Axa Assurance Maroc - Insurer Innovation Award 2024
Digital multiplexing and transmission concept
1.
2. Europe bit rate(Mb/s)
2.048
8.448
34.368
139.264
565.148
Telephone
channel
30
120
480
1920
7680
Telephone
channel
North America bit
rate(Mb/s)
24 1.544
48 3.152
96 6.321
672 44.736
4032 274.176
Bit rate for PCM & Higher Order Mux
SDH 2.5Gb/s
European standard : A-Law
30 + 2 control channel = 32
Bit rate= 32 x 8 bit/sample x 8000 sample/s
= 2.048 Mb/s
North American standard (NAS) : μ-Law
For every 24 sample, 1 bit is added for
synchronization
For 24 sample => 24 x 8 bit/sample + 1 bit
= 193 bits
Bit rate= 193 x 8000 = 1.544 Mb/s
Needs MultiplexingNeeds Multiplexing –– Process of transmitting two or moreProcess of transmitting two or more
signals simultaneouslysignals simultaneously
2
3. SIGNAL :-
• PLESIOCHRONOUS SIGNAL
SIGNALS WHOSE CLOCK CAN VARRY
INDEPENDENT OF ONE ANOTHER BUT THE
RANGE OF SIGNAL VARIATION IS RESTRICTEDRANGE OF SIGNAL VARIATION IS RESTRICTED
WITHIN CERTAIN LIMITS.
• Synchronous Signal
• Asynchronous Signal
4. MULTIPLEXING OF SYNCHRONOUS DIGITAL
SIGNALS
Block interleaving :
Bunch of information taken at a time from each
tributary and fed to main multiplex output
stream. The memory required will be verystream. The memory required will be very
large.
Bit interleaving :
A bit of information taken at time from each
tributary and fed to main multiplex output
stream in cyclic order, a very small memory
is required.
5. Justification
• In general, incoming tributaries have
independent clocks. In that case, it is
inevitable that clock rate of a tributary and the
(divided) clock rate of the multiplexer (in(divided) clock rate of the multiplexer (in
second order TDM, it is 8448/4 = 2112 KHz)
are not the same. Without any precautions,
the result will be Slip.
7. MULTIPLEXING OF ASYNCHRONOUS
SIGNAL
• Positive justification : Common synchronization bit
rate offered at each tributary is higher than the bit
rate of individual tributary.
• Positive-negative justification : Common
synchronization bit rate offers is equal to thesynchronization bit rate offers is equal to the
nominal value.
• Negative justification : Common synchronization
bit rate offered is less than the nominal value.
12. U N
AlarmsFrame alignment pattern
0 01 0 0 01111
1 2 3 4 1 2 3 4 5 6 7 81 2 3 4
Justification control bits
1 bit per channel and frame
(transmitted 3 times)
0=no stuffing; 1=stuffing
Justification bits
1 bit per ch. and frame
no stuffing: information
stuffing: fixed value
Frame structurePDH E2 signal
8Mb FRAME STRUCTURE
Block 1
200 info bits
Block 2
208 info bits
Block 3
208 info bits
Block 4
204-208 info bits
1..12
848 bit
100,38 µs
13..212 5..212 5..212 9..212
1 2 3 4 1 2 3 4 5 6 7 81 2 3 4
12
13. Frame Alignment
• Bunched words (first 10 bits in second order
multiplex frame) is preferred to distributed
bits to prevent imitation by any other bit
sequence.sequence.
• The sequence used in Second and Third Order
MUX is 1111010000.
14. • Four bit stream of 2048 Kb/s are multiplexed. The resulting bit
stream of 8448 Kb/s can be thought of being composed as
follows :- Per tributary=8448÷4=2112Kb/s
• No of frame per second =8448kb/s÷848=9962≈10000
• Nominal bit rate : 2048 Kb/s
• Frame alignment information Per tributary: 30 Kb/s• Frame alignment information Per tributary: 30 Kb/s
• Justification control digits : 30 Kb/s
• Sub total : 2108 Kb/s
• Justification digits : 2112-2108= 4 Kb/s used to
allow over speed
• Justification rate per frame and E1 signal 0.42 bit
15. U N
AlarmsFrame alignment pattern
0 01 0 0 01111
Frame structurePDH E3 signal
1 2 3 4 1 2 3 4 5 6 7 81 2 3 4
Justification control bits
1 bit per channel and frame
(transmitted 3 times)
0=no stuffing; 1=stuffing
Justification bits
1 bit per ch. and frame
no stuffing: information
stuffing: fixed value
Block 1
372 info bits
Block 2
380 info bits
Block 3
380 info bits
Block 4
376-380 info bits
1..12
1536 bit
44,6927 µs
13..384 5..384 5..384 9..384
1 2 3 4 1 2 3 4 5 6 7 81 2 3 4
15
16. PDH E3 signal
2nd multiplex level of PDH
Multiplexing of four E2 tributaries
Features
Bit rate 34,368 Mbit/s ±20 ppm.
Frame duration 44,6927 µsFrame duration 44,6927 µs
Frame frequency 22,375 kHz
Bits per frame 1536
Bit interleaved multiplexing of 4 E2 signals
1 justification bit per frame and E2 signal
3 justification control bits per frame and E2 signal
Justification rate per frame and E2 signal 0,4357 bit
16
18. Alarms
D N
Frame alignment pattern
0 01 0 0 01111 1 0 Y1 Y2
Data communication channel
1 2 3 4 1 2 3 4 5 6 7 8
Justification control bits
1 bit per channel and frame
(transmitted 5 times)
0=no stuffing; 1=stuffing
Justification bits
1 bit per ch. and frame
no stuffing: information
stuffing: fixed value
Frame structurePDH E4 signal
Block 1
472 info bits
Block 2, 3, 4, 5
je 484 info bits
Block 6
480 - 484 info bits
1..16
2928 bit
21,024 µs
17..488 5..488 9..488
1 2 3 4 1 2 3 4 5 6 7 8
18
19. PDH E4 signal
3rd multiplex level of PDH
Multiplexing of four E3 tributaries
Features
Bit rate 139,264 Mbit/s ± 15 ppm
Frame duration 21,024 µs
Frame frequency 47,564 kHz
Bits per frame 2928Bits per frame 2928
Bit interleaved multiplexing of 4 E3 signals
1 justification bit per frame and E3 signal
3 justification control bits per frame and E3 signal
Justification rate per frame and E3 signal 0.41912 bit
19
20. Specification at Output Port
E1 E2 E3 E4 E5
Bit rate in Mbit 2.048 8.448 34.368 139.264 565.14
8
Clock tolerance ±50PPM ±30PPM ±20PPM ±15PPM ±5PPM
Frame length in 256 848 1536 1928Frame length in
bits
256 848 1536 1928
Stuffing rate per
frame
0.42 0.4357 0.4192
Impedance in Ω 120/
75
75 75 75 75
Line code HDB–
3
HDB–3 HDB–3 CMI
21. JITTER ASPECT OF MULTIPLEX
EQUIPMENT
• Jitter introduced by the multiplex system:
1. Jitter introduced due to the routine insertion of the
frame alignment words and of the service digits
and justification instructions.
