IDL 101
SIGNAL PROCESSING
HB_IDL101_E_V222.doc
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Gantner Instruments Test & Measurement GmbH
The analog multiplexer at the input of the circuit collects the internal reference voltage, beside collecting the analog
input signals. All these values are then transmitted to the programmable amplifier PGA, where the signals are amplified
according to the kind and type of the connected sensors and are then supplied to the A/D converter.
The A/D converter digitizes all incoming signals with a definition of 10 bit and at a rate that can be preset for the
module by the user (see section 5.5). The amplification in alignment with the accuracy and resolution of the calculated
measuring values does resolve from the selection of the measuring range which will be configured by assistance of the
Configuration Software ICP100.
The microprocessor further edits the measuring signal on hand in digital form. First there is the option of having the
processor carry out a signal filtering or an arithmetic averaging of the measuring signal (see section 5.6). The user can
preset this by configuring the data logger accordingly.
Subsequently the processor linearizes and scales the signal and holds it ready for transmission via bus. In addition to
that the processor monitors the measured value as to freely configurable limiting values. Thus a monitoring as to
breaking of the sensing element or short circuit can also be realized easily, among other things. So the data logger can
be occasioned - by means of appropriate configuration - to provide a corresponding signal at the digital I/O in case of
alarm. The digital I/Os are directly addressed and monitored respectively by the microprocessor.
In order to output analog signals the processor sends the values in digital form to a digital/analog converter, which
converts the values into analog values and switches them onto the analog output.
The special user program, the data for configuration, linearization and scaling etc. that are required by the processor
µP1 for the execution of its tasks all are retentively deposited in a Flash EPROM.
5.5. Measurement Rate
The A/D-converter digitalizes every signal at a rate that can be preset by the user. The sampling rates are selectable
between 1 s and 60 s. In the “Fast“ (0s) mode the sampling rate is depending to the number of channels at least 20ms.
5.6. Signal Preparation
The great amplification of signals required with small signals naturally also entails a higher photoelectric noise level. An
averaging for signal preparing serves to increase the measuring accuracy. This can be connected and configured
separately for each measurement channel by the user. In this way some samples get an arithmetic averaging. Thus the
measurement rate is decreased, but the definition is considerably increased.
The averaging interval can be set for all channels same to a value between 1 s and 12 h.
The number of measurement values for an averaging depends to the interval and sampling rate (e.g. Interval = 15 s,
Sampling rate = 1 s => Number of measurements = 15).
