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Two threshold levels are established wit11 a gray region in between. If the output is definitely below the lower threshold, noise alone is snit1 to hc prcscrlt. If the upper tl~rcshold is exceeded, the signal is declared to be present along with the noise. |
SPHERIC CONDITIONS )N THIS EXAMPLE A SINGLE IONOSPHERIC LAYER IS CONSIDERED .ORMALLY THERE ARE TWO OR THREE DISTINCT LAYERS SUCH THAT SIGNALS MAY PARTIALLY PENETRATE THE LOWER LAYERS TO BE REFLECTED BY A HIGHER LAYER !S A CONSEQUENCE THE RELATIONSHIP BETWEEN THE RANGE TO A TARGET AND THE MEASURED ECHO TIME DELAY BECOMES MULTIVALUED WITH UNKNOWN PARAMETERS SUCH AS LAYER HEIGHTS THAT MUST BE ESTIMATED BY VARIOUS TECH |
13, pp. 816–827, 1983. 20. |
,p.uf ___---jqlf—- .? 0.001 A 8’= %220:E ~8<220 0U“ 1.. J, Allresistors~watt Interstate coilsclose woundwith#30wire on#’O.D.form iii220 v~ :$k AK5 10( ------ WJ 0.00 220 0.001Ii220 ~%k 6AK5 100 ---JIpf--- ~ 0 z 2200< &0.001 “’”\-controlI13to-lov.. -/220 !220 II+105V %0.001 —)1 —1. |
It is the basis for several of the chapters in this Handbook. Some transmitter types, however, are far better than others when the radar has to employ the doppler-shifted signal to detect moving targets in the midst of heavy clutter echoes. Examination of the basic radar equation for detection of targets at long range indi - cates that the average power is far more important than the peak power as a measure Chapter 10 ch10.indd 1 12/17/07 2:19:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. |
2.Change ofPRF from 810 to405 pps. 3.Change ofTR-switch resonant frequency from the magnetron frequency tothebeacon frequency. 4.Change from search tobeacon local oscillator. |
Radar data were collected only below 4700 km altitudes, with a resolved footprint on the surface of 23 km along track and 7 km across track.TABLE 18.6 Planetary Radars Mission URL Planet Year Radar Venera -8;9/10 (USSR) 1 Venus 1972, 75 Radar altimetry Pioneer Venus Orbiter (PVO) (USA)2 Venus 1978–92 ORAD: Altimeter (also coarse imagery); 17 cm Venera 15/16 (USSR) 3 Venus 1983–84 SAR and altimeter; 8-cm wavelength Magellan (USA) 4 Venus 1990–94 SAR: 12.6 cm (125 m, 75 m pixels), 95% coverage Clementine (USA) 5 Moon 1994 Bistatic scatterometer experiment; 6 cm Cassini (USA) 6 Titan 2004 TRM: 2 cm, SAR (resolution 0.35–1.7 km) and altimeter Chandrayaan-1 (India) 7 Moon 2008 Forerunner Mini-RF (USA): 12-cm SAR, scatterometer Lunar Reconnaissance Orbiter LRO (USA)8 Moon 2008 Mini-RF: SAR (12 cm and 4 cm), imager and interferometer 1. http://www.mentallandscape.com/V_RadarMapping.htm 2. http://heasarc.nasa.gov/docs/heasarc/missions/pvo.html#instrumentation 3. |
7 .30 RADAR HANDBOOK 6x9 Handbook / Radar Handbook / Skolnik / 148547-3 / Chapter 7 using the Kalman gains Kk+1 = P(k + 1 | k)HT(tk+1)[H(tk+1)P(k + 1 | k)HT(tk+1) + ℜk]−1 (7.33) Because the gains are calculated using the history of all past update times and accuracies, the gains automatically increase after missed detections and automatically increase to give greater weight to a detection when it is known to be more accurate, and they automatically decrease as the track ages, reflecting the value of the detections already filtered. For example, for a zero random acceleration, Qk = 0, and a constant detection covariance matrix, ℜk, the a – b filter can be made equivalent to the Kalman filter by setting α=− +2 2 1 1( ) ( )k k k (7.34) and β=+6 1 k k( ) (7.35) on the kth scan. Thus, as time passes, a and b approach zero, applying heavy filtering to the new samples. |
Ma, J.; Tao, H.; Huang, P . Subspace-based super-resolution algorithm for ground moving target imaging and motion parameter estimation. IET Radar Sonar Navig. |
2X. Kerr. D. |
