Seminar Report on UWB FM -CW RADAR


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Seminar Report on UWB FM -CW RADAR

  1. 1. 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
  2. 2. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  3. 3. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  4. 4. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  5. 5. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  6. 6. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  7. 7. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  8. 8. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  9. 9. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  10. 10. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  11. 11. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  12. 12. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building  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
  13. 13. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  14. 14. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  15. 15. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  16. 16. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building  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
  17. 17. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  18. 18. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  19. 19. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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
  20. 20. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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. 21. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 21
  22. 22. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 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. html 4. tml 5. c_Aperture_Radar 6. le/vorlesung07-08/SAR.pdf 7. y/A743807 8. es/raq43f463831e0b7 9. TATIC/index.html 10. Silent Sentry.Passive Surveillance 22
  23. 23. A Study of UWB FM-CW Radar for the Detection of Human Beings in Motion Inside a Building 11. 12. radar-technology-looks-to-thefuture.html 13. nas/an17.en.html 23