EC 1255 – MEASUREMENT AND INSTRUMENTATION

B.E./B.Tech. DEGREE EXAMINATION, MAY / JUNE 2006

FOURTH SEMESTER

ELECTRONICS AND COMMUNICATION ENGINEERING

EC 1255 – MEASUREMENT AND INSTRUMENTATION

(Regulation 2004)

TIME: THREE HOURS                                             MAXIMUM: 100 MARKS

ANSWER ALL QUESTIONS

PART A – [10 X 2 = 20 MARKS]

1) Differentiate zero drift and span drift.

2) Compare attraction and repulsion type instruments.

3) Define deflection sensitivity.

4) Give the characteristics of probes used in CRO.

5) Define harmonic distortion.

6) What is a spectrum analyzer?

7) What are the advantages of digital instruments?

8) Give the various types of digital volt meter.

9) What is the necessity of digital interface?

10) Differentiate synchronous from asynchronous transmission of data.

PART B – [5 X 16 = 80 MARKS]

11) (i) Give a block diagram of computer – based data Acquisition system. Explain each block elaborately. [10 MARKS]
(ii) Discuss in detail the various techniques of multiplexing. [6 MARKS]

12) (a)(i) What are the types of errors? [6 MARKS]
(ii) With a neat circuit diagram and phasor explain Anderson Bridge. Derive suitable expression. What are its advantages and disadvantages? [10 MARKS]

OR

(b)(i) With a neat circuit diagram and phasor diagram discuss in detail about schering bridge. Find an expression for the capacitance, and dissipation factor. [6 MARKS]
(ii) With a neat diagram explain the (1) Construction (2) Working (3) torque equation and (4) advantages and disadvantages of a PMMC instrument. [10 MARKS]

13) (a)(i) With a neat diagram explain the various parts of CRO. [10 MARKS]
(ii) Explain the working of a Qmeter with a neat circuit diagram. List the applications of Q meter. [6 MARKS]

OR

(b)(i) With a block diagram, explain in detail sampling oscilloscopes. [10 MARKS]
(ii) Draw a test setup to measure power at high frequencies. [6 MARKS]

14) (a) (i) With a neat block diagram, explain signal generator. [6 MARKS]
(ii) With a neat block diagram, explain the working of harmonic distortion analyzer and intermodulation distortion meter. [10 MARKS]

OR

(b) (i) Draw a block diagram of heterodyne frequency generator and explain. [6 MARKS]
(ii) Define standing wave ratio. Explain in detail the method of measuring standing wave ratio. [10 MARKS]

15) (a) (i) With a neat block diagram and circuit, explain in detail the digital frequency meter. [8 MARKS]
(ii) Explain with neat diagram the working of integrating type digital voltmeter. [8 MARKS]

OR

(b) (i) With a neat block diagram explain the time interval measurement. [8 MARKS]
(ii) Explain the working of a potentiometric DVM, with a neat block diagram. [8 MARKS]