Seminar Report on UWB FM -CW RADAR

A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building

radar situated outside but in the vicinity of
the

first

wall.

After

modeling

the

propagation through various walls and

Abstract

quantifying the backscattering by the human

Today world is going very fast in

body,

an

analysis

of

the

technical

terms of technology, and triggering to latest

considerations which aims at defining the

technologies,

technologies

radar design is presented. Finally ultra

evolved far back is detecting humans, the

wideband (UWB) frequency modulated

detection of human beings is done in various

continuous

ways like Imaging Techniques, Sensing

proposed, designed, and implemented. The

Techniques, both the imaging and sensing

FM-CW Radar with an extended frequency

techniques will work when the human is in

sweep form 0.5 to 8 GHz is presented it has

front of the equipment or the machine, the

been applied to the TTW human detection.

disadvantage of the imaging and sensing

Some representative trials show that this

techniques can’t detect humans behind the

radar is able to localize and track moving

obstacle, this disadvantage evolved to detect

people behind a wall in real time. This

human beings behind the walls or obstacles

Radar will enable large stand-off distance

this can be achieved using RADAR. We

capabilities and in depth building detection.

one

of

the

know that Radar is conventional and
commercial equipment that had been serving

wave

(FMCW)

radar

is

1. INTRODUCTION

for different purposes in different ways, the

Here we assess human detection through

working nature of radar helped to improve

the wall using UWB (Ultra Wide Band)

the security more by introducing the latest

radars, we know that radar stands for radio

technology i.e, through the wall human

detection and ranging, i.e, using RADAR we

detection.

can find the Range, Direction and angle of

The

technology

through-the-wall

(TTW) radar demonstrator for the

the object, radar uses electromagnetic waves
that are transmitted by the transmitter into
the air to detect the object or reflecting

detection and the localization of people in a

material, the reflected echo signal from the

room (in a no cooperative way) with the

object must be in the direction of the
Receiver to find the range, there are
1


different

types

of

radars

have

been

developed for different applications

which distracts rescuers from locations
where living people can still be found [1].
Due to the ability of electromagnetic waves

The detection of humans hidden by walls

to

penetrate

through

typical

building

or rubble, trapped in buildings on fire or

materials and its significant (in order of

avalanche victims are of interest for rescue,

centimeters) spatial resolution, UWB radar

surveillance and security operations. The

is considered as preferred tool for detection

problem of rescuing people from beneath the

and localization of people. Detection of

collapsed buildings does not have an

human beings with radars is based on

ultimate technical solution that would

movement detection – respiratory motions

guarantee efficient detection and localization

and movement of body parts. These motions

of victims. The main techniques used are:

cause

Cameras with long optical fibers that are

amplitude and periodic differences in time-

injected into the holes or fissures in the

of-arrival of scattered pulses from the target,

collapsed buildings (the usability of such

which are result of periodic movements of

devices and their efficiency depend on the

the chest area of the target [2].

structure of collapsed building and besides,

Typical radar applications are listed here to

when the victim is detected it is difficult in

give an idea of the huge importance of

the most cases to determine its actual

radar in our world.

position). Sledge hammers are used to give a

Surveillance

signal to potential victims, and rescuers with

Military and civil air traffic control, ground-

microphones are waiting for hearing the

based, airborne, surface coastal,

response (obvious limitation of this method

satellitebased

is that unconscious people cannot be

Searching and tracking

detected. Localization of victims is a

Military target searching and tracking

problem as well). Search dogs are deployed

Fire control

in the disaster area. They detect presence of

Provides information (mainly target

victims efficiently by smell, but information

azimuth, elevation, range and velocity) to a

about their actual positions or quantity

firecontrol

cannot be indicated. Moreover, dog is likely

system

to indicate the presence of dead person

Navigation

changes

in

frequency,

phase,

2


Satellite, air, maritime, terrestrial navigation

countries all around the world. It addresses

Automotive

the ability to see behind walls in order to

Collision warning, adaptive cruise control

detect, count, and localize people inside a

(ACC), collision avoidance

building. We would like to remain at large

Level measurements

stand off distances (5-10 or even 50 m) if

For monitoring liquids, distances, etc.