2. Justification jitter.2. Justification jitter.
3. Waiting time jitter :-waiting time jitter which is due
to phase difference between write and read clock
and varies from frame to frame, has a low
frequency component and cannot be jittered out
by P.L.L. at the demultiplexer
22.
23. • M/W systems used to provide communication on
major trunk routes with high traffic density and
serving long distances are classified as long haul
M/W systems. 2, 4, and 6 GHz systems are long haul
systems.systems.
• Systems used to provide communication over short
distances for trunk routes with light traffic density
are classified as short haul system. 7 and 11 GHz
systems are short haul systems.
24. RANGE NAME WAVELENGTH USES
0–30 KHz V.L.F. Up to 10 km. Used for long communication. Has limited
information. Bandwidth require very high
power.
30–300 KHz L.F. 10 km to 1 km
0.3–3 MHz M.F. 1 km to 100 m Radio Broadcast, Marine Power in KW,
ground wave propagation, i.e. follows the
curvature of the Earth.
3–30 MHz H.F. 100 m to 10 m Long haul point to point communication.
Propagation is by one or more reflectionsPropagation is by one or more reflections
from ionosphere layers and so subject to
variations.
30–300 MHz V.H.F. 10 m to 1 m Line of sight, Tropo-scatter
communication.
0.3–3 GHz U.H.F. 1 m to 10 cm. –––––– do ––––––
3–30 GHz S.H.F. 10 cm to 1 cm. Line of sight, terrestrial M/W and Satellite
communication.
30–300 GHz E.H.F. 1 cm to 1 mm. Experimental.
25. APPLICATIONS:
• Fixed Radio Communication Services.
• Fixed Satellite Services.
• Mobile Services.
• Broadcasting Services.• Broadcasting Services.
• Radio Navigation Services.
• Meteorological Services.
• Radio Astronomy Services.
26. WPC
• In this regard (in the national context) the wireless planning
and co–ordination wing (WPC) of the ministry of
communication has allotted m/w frequencies spectrum, on
the basis of various wireless users classified as general users
and major users. Wireless users who are permitted to plan
their services and take action for the development of thetheir services and take action for the development of the
required equipments are major users. BSNL has been
nominated as a major wireless user by the WPC in 1981 in
the following sub base band of the M/W spectrum for fixed
radio communication. Microwave Spectrum Available for
BSNL
28. RF channel arrangement
Let us look at a typical RF channel arrangement for a 6
GHz band 5925 to 6425 MHz). This band of 500 MHz
is designed for 1800 channel capacity system with 8
pairs of frequencies. The individual channel
frequencies are given byfrequencies are given by
Fn = Fc - 259.45 + 29.65 n
Fn' = Fc-7.41 + 29.65 n
Where Fo = Centre freq. of band= 6175 MHz.
Fn and Fn’ are centre frequencies of nth channel in
lower and upper half .
29. Digital system route
The RF channel occupy 6430–7110
MHz, accommodating 8 both way
RF channels with 40 MHz spacingRF channels with 40 MHz spacing
between adjacent RF channels.
The radio frequency channels
assignment for Bombay Panjim
route is shown in Fig.3 as an
example. Polarization employed
(V/H) at various stations is also
depicted in the figure.
37. Quadrature Phase Shift Keying
• – Multilevel modulation technique: 2 bits per symbol
• – More spectrally efficient, more complex receiver
• Output waveform is sum of modulated ±Cosine and
±Sine wave
• 2x bandwidth efficiency of BPSK
39. Minimum Shift Keying
• Special form of (continuous phase) frequency shift keying
– Minimum spacing that allows two frequencies states to be
orthogonal
– Spectrally efficient, easily generated
41. Gaussian Minimum Shift
Keying(GMSK)
• MSK + premodulation Gaussian low pass filter
• Increases spectral efficiency with sharper cutoff,
excellent power efficiency due to constant envelope
• Used extensively in second generation digital cellular
and cordless telephone applicationsand cordless telephone applications
– GSM digital cellular: 1.35 bps/Hz
– DECT cordless telephone: 0.67 bps/Hz
– RAM Mobile Data
42. π/4-Shifted QPSK
• Variation on QPSK
– Restricted carrier phase transition to +/-π/4 and +/- 3π/4
– Signaling elements selected in turn from two QPSK constellations,
each shifted by π/4
– Maximum phase change is ±135° vs. 180° for QPSK, thus
maintaining constant envelope (i.e., amplitude of QPSK signal not
constant for short interval during 180° phase changes)constant for short interval during 180° phase changes)
• Popular in Second Generation Systems
– North American Digital Cellular (IS-54): 1.62 bps/Hz
– Japanese Digital Cellular System: 1.68 bps/Hz
– European TETRA System: 1.44 bps/Hz
– Japanese Personal Handy Phone (PHP)
43. π/4-Shifted QPSK (Cont’d)
• Advantages:
– Two bits per symbol, twice as efficient as GMSK
– Phase transitions avoid center of diagram, remove some design
constraints on amplifier
– Always a phase change between symbols, leading to self clocking
44. Quadrature Amplitude
Modulation (QAM)
• Quadrature Amplitude Modulation (QAM)
– Amplitude modulation on both quadrature carriers
– 2n discrete levels, n = 2 same as QPSK
• Extensive use in digital microwave radio links
45. Differential PSK
– simple receiver – no carrier recovery mechanism and
still good performance.