DC POWER CONDITIONERS ARE USED FOR VOLTAGES APPLIED TO TRANSMITTING DEVICES THE FREQUENCY AND ITS HARMONICS OF THE CONVERTER MUST BE ATTEN |
Theantenna Figure7.17Principle ortheorgan-pipe scanner.. 248 INTRODUCTION TO RADAR SYSTEMS cannot be used during this period of ambiguity, called the dead tinte. In one model of the organ-pipe scanner, 36 elements were fed, three at a time.''* The dead time for this model is equivalent to rotation past two of the 36 elements; conseqi~ently it was inoperative about 6 percent of the time. |
interference prior to any nonlinear operation. A digital word in the power-of-2 binary format may be written £ = 2»-(»N+1_M + ^ + ^+...+^) (3,1) where M is the place beyond which all coefficients to the left are zero. Note that M has essentially the same significance as in previous sections. |
60, pp. 1551-1552, December, 1972. 16. |
62.Peeler.G.D.M..K.S.Kelleher. andH.P.Coleman: VirtualSourceLuneburg Lenses,Symposium 011 Micr(/\\'Clre Optics,McGillUniversity, Montreal. AFCRC-TR-59-118(1), ASTIADocument 211499. |
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30, pp. 723–735, 1992. 34. |
G. M. Dillard and C. |
For a circular aperture with uniform distribution, the field intensity is proportional to E(4>) = ("do (0 exp (j2rc ~ sin tp cos o)r dr = 1r.r52J 1(~)/~ (7.19} where c; = 2tr(r0/,l.) sin tp and J 1(~) first-order Bessel function. A plot of the normalized radiation pattern is shown in Fig. 7.4. |
I.: Survey of Phased Array Accomplishments and Requirements for Navy Ships. "Phased Array Antennas." ed. by A. |
Hadjifotiou, A.: Round-off Error Analysis in Digital MTI Processors for Radar. The Radio and Electronic Engineer, vol. 47, pp. |
LAW |
9.17). This radar isused forairborne detec- tion ofaircraft under blind conditions, and therefore requires asearch over asolid angle intheforward direction. The beamwidth isabout 5°. |
75. Hansen, V. G.: Constant False Alarm Processing in Search Radars, International CoMerence on Radar-Present and Future, Oct. |
One of •the first techniques for achieving frequency-agile magnetrons was known as spin tw1i11g. or rotary tu11ing. In this device a rotating slotted disk is suspended above the anode resonators. |
A well-known form of the logarithmic detector uses successive detection,6 wherein the detected outputs of Af similar limiter stages are summed as shown by Fig. 3.13. If each stage has a small signal gain G and a limited output level E, the intersections of the approximating segments fall on a curve described by [ 1OgEXM)G^+1 / i I l\]E0(M) = n\E / ^ + E I—J- + - • - + —7 + - (3.6) L log G \GM~l G2 G/J where n is the detector efficiency and E1(M) represents the particular input levels that correspond to the intersections of the line segments, E1(M] = ^- (3.7) GM (b) FIG. |
SISC.17.7]GENERAL METHODS OFRELAYING SINEANDCOSINE 703 \ b0?Radarvideosignals andtriggerpulse o f2 o ~llj,;,w1 Totransmitter -L= Transformer Audio C+D sine filter/1b iFromC>Ll receiverVideofilter Audio C!+D COS@ 1+3Mc\sec filterjz v wEzil Y1Audio AVC filterf~e I videoandtrigger o !%.o rr 2r7 B Signalata Potential atb FIG. 17.11.—Method ofrelaying sine and cosine by c-w on one r-f carrier. Atleast two methods ofsupplying slowly varying sine and cosine voltages have been successfully applied. |
H. Pearce, “Calibration of a large receiving array for HF radar,” Proc. Int. |
BANDWIDTH SIGNAL )N THIS CASE THE MOST APPROPRIATE hTHEORY OF THE EXPERIMENTv IS THE TIME |
The receiver frequency-response function, for purposes of this discussion, is assumed to apply from the antenna terminals to the output of the IF amplifier. (The second detector and video portion of the well-designed radar superheterodyne receiver will have negligible efTect on the output signal-to-noise ratio if the receiver is designed as a matched filter.) Narrowbanding is most conveniently accomplished in the IF. The bandwidths of the RF and mixer stages of the normal superheterodyne receiver are usually large compared with the IF bandwidth. |
