Digital counting

The microwave frequency can measured with great precision using the variable-length cavity of a wavemeter Its resonant absorption is detected electronically by the extra "cavity dip," and its frequency is calculated from the mechanically calibrated dimensions of the cavity. The microwave frequency (say 10 GHz) can be read with a precision of even 1 Hz by digital counting and by using a built-in transfer oscillator in a microwave frequency counter. 

The number of particles in one mole of a substance (the Avogadro constant) is often rounded down to 602 000 000 000 000 000 000 000. When performing calculations, however, this number is still too unwieldy. To simplify it, you can express it as a number between 1 and 10, multiplied by factors of 10. To do this, move the decimal point behind the left-most non-zero digit, counting the number of places that the decimal point moves. The number of places moved is the exponent for the base 10. 

In the production of sheets and plates cut to a certain length, special steps are taken to measure the exact length of material when it passes the gauge. Digital counting techniques are preferred for this type of measurement because the timing of the measurement can be made to fit exactly the desired stretch of material. 

Figure 28. Digital counting circuit with drive circuit 1907 and liquid crystal display, a to k Face electrodes 1 Back electrode...

The scaling, or gain, of the CCD is the number of electrons required to produce a digitized count. The well capacity of a modern MPP-modified CCD will be around 200,000 electrons. The gain of the CCD is usually set such that the well capacity for each wavelength channel is matched to the range of the digitizer. Typically, several pixels are com-... 

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