– logic ‘1’ –> change of logic state from previous coded bit
– logic ‘0” –> no change of state from the previous coded bit– logic ‘0” –> no change of state from the previous coded bit
46. Quadrature amplitude modulation is a
combination of ASK and PSK so that a
maximum contrast between each
Note:Note:
maximum contrast between each
signal unit (bit, dibit, tribit, and so on)
is achieved.
56. Pulse Transmission
• Channel Capacity or Information Rate
In general, the capacity of a channel for information
transfer is proportional to its bandwidth. Two major
theories that relate to the amount of data that can
be transmitted based upon the bandwidth of abe transmitted based upon the bandwidth of a
medium are the Nyquist Relationship and Shannon's
Law. Prior to discussing these theories, it is important
to understand the difference between bit and baud
due to the confusion that dominates the use of these
terms.
57. Bit versus baud
• The binary digit or bit is a unit of information transfer. In
comparison, the term baud defines a signalling change rate,
normally expressed in terms of signal changes per second.
• In a communications system, the encoding of one bit per
signal element results in equivalency between bit and baud.
That is, an information transfer rate of X bits per second is
carried by a signalling change rate of X baud, where each
That is, an information transfer rate of X bits per second is
carried by a signalling change rate of X baud, where each
baud signal represents the value of one bit. Now, suppose our
communications system was modified so that two bits are
encoded into one signal change. This would result in the baud
rate being half the bit rate, which obviously makes bit and
baud non–equivalent.
• The encoding of two bits into one baud is known as dibit
encoding.
58. Nyquist relationship
In 1928, Harry Nyquist developed the
relationship between the bandwidth and the
baud rate on a channel as
B = 2WB = 2W
where B is the baud rate and W the bandwidth
in Hz.
59. Shannon's law
In 1948, Claude E. Shannon presented a paper
concerning the relationship of coding to noise and
calculated the theoretical maximum bit rate capacity
of a channel of bandwidth W Hz. The relationship
developed by Shannon is given by
C = W log2 (1+S/N)C = W log2 (1+S/N)
where
C = capacity in bits per second,
W = bandwidth in Hz,
S = Signal power at the receiver input
N = power of thermal noise = No.W
60. Bit Baud Rate, Symbols
• We wish to transmit fb bits/s in a baseband channel having a bandwidth of
B Hz. In most applications, the transmission system is considered to be
more cost effective, if, in a given bandwidth, more bits/sec can be
transmitted. If fb, the transmission rate, is normalized to a Bandwidth B =
1 Hz, then the system efficiency can be characterised in terms of
transmitted bits per second per Hz (b/s/Hz).
• Nyquist theorem on minimum Bandwidth transmission systems states that
it is possible to transmit fs independent symbols in a channel (low pass
• Nyquist theorem on minimum Bandwidth transmission systems states that
it is possible to transmit fs independent symbols in a channel (low pass
filter) having a bandwidth of only B = fn = fs/2 Hz.
• If the digital signal changes at a rate of N bits/sec, then the modulated
phase would change at a rate of N/2 symbols/sec. This rate of change of
symbols is known as the Baud–rate (R).
61. Nyquist Criteria, Roll Off Factor
• Optimize the transfer function HT(f) of the
transmitting filter and the transfer function HR(f)
of the receiving filter, so that the following 3
requirements are jointly satisfied.
• ISI is Zero.
• Probability of symbol error is minimized.
• Constant power is transmitted.
• Nyquist BW required has been defined as equal to
half the symbol rate, i.e. N.BW = R/2
64. Nyquist Pulse with Zero Intersymbol
Interference
• For channel with ideal lowpass amplitude response of
bandwidth Wc, the impulse response is a Nyquist pulse
h(t)=s(t – t), where T = 1/2 Wc, and
1
1.2
s(t) = sin(2pWc t)/ 2pWct
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
t
T T T T T T T T T T T T T T
• s(t) has zero crossings at t = kT, k = +1, +2, …
• Pulses can be packed every T seconds with zero interference
65. 0
1
-2 -1 0 1 2 3 4
t
T T T T TT
Example of composite waveform
Three Nyquist pulses shown
separately
• + s(t)
• + s(t-T)
• - s(t-2T)
Composite waveform
+s(t) +s(t-T)
-2
-1
0
1
2
-2 -1 0 1 2 3 4
t
T T T T TT
-1
Composite waveform
r(t) = s(t)+s(t-T)-s(t-2T)
Samples at kT
r(0)=s(0)+s(-T)-s(-2T)=+1
r(T)=s(T)+s(0)-s(-T)=+1
r(2T)=s(2T)+s(T)-s(0)=-1
Zero ISI at sampling times kT
r(t)
-s(t-2T)
66. Nyquist pulse shapes
• If channel is ideal low pass with Wc, then pulses maximum
rate pulses can be transmitted without ISI is T = 1/2Wc sec.
• s(t) is one example of class of Nyquist pulses with zero ISI
– Problem: sidelobes in s(t) decay as 1/t which add up quickly
when there are slight errors in timing
• Raised cosine pulse below has zero ISI
0
f
A(f)
– Requires slightly more bandwidth than Wc
– Sidelobes decay as 1/t3, so more robust to timing errors
1
sin(pt/T)
pt/T
cos(pαt/T)
1 – (2αt/T)2
(1 – α)Wc Wc (1 + α)Wc
69. Example:
Thus, for a 140 Mb/s signal,
the symbol rate = 70 Mb/s if QPSK is employed. The
minimum BW needed for transmitting so many
symbols without ISI is 35 MHz. This is the one sited
filter Bandwidth. The total RF BW would include both
sides of the spectrum and be equal to 70 MHz. This is
filter Bandwidth. The total RF BW would include both
sides of the spectrum and be equal to 70 MHz. This is
the theoretical minimum BW.