possible, according to the allowed emitted

Proximity fuses

power. TTW Radars utilize frequencies

Military use: Guided weapon systems

ranging from UHF to S band in order to

require a proximity fuse to trigger the

have better wall penetration for any kind of

explosive

wall. It is further more recommended to use

warhead

ultrawideband (UWB) modulations in order

Altimeter

to achieve range resolution for human

Aircraft or spacecraft altimeters for civil and

localization

military use

propogation

Terrain avoidance

(TTW)

Airborne military use

electromagnetic “vision” behind walls in

Secondary radar

order to detect, count, and localise people

Transponder in target responds with coded

inside a building. Considering one by one

reply signal

these three objectives: detect, count, and

Weather

localise, it is possible to situate our work

Storm avoidance, wind shear warning,

among the various researches that are

weather mapping

ongoing in the TTW radar field.In order to

Space

detect one or more persons in a room, it is

Military earth surveillance, ground mapping,

necessary to take into account the fact that

and exploration of space environment

these people move. In fact, the radar return

Security

coming from the human body is not high

Hidden weapon detection, military earth
surveillance
Through

and

to

channel.

radar

deal

with

indoor

Through-the-wall

technique

addresses

enough compared to the backscattering of
the indoor environment to ensure detection.

The Wall

(TTW) human

detection using radar is a relatively new
topic that has been investigated in many

So that, Doppler effect has been used
historically to detect motion through walls
[1]. Nevertheless, Doppler radar has also
3


some drawbacks. The first one is its high

considerations which aims at defining the

sensitivity to all kinds of motions bringing

best radar design. And finally, Sections 5

false alarms. The second one is that target

and 6 present the radar implementation and

localisation and Doppler filtering seems

a trial of people detection and localization

incompatible. This is why emphasis was

through a wall.

made on imaging radar with the ability to
count and localise targets.Small TTW radars
based on the technology of UWB pulses
appeared since the 2000s. The famous ones

So many radars have been developed to
detect ranges of any distinct object, the
various radars are

by

1. Pulsed Doppler radar

CAMERO. There is no publication about

2. Continous wave radar

them in the open literature. Besides, some

3. FM-CW radar

radar and signal processing specialized

4. MTI Radar

laboratories

5. Phased Array Radar

are

Radarvision

and

have

then

studied

Xaver

UWB

radar

imaging or SAR imaging applied to through-

6. Synthetic Aperture Radar

wall vision [2, 3].The work presented here

7. Bi Static and Multi Static radar

gives the last advances from our laboratory

8. Passive Radar

in the “see-through” radar topic. It aims at

9. Multimode Radar

giving a global approach of the TTW radar
detection. It shows step by step the design
process

after

radar

modelling:

from

theoretical background to radar realization
followed by experimental assessment.
In

Section

2,

the

through-the-wall

propagation physics has been studied by
simulation

and

also

assessed

by

measurements. Then, in Section 3, the
backscattering strength of the human body is
quantified in an anechoic chamber with
various people under test. Section 4 is
centred

on

an

analysis

of

technical
4


penetrating,
foliage
penetrating;
’ultra
high
frequency’
Long-range
air traffic
control and
surveillance;
'L' for 'long'

L

1–2
GHz

15 cm to
30 cm

S

2–4
GHz

7.5 cm to
15 cm

Terminal air
traffic
control, longrange
weather,
marine radar;
'S' for 'short'

C

4–8
GHz

3.75 cm
to 7.5 cm

Satellite
transponders;
a
compromise
(hence 'C')
between X
and S bands;
weather
radar

X

8 – 12
GHz

2.5 cm to
3.75 cm

Missile
guidance,
marine radar,
weather,
mediumresolution
mapping and
ground
surveillance;
in the USA
the narrow
range 10.525
GHz ± 25
MHz is used
for
airport
radar. Named
X
band

2. Literature Survey
Before moving into the different types of
radars used for different applications, let’s
check the radar frequencies, Bands,
Wavelengths and its applications.

