# Digital Measurement Techniques 2007

Note :  Attempt all questions

1. Attempt any two parts of the following :

(a) Explain in brief the philosophy of digital and microprocessor / microcontroller based instruments.

(b) What are different time measurement techniques ? Explain how time interval between two events can be measured.

(c) Explain vernier techniques.

2. Attempt any two parts of the following :

(a) With the half of a neat sketch, explain the working principle of a deviation meter.

(b) Discuss a scheme for low frequency measurement.

(c) Enumerate the salient features of programmable filters.What are their main advantages and disadvantages ?

3. Attempt any four parts of the following :

(a) What is voltage to time converter ? Draw the circuit diagram of a basic v/t convertor and explain it. Also draw its output waveforms.

(b) Indicate the design produce for a dual-slope v/t converter capable of handling a maximum input voltage of +lv in the basic range and with a four-digit display of data.

(c) What are the major circuit blocks of a D/A convertor ? Draw the circuit diagram of the resistor network of a typical D/A convertor and explain it.

(c) What is pulse width-to-voltage convertor ? Show its schematic diagram, input and output waveforms and practical circuit.

(e) Explain the terms sampling and quantization related to A/D conversion.

(f)  Explain the sampling theorem. What are its main applications ?

4. Attempt any four parts of the following :

(a) Explain the working principle of a digital ohmmeter. What are its main advantages ?

(b) Show the schematic of a ‘Q’ meter and explain in detail.

(c)   Derive the signal flow graph for the N= 16 point, radix-4 decimation in frequency FFT algorithm in which the input sequence is in digit-reversed order and the output DFT is in normal order.

(d) Show the pole-zero pattern of a high pass filter and explain it.

(e) Show the pole-zero pattern of second order all pass filter and explain it.

(f)  Convert the low pass filter described by the diffluence equation

y(n) = 0.9yh(n-l) + 0.1x(n) in to a high pass filter.

(f) The difference equation for the high pass filter is y(n) = -0.9;y (n -1) + 0.1 x(n) and its frequency response is Hhn(w) = —0,1 . hp l + 0.9e~JW