Lab Manual – Advanced Communication Systems Vishwakarma Institute of Information Technology, Pune 1 Table of contents Sr. No Contents Page No 1 1. To calculate look angles from ES listed below to each of geosynchronous satellite listed • Azimuth Angle • Elevation Angle 2. To calculate distance between ES & satellite 3. Determine if satellite is visible from Es and indicate if not 2 2 1. To study the characteristics of Horn Antenna & Parabolic Antenna 2. To plot its radiation pattern 3. To calculate its gain and beam-width 9 3 1. To Study the Satellite Communication System 2. To determine the Carrier to Noise ratio of Analogue Satellite Receiving system at base band 12 4 Program for Simulation of Satellite link design using MATLAB 15 5 To Study of Wavelength Division Multiplexing 30 6 To prepare Optical Link Power Budget for Repeater less Optical Fiber Link using MATLAB & Microsoft Excel 33 7 Displacement Measurement using Optical sensors 36 8 Case study 47 H.O.D – E&TC
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Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 1
Table of contents
Sr.
No Contents Page No
1 1. To calculate look angles from ES listed below to each of
geosynchronous satellite listed
• Azimuth Angle
• Elevation Angle
2. To calculate distance between ES & satellite
3. Determine if satellite is visible from Es and indicate if not
2
2 1. To study the characteristics of Horn Antenna & Parabolic
Antenna
2. To plot its radiation pattern
3. To calculate its gain and beam-width
9
3 1. To Study the Satellite Communication System
2. To determine the Carrier to Noise ratio of Analogue
Satellite Receiving system at base band
12
4 Program for Simulation of Satellite link design using MATLAB 15
5 To Study of Wavelength Division Multiplexing 30
6 To prepare Optical Link Power Budget for Repeater less Optical
Fiber Link using MATLAB & Microsoft Excel 33
7 Displacement Measurement using Optical sensors 36
8 Case study 47
H.O.D – E&TC
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 2
EXPERIMENT NO: 01
TITLE OF EXPERIMENT :
4. To calculate look angles from ES listed below to each of
geosynchronous satellite listed
• Azimuth Angle
• Elevation Angle
5. To calculate distance between ES & satellite
6. Determine if satellite is visible from Es and indicate if not
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 3
1.1 Aim: 7. To calculate look angles from ES listed below to each of geosynchronous satellite
listed
• Azimuth Angle
• Elevation Angle
8. To calculate distance between ES & satellite
9. Determine if satellite is visible from Es and indicate if not
Earth Station
1. 44° 48' 59'' N
70° 42' 52'' W
2. 24° 52' 13'' S
113° 42' 13'' E
Satellites
1. 87° W
2. 127.5° W
3. 110° E
1.2 Theory: 1. Elevation Angle: It is the angle measured upward from the local horizontal plane
at ES to the Satellite path
Cos (EL) = __________Sin (r)_________
[1 + (re/rs) ² – 2(re/rs) Cos(r)] ½
Cos (r) = Cos (le) Cos (ls-le)
…… for geosynchronous
2. Azimuth Angle: It is the angle measured eastward(clockwise) from geographic
north to the projection of satellite path on a locally horizontal plane at ES
S = _a + c+ r_ a = ls-le
2 c = Le
Tan² (α / 2) = _Sin(s-r) Sin (s-c)_
Sin(s-a) Sin (s)
Case 1:-
• Satellite to SE of ES :- Az = 180 – α
• Satellite to SW of ES :- Az = 180 + α
Case 2:-
• Satellite to NE of ES :- Az = α
• Satellite to NW of ES :- Az = 360° - α
3. Distance between ES and satellite is given by-
d = [rs² + re² -2 (re)Cos(r)] ½
4. For a satellite to be visible from ES, its EI must be above some min value, which
is at least 0°. A positive or zero EI requires that-
rs ≥ __re__
Cos(r)
1.3 Result: Comparison of Matlab and Theoretical output
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 4
Vishwakarma Institute of Information Technology, Pune 5