2.1. Radar Frequencies, - Bands,
Wavelength and Applications
Ban
d

HF

Frequen
cy

Wavelen
gth

Application

3-30
Mhz

10m100m

Coastal radar
systems,
over-thehorizon
(OTH)
radars; ’high
frequency’
’P’
for
’previous’,
applied
retrospectivel
y to early
radar
systems
Very
long
range (e.g.
ballistic
missile early
warning),
ground

P

30 to
300 Mhz

1m to 10
m

UH
F

3001000Mh
z

0.3-1m

5


because the
frequency
was
kept
secret during
World War
2.
KU

12 – 18
GHz

1.67 cm
to 2.5 cm

Highresolution
mapping,
satellite
altimetry;
frequency
just under K
band (hence
'u')

trigger
cameras that
take pictures
of
license
plates
of
carsrunning
red
lights,
operates at
34.300
±
0.100 GHz

Ka

18 – 27
GHz

27 – 40
GHz

1.11 –
1.67 cm

0.75 cm
to 1.11
cm

K band is
used
by
meteorologis
ts
for
detecting
clouds and
by police for
detecting
speeding
motorists. K
band radar
guns operate
at 24.150 ±
0.100 GHz.
Automotive
radar uses 24
– 26 GHz.

Mapping,
short range,
airport
surveillance;
frequency
just above K
band (hence
'a');
photo
radar, used to

40 – 300
GHz

1 mm to
7.5 mm

Q

40 – 60
GHz

5 mm to
7.5 mm

V

K

Mm

50 – 75
GHz

4 mm to 6
mm

Very
strongly
absorbed by
the
atmosphere

W

75 – 110
GHz

2.7 mm to
4 mm

76 GHz LRR
and 79 GHz
SRR
automotive

Millimeter
band,
subdivided
as
below.
The
letter
designators
appear to be
random, and
the
frequency
ranges
dependent on
waveguide
size.
Multiple
letters
are
assigned to
these bands
by different
groups
Used
for
military
communicati
ons

6


radar, highresolution
meteorologic
al
observation
and imaging

delay between the transmitted and received
signal the distance to the plane can be
calculated. Additional information can be gained
from the frequency shift of the received signal,
which is proportional to the speed of the plane.
Receiving a signal of sufficient power by an
adequate power to noise ratio is the biggest

2.2. Radar Equation
The acronym RADAR stands for Radio
Detection And Ranging. Figure 1 shows the
basic principle.

challenge of radar systems. The so called .Radar
Equation. gives hints on the power relations
within the system as indicated in Figure1. The
Radar Equation delivers the received power Pr
as result. According to the Radar Equation
following independent parameters determine the
received power Pr.

Pt: The power transmitted by the antenna,
dimension is dBm. Numeric examples : 63
dBm for real world Radar applications, 13
dBm for laboratory tests
G: Gain of the transmitting antenna,
dimension in dBi. The parameter determines
how much the radiation beam of the antenna
is focused toward the direction of the target.
Numeric examples are 12 dBi for a BiQuad
antenna and 70 dBi for a highly focusing
parabolic antenna.
Figure 1: Basic principle of Radar and its
parameters
σ is

An electromagnetic wave of power Pt is
transmitted to a flying object, for example to a
plane and is partly reflected back to the antenna

The wavelength of the transmitted

signal, dimension in meter. The wavelength
can

be

directly

calculated

from

the

frequency. Numeric examples: 0.03 m for a

with the receiving power Pr. From the time
7


10 GHz signal and 0.12 m for a 2.54 GHz
signal

Parame

Abbrevi

ter

ation

Value Value
,

Exam

Radar cross section, RCS, is a virtual area

Exam

ple 2

representing the intensity of the reflection.

Uni

ple 1

Not all of the radiated power is reflected

Transm

back to transmitting antenna, as indicated by

itted

the small waves close to the plane in Figure

power

1. The .Sigma. ( ) of the objects determines

Gain of

the virtual area of the reflecting object

transmi

(plane) from which all of the incoming

t

radiation energy is reflected back to the

antenna

antenna. The dimension is square meter,

Wavele

.m2. in short. Practical examples are 12 m2

t

Pt

63

13

dB
m

G

28

12

dBi

 (f)

0.03

0.12

m(

ngth

(10*1

(2.5*1

Hz)

for a commercial plane, 1 m2 for a person or

(freque

09)

09)

0.01 m2 for a bird. Refer to [18], page 6665

ncy)


12

0,3

m2

R

8114

5

m

Pr

1

17.4*

pW

for further

Radar

examples.

cross
section

R: Distance between the transmitting

Distanc

antenna and the reflecting object. Dimension

e

in m. Numeric examples are 8000 m for real
world applications or 5 m for laboratory

Receive

conditions. It has to be stressed that this

d

parameter reduces the result, i.e. the

power,

received signal by the power of 4, with the

linear

effect that far distant objects are providing

Receive

only a small amount of received power.

d

103

Prlog

-90

-48

dB
m

power,
Table 1: Parameters of Radar Equitation and two
examples

logarith
mic
8


example 1 the received reflected power of
Example 1 shows a a real world example,

example 1 is almost 50 dB lower than the

derived from [Pozar], example 2 shows a

received signal of example 2. The reason is

radar application which can be realized

the smaller wavelength lambda which

under laboratory conditions for example

affects the result by a power of 2 and

in an anechoic chamber.

especially the bigger distance R of example
1 which affects the result by a power of 4.

