ABEM Terrameter LS
32
4.4
Calibration
Calibration of the instrument is done at the factory before delivery. Users has no need
to access this page. An unlock key must be typed in to access the
View
(
Figure 35
),
and a complete calibration requires special equipment.
Figure 35.
Calibration view
4.5
The Relay Switch
The relay switch consists of four relay cards that can handle 16 electrodes each. The
VES version of the instrument has one relay card. The relay switch can be re-
configured by an optimisation routine in the instrument software depending on how
many measuring channels the instrument is equipped with. This design allows
measurement with many receiver channels without having a prohibitively large relay
switch
2
. The design chosen here provides a good compromise between capability vs.
physical size and cost, and is suitable for multi-channel measurements.
For a 4-channel instrument it is possible for each measuring channel to measure on an
arbitrary electrode pair between 1 and 64 with no restriction. For an instrument with 8
or 12 measuring channels the measuring channels will be distributed in the relay
switch by an optimisation algorithm, and the efficiency of use of the channels will
depend on which potential electrode pairs are to be measured for a current
2
For example; a regular matrix switch with full freedom in switching for 12 measuring channels and
64 electrodes would require 1664 relays, which would be bulky and expensive.
Summary of Contents for Terrameter LS
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