SP-100A ADC and Data Logger

Overview: The SP-100A is a hardware companion of the ScintPack SA data acquisition software system. It is designed to digitize and store slowly varing analog voltage signals commonly found among a wide variety of laboratory instuments. Many Physical and Chemical measurements begin as analog signals arising from a transducer or detector. The voltage or current level at the detector is usually related to the measurement of interest.

After some appropriate signal conditioning and interfacing the signal is ready to be digitized, then transferred to a computer for display and analysis. These data are most often acquired with respect to time, such as in monitoring the temperature of a stream of liquid or gas in order to determine the conditions of some process upstream. Digitization partitions the data into discrete, equally spaced, (in time) 'data points', with a time seperation sometimes referred to as the 'dwell period'.

The SP-100A's ADCs integrate the signal for the entire dwell period and produce a data point value which equals the time weighted average of the signal level.

Note: Some data acquisition systems, time multiplex a number of input signals into a sampleing ADC. The values of the digitized data points represent only the value of the samples. The time between samples does not contribute to the value of the data points. This sampeling method usually results in a reduced signal to noise ratio.

The SP-100A communicates with ScintPack through an RS-232 serial interface. Data acquisition parameters established by the user are downloaded to the SP-100A and effect its configuration. With the passing of each dwell period, the data elements are arranged into a data frame and are transmitted from the serial port. The data frame also contains a mode prefix or signature so that a software system capturing the data frames can respond in an appropriate way.

Mode signatures characterize an acquisition session as follows:

Commonly Measured Quantities

        Temperature		UV/VIS/IR		Radioactivity
	Pressure		Luminescence		pH / Selective Ion
	Strain / Load		Phosphorescence		Restivity
	Mass / Weight		Fluorescence		Conductivity
	Flow Rate		Refracitive Index	Diffraction



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