Example 1 read in clear text : A radar

Small wavelengths, i.e. high frequencies are

transmitting antenna with gain of 28 dBi is

aimed for in most radar systems, especially

transmitting an electromagnetic wave at 10

in antenna arrays, because of the resulting

GHz with a power of 63 dBm to a plane in a

small antenna size. It is obvious also, that in

distance of about 8000 m. The plane has a

radar technology one has to deal with very

radar cross section of 12 m2 . By means of

small receiving power especially for far

the Radar Equation the received power back

distant objects.

at the antenna is calculated to -90 dBm.

2.3. Common Radar types for
Example 2 read in clear text: In a radar test

Common Applications

laboratory implemented in an anechoic
chamber a test transmitter provides 13 dBm
to a matched antenna of 12 dBi with a

2.3.1.Simple Pulse (Range) and Pulse
Doppler (Speed/Range)Radar

frequency of 2.5 GHz. The reflecting object
with a cross section of 0.3 m2 is located in 5
m distance from the transmitting antenna.
According to the Radar Equation the test
receiver is going to receive a reflected signal
of -48 dBm.

When comparing example 1 to example 2
we can conclude that despite much bigger

Basic principle of a simple pulse radar system

transmitting power, better transmit antenna
gain and bigger radar cross section in
9


A simple pulse radar system only provides

receiver, peak power, frequency stability,

range (plus direction) information for a

phase noise of the LO and all of the pulse

target based

parameters.

on the timing difference between the

The AGC circuit of the receiver

transmitted and received pulse. It is not

protects the radar from overload conditions

possible to

due to nearby collocated radars or jamming

determine the speed. The pulse width

counter measures. The attack and decay time

determines the range resolution.

of the AGC circuit can be varied based on
the operational mode of the radar. Since the
roundtrip

of

a

radar

signals

travels

approximately 150 meters per microsecond,
it is important to measure the response of the
AGC for both amplitude and phase response
when subject to different overload signal
conditions. The measured response time will
dictate the minimum detection range of the
radar.

Pulse Doppler radar
Direction information with azimuth angle
determination in a radar system with a rotary
antenna

The direction information (azimuth angle) is
determined from the time instant of the
receive

pulse

with

reference

to

the

instantaneous radiation direction of the
rotating

antenna.

measurements

on

The

important

(non-coherent)

radar

equipment of this sort are the range accuracy
and resolution, AGC settling time for the

A pulse Doppler radar also provides
radial speed information about the target in
addition to range information (and direction
information). In case of coherent operation
of the radar transmitter and receiver, speed
information can be derived from the pulseto-pulse phase variations. I/Q demodulators
are normally used. The latest pulse Doppler
radar systems normally use different pulse
repetition frequencies (PRF) ranging from
10


several hundred Hz up to 500 kHz in order
to clarify any possible range and Doppler

 result in added noise contribution
uncertainty.

ambiguities. More advanced pulse Doppler
radar systems also " use "staggered PRF, i.e.
the PRF changes on an ongoing basis to get

 Reference

(or

timebase)

clock

stability.

rid of range ambiguity and reduce clutter as
well. Important criteria for achieving good

 Jitter or uncertainty due to the

performance in pulse Doppler radar systems

measurement point of the rising edge

include very low phase noise in the LO, low

of

receiver noise and low I/Q gain phase

interpolation or signals that have

mismatch (to avoid "false target indication")

changing

in addition to the measurement parameters

uncertainty.

the

signal

edges

.

rising

impact

edge

this

listed above. When measuring the pulse-topulse performance of a radar transmitter, it

 Overshoot and preshoot of the rising

is important to understand the variables that

and falling edges . any ringing on the

can

the

rising and falling edges can impact

measurement system for accurate Doppler

the measurement points adversely on

measurements:

a pulse to pulse basis. It is important

impact

the

uncertainty

of

that the measurement point, or the
 Signal-to-noise ratio of the signal the better the signal to noise ratio of

uncertainty

are sufficiently far
 away in time from the leading and

the signal, the lower
 the

average set of measurement points,

due

to

noise

contribution.

