Table of Contents
Advertisement
Functions
Multidrop mode
In multi-drop communication additional modems can be added ("staggered") between the two
modems at the end of the line, i.e. they are connected in parallel to the line with high impedance.
It is a high-resistance connection. See Fig. 7 and Fig. 9. The transmitter of a staggered modem
should be configured as current-source. The receiver will not be terminated in 4-wire mode.
Commands to configure multidrop mode
< s e t i n t e r f a c e f s k 0 t x m o d e c u r r e n t - s o u r c e >
< s e t i n t e r f a c e f s k 0 p o s i t i o n n o e n d >
Star mode
In the star mode up to three transmission lines can be arranged in a star configuration using LF
line transformers without additional line amplifiers, see Fig. 10. This mode can be implemented
using both two-wire and four-wire lines. The transmitter has to be configured as current-source.
Transmitter as well as receiver at 4-wire operation have to be provided with externally placed
termination resistors.
Commands to configure star mode
< s e t i n t e r f a c e f s k 0 t x m o d e c u r r e n t - s o u r c e >
< s e t i n t e r f a c e f s k 0 p o s i t i o n e n d s t a r >
2.9.9
Transmitter predistortion
Setting a transmitter predistortion to compensate for linear channel distortion on poor-quality
transmission lines. In this case, the level is lowered at the high or low key frequency, so that a
difference in the levels between the two key frequencies of 0 dB to max. 10 dB occurs. This drop
means that linear channel distortion can be compensated for. The transmitter predistortion has the
greatest effect at the higher bit rates because at low bit rates the impact of the channel distortion is
low.
Transmier
level
Figure 2: Transmitter predistortion
The predistortion has either a high-pass or low-pass characteristic, depending on which key
frequency is influenced.
• Normal U
• High-pass U
• Low-pass U
1KGT151043 V001 1
-ΔF
= U
-ΔF
+ΔF
> U
-ΔF
+ΔF
< U
-ΔF
+ΔF
+ΔF
Fc
Settings
ΔU
F [Hz]
25
Advertisement
Table of Contents