If 16 PSK is used, then Baud rate = 35 MB/s. Nyquist
BW = R/2 = 17.5 MHz.
Total channel BW = 35 MHz.
70. Bit rate,Baud rate,Roll off & Modulation
N=Ny. B/W = R/2
R = Bit rate/log2 n n being the Modulation level.
Bandwidth with roll off B= N(1+α )
Channel BW= 2N(1+ α)Channel BW= 2N(1+ α)
Example:- what is the minimum RF B/W needed
to transmit a 2048 Kb/s digital Signal with 16
psk modulation? With IF/IR filter have a roll
off factor of 40%.
71. Example:-
• what is the minimum RF B/W needed to transmit a 2048
Kb/s digital Signal with 16 psk modulation? With IF/IR filter
have a roll off factor of 40%.
Ans. Baud rate( R) = 2048Kb/s =512 Kb/SAns. Baud rate( R) = 2048Kb/s =512 Kb/S
log2 16
Nyquist BW =R/2=256 KHz.
Bandwidth (one sided) B=256(1+0.4)=358.4KHz
RF BW= 2 x358.4 = 716.8 KHz.
74. CCIR
Frequency band
The CCIR Upper 6 GHz frequency plan as shown
in Fig.2(a) and 2(b) is employed in these
systems.systems.
fo : 6770 MHz
Lower half of band : fn = fo–350+40n
Upper half of band : fn' = fo–10+40n
n = 1, 2, 3, 4, 5, 6, 7 or 8
75. Lower half band Upper half band
RF CH No. Radio frequency (MHz) RF CH No. Radiofrequency (MHz)RF CH No. Radio frequency (MHz) RF CH No. Radiofrequency (MHz)
1 6460 1' 6800
2 6500 2' 6840
3 6540 3' 6880
4 6580 4' 6920
5 6620 5' 6960
6 6660 6' 7000
7 6700 7' 7040
8 6740 8' 7080
76. CCIR
The CCIR recommends 2 GHz band for 60,120, 300 and 600-1800 channel
systems, 6 GHz for 1800 channel systerrrupper 6 GHz band for 960 to
2700 channel system, and 7 GHz band for 60, 120 and 300 channel
systems. Taking into account various factors the following gives some of
the trends of frequency usage in India.
1. Longhaul wideband systems-4 GHz and 6 GHz1. Longhaul wideband systems-4 GHz and 6 GHz
2. Narrowband Longhaul system -2 GHz
3. Narrowband shorthaul systems -7 GHz and 13 GHz.
4. Wideband shorthaul systems -11 and 12 GHz.
Besides this digital microwave systems are proposed to be used in the band
2GHz and 13 GHz which is also recommended for digital transmission by
CCIR.
77. Nomenclature Bit rate No. of
chls.
Frequency band
Small capacity 0.704 10 658–712 MHz (UHF)
Small capacity 2.048 30 400 MHz band (UHF)
Small capacity 8.448 120
520–585 MHz (UHF)
622–712 MHz (UHF)
Small capacity 8.448 120 2 GHz band (M/W)(2.0–2.3 GHz)
Medium capacity 34.368 480
7 GHz band (M/W)
(7.425–7.725 GHz)
Medium capacity 34.368 480
(7.425–7.725 GHz)
Medium capacity 34.368 480
13 GHz band (M/W)
[12.75–13.25 GHz band (M/W)]
High capacity 139.264 1920
4 GHz band (M/W)
(3.3–3.8 and 3.8–4.2 GHz)
High capacity 139.264 1920
6 GHz band (M/W)
(5.925–6.425 GHz : Lower)
(6.430–7.110 GHz : Upper)
High capacity 139.264 1920
11 GHz band (M/W)
(10.7–11.7 GHz)
78. Nomenclature Bit rate
Mb/s.
No. of
chls.
Frequency band
Small capacity 0.704 10 658–712 MHz (UHF)
Small capacity 2.048 30 400 MHz band (UHF)
Small capacity 8.448 120 520–585 MHz (UHF)/622–712 MHz (UHF)
Small capacity 8.448 120 2 GHz band (M/W)/(2.0–2.3 GHz)
Medium capacity 34.368 480 7 GHz band (M/W)/(7.425–7.725 GHz)
Frequency Bands
Medium capacity 34.368 480 13 GHz band (M/W)/(12.75–13.25 GHz) band
M/W
Medium capacity 34.368 480 15 GHz band (M/W)/(14.75–15.75 GHz)
High capacity 139.264 1920 4 GHz band (M/W)/(3.3–3.8 and 3.8–4.2 GHz)
High capacity 139.264 1920 6 GHz band (M/W)/(5.925–6.425 GHz; Lower)
(6.430–7.110 GHz; Upper)
High capacity 139.264 1920 11 GHz band (M/W)/(10.7–11.7 GHz)
81. The preferred application in the BSNL
network is as follows
Capacity channel Base band GHz Prot/
unprot
configurati
on
makes
Small 10
30
704KBPS,
2.048MBPS
.7
.4 to .6
1+0 ITI, BEL
and PCL.30
120
2.048MBPS
8.448MBPS
.4 to .6
2GHz ITI
Medium 480 34 Mbps 2,
7,
13
4+1
7+1
High 1920 140 Mbps 6 7+1 NEC
83. Digital System
• 1 x 10–7 BER for more than 1% of any
month.
• 1 x 10–3 BER for more than 0.5% of any
month.
• HRDP (2500 kms), but greater than 280 kms• HRDP (2500 kms), but greater than 280 kms
• 1 x 10–7 BER for more than (L/2500) x 1% of
any month.
• 1 x 10–3 BER for more than (L/2500) x
0.05% of any month
84. Link is less than 250 kms
• 1 x 10–7 BER for more than (280/2500) x 1% of any month.
• 1 x 10–3 BER for more than (280/2500) x 0.05% of any
month.
• This takes into account fading, interference and all other
sources of performance degradation. It does not include
BER greater than 1 x 10–3 for periods exceeding 10BER greater than 1 x 10–3 for periods exceeding 10
consecutive seconds. This condition is included in the
availability criterion. The high BERs caused by switching
operations are included in the above criterion, but not the
ones caused by scheduled switching for maintenance).