falling edges of a pulse. Applying a
Gaussien filter to smooth the impact
of the rising and falling edges can

 Bandwidth of the signal - the

reduce this phenomena and is often

bandwidth of the IF acquisition

implemented

system must be sufficient to

measurement system of a radar

 accurately represent the risetime of

in

the

Doppler

receiver.

the pulsed signal, however too much
bandwidth can
11


 Time between measured signals . due

detecting slow changes in the received field

to the PRI of the measured signal,

strength

due

to

variable

the close-in phase noise of the

interference

conditions that may exist.

measurement system needs to be
considered due to the integration
time at lower offset frequencies.

Radar speed traps operated by the
police use this same technology. Camera
systems take a picture if a certain speed is

 The

same

variables

can

also

contribute to the uncertainty in the

exceeded at a specified distance from the
target.

signal generator when testing the
receiver

circuit

and

Doppler

measurement accuracy.

Continuous Wave (CW) Radar:
A continuous wave (CW) radar
system with a constant frequency can be
used to measure speed.However, it does not
provide any range (distance) information. A
signal at a certain frequency is transmitted
via an antenna. It is then reflected by the
target (e.g. a car) with a certain Doppler
frequency shift. This means that the signal’s

Mobile

traffic

monitoring

radar

reflection is received on a slightly different

MultaRadar CD - Mobile speed radar for speed

frequency. By comparing the transmitted

enforcement from Jenoptic

frequency with the received frequency, we
can determine the speed (but not the range).
Here, a typical application is radar for

There are also military applications:
CW radars are also used for target

monitoring traffic.

illumination. This is a straightforward

Radar motion sensors are based on the same

application: The radar beam is kept on target

principle, but they must also be capable of

by linking it to a target tracking radar. The
12


reflection from the target is then used by an

due to the lack of atiming reference.

antiaircraft missile to home in on the target.

However, it is possible to generate a timing

CW radars are somewhat hard to detect.

reference

Accordingly, they are classified as low-

stationary objects using what is known as

probability-of intercept radars.

"frequency-modulated

for

measuring

the

continuous

rangeof

wave"

(FMCW) radar. This method involves
CW radars lend themselves well to

transmitting a signal whose frequency

detecting low-flying aircraft that attempt to

changes periodically. When an echo signal

overcome an enemy’s air defense by

is received, it will have a delay offset like in

"hugging the ground". Pulsed radar has

pulse radar. The range can be determined by

difficulties

between

comparing the frequency. It is possible to

ground clutter and low-flying aircraft. CW

transmit complicated frequency patterns

radar can close this gap because it is blind to

(like in noise radar) with the periodic

slow-moving

can

repetition occurring at most at a time in

pinpoint the direction where something is

which no ambiguous echoes are expected.

going on. This information is relayed to co-

However, in the simplest case basic ramp or

located pulse radar for further analysis and

triangular modulation is used, which of

action. [7]

course will only have a relatively small

in

discriminating

ground

clutter

and

The disadvantage of CW radar is that

unambiguous measurement range.

it cannot detect the Range due to Narrow
Bandwidth of the transmitted signal, to
measure the range we are moving forward to
the Frequency modulated transmitted signal,
which can be used to find the range of ay
distinct object.

FM-CW

Radar

(

Frequency

Modulated – Continuous Wave)
The disadvantage of CW radar
systems is that they cannot measure range
13

Basic principle of FMCW radar. The target’s
velocity is calculated based on the measured delay

t
between the transmit signal and the received
signal, whereas the frequency offset  gives the
f

offset vs. the transmitted frequency which is
proportional to their speed (e.g. in linear FM
radar).

range

In pulse radar systems, the pulses
This type of range measurement is

reflected by moving objects have a variable

used, for example, in aircraft to measure

phase from pulse to pulse referenced to the

altitude (radio altimeter) or in ground

phase of the transmitted pulses.

tracking radar to ensure a constant altitude
above ground. One benefit compared to
pulse radar is that measurement results are
provided continuously (as opposed to the
timing

grid

of

the

pulse

used commercially for measuring distances
other

ways,

e.g.

level

Technology

repetition

frequency). FMCW radar is also commonly

in

3. UWB RADAR

indicators.

