Download - UWB Radars [EDocFind.com]
-
8/7/2019 UWB Radars [EDocFind.com]
1/22
UWB Radars: Possibilities and
Problems
Dr. Amit Kumar Mishra
Department of ECEIIT Guwahati
-
8/7/2019 UWB Radars [EDocFind.com]
2/22
Signposts!
Plan of presentation:
UWB radars: an introduction
UWB radars: types
UWB radars: usages
Problems and challenges
Talk timing = 20min (talk) + 10min (QA)
-
8/7/2019 UWB Radars [EDocFind.com]
3/22
UWB: A brief introduction
Ultra wide band
BW > 20% of central frequency, OR
BW > 500 MHz
Three types:
Impulse UWB radar
LFM UWB radar
Noise UWB radar
Recent FCC regulation
-
8/7/2019 UWB Radars [EDocFind.com]
4/22
UWB Spectrum FCC ruling permits UWB spectrum overlay
1.6 1.9 2.4
Bluetooth,
802.11b
Cordless Phones
Microwave OvensGPS
PCS
5
802.11a
-41 dBm/Mhz Part 15 Limit
UWB
Spectrum
Frequency (Ghz)
Emitted
Signal
Power
10.63.1
FCC ruling issued 2/14/2002 after ~4 years of study & public
debate
FCC believes current ruling is conservative
-
8/7/2019 UWB Radars [EDocFind.com]
5/22
Summary of the FCC Rules
Significant protection for sensitive systems GPS, Federal aviation systems, etc.
Lowest Limits Ever by FCC
Incorporates NTIA recommendations
Allows UWB technology to coexist with existingradio services without causing interference
The R&O rules are designed to ensure that existing andplanned radio services, particularly safety services, are
protected.
-
8/7/2019 UWB Radars [EDocFind.com]
6/22
Some typical advantages of UWB
Multipath immunity
Ease of signal generation and processing architectures (!) Radar
Inherent high precision sub-centimeter ranging
Wideband excitation for detection of complex, low RCS targets
Geolocation/Positioning Sub-centimeter resolution using pulse leading edge detection
passes through building blocks, walls, etc. (LOS not required) Low Cost
Nearly all-digital architecture
ideal for microminiaturization into a chipset Frequency diversity with minimal hardware modifications
-
8/7/2019 UWB Radars [EDocFind.com]
7/22
UWB Radar types
LFM UWB radars: Not much different from
any other radar system
Noise Radar: UWB feature from the BW of
noise
Impulse Radar: Time frequency
uncertainty!
-
8/7/2019 UWB Radars [EDocFind.com]
8/22
LFM UWB Radar
Tx signal is a simplechirp with UWBproperties
e.g. VHF radar image 20-90 MHz (but BW >
25% of fc)
In use since long
Problems: target modeling!
too much information!Courtesy SDMS
-
8/7/2019 UWB Radars [EDocFind.com]
9/22
Noise UWB Radar
The question is how you model noise!
Advantages:
Frequency diversity
Immunity to detection, jamming etc.
Spectral efficiency (little cross-interference
between 2 noise radars)
Many proofs of concept available
-
8/7/2019 UWB Radars [EDocFind.com]
10/22
Impulse UWB radar
Non-sinusoidal waveforms
Fav. Shape: Gaussian waveforms Autocorrelation is Gaussian shape!
FT is also Gaussian shape!
Major advantages obtained from timedomain analysis
Impulse waveform: ~1ns Depth of pulse: ~ 30cm
Finer resolution
-
8/7/2019 UWB Radars [EDocFind.com]
11/22
Possibilities of impulse radar
Resolution
Target identification
Low elevation performance (time of arrival is different!)
Antenna pattern depend on signal characteristics
Both range and X-range resolution improved by higherBW
Immunity to interference and noise
Decreased dead-zone
MTI without using Doppler
Theoretically no side-lobes!
-
8/7/2019 UWB Radars [EDocFind.com]
12/22
Ranging and Imaging Capabilities
Many early applications of modern
UWB technology were in radar systems
Sub-nanosecond time resolution leadsto precision ranging and imaging
capabilities
Capabilities result from the largerelative and coherent bandwidth
-
8/7/2019 UWB Radars [EDocFind.com]
13/22
Bio-medical sensing using UWB
radar imaging
the required power for a UWB to image human
body is much lower than the permitted
maximum level of electro-magnetic (EM) energy
One of the major uses of UWB radar imaging forbiomedical purpose has been to get information
about the heart beat of a person. Termed as
heart rate variability (HRV), this diagnosed
information has been shown to be of immense
utility
-
8/7/2019 UWB Radars [EDocFind.com]
14/22
Imaging through obstacles
Foliage penetration (FOPEN) has been an
active research area for the military radar
community
With UWB techniques, systems can have
both good resolution as well as FOEN
capabilities
-
8/7/2019 UWB Radars [EDocFind.com]
15/22
Problems and challenges
Impulse radar:
Shape change during propagation
Time domain analysis: yet to achieve all the promises
Noise radar: Yet to fully prove its capacities
Energy control is difficult
LFM radar: Not suitable for FCC based utilities
Difficult and costly to generate UWB using LFM
-
8/7/2019 UWB Radars [EDocFind.com]
16/22
Related Standards
IEEE 802.15 : Wireless Personal Area Network (WPAN)
IEEE 802.15.1 : Bluetooth, 1Mbps
IEEE 802.15.3 : WPAN/high rate, 50Mbps
IEEE 802.15.3a: WPAN/Higher rate, 200Mbps, UWB IEEE 802.15.4 : WPAN/low-rate, low-power, mW level, 200kbps
-
8/7/2019 UWB Radars [EDocFind.com]
17/22
FCC UWB Device
Classifications
R&O authorizes 5 classes of devices Different limits for each:
Imaging Systems
1. Ground penetrating radars, wall imaging, medical imaging2. Thru-wall Imaging & Surveillance Systems
Communication and Measurement Systems3. Indoor Systems
4. Outdoor Hand-held Systems
Vehicular Radar Systems5. collision avoidance, improved airbag activation,
suspension systems, etc.
-
8/7/2019 UWB Radars [EDocFind.com]
18/22
Summary of Preliminary R&O
Limits
Application Frequency Band for Operation at Part 15 Limits
UserRestrictions
Imaging 3.1 to 10.6 GHz
(GPR
-
8/7/2019 UWB Radars [EDocFind.com]
19/22
0.96 1.61
1.99
3.1 10.6
GPS
Band
UWB Emission Limit for Indoor Systems
-
8/7/2019 UWB Radars [EDocFind.com]
20/22
0.96 1.61
1.99
3.110.6
GPS
Band
UWB Emission Limit for Outdoor Hand-held
Systems
-
8/7/2019 UWB Radars [EDocFind.com]
21/22
0.96 1.61
1.99
3.1 10.6
Operation is limited to law enforcement, fire and rescue organizations, scientific research
institutions, commercial mining companies, and construction companies.
GPS
Band
UWB Emission Limits for GPRs, Wall Imaging, &
Medical Imaging Systems
-
8/7/2019 UWB Radars [EDocFind.com]
22/22
0.96 1.61
1.99 10.6
Operation is limited to law enforcement, fire and rescue organizations.
Surveillance systems may also be operated by public utilities and industrial entities.
GPS
Band
UWB Emission Limits for Thru-wall Imaging &
Surveillance Systems