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M20 & M20T have been superceded.
M20T is the GSM Terminal with RS232 interface. M20 is the Siemens GSM engine module in the M20T
1.
The standard antenna cable supplied with the M20T is four metres long.
Whilst it is possible to extend this length to a maximum of ten metres,
we
suggest that a better solution would be to locate the M20T closer to the
antenna by extending the serial cable, since this would not increase
radiation losses in the antenna cable.
Longer
antenna cables, with connectors, can be supplied at an additional
cost
of $8+GST per metre of cable, provided that this requirement is specified at time
of ordering.
2. The difference between an A3 antenna
and an A5 antenna is that
the A3 whip has a signal gain factor of 3 dB,
whereas
the A5 whip has a gain of 5 dB.
As a guide, we would recommend
the A3 in suburban areas where there is
good GSM cell'phone coverage and
we would recommend the A5 in those
locations where the signal strength is
not as good.
3. We do not know the IP rating of the
antennas, but they are certainly
designed for outdoor use.
4.
Cellular antennae require a ground plane, which is normally provided by
the metal surtface to which the antenna is mounted. As a rule of thumb,
the diameter of the groundplane should, at least, be a circle of
approximately
the same radius as the height of the whip.
If this is not possible to achieve,
then we can supply an 'elevated-feed' antenna (such as
the CD1625F) which
overcomes the need for a goundplane to be provided, but
is more expensive.
5.
The transmission range is entirely dependent on the coverage provided by
the service provider, be it Telstra, Optus or Vodafone. As a guide, if you
can see at least half of the signal strength bars on the display of a
hand-held GSM cell'phone in the same location that you want to position the
M20T, then there should be no problem.
6. For use
with Datataker DT50/500 series data loggers, the M20T does not come with
a Datataker-to-M20T serial cable.
We can supply these for $ 45.00+GST
The Datataker DT800 can use the M20 to PC cable (DB9 straight through
cable) supplied with the first M20T kit ordered.