Availability criterion is 1 x 10–3 BER (measured for 10s
time interval) not exceeding 0.3% of a year.
85. SACFA Clearance
• As stated in the previous paragraph, all the
user Departments, like Railways, Civil
Aviation, Defense, Telecommunications
Department, etc. are members of the SACFADepartment, etc. are members of the SACFA
Board. There is a Central Board at Delhi and
Regional Boards at Madras, Bombay and
Hyderabad, etc.
86. SACFA
• The main objective of the function of the
SACFA Board is to investigate the interference
possibilities, etc. and allot the frequency and
spectrum for new routes. All types ofspectrum for new routes. All types of
Microwave routes should be cleared by this
body as far as the frequency to be used, the
location, the height of tower are concerned.
87. Aviation
• This body takes the safety aspect from Aviation
point of view (of civil as well as Defense flights)
also. Hence, while clearing the license for a new
route, this Body specifically mentions whether night
warning or both Day and Night warning are to bewarning or both Day and Night warning are to be
provided for the Microwave towers. Night warning
is by means of aircraft warning lamps and day
warning is by means of painting the tower with
alternate bonds of international orange and white.
88. SACFA
• The SACFA Board also considers the distance
of tower location from the nearby Airports
and ensures that the specified minimum
distance is maintained from the airport .distance is maintained from the airport .
89. SACFA
• The SACFA Board takes the individual
clearance from the member Departments,
before clearing a particular Microwave route.
In Project Organization takes up theIn Project Organization takes up the
responsibility of obtaining SACFA clearance for
MW routes for BSNL.
90. 1. System Parameter
(1) Frequency range 6430 to 7110 MHz (6 GHz band)
(2) Modulation 16 QAM
(3) Repeating Regenerative repeating
(4) Transmission data rate
139.264 Mbit/s (equivalent to 1920 telephone
channels).
(5) Environmental conditions
a.Performance guaranteed
b.Operation without damage
c.Transportation and storage
Temperature, Relative humidity.
0 to +50oC, up to 95% at 35oC
–10 to +55oC, up to 95% at 45oC
–40 to +65oC, up to 95% at 45oC
(6) Altitude of installation Up to 4500 m
2. Transmitter–Receiver
(1) Transmitter output power
+30 dBm typical at the TX unit output (+27
dBm to +32 dBm)
(2) Receiver noise figure
3.5 dB typical, 4 dB guaranteed, measured at
RX unit input.
(3) Frequency stability + 2 x 10–5
(4) Receiver threshold level
–74 dBm to –17 dBm for BER of 1 x 10–3
measured at RX unit input
3. Modulator–Demodulator
(1) Modulation 16 QAM
(2) Demodulation Coherent/Instantaneous decision
(3) Spectrum shaping 35% roll–off at baseband
(4) IF frequency 70 MHz
91. 4. Base band switching
(1) Switching capacity
One protection channel for maximum seven
main channels. At the initial stage of this system,
number of main channels is three.
(2) Switching method
Hitless switching without frame loss on fades or
maintenance actions.
(3) Switching threshold
a.Switching initiation BER
b.Restoration BER
c.Switching time
1 x 10–4 to 1 x 10–9 (1 x 10–4, adjustable on site).
1 x 10–4 to 1 x 10–9 (1 x 10–6, adjustable on site).
Less than 15 ms excluding propagation time.
5. Baseband signal interface to/from MUX
(1) Bit rate 139.264 Mbit/s + 15 ppm
(2) Code format CMI(2) Code format CMI
(3) Level in accordance with CCITT G.703
(4) Impedance 75 W unbalanced
6. Digital service channel
(1) Maximum number of 64 kbit/s channel 24
(2) Digital interface
64 kbit/s, co–directional in accordance with
CCITT G.703.
(3) Analog interface
a.Input/Output level
b.Connection method
c.Impedance
d.Signalling
–16 dBm/+7 dBm
4–wire
600 ohms, balanced
E&M
92. 7. Auxiliary signal (option)
(1) Wayside signal 2,048 Mb/s
(2) Analog service channel 1 voice channel (Omnibus OW)
(3) Transmission line Protection and No.1 working channel
8. Interface connector
(1) RF (at antenna port)
PDR–70 at antenna side JIS BRJ–7 at radio
equipment side.
(2) IF and baseband SP3CJ coaxial, 75 W
(3) Alarm and auxiliary signals Multipin jack
(4) DC power supply and ground Crimp terminal(4) DC power supply and ground Crimp terminal
9. Power supply
(1) Input voltage
–48V nominal, positive ground
(–40 to –60 V)
(2) Power consumption (typical)
a. Terminal (3+1) with SD including SC WS
and MSTR SV
b. Repeater (3+1) with SD including SC–WS
and sub SV
1,074 W
1,358 W
10. Physical dimensions
(1) Rack, excluding RF branching network
2500 mm high, 120 mm wide,
225 mm deep.
96. Switching Criteria and Switching
Priority
• The switching is initiated by the detection of transmission
quality degradation or manual control.
• The automatic switching criteria are as follows :
• Bit error rate degradation.• Bit error rate degradation.
1. Initiation : BER = 1 x 10–4 (1 x 10–4 to 1 x 10–9)
2. Restoration : BER = 1 x 10–6 (1 x 10–4 to 1 x 10–9)
3. Threshold setting can be made on site.
• Loss of frame alignment.
• Mismatch of route identification.
• Loss of data stream.
97. Switching
• Case A
• Forced switching
• Automatic switching
• Manual switching
• Occasional switching• Occasional switching
• Case B
• Forced switching
• Automatic switching
• Manual switching
• Occasional switching
98. PARABOLIC ANTENNA
• The parabolic antenna is used
almost universally in point-to-
point systems. The parabolic
antenna utilizes a reflector
consisting of a paraboloid of
revolution and primary
radiator at the focal point .Theradiator at the focal point .The
reflector converts the
spherical wave radiating from
the focus to the planar wave
across the face of the
paraboloid to concentrate the
energy in a beam much like a
searchlight beam as discussed
below.