Program: clc; clear all; close all; Le_arr = input(' enter ES latitude '); Ie_arr = input(' enter satellite longitude '); Is_arr = input(' enter satellite longitude '); % Ls = 0 for GEO Le_deg = Le_arr(1) + [Le_arr(2)/60] + [Le_arr(3)/3600]; Ie_deg = Ie_arr(1) + [Ie_arr(2)/60] + [Ie_arr(3)/3600]; Is_deg = Is_arr(1) + [Is_arr(2)/60] + [Is_arr(3)/3600]; Le = Le_deg * 3.142 / 180; Ie = Ie_deg * 3.142 / 180; Is = Is_deg * 3.142 / 180; re = 6370; rs = 42242; % caculate gamma gamma = acos (cos( Le ) * cos ( Ie - Is) ); if ( rs < [re/cos(gamma)] ) disp('Satellite is not visible from earth station '); else disp ('Satellite is visible from the earth station '); % calculate 'd' d = sqrt ( rs^2 + re^2 - 2*re*cos(gamma)) ; disp('Distance between ES and satellite is :- '); disp(d); % calculate elevation angle temp = sqrt ( 1 + (re/rs)^2 - 2*(re/rs)*cos(gamma) ) ; EI_rad = acos ( [sin(gamma)] / temp ) ; EI = 180 * EI_rad / 3.142; disp('Elevation Angle is :- '); disp(EI); % calculate 's' a = abs( Is - Ie ); c = abs(Le); temp = ( a + c + gamma )*180 / 3.142; s_deg = temp / 2; s = s_deg*3.142 / 180; % calculation of alpha p = sin(s-gamma); q = sin(s-c); r = sin(s-a); s = sin(s); alpha_rad = 2 * atan( sqrt([p*q]/[r*s])); alpha = alpha_rad*180 / 3.142; % calculation of azimuth angle if ( Le >= 0 ) if ( Is < Ie) AI = 180 + alpha;
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 6
else AI = 180 - alpha; end ; else if ( Is < Ie) AI = 360 - alpha; else AI = alpha; end ; end ; disp('Azimuth Angle is :- '); disp(AI); end;
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 7
Result: Enter ES latitude [44 48 59] Enter satellite longitude - [70 42 52] Enter satellite longitude - [87 0 0] Satellite is visible from the earth station Distance between ES and satellite is:-
4.2719e+004 Elevation Angle is:-
35.8868 Azimuth Angle is:-
202.5112 Enter ES latitude [44 48 59] Enter satellite longitude - [70 42 52] Enter satellite longitude - [127.5 0 0] Satellite is visible from the earth station Distance between ES and satellite is:-
4.2720e+004 Elevation Angle is:-
14.4604 Azimuth Angle is:-
245.2228 Enter ES latitude [44 48 59] Enter satellite longitude - [70 42 52] Enter satellite longitude [110 0 0] Satellite is visible from the earth station Distance between ES and satellite is:-
4.2720e+004 Elevation Angle is :-
50.6521 Azimuth Angle is :- 1.0699 enter ES lattitude -[24 52 13] enter satellite longitude [113 42 13] enter satellite longitude -[87 0 0] Satellite is visible from the earth station Distance between ES and satellite is :-
4.2720e+004 Elevation Angle is :-
62.0882 Azimuth Angle is :-
221.9980 enter ES lattitude -[24 52 13] enter satellite longitude [113 42 13] enter satellite longitude >> -[127.5 0 0]
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 8
Satellite is visible from the earth station Distance between ES and satellite is :-
4.2720e+004 Elevation Angle is :-
33.1357 Azimuth Angle is :-
257.0115 enter ES lattitude -[24 52 13] enter satellite longitude [113 42 13] enter satellite longitude >> [110 0 0] Satellite is visible from the earth station Distance between ES and satellite is :-
4.2719e+004 Elevation Angle is :-
60.6201 Azimuth Angle is :-
351.2512
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 9
EXPERIMENT NO: 02
TITLE OF EXPERIMENT : 4. To study the characteristics of Horn Antenna & Parabolic Antenna
5. To plot its radiation pattern 6. To calculate its gain and beam-width
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 10
2.1 Aim:
1. To study the characteristics of Horn Antenna & Parabolic Antenna
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EXPERIMENT NO: 03
TITLE OF EXPERIMENT : 3. To Study the Satellite Communication System
4. To determine the Carrier to Noise ratio of Analogue Satellite Receiving
system at base band
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 13
3.1 Aim:
5. To Study the Satellite Communication System
6. To determine the Carrier to Noise ratio of Analogue Satellite Receiving system at
base band
3.2 Apparatus:
Satellite uplink transmitter, satellite downlink receiver and satellite link emulator,
Helix antennas Antenna stands with connecting cables, mic, video monitor, CCTV camera,
Function generator, CRO, spectrum analyzer, etc.
