This is the content for Satellite Communication and Radar Communication.Types of Military radar and Satellite switching on broad processing.

1. Types of military Radar, Satellite
switching and on board
processing
PRESENTED BY:
Md.Kawsar Ahmed
Department of
ICE,PUST
Presentation on

2. CONTENTS: Types of Military Radar
 Introduction
 Definition of Radar
 Working Principle of Basic Radar
 Basic Types of Military Radar

3. INTRODUCTIO
N
• RADAR is acronym for Radio Detection and Ranging.
• First successfully demonstrated in 1936.

4. DEFINITION OF RADAR
A radar is an object detection device that uses radio waves to determine the speed, altitude
and direction of objects. Radio waves, or microwaves, are transmitted from a radar dish.
These waves then continue in their paths until they hit an object. A small bit of the wave is
returned to the transmitter, making it possible to determine the speed and other
characteristics of the object. Radar is a very important tool in the military as it is used to
detect aircrafts, vehicles and missiles.

5. WORKING PRINCIPLE OF BASIC RADAR

6. Types of Radar

7. Air Defense Radar
Air-Defense Radars can detect air targets and determine their position, course, and speed in a relatively
large area. The maximum range of Air-Defense Radar can exceed 300 miles, and the bearing coverage is a
complete 360-degree circle.
Surveillance
Air Policing
Missile Control

8. Battle Field Radar
Battle field radars usually have a shorter range and are highly specialized for a particular task. On ships of the
navy the number of specialized radar antennas are more and more replaced by a multifunction radar.
 Surveillance
 Navigation
 Weapon Control
 Missile Control

9. Air Traffic Control Radar
The air traffic control radar beacon system (ATCRBS) is a system used in air traffic control
(ATC) to enhance surveillance radar monitoring and separation of air traffic.
 En-Route Radar
 ASR ( Airport Surveillance Radar)
 PAR (Precision Approach Radar)
 ASDE (Airport Surface Detection Equipment)
 Weather Radar

10. Types of Military Radar
1. Simple Pulse Radar
2. Moving-Target Indication (MTI) Radar
3. High –Range Resolution Radar
4. Imaging Radar
5. Tracking Radar
6. Electronically Scanned Phased-Array Radar
7. Precipitation Radar
8. Cloud Profile Radar
9. Scatter meter Radar
10. Naval Fire-Control Rader.
11. Airborne Surveillance Radar
12. Airborne Fire-Control Radar
13. Military Air Traffic Control and Ranging Radar
There are 13 types of Military Radar

11. Types of Military Radar..
1. Simple Pulse Radar
This type is the most typical radar with a waveform
consisting of repetitive short-duration pulses. Typical
examples are long-range air and maritime surveillance
radars, test range radars, and weather radars. There are
two types of pulse radars that uses the Doppler
frequency shift of the received signal to detect moving
targets, such as aircraft, and to reject the large
unwanted echoes from stationary clutter that do not
have a Doppler shift.
2. Moving-Target Indication (MTI) Radar
By sensing Doppler frequencies, an MTI radar can
differentiate echoes of a moving target from stationary
objects and clutter, and reject the clutter. Its waveform
is a train of pulses with a low PRR (Pulse Repetitive
Frequency) to avoid range ambiguities. What this
means is that range measurement at the low PRR is
good while speed measurement is less accurate than at
a high PRR’s

12. Types of Military Radar..
3. High-Range Resolution Radar
This is a pulse-type radar that uses
very short pulses to obtain range
resolution of a target the size ranging
from less than a meter to several
meters across. It is used to detect a
fixed or stationary target in the clutter
and for recognizing one type of target
from another and works best at short
ranges.
4. Imaging Radar
Synthetic aperture, inverse synthetic
aperture, and side-looking airborne radar
techniques are sometimes referred to as
imaging radars. The Army, Navy, Air Force,
and NASA are the primary users of imaging
radars.