102. Cassegrain feed
• The Cassegrain feed is used when it is desired to place the
primary antenna at a convenient position and to shorten the
length of the transmission line or wave guide connecting the
receiver (or transmitter) to the primary. This requirement in
the line or waveguid may not be tolerated, specially over
lengths which may exceed 30 m in large antennas. Another
solution to the problem is to place the active part of the
transmitter or receiver at the focus. With transmitters this can
almost never be done because of their size, and it may also bealmost never be done because of their size, and it may also be
difficult to place the RF amplifier of the receiver there. This is
either because of its size or because of the need for cooling
apparatus for very low-noise applications in which case the RF
amplifier may be small enough, but the ancillary equipment is
not. In any case, such placement of the RF amplifier causes
servicing and replacement difficulties, and the Cassegrain
feed is often the best solution.
103. ELECTRICAL CHARACTERISTICS
• Antenna Gain
• Beam width
• Voltage to Standing Wave Ratio (VSWR)• Voltage to Standing Wave Ratio (VSWR)
• Radiation Patterns
• Front-to-back ratio
105. Conventional feeds provide an illumination of
approximately -10 dB at the edge of the parabola from
that at the centre, which results in an antenna efficiency of
58 to 63 percent for production antennas. Taking other
factors into account, most manufacturers guarantee
antenna efficiencies of 55 percent.
107. Beam width
The value of is approximately 1.1 degree at 6 GHz and 3.4
degree at 2 GHz for a 3.0 m diameter antenna. The main lobe
drops off to a null at 1.1 degree beam width off axis. This may
mean that signal could drop as much as 40 dB if a 3.0 m antenna at
6 GHz is moved 1.1 degree off axis. One can appreciate the need
for sturdy mounts and careful tower design .
108. Antenna Impedance
A proper Impedance Match is essential for maximum power
transfer. The antenna must also function as a matching load for
the Transmitter ( 50 ohms).
Voltage Standing Wave Ratio (VSWR), is an indicator of how
well an antenna matches the transmission line that feeds it. Thewell an antenna matches the transmission line that feeds it. The
antenna VSWR is the ratio of the amplitude of the voltage
standing wave at the maximum to the amplitude at the minimum.
It is the ratio of the forward voltage to the reflected voltage
. The better the match, the Lower the VSWR. VSWR is always
equal to or greater than 1.0. A 1.000 VSWR indicates that an
antenna is perfectly matched to a transmission line. A value of
1.5:1 over the frequency band of interest is a practical maximum
limit.
109. VOLTAGE STANDING WAVE RATIO
(VSWR)
• The antenna VSWR is the ratio of the
amplitude of the voltage standing wave at the
maximum to the amplitude at the minimum.
VSWR is always equal to or greater than 1.0.VSWR is always equal to or greater than 1.0.
• A 1.000 VSWR indicates that an antenna is
perfectly matched to a transmission line.
110. Return Loss is related to VSWR, and is a measure of the
signal power reflected by the antenna relative to the
forward power delivered to the antenna.
The higher the value (usually expressed in dB), the
better. A figure of 13.9dB is equivalent to a VSWR of
Return Loss
better. A figure of 13.9dB is equivalent to a VSWR of
1.5:1. A Return Loss of 20dB is considered quite good,
and is equivalent to a VSWR of 1.2:1.
Return Loss [in db] = 20 log VSWR +1
VSWR –1
114. Satellites
• The basic component of a communications
satellite is a receiver-transmitter combination
called a transponder.
• A satellite stays in orbit because the• A satellite stays in orbit because the
gravitational pull of the earth is balanced by
the centripetal force of the revolving satellite.
Satellite orbits about the earth are either
circular or elliptical.
118. SKG Satellite categories
categories
Low Earth
Orbit (LEO)
0 - 2,000 km 17,000 miles
per hour
90 minutes Mobile Satellite
Services (MSS)
Medium
Earth Orbit
(MEO)
2,000 -35,760km
R=11400 km T=201 minutes
Geosynchron 35,786 km 23 Hrs 56 MinGeosynchron
ous Orbit
(GEO)
35,786 km
(22,240 miles).
23 Hrs 56 Min
4 Sec
High Earth
Orbit (HEO)
Above 35,786 km
(22,240 miles).
So, an object placed at the orbit approx. 36 000 km above the
equator will be seen at the same position in the sky from Earth.
119. Important Satellite Classifications
• GEO (Geostationary Earth Orbit) satellites orbit about
36,000 km above Earth’s surface.
• LEO (Low Earth Orbit) satellites are about 500-2500 km
above earth’s surface.above earth’s surface.
• MEO (Medium EO) satellites are about 6000-20,000 km
above earth’s surface.
• There are also HEO (Highly Elliptical Orbit) satellites.
120. Orbits of Different Satellites
LEO (Iridium) GEO (Inmarsat)
Earth
2000 km
35,768 km
•10,000 km
MEO
MEO (ICO)
Not drawn to scale
123. Hardware: ground segment
• Antenna
• Receiving/transmitting chain
• Types of connection
• Link budget• Link budget
August 26, 2001 123
124. Antenna
• Parabolic or offset
• diameter - gain (as a function of frequency)
• noise - temperature (as a function of elevation)
• cross-polarisation isolation• cross-polarisation isolation
• de-icing (if required)
• wind resistance
• temperature variations tolerance
• tracking...
August 26, 2001 124
125. CHOICE OF FREQUENCY
Band UP LINK DOWN LINK BANDWIDTH
“C” BAND 5.925 to 6.425GHz 3.7 to 4.2 GHz 500 MHz
Extended “C”
Band
5.85 to 5.9 GHz 3.4 to 3.7GHz
Band
6.425 to 7.025GHz 4.5 to 4.8 GHz
“Ku” Band 12.75 to 13.25 GHz 500 MHz
14.00 to 14.5 GHz 10.7 to 11.7 GHz 500 MHz
“Ka” Band 27.00 to 30.00 GHz 18.10 to 20.20GHz
126. RF Channels
UPLINK FREQUENCY BAND 5925-6425 MHz.
Receive by satellite and modulated with 2225 MHz
before retransmitted to earth station.