3.3 Procedure:
1. Setup the link as before. Press the frequency select switch of satellite emulator down link
channel several times so as to set the frequency display from 2.400, 2.427, 2.454, and
2.481 and then back to 2.400.
2. Now, switch off the carrier by switching of both Transmitter (TX) and satellite.
3. Receiver (Rx) will read only its noise floor at RSSI output which has a DC voltage output
in proportion to the received signal strength.
4. The chart at the back of the manual can be used to convert DC voltage to corresponding
RF signal level in dBm or dBuV.
5. Say, in absence of any carrier Rx reads 0.92 V which is equal to -96 dBm (refer chart).
6. Thus, -96 dBm is noise floor of Rx that means if carrier received by Rx is less than -96
dBm it will be unable to measure it.
7. Now, switch on Tx and satellite and say, the Rx reads 1.93 V which equals to -59 dBm of
carrier level being received.
8. Thus, C/N = carrier level / noise level. As both noise and carrier signal detected are
measured in dB, C/N can be calculated by taking the difference of two readings or C/N =
carrier level (in dB) - noise level (in dB).
9. Hence, C/N = -59-(-96) =37 dB.
10. Make sure the Rx is not saturated with carrier otherwise incorrect C/N will be read. This
can be done by increasing path loss at Rx and satellite and or taking Rx farther away from
satellite.
11. Measure the C/N readings for different levels of pathless.
12. Monitor the audio and video transmissions and correlate them to various levels of C/N.
Thus higher level of C/N results in better picture and sound quality.
13. If you are able to receive audio & video sent, clearly it means you are well above
threshold level of signal. Now, the effect of noise can be seen if you decrease the received
signal strength to a considerable level. This can be achieved by increasing the path loss.
14. This means the received signal is just above the noise floor of receiver. Although we are
using FM demodulator but because the received signal is barely above the noise floor you
can hardly receive any intelligent information. Thus, signal cannot be received below
noise floor of Rx.
3.4 Observations:
Noise Voltage [RSSI]= _____ (Volts)
From table, Noise power in dB = _______dBm ---- (1)
Carrier Voltage [RSSI]= _____ (Volts)
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 14
From table, Carrier power in dB = _______dBm ---- (2)
Therefore,
=dBmin power Noise
dBmin power Carrier
N
C = ( )dBm – ( )dBm = ______ dBm
3.5 Result: 1. Satellite Communication System have been studied
2. Measured Carrier to Noise ratio of the given Satellite Receiving
3. System at base band is ______dB
3.6 Conclusion:
1. The difference between two readings of receiver noise level and carrier level is the C/N ratio
in dB. Actual reading will depend on a number of factors and will differ from to case to case.
Increasing the path loss and distance between antennas shall result in lower C/N ratios due to
lower levels of received carrier. Amount of noise received/generated remains constant.