Automotive radar is in most cases FMCW

Ultra Wideband technology has been an
extremely evolving technology because of
its appealing characteristics like achieving
high data rates, more capacity as compared
to narrowband systems, and co-existence

radar too

with the existing narrowband wireless
Moving-Target

Identification

(MTI)

technologies. A signal is categorized as
UWB if its bandwidth is very large with

Radar

respect to its center frequency. That results
The idea behind MTI radar is to
suppress reflected signals from stationary
and slow-moving objects such as buildings,
mountains, waves, clouds, etc. (clutter) and
thus obtain an indication of moving targets
such as aircraft and other flying objects.
Here, the Doppler effect is exploited, since
signals reflected by targets moving radially
with respect to the radar system exhibit an

that the fractional bandwidth should be very
high. The FCC defines UWB as a signal
with either a fractional bandwidth of 20% of
the center frequency or 500 MHz (when the
center frequency is above 6 GHz). The
formula proposed by the FCC commission
for calculating the fractional bandwidth is
[3, 4]: Where fH represents the upper
frequency of the -10 dB emission limit and

14


fL represents the lower frequency limit of

frequencies. Impulse radios operating in the

the -10dB emission limit

highly populated frequency range below a
few gigahertz must contend with a variety of

UWB is based on the generation of very

interfering signals. They must also guarantee

short duration pulses of the order of

that they do not interfere with the narrow-

picoseconds. The information of each bit in

band radio systems operating in dedicated

the binary sequence is transferred using one

bands. These requirements necessitate the

or more pulses by code repetition. This use

use of spread spectrum techniques. A means

of number of pulses increases the robustness

of spreading the spectrum of the ultra-

in

In

wideband pulses is to employ time hopping

UWBcommunications there is no carrier

with data modulation accomplished by

used and hence all the references are made

additional pulse position modulation at the

with respect to the center frequency. In Ultra

rate of many pulses per data symbol. The

wideband communications, a signal with a

use of signals with gigahertz bandwidth

much larger bandwidth is transmitted with a

means that multipath is resolvable down to

reduced

This

path differential delays on the order of

approach has a potential to produce signal

nanoseconds or less i.e. down to path length

which has higher immunity to interference

differentials on the order of foot or less. This

effects and improved time of arrival

significantly reduces fading effects even in

resolution. Ultra wide band communications

indoor environments. The advantages of

employ the technique of impulse radio.

UWB

Impulse radio communicates with the help

systems are [3]:

the

transmission

power

of

spectral

each

bit.

density.

over

conventional

narrowband

of base band pulses of very short duration of
the order of nanoseconds, thereby spreading

 Large Instantaneous bandwidth that

the energy of the signal from dc to few

enables fine time resolution for

gigahertz. The fact that the impulse radio

network time

system operates in the lowest possible
frequency band that supports its wide
transmission bandwidth means that this

 distribution,

precision

location

capability, or use as a radar.
 Short duration pulses that provide

radio has the best chance of penetrating

robust

objects which become opaque at higher

performance

in

dense

multipath
15


 environments by exploiting more
resolvable paths.
 Low power spectral density that
allows coexistence with existing
users and has a
 Low Probability of Intercept (LPI).
 Data rate may be traded for power
spectral

density

and

multipath

performance

3.1Salient Features of Ultrawideband Radars

Maximum range and data rate of different
wireless technologies

3.1.1 High Data rate
Low power consumption
UWB can handle more bandwidthintensive applications like streaming video,
than either 802.11 or Bluetooth because it
can send data at much faster rates. UWB
technology has a data rate of roughly 100
Mbps, with speeds up to 500 Mbps, This
compares with maximum speeds of 11 Mbps
for 802.11b (often referred to as Wi-Fi)
which is the technology currently used in
most wireless LANs; and 54 Mbps for
802.11a, which is Wi-Fi at 5MHz. Bluetooth

UWB

transmits

short

impulses

constantly instead of transmitting modulated
waves continuously like most narrowband
systems do. UWB chipsets do not require
Radio Frequency (RF) to Intermediate
Frequency (IF) conversion, local oscillators,
mixers, and other filters. Due to low power
consumption,battery-powered devices like
cameras and cell phones can use in UWB
[3].

has a data rate of
about1Mbps.