13. Types of Military Radar..
5. Tracking Radar
This kind of radar continuously follows
a single target in angle (azimuth and
elevation) and range to determine its
path or trajectory, and to predict its
future position. The single-target
tracking radar provides target location
almost continuously. A typical tracking
radar might measure the target
location at a rate of 10 times per
second. Range instrumentation radars
are typical tracking radars.
6. Electronically Scanned Phased-Array Radar
An electronically scanned phased-array
antenna can position its beam rapidly
from one direction to another without
mechanical movement of large antenna
structures. Agile, rapid beam switching
permits the radar to track many targets
simultaneously and to perform other
functions as required. The Army, Navy,
and Air Force are the primary users of
electronically scanned phased-array
radars.

14. Types of Military Radar..
7. Precipitation Radar
This radar is employed on an aircraft or
satellite and generally its antenna beam is
scanning at an angle optimum to its flight
path to measure radar returns from rainfall
to determine rainfall rate.
8. Cloud Profile Radar
Usually employed aboard an aircraft or
satellite. The radar beam is oriented at
nadir measuring the radar returns from
clouds to determine the cloud reflectivity
profile over the Earth’s surface.
9. Scatterometer Radar
This radar is employed on an aircraft or
satellite and generally its antenna beam is
oriented at various aspects to the sides of
its track vertically beneath it. The
scatterometer uses the measurement of
the return echo power variation with
aspect angle to determine the wind
direction and speed of the Earth’s ocean
surfaces.

15. Types of Military Radar..
10. Naval Fire-Control Radars.
These are shipborne radars
that are part of a radar-based
fire-control and weapons
guidance systems.
11. Airborne Surveillance Radars.
These radar systems are designed for early
warning, land and maritime surveillance,
whether for fixed-wing aircraft,
helicopters, or remotely piloted vehicles
(RPV’s).
12. Airborne Fire-Control Radars.
Includes those airborne radar systems
for weapons fire-control (missiles or
guns) and weapons aiming.
13. Military Air Traffic Control and Ranging Radars.
These include both land-based and shipborne
ATC radar systems used for assisting aircraft
landing, and supporting test and evaluation
activities on test ranges.

16. ADVANTAGES OF MILITARY
RADARS
• All-weather day and night capability.
• Multiple target handling and engagement capability.
• Short and fast reaction time between target detection and ready to fire moment.
• Easy to operate and hence low manning requirements and stress reduction under
severe conditions
• Highly mobile system, to be used in all kind of terrain
• Flexible weapon integration, and unlimited number of single air defense weapons can be
provided with target data.

17. DISADVANTAGES OF MILITARY
RADAR
• Time - Radar can take up to 2 seconds to lock on
• Radar has wide beam spread (50 ft diameter over 200 ft range).
• Cannot track if deceleration is greater than one mph/second.
• Large targets close to radar can saturate receiver.
• Hand-held modulation can falsify readings.

18. CONCLUSIO
N
• Military radars are one of the most important requirements during the wartime, which can be
used for early detection of ballistic missile and also for accurate target detection and firing.
Radar system discussed here has a built in threat evaluation program which automatically
puts the target in a threat sequence, and advises the weapon crew which target can be
engaged first.

19. Contents-2: Satellite Switching and on Board
Processing
Satellite Switching
On Board Processing

20. Definition
A multi-beam satellite switching system employs onboard switching for the purpose of
increasing the up path and down path antenna gain. A switching and control circuit
accepts an up path signal from only the desired input amplifier and connects the
desired output amplifier to the desired down path beam.
Onboard processing can also be used to reduce bit error rates for the uplink and
downlink transmissions and to allow satellites to be optimized to provide a wider
range of service applications more efficiently.

21. Basic of Satellite Switching
Imagine there are five locations A, B, C, D and E from where people travel to a central location S. Here they get
down from the bus they arrived and get into a bus going to their destination, A, B, C, D or E. Thus some people
arriving from locations A, B, D and E and intending to go to location C board the bus going to location C. Similar
shuffling takes place for others going to A, B, D or E. Here the locations A,B, C, D, and E are the earth stations.
People are the data. The central station S is the satellite. The buses going to central station S are up links and those
going from central station S to stations A, B. C, D and E are the down links. People alighting from one bus and
boarding another bus to their destination is Satellite Switching.

