Digital measuring devices

With the advent of the microprocessor, digital technology began to be used for data collection, feedback control, and aU other information processing requirements in production facUities. Such systems must acquire data from a variety of measurement devices, and control systems must drive final actuators. 

Pulse Inputs Where the sensor within the measurement device is digital in nature, analog-to-digital conversion can be avoided. For rotational devices, the rotational element can be outfitted with a shaft encoder that generates a known number of pulses per revolution. The digital system can process such inputs in either of the following ways ... 

All measurements involve uncertainty. One source of this uncertainty is the measuring device itself. Another source is your ability to perceive and interpret a reading. In fact, you cannot measure anything with complete certainty. The last (farthest right) digit in any measurement is always an estimate. 

Figure 4.47 Typical electronic circuit for the measurement of electron-electron coincidences with two spectrometers (SP1, SP2) placed at the positions 0 , and 5, , respectively. The pre- and main amplifiers are together represented by a triangle. The delay retards the signal from SP1, thus providing a STOP of the time-to-digital converter (TDC) if this time measuring device has been initiated by a START signal from a time-correlated event registered in SP2. The output of the TDC, i.e., the number of time-correlated events as function of the correlation time is stored in a histogramming memory (HIS. MEM.) which then is read out by a computer (COMP.).

After amplification, the signals from the photo- and Auger electrons were fed to the time-measuring device, a time-to-digital converter (see Fig. 4.47). To reduce the total dead time of the device, the Auger electrons which had a lower counting... 

Flash converters are mainly used in very fast measurement devices with low to medium requirements on resolution (e.g. digital sampling oscilloscopes or video digitizers). 

You know that the precision of a measuring device affects the number of significant digits that you should report. In this activity, each group will use different glassware and a different balance to collect data. 

Record the of digits appropriate for the measuring device, plus record one approximate digit. Exponents are always significant. 

As early as in the middle of the 1980s the Rosemount company introduced a technology outlined for transmitters. It combined the classic 4. ..20mA current loop with a digitized data transmission - on a single pair of wires. Basically, even several measuring devices can be operated on a single cable. This operational mode is called multi-drop. ... 

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