1

REGIONAL TELECOM TRAINING CENTRE, BHUBANESWARQUESTION PAPER ON 6 GHz DIG.M/W (Q-1)

BATCH : JTO(BSNL) –08 [ PH-II ] Trans FULL MARKS : 50 TIME : 1 Hr

NAME : ___________________________ ROLL NO: ________ DATE OF EXAM:

Q.1: EXPAND THE FOLLOWING TERMS RELATED TO M/W. (0.5X10)

1. SACFA:-

2. VSWR:-

3. DADE :-

4. ALC :-

5. MPT:-

6. ASC :-

7. IFRB :-

8. TPM :-

9. DSC:-

10. WPC :-

Q.2: FILL IN THE BLANKS. (1X10)

1. Trans & Receive frequency separation is __________MHz for 6GHz system.

2. Adjacent channel spacing is __________MHz for 6GHz digital M/W for cross

polarization.

3. Maximum __________No of 64kbps data is used for 140 Mbits digital M/w

system.

4. _________________________Modulation is used for 6GHz system.

5. Transmitter power more than _______________dbm causes power Alarm.

6. IF Band width is 70 +/- ____________ Mhz.

7. Frame loss raised when BER is more than ____________________ .

8. _____________________ type of building is used for wide band terminal.

9. Minimum distance between tower foundation & building foundation is

___________________ meters.

10. Microwave tower earth should be less than _______________ ohms.

2

Q.3:STATE “TRUE” OR “FALSE” ? (1X10)

1.The trans & receive frequency between two repeater are normally kept cross

polarization.

2. A special heavy weight tower can carry 8 nos of 3.7 meter dia antenna.

3. The Orthogonal polarization is used to avoid interference while allotting

frequency on the route.

4. The EPS shift arbitrarily the SD local signal phase from 0 to360.

5. DEL EQL equalizes group delay caused by branching filters

6. Binary signals are converted to gray code for minimizing the error.

7. 6 Ghz lower band is used in DOT for digital microwave.

8. 4 X 64KBPS service channels are used by DOT.

9. Transmitting power at antenna port is +20 dbm. for 6 Ghz system.

10. EPS is located in SD RX.

Q.4: CORRECT THE UNDER LINED PORTIONS IF FOUND FALSE ? (1x10)

1.The Radio frequency below 10 GHz are affected by rain.

2.For night warning 7 numbers of red lamps are used in 100 meter tower.

3.The Eqpt. Earth for microwave system should be more than 4 .

4. TPG and TPD units are available in the modem swith rack of Main –1

channel.

5.Gain of the antenna decreases with increase in the diameter of antenna.

6.The tower should be capable to tolerate the wind speed of 100km /H.

7.While planning, the M/W route should not paralleled to NH.

8. The energy in the first fresnel zone is phase opposing.

9.Normally wave guides are used for systems upto 2 Ghz.

10.Maximum 8+1 system can possible for 6GHz digital M/W routes.

Q.5:DO AS DIRECTED ? (1x6)

i).Name two type of diversity used in D.M/W.

a)

b)

3

ii) State the service channels used by DOT in 6GHz system?

a)

b)

c)

d)

iii)Write the specifications for aviation warning tower lights of a 100 mt. Tower?

iv) State different types of Earthings followed in microwave stations.

V) Write the formula for radius of first fresnel zone ( F1) denoting the terms.

vi) Arrange the change over priority basis?

BER, Frame Sync., Base band failure .

4

Q.6: MATCH THE FOLLOWINGS ? (Give Sl.No of A against B) (0.5 x 8 )

“ A” “B”

1. IF level [ ] 75ohms

2. REC RF level(Nom) [ ] 2048 Kbps

3. Impedance at Baseband [ ] MOD

4. WS signal [ ] -10 dbm

5. ASC [ ] 139.264Mbits/sec

6. DSC [ ] TCC

7. TX power [ ] -77 dbm

8. Base band signal [ ] -32 dbm

[ ] +30 dbm

[ ] 50 ohms

Q.7: FILL IN THE BLANKS . (0.5 x 10 )

a. ___________ modulation is used 140 MB d.M/W system.

b. 11 & 13 Ghz systems are ___________haul systems.

c. ________system is used as end link between a local TV center and M/W

terminal. (11 Ghz, 13 Ghz)

d. The angle between the beam direction & true north is called __________.

e. Free space loss is = (_________ + 20 Log FD) in db ,where F isin Mhz & D is

distance in K.M. (32.2, 23.4, 32.4, 43.2 )

f. _____________ antenna is used in UHF systems .( Yagi, Parabolic reflector,

Grid paraboloid)

g. The top and bottom portion of the M/W tower is painted with ________.

(orange, red)

h. ___________station of a 6 Ghz system contains a Service Channel Unit (SCU).

i. Impendance at RF port is __________ ohms.

j. _________ has no local oscillator. ( TRF, Main RX,SD RX ).

5