22. Satellite Switching on board processing
1. Satellite Switched TDMA System
2. Satellite Switched FDMA System
3. Satellite Switched CDMA System
There are Three Types

23. Satellite Switching TDMA
SystemMore efficient utilization of satellites in the geostationary orbit can be achieved through the use of antenna
spot beams. The use of spot beams is also referred to as space division multiplexing. Further improvements
can be realized by switching the antenna interconnections in synchronism with the TDMA frame rate, this
being known as satellite switch TDMA (SS/TDMA).

24. Satellite Switching TDMA System

25. Satellite Switching FDMA System
A satellite communication system based on the use of a multiple, contiguous beam satellite antenna and
frequency division multiple access (FDMA) is studied. Emphasis is on the evaluation of the feasibility of
SS (satellite switching) FDMA technology, particularly the multiple, contiguous beam antenna, the
onboard switch and channelization, and on methods to overcome the effects of severe Ka band fading
caused by precipitation. This technology is evaluated and plans for technology development and
evaluation are given. The application of SS-FDMA to domestic satellite communications is also
evaluated. Due to the potentially low cost Earth stations, SS-FDMA is particularly attractive for thin
route applications up to several hundred kilobits per second, and offers the potential for competing with
terrestrial facilities at low data rates and over short routes. The onboard switch also provides added route
flexibility for heavy route systems. The key beneficial SS-FDMA strategy is to simplify and thus reduce
the cost of the direct access Earth station at the expense of increased satellite complexity.

26. Satellite Switching FDMA
System

27. Satellite Switching CDMA
System
The Satellite Switched Code Division Multiple Access (SS/CDMA) is a system proposed for geostationary
satellite fixed service communications and provides both multiple access and switching to a multibeam
satellite. Multiple access is achieved by space, frequency and code division while the switching function is
based on code division methods. In this article, we present an overview of the system architecture, focus on the
demand assignment control mechanism and describe the call control operation
In this method each signal is associated with a particular code that is used to spread the signal in frequency
and/or time. All such signals will be received simultaneously at an earth station, but by using the key to the
code, the station can recover the desired signal by means of correlation. The other signals occupying the
transponder channel appear very much like random noise to the correlation decoder.

28. Satellite Switching CDMA System
CDMA is not common in satellite communications because of near-far effect and cell breathing. Because
CDMA system uses the same frequency range to operate, so when there are so many subscriber's are
using a satellite network, the background noise in this system will be extremely high, and weak signals
which come from far distance will not be able to communicate anymore. This effect is called near-far
effect. And because that users who have a weak signal reception is not be able to communicate with
tower, they may presume the coverage area of this tower is reduced, this effect is called cell breathing. In
satellite network, signal strength from user’s handset is quiet low. Generally the Tx power of a mobile
satellite phone is about 2 watts, and it will travel several hundreds of kilometers or even 36 000
kilometers. Another factor in satellite network is that all users have the similar distance to satellite, so if
we use CDMA in this situation, when number of users increases, all users will drop out. OFDMA system
also has near-far and cell breathing effects even it is not so serious because users are operating on
orthogonality spectrum. And deploying OFDMA will NOT take the system big advantages. So modern
satellite networks are based on TDMA network for end user side.

29. Comparison of FDMA, TDMA schemes
Several satellite uplink and downlink accessing schemes for customer premises service are
compared. Four conceptual system designs are presented: satellite-routed frequency division
multiple access (FDMA), satellite-switched time division multiple access (TDMA), processor-
routed TDMA, and frequency-routed TDMA, operating in the 30/20 GHz band. The designs are
compared on the basis of estimated satellite weight, system capacity, power consumption, and cost.
The systems are analyzed for fixed multibeam coverage of the continental United States. Analysis
shows that the system capacity is limited by the available satellite resources and by the terminal
size and cost.

30. THANK YOU