2. More power at transmitter shall result in better picture quality and more C/N ratio. Lower
noise at receiver is essential for better picture. Higher gain antenna could be used to capture
more signals. Hence a helix antenna could result in higher C/N.
3. When noise is increased, sparkles start appearing on black or white portions of picture.
Further increasing the noise will make the picture lose its sync resulting in complete loss of
information.
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 15
EXPERIMENT NO: 04
TITLE OF EXPERIMENT : Program for Simulation of Satellite link
design using MATLAB
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 16
Program No. 1
A regional Satellite Communication System using 4/6 GHz band has following
parameters.
Satellite
1. Transponder Gain variable between 85 to 100 dB
2. Transponder Bandwidth 36 MHz
3. Transponder peak output power 6.3 watt
4. Antenna Gain (Transmit) 20 dB
5. Antenna Gain (Receiver) 22 dB
6. Satellite Receiver noise temperature 100° K
Earth Station
1. Antenna Gain (Transmit) 61.3 dB
2. Antenna Gain (Receiver) 60.0 dB
3. Receiver Noise Temp 100° K
Four Identical earth stations share one transponder in an FDMA mode. The
allocated channel capacities and B.W are:
Station 1 and Station 2, 132 channels/ 10 MHz BW
Station 3 and station 4, 24 channels/ 5 MHz BW
Assume, in FDMA mode. Transponder is operated at 5 dB output back off to minimize
the IM noise.
Slant distance is such that
FSL Uplink 200 dB
FSL Downlink 196 dB
Determine the following:
• Assuming Earth Station to be located at center of beam coverage, determine the transmitter power required for E.S, if transponder gain setting is at 90dB.
• Determine C/N at receiving E.S. for station 1 and station 3, assuming that these station are located at 3 dB contour of satellite foot print.
• Assuming station 1 and station 3 at 3 dB contour and station 2 and station 4 of beam centre, determine transmitter power levels for E.S.1 and E.S. 4 , if we have
to get minimum weighted signal to noise ratio 47 dB in any worst channel for
station 1 to station 2 and station 4 and station 3
Assume - a) Standard pre-emphasis filters are used.
b) I.M. Noise to be negligible
c) Terrestrial interference noise 1000 pwpo
d) Satellite interference 2000 pwpo
Lab Manual – Advanced Communication Systems
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Program No. 2
A Satellite provides direct television broadcast service in USA with beam width
1° wide at 3 dB points. The uplink frequency is 30 GHz and down rank frequency is 42
GHz. The Satellite supports two transponders, with each capable of relay one television
channel.
Receiving station uses antenna of 0.8 meter diameter (Assume η= 0.60), an
antenna random (to prevent build up of snow) with loss of 1 dB when the surface is wet.
A LNA is directly mounted on antenna feed with noise figure of 7.0 dB at ambient
temperature of 17° C
The TV signal with video BW of 4.2 MHz is frequency modulated on uplink freq
and occupies the R.F. Bandwidth of 30 MHz
Determine the following:
1. G/T ratio of Receiving Station.
2. C/N for I.F. bandwidth of 30 MHz for receiver, if satellite transmitter has power
output of 1 watt (Assume No losses in Atmosphere, coupling etc.)
3. C/N for receiver located at the edge of the coverage zone(i.e.3 dB contour point),
Assuming (a) 1 dB clear air atmospheric loss, ( b) Attenuation due to Rain is 10
dB, (c) pointing error of 0.33° in receiving antenna.
4. Assuming FM threshold for domestic receivers is 13 dB; determine minimum
power output of transponder to provide satisfactory service of receivers located at
‘C’ above.
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 18
Program No. 3
A Ku - band Satellite carries a number of narrow bandwidth transponders to
permit communications between small earth stations. The major parameters of satellite
are given below.
