Figure 5-10: One channel measuring unit frontplaneand module detached
Description:
The T3Ster equipment has 8 slots for 8 identical measurement channels and can be ordered with the required number of measurement channels between 1 and 8. Each channel has an own programmable amplifier, a sample-and-hold circuit, an A/D converter circuitry and data storage memory. This way, correct multi-channel measurements are possible, with a time resolution of 1 ms. The voltage resolution is 12 bit and the noise amplitude is less than 2 bit. This means that the signal-to-noise ratio of the measurement is about 70dB (typically 1 bit of noise). This good accuracy is essential for the subsequent evaluation.
The input voltage range is programmable: the ranges 50-100-200-400mV are available. In the most sensitive range the temperature resolution (using a diode sensor) is about 0.01 Celsius. The internal amplifier has a bandwidth of 2 MHz, the input impedance is approximately 100 kOhm.
The maximum sampling rate of the sampler is 1 MHz.
The measurement channels are provided with an internal, programmable compensation circuit. This circuit is needed by the diode thermometers where the ~0.7 V forward voltage has to be compensated in order to measure only the voltage variation. The operating software provides compensation algorithms for using full input voltage range for variation measurement. In order to use "MOS diodes" as sensors, the range of the compensation voltage extends to ±5 V.
The unit has an own data memory, 64k of 16 bit words.
Pin definitions for the MEASU unit can be found in Figure 5-11and Table 5-C.
The unit has a floating, differential input with guard. The 5-pole input connector provides supply voltages for the preamplifier required by optional thermocouple sensors.
