Rajasthan Technical University 2011-5th Sem B.Tech Electronics and Communications Engineering 5ec4 analog communication - Question Paper
B.Tech. Vth Semester (MaiiBack) Examination - 2011 5EC4 ANALOG COMMUNICATION (Common for 5AI4 & 5EX4)
Maximum Mtrb t 90 Min. Pasting Mark* 3 24
Ttaw: J Hotn
Instruction to CmndMtte:
AtKtyt overall Five Qtmuotu selecting one question firm each unit All questions carry equal mark* fohemm* jmmr must be shewn whenever mcessary Any 4aft* von fM missing may suitably be assumed ami JMMtff deaHy Units of quantum us*d/colc*ht+4 must be swed clearty)
UNIT * I
(a) A receiver has an overall fatfi A an output neaiitanee RL, a bandwidth 8/ and an absolute
operating temperature T If receiver h input reustance is equal to the antenna resistance Ra, Drive a formula for (he nos* figure of thjs receiver, noise output power. {$)
(b) Compute the noise vortae if the input of* video amplifier using a device having 3000 equivalent noise resistant* **i 400U input resistance The bandwidth of the amplifier is 7 MHz and the amfcweot mnperacurc is 2T C |8|
OR
2. (a) Name the different noise which be created within a receiver or amplifier Discuss the effects of these noises oe the performance of a receiver. |Jt|
(b) Compute the noise figure for amplifier if the amplifier is driven by a generator who**
output impedance is 40Q The necessary data as given below Find Ret], #</' 4 / *
/?, * 400kQ R, * 26kil H, = 500 kQ 4, = 10 equivalent noise resistance a JOOOU
(a) Drive the relation between (lie vuipui power of an Am transmitter and depth ot meduiMttn A 400 watt (400-W) vtinio is modulated to depth of 75 percent. C *lcul*t* fee Iottri power in the modulated wav*, (t|
OK
Itf Wb*i m different square law modulation methods ? Explain Balawnrt fctodetoier in
Id g linear series plate modulated amplifier, the plate supply voltage is *00 veto a*4 the D C plate current under unmodulated condition is 20 Amperes The sinusoidal moduiafcng voltage, which appears in the plate circuit of modulated amplifier, has amplitude of 150 volts The unmodulated O/P earner power is 4.5 KW Calculate
1.
(I) Hmfchrifln Index.
Camer power under modulated condition.
(at; nmt cviw cmcicncy .
(rr) *faae dfesspction under unmodulated conditions
5. <s) What is pw-wpteg ? Why is H used ? Sketch a typical pre-emphasis circuit and exptafe urtiy de-emphasn imat be used also. |t|
(b) Determine the vafoe of capacity reactance obtainable from a reactance FET. who* pt> fe 12 milli siemevt* (12 im)l Asaume that gate to source Resistance Is one ninth of 4 reactance otthe gaae to dram capacitor and that the frequency is 5 MHz. (If
4. (a) What is the function of balanced modulator in the Armstrong modulation system? (S| (b) Discuss relationship tewaa phase and frequency modulation. ftf
| UMT-IV )
7. (a) What is blockii in a rweww How ia good blocking athwved ? What will be the eflbd
on a communicaliaA if * Mutitng performance a pooer ? |l)
(b) What does e Nkxse hweei e A M Keceiver ? How does it do thid, (t|
o u
8. (a) Discuss the merits of delay*! AGC as a>mpered with simple AGC , Show AGC curves H
illustrate ihc compansoc aarf captain how dela>ed AGC may be obtained and applied ? What does the "delated AGC CoBtEoT Adjust? (I{
<b> With the aid oi block fliigrw of a smpfe receiver, explain thc baste supertatro dyat principle W
[unit '
(a) What is sampling ? Dimtuw the type* vf tamplmg
0) NtunU (it) Mat top tamplmg W
0) Wrtitf *hM#t note on any mo |4W|
Oft
14 (f WbM mw methods for demodulation of PPM ? <b> Diaciim thc Advantage of AM over PAM or vice vu
!
|
Attachment: |
| Earning: Approval pending. |
