
Ch 1 Ch 2 Ch 3
Fn
Bn
Use of nominal frequency band for pure APLC (a), pure
DPLC (b) or mixed APLC/DPLC (c) operation in ETL600
erect mode
November 2005
Ch 3
Frequency
Frequency
Bn
DPLC
is defined as the lower
n
Structure and Function
ETL600
Frequency