Parameter Uplink Downlink
Frequency 14.9 GHz 11.30 GHz
3 dB contour zone of antenna 3.6° x 2.4° 3.6° x 2.4°
Antenna efficiency 65% 65%
Transponder output power (saturated) ----- 20 watt
Transponder I/P noise Temp 520° K -----
Transponder gain, B.W 125dB, 5MHz -----
Pointing Accuracy +1°
Assume the slant distance between E.S. and Satellite - 39000 Km
Determine following:
1. Assuming Satellite Antennas to be having rectangular shape, dimension of
transmitting and receiving antennas in meters and gains of antennas in dB.
2. Determine the power flux density at the center of the coverage area, when
transponders are fully saturated. What is the flux density at the edge of the
coverage zone?
3. Determine the G/T of E.S. located at the edge of the coverage zone to achieve C/N
of 22 dB in 5 MHz bandwidth when transponder in fully saturated by single
carrier.
4. Determine the G/T of E.S. located at edge of the coverage zone to achieve C/N of
10 dB in the bandwidth of 50 kHz, when 20 carriers access the transponders with
equal power, simultaneously and transponder is used at 5.0 dB back- off at the
output.
5. Determine E.S. ‘EIRP’ to fully load the transponder up to saturation with single
carrier.
Lab Manual – Advanced Communication Systems
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Program No. 4
The Characteristics of a digital service transponder are as follows.
Frequencies Terminal A to Terminal B 14.9/11.3 GHz
Frequencies Terminal B to Terminal A 14.4/10.8 GHz
Vishwakarma Institute of Information Technology, Pune 36
EXPERIMENT NO: 07
TITLE OF EXPERIMENT : Displacement Measurement using Optical
sensors
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 37
7.1 Aim: To study working and characteristics of fiber optic displacement transducer
7.2 Apparatus: Optical Transmitter and Receiver Box, fiber cable, micrometer, digital
multimeter, LVDT Kit, etc
7.3 Theory:
7.3.1 Fiber optic sensors Optical fibers can be used as sensors to measure strain, temperature, pressure,
displacement and other parameters. The small size and the fact that no electrical power is
needed at the remote location give the fiber optic sensor advantages to conventional
electrical sensor in certain applications.
7.3.2 Optical Sensor Technologies
7.3.2.1 Measurands and Sensor Categories
At this point in the evolution of optical sensing technology, one can measure
nearly all of the physical Measurands of interest and a very large number of chemical
quantities. The Measurands possible are listed in Table
Optical Sensor Measurands
Techniques by which the measurements are made can be broadly grouped in three
categories depending on (a) how the sensing is accomplished, (b) the physical extent of
the sensing, and (c) the role of the optical fiber in the sensing process.
7.3.2.2 Means of sensing
In this category, sensors are generally based either on measuring an intensity
change in one or more light beams or on looking at phase changes in the light beams by
causing them to interact or interfere with one another. Thus sensors in this category are termed either intensity sensors or interferometer sensors. Techniques used in the case of
intensity sensors include light scattering, spectral transmission changes (i.e., simple
attenuation of transmitted light due to absorption), micro bending or radioactive losses,
reflectance changes, and changes in the modal properties of the fiber. Interferometer
sensors have been demonstrated based upon the magneto-optic, the laser-Doppler.
7.3.2.3 Extent of sensing
This category is based on whether sensors operate only at a single point or over a
distribution of points. Thus, sensors in this category are termed either point sensors or
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 38
distributed sensors. In the case of a point sensor, the transducer may be at the end of a
fiber the sole purpose of which is to bring a light beam to and from the transducer.
7.3.2.4 Role of optical fiber
Further distinction is often made in the case of fiber sensors as to whether
Measurands act externally or internally to the fiber. Where the transducers are external to
the fiber and the fiber merely registers and transmits the sensed quantity, the sensors are
termed extrinsic sensors. Where the sensors are embedded in or are part of the fiber -- and
for this type there is often some modification to the fiber itself -- the sensors are termed
internal or intrinsic sensors. Examples of extrinsic sensors are moving gratings to sense
strain, fiber-to-fiber couplers to sense displacement, and absorption cells to sense
chemistry effects. Examples of intrinsic sensors are those that use micro bending losses in
the fiber to sense strain, modified fiber claddings to make spectroscopic measurements,
and counter-propagating beams within a fiber coil to measure rotation.
