Siemens TC35T GSM Digital Transceiver
6
4. Power Supply
The TC35T module requires a power supply capable of supplying 8-30V DC, at an
average current of up to 200mA, with short peak currents of 2A. Siemens
recommend that a 1.25A, ‘fast blow’, fuse is inserted in the positive rail of the
supply, to minimise damage in the event of a failure. Campbell Scientific fit such a
fuse in an in-line fuse carrier. Additionally, Campbell Scientific power supplies
include a slow response solid-state automatic resetting fuse.
If the TC35T is to be powered from the same supply as the datalogger, ensure that
the power connections for the TC35T are made as close as possible to the battery
outputs. This will prevent the TC35T causing voltage drops and noise on the
supply to the datalogger.
Although the TC35T has an ‘Ignition Sense’ line, this line does not have the same
function as was provided in earlier Siemens models, and cannot be used to turn the
unit on and off. For units supplied by Campbell Scientific, this line is tied to the
positive supply and a power switch is incorporated in the cable to allow the
datalogger to turn the unit on and off via a wire connected to one of its control
ports. During testing or configuration it may be necessary to move this wire to the
12V supply to ensure that the module is powered continuously.
The TC35T may not power up correctly if its power cable is
removed and re-inserted while 12V power is applied. Always
switch off the power supply before unplugging or inserting the
cable.
Table 1 TC35T Power Supply Connections
TC35T Cable Colour
Connection
Red (positive supply)
+12V
Black (negative supply) G
Yellow (power control)
Control Port (or +12V for testing)
N.B. These colours and connections only apply to the cable supplied by
Campbell Scientific Ltd.
If you are not using the Campbell Scientific power lead, the 12V power supply can
be controlled using a solid-state power relay (such as the Campbell Scientific
PSW12) or you can use the power switch fitted to recent CR10X or CR23X
dataloggers.
Only the power switch in CR10X wiring panels fitted with
green
terminal blocks
is suitable.
5. Antenna – General Notes
When selecting an antenna, please note the following points:
•
make sure the antenna used covers the frequency you intend to use the TC35T
on, i.e. does the antenna cover 900 or 1800 MHz, or both (dual band).
•
Low cost,
¼
- or
½
-wave antennae are adequate for most applications where
signal coverage is good. It is important to realise that most cheap antennae
designed for vehicle mounting require a flat, metal sheet to form a ground
plane at the base of the antenna to achieve the specified gain figure and to
CAUTION
NOTE