Interference Immunity

Due

to

low

power

and

high

frequency transmission, USB’s aggregate
16


interference is “undetected” by narrowband

technologies

receivers. Its power spectral density is at or

demodulatecomplex

below narrowband thermal noise floor. This

waveforms. In UWB, Due to the absence of

gives rise to the potential that UWB systems

Carrier, the transceiver structure may be

can coexist with narrowband radio systems

very simple. The techniques for generating

operating in the same spectrum without

UWB signals have existed for more than

causing undue interference [3].

three Decades. Recent advances in silicon

modulate

and

analog

carrier

process and switching speeds make UWB
system as low-cost. Also home UWB
wireless devices do not need transmitting

High Security

power amplifier. This is a great advantage
Since UWB systems operate below

over narrowband architectures that require

the noise floor, they are inherently covertand

amplifiers with significant power back off to

extremely difficult for unintended users to

support high-order modulation waveforms

detect [3].

for high data rates [3].

Reasonable Range

Large Channel Capacity

IEEE 802.15.3a Study Group defined
10 meters as the minimum range at speed
100Mbps However, UWB can go further.
The Philips Company has used its Digital
Light Processor (DLP) technology in UWB
device so it can operate beyond 45 feet at 50
Mbps for four DVD screens [3].

The capacity of a channel can be
express

as

the amount

of data bits

transmission/second. Since, UWB signals
have

several

gigahertz

of

bandwidth

available that can produce very high data
rate even in gigabits/second. The high data
rate capability of UWB can be best
understood

Low Complexity, Low Cost

by

examining

the

Shannon’s

famous

capacity equation:
The most attractive of UWB’s
advantages are of low system complexity
and

cost.

Traditional

carrier

based

=

log!(1 + !

!) (1.4)
17


Where C is the channel capacity in

dynamically trade-off high-data throughput

bits/second, B is the channel bandwidth in

for range [6].

Hz, S is the signal power and N is the noise
power. This equation tells us that the

Application of UWB

capacity of a channel grows linearly with the
Wireless technology is playing now

bandwidth W, but only logarithmically with
the signal power S. Since the UWB channel
has an 19 abundance of bandwidth, it can
trade some of the bandwidth against reduced
signal power and interference from other
sources. Thus, from Shannon’s equation we
can see that UWB systems have a great
potential

for

high

capacity

wireless

communications [7].

main role in our daily lives. In recent years,
demand of higher quality and faster delivery
of data is increasing day by day. The need of
more speed and quality brought up many
wireless

solutions

communication.
standards

for

The

short

family

rang

of

(IEEE802.11),

Wi-Fi
Zigbee

(IEEE802.15.4) and the recent standard
802.15.3, which are used for wireless local

Resistance to Jamming

The UWB spectrum covers a huge
range of frequencies. That’s why, UWB
signals are relatively resistant to jamming,
because it is not possible to jam every
frequency in the UWB spectrum at a time.
Therefore, there are a lot of frequency range
available even in case of some frequencies
are jammed.

area

networks

(WLAN)

and

wireless

personal area networks (WPAN), can’t meet
the demands of applications that needs much
higher data rate. UWB connection function
as cable replacement with date rate more
than 100 Mbps. Applications of UWB can
be categorized in following section.
Imaging Systems
UWB was firstly used by military
purpose to identify the buried installations.
In imaging system emission of UWB is used

Scalability

as illuminator similar to radar pulse. The
receiver receives the signal and the output is

UWB systems are very flexible

processed

using

complex

time

and

because their common architecture is

frequency functions to differentiate between

software re-definable so that it can

materials at varying distance. The lower part
18


of radio spectrum < 1 GHz have ability to

criminals hidden in shelters. These radars

penetrate the ground and solid surfaces. This

are able to measure the patient’s cardiac and

property makes UWB a best choice for

breathing activity in hospitals as well as at

detection of buried objects and public

home [21].

security and protection organizations.