DOWNLINK FREQUENCY BAND 3700-4200
MHz.
1 2 3 4 5 6 7 8 9 10 11 12
36 MHZ
4
MHZ
BEACON SIGNAL IN THE
DOWNLINK FREQUENCY BAND
MHz.
500 MHz
127. Transponder
• Some satellites have (hundreds of) transponders for
communication purposes.
• A transponder
1) receives transmissions from earth (uplink);
2) changes signal frequency;
3) amplifies the signal; and
4) transmits the signal to earth (downlink).
128. Satellite Subsystems
• The main subsystems in a satellite are
– communications;
– power;
– telemetry; tracking, and control (TTC);
– propulsion;
– attitude stabilization; and
– antenna subsystems.
• Power subsystem consists of solar panels, batteries, dc-
to-dc converters, and regulators. Solar panels convert
sunlight into power to operate all satellite electronics
and to charge batteries (used when sunlight is blocked).
129. Satellite Subsystems (Cont’d)
• The TTC subsystem contains a receiver that picks up
commands from a ground station and translates them
into control signals that initiate some action on board.
• The telemetry system monitors physical conditions within
the satellites and converts them into electrical signals
that are transmitted back to earth.
130. Ground Stations: The Other End
• Satellites in space communicate (transmit/receive radio
waves) with ground stations.
• Ground stations consist of subsystems:
– transmit/receive;
– Power;
– Antenna;
– TTC; and
– ground control equipment (GCE).
131. Satellite Dish
• Ground stations feature large parabolic dish
antennas with high gain and directivity for
receiving the weak satellite signal.
Satellite signalsSatellite signals
The larger the dish is
the higher the received
signal power.
132. Satellite Launch Date
Launch
Vehicle
Remarks
INSAT-1A Apr 10, 1982
Delta
3920
Could not fulfill mission
INSAT-1B Aug 30, 1983 Space Shuttle Fulfilled mission
INSAT-1C Jul 22, 1988 Ariane-3 Could not fulfill mission
INSAT-1D Jun 12, 1990 Delta 2 Fulfilled mission
INSAT-2A July 10, 1992 Ariane 4 Fulfilled mission
INSAT-2B July 23, 1993 Ariane 4 Fulfilled mission
INSAT-2C Dec 7, 1995 Ariane 4 Fulfilled mission
INSAT-2D Jun 4, 1997 Ariane 4 Could not Fulfill mission
INSAT-2DT In-orbit procurement from Arabsat- In service
INSAT-2E Apr 3, 1999 Ariane 4 C/14, Ext. C/05, Ku/00, MSS/00 In service
INSAT-3B Mar 22, 2000 Ariane 5
C/00, Ext. C/12, Ku/06, MSS/00
In service
INSAT-3C Jan 24, 2002 Ariane 4
C/24, Ext. C/06, Ku/00, MSS/01
In service
KALPANA-1 Sep 12, 2002 PSLV In service
133. SATELLITEs AND TRANSPONDER
CAPACITIES
S.
N
o.
NAME OF
SATELLITE
Transponder capacity Orbit
location
(Longitu
de)
C -
Band
Ext-C
band
Ku-
band
S-band Mobile
(MSS0
(CxS
&SxC)
1 INSAT-1D 12 - - 2 - 830 E
2 INSAT-2A 12 6 - 2 - 740 E2 INSAT-2A 12 6 - 2 - 740 E
3 INSAT-2B 12 6 - 2 - 93.50 E
4 INSAT-2C 12 6 3 1 1 93.50 E
5 INSAT2E 12 5 - - - 830 E
6 INSAT-2DT 25 - - 1 - 550 E
7 INSAT-3B - 12 3 - 1 830 E
134. INSAT Satellite :
Satellite Location C-
Band
Xc-
Band
Ku-
band
Life
2E 830 E 12 5 - 2011
3A 930 E 12 6 6 2016
3B 830 E - 12 3 20103B 830 E - 12 3 2010
3C 740 E 24 6 - 2015
3E 550 E 24 12 - 2016
136. INSAT Satellite (Planned)
Satellite Location C-band Xc-band Ku-band Planned
4A 830 E 12 - 12 9-05
4B 930 E 12 - 12 9-06
4C 740 E - - 12 3-06
4D 930 E 12 - - 9-07
4E 830 E - - - 9-08
137. Frequency Bands For Satellite
Communication
• C- Band :
• U/L : 5.925 – 6.425 GHz.
• D/L : 3.7 – 4.2 G Hz.
• Total 500 M Hz BW.
• Extended C- Band :
• U/L : 6.725 – 7.025 GHz.
• D/L : 4.5 – 4.8 G Hz.
• Additional 300 MHz BW.
• Ku band :
• U/L : 14.0 - 14.5 G Hz.
• D/L : 10.95 – 11.2 and 11.45 - 11.7 GHz.
• A total of 500 MHz BW in Ku band.
139. Ku Band VSAT
• Range of frequencies from 11 to 18 GHz. BSNL
Ku band service works on:
• - 11.637 GHz downlink frequency
• - 14.437 GHz uplink frequency• - 14.437 GHz uplink frequency
• Presently Ku Band Hub (Gateway) uses INSAT-
3B satellite to provide broadband packet-
switched communications to a large number
of user terminals.
140. What is VSAT
• VSAT stands for Very Small Aperture Terminal. VSAT is a small
earth station which provides a communication link required to
setup a satellite based communication network. It is a small
satellite dish diameter is typically 1.2-1.8 meters for Ku-band
systems that is capable of both receiving and sending satellite
signals. VSAT systems can be designed to serve both broadcastsignals. VSAT systems can be designed to serve both broadcast
and interactive applications whether data, voice or video,
which are now being served by terrestrial lines.
• VSAT Equipment is mainly consist of-
• ODU ( Outdoor Unit )
• IDU ( Indoor Unit )
141. Outdoor Unit (ODU):
• Antenna (0.75m - 1.8m)
• Block Upconverter (BUC) (1W-2W)
• Low Noise Block-Down converter (LNB)
• Feed Assembly (Co-pol or X-pol)
ODU
IDU (IPX-5100)
Dish Power
LAN Link
Ethernet
SyncFeed horn
LNB
BUC
142. • BUC :
• Block Up Converter; Up converts and amplifies
modem information for transmission to the satellite.