7.3.2.5 Displacement and position sensors
The simplest sensors rely on the change in retro reflectance of light into a fiber
because of movement of a proximal mirror surface. One of the first Photonics sensors was
of this type, in which a conical tip is applied to the end of a fiber. Light is totally reflected
back into the fiber if the surrounding medium is air; however, if the fiber is inserted into a
liquid matching the fiber index, light is extracted from the fiber and lost. Thus,
displacement of the liquid surface can be tracked.
7.3.3 Enabling Sensor Components
7.3.3.1 Specialty fibers for sensors
Since a large percentage of today's optical sensors involve optical fibers in some
form, it is important to discuss the status of fiber R&D. For much of the work, sensor
designers have made use of the all-glass fibers that are readily available commercially
due to high-volume use in telecommunications. Interferometer sensors need single-mode,
all-glass fibers; intensity type sensors typically utilize multimode fiber for greater light-
gathering capability. While high-NA (numerical aperture) plastic fibers are used for some
intensity type sensors, the transmission and fluorescence properties of the plastic
complicate the spectral response, so all-glass fibers are favored for many spectroscopic-
type sensors. Polarized light transmission is important for a number of sensors (e.g., the
fiber-optic gyroscope, FOG); many fiber devices are designed to retain this property
along the length of the fiber and in the presence of macro- and micro-bending. In the case
of the FOG, the requirements are for a small coil of fiber for which the bending loss must
be small, the polarization properties of the light must be maintained, and the physical
strength of the fiber must not be jeopardized. For many of the chemical sensors, it is
important for the light wave to interact with its surroundings. Therefore, fibers have been
made where the core is close to the cladding-outside interface. An example of this type of
fiber is the "D-fiber." Shown in Figure are the cross-section views of several types of
fiber manufactured and used today.
Lab Manual – Advanced Communication Systems
Vishwakarma Institute of Information Technology, Pune 39
Fig. End view of specialty fibers.
7.3.3.2 Detectors
While not much change has taken place in the semiconductor devices actually
used to convert photons into electrons, progress continues to be made in readout
techniques for the sensor signals. Of particular note is the use of optical fiber
interferometers to monitor other interferometer sensors.
7.3.3.3 Light sources The majority of optical sensors still utilize semiconductor lasers and LEDs as light
sources. Increasingly, however, the low-cost semiconductor lasers have been used to
pump rare-earth-doped fibers to provide excellent, stable fluorescent sources for chemical
monitoring.
7.4 Procedure:
1. Connect power cord to the transmitter box and Receiver Box, and then switch ON
the power supply.
2. Insert the fiber optic cable from transmitter to LVDT kit
3. Insert other fiber optic cable from LVDT to Receiver Box.
4. Attach DVM at the output of the Receiver
5. Move the LVDT using micrometer; i.e. assembly attached with the LVDT kit
6. Measure the DC output voltage and plot the graph of displacement vs. DC output
Vishwakarma Institute of Information Technology, Pune 40
Isolator
Klystron Oscillator
Attenuator
Klystron Power Supply
Frequency Meter
Fig. Horn Antenna Bench Setup
Detector
CRO
Lab Manual – Advanced Communication Systems
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Block Diagram of WDM:
Laser (D1) 1310nm
Laser (D2) 1550nm
Multiplexer Power Supply
De- Multiplexer
1310nm Photo Detector
1550nm Photo Detector
CRO
Analog Signal
Digital Signal
ST to ST Coupler
Lab Manual – Advanced Communication Systems
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• Connect Ammeter cable to J2 with White dot of connector on right while facing back side of it to you. Keep J3 (Digital_CON), J4 (ANALOG_CON), J7 (TDM_CON) open.