Functional Description SWT 3000 Equipment Manual
Page - 14 Edition p3_3_2x 08/09 © SIEMENS AG 2008
Narrow band version
Application:
Equipment in the narrow band version can be operated on VF links and
over CF and radio relay routes. Security against impulse noise and inter-
ference voltages is somewhat lower than with the broadband version.
Frequency space: The wanted frequencies are closer together in this equipment version. As
a result up to three of the 4 possible channels (channel 1, 2, 3) can be
operated simultaneously within an ITU-T voice band of 3.1 kHz band-
width (0.3 ... 3.4 kHz).
SWT unit: Each of these channels requires a separate SWT 3000 unit. There is
space for accommodating two SWT 3000 units in an equipment frame.
These two units are totally independent from one another and no compo-
nents are shared.
Multi-purpose: Use in conjunction with PLC transmission is possible in multi-purpose
operation. However, a smaller range (transmit level distribution for all
services) and less security against interference must be expected com-
pared with the broadband version.
Alternate multi-purpose: Use in conjunction with PLC transmission is not possible in alternate
multi-purpose operation.
Channel 4: Channel 4 can be used with a 4 kHz frequency space. Its position in the
VF frequency band is defined so that it is operated in the upper half of the
transmission bands 2.67 ... 3.7 kHz (voice band limitation 2.4 kHz with pi-
lot 2.58 kHz) and 2.1 ... 3.6 kHz (voice band limitation 2.0 kHz with pilot
3.78 kHz). In the second case another four 50 Bd WT channels can be
accommodated between the voice band and channel 4.
Applications for narrow band devices:
4-wire connections The operation of several units in parallel at a connection is possible by
using narrow band devices.
T
R
T
R
SWT 3000 SWT 3000
NB1
T
R
T
R
SWT 3000 SWT 3000
NB2
NB1
NB2
Figure 6: Parallel connection of several SWT 3000 units at one connection
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