A BUC (Block Up-Converter) takes an L-band input
and transmits it upstream to the satellite on Ka, Ku,
or C band.(1W,2W,4W BUC)
and transmits it upstream to the satellite on Ka, Ku,
or C band.(1W,2W,4W BUC)
• LNB :
• Low Noise Block Down Converter; Down converts
and amplifies signals received from the satellite to
the modem or receiver. In addition to amplifying the
signal, the LNB also converts the signal to a
frequency usable by the In-Door-Unit.
143. IDU ( Indoor Unit )
• High Performance Satellite Terminal:
– Download speeds of up to 4 Mbps
– Upload speeds of up to 2 Mbps
• Flexible Interfaces:• Flexible Interfaces:
– Ethernet 10/100 BaseT (RJ45)
– USB 1.1
– 100-240 V AC Power Supply
– -48 V DC,12 VDC Power Supply
145. There are three basic VSAT
transmission types
• TDMA, time-division multiple access; DAMA, demand-
assigned multiple access; and SCPC/MCPC, single/multiple
channels per carrier. Interactive VSAT systems come in two
main network topologies - star and mesh. The former tends to
be based either on a shared access scheme (TDM/TDMA),
which is designed to support transactional processingwhich is designed to support transactional processing
applications, or on a dedicated link (the satellite equivalent to
a leased line). The latter usually uses links which are set-up
and torn-down on request to establish a direct link between
two sites on a demand assigned basis.
146. Ku Band HUB
(Earth Station)
Satellite antenna of 8.1 m
Cassegrain feed type.
BANGALORE
147. 1.Satellite antenna of 8.1 m – Cassegrain feed
type.
2.Ku Band RF equipment and its control
systems.systems.
3.GATEWAY Networking Equipment with
interfaces to Terrestrial Networks like MLLN,
MPLS and NIB.
148. VSAT SERVICES OFFERED
Voice Application
-Facsimile
-E-learning
- Financial Management
- Data processing
- Reservation System
- Telemetry & Data Collection
- News Wire Services- News Wire Services
- Private-Line Voice
- Virtual Private Networks
- Distance Education
- High Speed Internet Access
- Telemedicine
-Voice over IP Telephony
-Broadcast and Multicast
150. Video Conferencing
• Supports Client/Server based video conferencing
with MPEG-4 protocol.
• Flexible data speeds ranging from 64, 128, 256, 384
kbps and above
• Broadcast and Multicast features - Supports both• Broadcast and Multicast features - Supports both
Point-to-Point and Point-to-Multipoint conferencing.
• Ideal for mass corporate training, internal corporate
TV Broadcasting and e-learning using Broadcast and
Multicast features
151.
152. DIGITAL SATELLITE PHONE TERMINAL
(DSPT)
• Digital Satellite Phone Terminal System (DSPT
system or DSPS) project involves setting up a
VSAT (Very Small Aperture Terminal) Based
network for BSNL. The system consists of HUBnetwork for BSNL. The system consists of HUB
Station and Remote Digital Satellite Phone
Terminals working in Ku-Band (Transmit
Frequency is 13.75-14.5 GHz and Receive is
10.7-12.75 GHz).
153. • For BSNL VSAT network the Hub shall be
located at Sikanderabad (A.P.), adjoining Delhi,
in Uttar-Pradesh and there shall be 15000
DSPT remotes located over several states inDSPT remotes located over several states in
India with higher proportions being in North,
North East and East provinces.
156. IDR
• With the rapid digitization of telecom networks ,
telephone switching and terrestrial links, INTELSAT
(International Telecommunications satellite
Organization) planned to introduce IDR carriers into
the system , to provide interconnection of thesethe system , to provide interconnection of these
networks with high quality digital communication
with information rates from 64 kb/s to 44.736 Mbps
between different type of earth stations.
157. Summary of INTELSAT Standard Earth Stations
Standard
Type
Frequency
Band (GHz)
G/T
(dB/K)
Approximate
Diameter(M)
Services used for
A 6/4 35.0
(earlier
40.7)
15-18 (30-32) All
B 6/4 31.7 10-12 All except FDM / FM and
TDMA/DSI
C 14/11,12 37.0 10-12 FDM / FM CFDM/FM IDR,IRS
D1 6/4 22.7 4.5-6 VISTAD1 6/4 22.7 4.5-6 VISTA
D2 6/4 31.7 11 VISTA
K1 14/11,12 25.0 3.5-4.5 IRS
K2 14/11,12 29.0 5.5-6.5 IRS
K3 14/11,12 34.0 5-10 IRS , IDR
F1 6/4 22.7 4.5-5.0 IRS
F2 6/4 22.0 7-8 IRS , IDR
F3 6/4 29.0 9-10 IRS , IDR, CFDM/FM
G 6/4 or 14/11,12 - All sizes International leased services
X 6/4 or 14/11,12 - All sizes Domestic leased services
158. Modes of Satellite services
• Modes of Satellite services
• Closed Net - Any data rate,
• - No over head
• Intermediate data Rate(IDR) - 2 Mbps,8Mbps & 34
Mbps Data rate
• - 96 k OH
• Intelsat Business Service - Any data rate for data• Intelsat Business Service - Any data rate for data
transmission
• (IBS) 16/15 OH
• Drop & Insert - Fractional N x 64 Kbps
• - Supports Multi-
destination communication
159. Intermediate data Rate (IDR)
• IDR system provides Trunk connectivity between
Telephone exchanges for Digital
• Telephony data via satellite.
• Data rate : 64 kbps to 44.736 mbps• Data rate : 64 kbps to 44.736 mbps
• E1- 2.048 Mbps
• E2- 8.448 Mbps
• E3- 34.368 Mbps
• Supports Engineering Service Channel (ESC) of 96
Kbps
160. • The 96 Kbps overhead (ESC) channel consists
of :
• 32 Kbps ADPCM two audio channel
• or• or
• 64 Kbps Data channel
• 8 Kbps Data channel
• Four independent Backward alarms