Home Networks
UWB plays an important role in
medical imagine and human body analysis.
Now a day’s ultra wideband radars are used
for heart treatment. All of inner body parts
of human being can be imaged by adjusting

In a home environment, variety of
devices are operating such as DVD players,
HDTVs, STBs, Personal video recorders,
MP3 players , digital cameras, camcorders
and others. The current popular usage of

the emitting pulse power [21].

home networking is sharing date from PC to
PC and from PCs to peripherals. Customers

Radar Systems

are demanding multiplayer gaming and
In early days military used UWB

video distributions in home network. These

technology in radar system to detect the

all devices are connected using wires to

object in high-density media like ground, ice

share contents at high speed. UWB is a wire

and air targets. Research and studies in this

replacement

area found, radar can be used everywhere

bandwidth more than 100 Mbps. These all

where we need sensing of moving objects.

devices can be connected in a home network

Radar systems can be installed in vehicle to

to share multimedia, printers, scanners and

avoid accident during driving and parking.

etc. UWB can connect a plasma display or

UWB radars can be used in guarding

HDTV to a DVD or STB without using any

systems

detect

cable. UWB also enables multiple streaming

unauthorized entrance into the territory.

to multiple devices simultaneously, that

These radars can be used to find objects or

allows viewing same or different content on

peoples in collapsed buildings by detecting

multiples devices. For example, movie

the movement of person; but in case person

content can be shared on different display

is not moving, it can still be detected by

devices in different rooms [1] [3]. The home

heart

Police

networks are directly connected to a

department can use such radars to find

broadband through a residential gateway.

as

beat

alarm

and

sensors

thorax

to

beats.

technology

provides

high

19


This approach is cost effective but is

systems. These systems enable us to locate

ineffective for whole house coverage.

and

Cables are installed to connect different

equipment’s, nurses, doctors and patients in

devices

a hospital [2]. Furthermore these systems

with

Internet

in

a

home

track

be

objects

used

in

including

factories

facilities,

environment. With a right UWB solution

can

to

Internet traffic from multiple users in a

track

equipment’s, employees and visitors.

home can be routed to single broadband
connection. UWB enable devices can be
connected in

an ad-hoc manner

like

Bluetooth to share contents. For example a
camera can be connected to a printer directly
to print pictures; MP3 player can be
connected to another MP3 player and shared
music.

Sensor Networks
Wireless sensor networks are an
important area of communication. Sensor
networks have many applications, like
building

control,

surveillance,

medical,

factory automation etc. Sensor networks are
operated under many constraints such as
energy

consumption,

communication

performance and cost. In many applications
sensor size is also considered to be smaller.
UWB use pulse transmission, with very low
energy consumption. This property enables
us to design very simple transmitters and
thus long time battery operated devices.
These sensors can be used in locating
hospitals,

tracking

and

communication
20


21


Finally, the speed of the digital back-end

The Future of Radar
Developments

equipment handling the radar raw data will
need to

In the future, we can expect to
encounter

multisensory

systems

that

combine radar and infrared (or other)

increase i.e. through parallel processing in
order to handle data rates as needed for high
resolution radar operating modes.[12]

systems[11]. This will make it possible to
combine the benefits of the different types
of

systems

while

suppressing

REFERENCES

certain

weaknesses [11].
Military onboard radar systems will

1. Merrill I. Skolnik,1990, Radar

be increasingly confronted with the stealth

Handbook, Second Edition McGraw-

characteristics of advanced aircraft. The

Hill

contradiction

between

the

different

2.

Merrill I. Skolnik,1990, Radar

requirements imposed on aircraft must be

Handbook, Second Edition McGraw-

solved (i.e. planes should exhibit stealth

Hill, Chapter 7

properties while not revealing their position
through the use of onboard radar). One
possibility involves the use of a bistatic
radar system with a separate illuminator and
only a receiver on-board the aircraft.
In the future, radar antennas will in
many cases no longer exist as discrete
elements with suitable radomes. Instead,
they will be integrated into the geometrical
structure of the aircraft, ship or other
platform that contains them. The next
generation of AESA radars used on-board
aircraft will have more than one fixed array
in order to be able to handle greater spatial
angles.

3. http://www.radartutorial.eu/index.en.
html
4. http://www.radartutorial.eu/rrp.117.h
tml
5. http://de.wikipedia.org/wiki/Syntheti
c_Aperture_Radar
6. http://keydel.pixelplaat.de/uploads/Fi
le/vorlesung07-08/SAR.pdf
7. http://www.h2g2.com/approved_entr
y/A743807
8. http://www.armedforces.co.uk/releas
es/raq43f463831e0b7
9. http://www.pa.op.dlr.de/poldirad/BIS
TATIC/index.html
10. Silent Sentry.Passive Surveillance

22


11. http://defenseupdate.com/20110721_superhornets-future-eo-radar
12. radar-technology-looks-to-thefuture.html
13. http://www.radartutorial.eu/06.anten
nas/an17.en.html

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