Theeffectoferrorsontheradiation patternhaslongbee"recognized bythepractical antenna designer. Theusualrule-of-thumb criterion employed inantenna practice isthatthe. phaseoftheactualwavefront mustnotdifferfromthephaseofthedesiredwavefront bymore than±A/16inordertoensuresatisfactory performance. |
As such, MOM is not a useful tool for predicting the RCS of, say, a jet fighter in the beam of a radar operating at 10 GHz. The second limitation is that MOM yields numbers, not formulas, and is therefore a numerical experimental tool. Trends may be established only by running a numerical experiment repeat- edly for small parametric changes in the geometry or configuration of an object or in the angle of arrival or the frequency of the incident wave. |
D.C.. Sept. 22, 1977. |
40. W. D. |
CODED WAVEFORMS 'ENERAL /FTEN USED FOR HIGH |
J., vol. 34, pp. 5-103, January, 1955. |
02& WAVEFORMS AND IT IS GENERALLY DONE WITH A SIMILAR UNFOLDING AND CORRELATION TECHNIQUE AS DESCRIBED PREVIOUSLY FOR RANGE AMBIGUITIES !S SHOWN IN &IGURE VELOCITY UNFOLDING OF DETECTIONS INVOLVES ADDING A SET OF SIGNED INTEGERS !$ " " # $ ! |
VARYING |
The factors affecting the design of an HF OTH radar are slightly different than those affecting conventional microwave radar. This is illustrated by the simple radar equation commonly used in OTH radar analysis, which is where R = range Pa, = average power G, = transmitting antenna gain (14.22)530INTRODUCTION TORADAR SYSTEMS sameasthoseofinterest tomicrowave radarandinclude aircraft, missiles, andships.In addition, thelongwavelengths characteristic ofHFradaralsoprovidedistinctive information regarding thesea,aswellasaurora, meteors, andlandfeatures. (Although theHFhandis officially defined asextending from3to30MHz,forradarusagethelowerfrequency limit mightliejustabovethebroadcast band,andtheupperlimitcanextendto40MHzormore.) Theabilitytoseeatargetatlongrangebymeansofionospheric refraction depends onthe natureoftheionosphere (thedensityofelectron concentration) andtheradarfrequency, as wellasthenormalparameters thatenterintotheradarrangeequation. |
BOARD PHASED ARRAYS FACTORY CALIBRATION IS USUALLY PERFORMED USING A PLANAR NEAR |
Thus ifzisthe size oftheclutter atthe. SEC. 16.8] RECEIVER CHARACTERISTICS 647 input ofthereceiver, thetotal increment inamplitude can bewritten as Ax=kx+N, where kzistheamplitude component oftheclutter fluctuation and Nis thecomponent ofthei-fnoise vector inthedirection ofx. |
Ferrite Phasers and Ferrite MIC' Corn- ponents," Artech House, Inc., Dedham, Mass., 1974. (A collection of reprints of papers covering toroidal waveguide phase shifters, dual-mode phase shifters. Reggia-Spencer phase shifters, other novel ferrite phaser configurations, and ferrite rnicro- wave integrated components.) 34. |
E. Nathanson, Radar Design Principles , New York: McGraw-Hill Book Company, 1969, p. 37. |
TURE n &OR A CONTINUOUS APERTURE THE FAR |
Analogously to the implementation of the cell-averaging CFAR processor, the ampli - tude x(i) can be obtained using a linear, square-law, or logarithmic detector. The loss in detectability due to the clutter map is analogous to the CFAR loss ana - lyzed in the literature for many different conditions. An analysis of the clutter map loss for single-hit detection using a square-law detector has been presented by Nitzberg.44 These and other results can be summarized into a single universal curve of clutter map loss, LCM, as a function of the clutter map ratio x/Leff, as shown in Figure 2.90, where x defines the required false-alarm probability according to Pf = 10−x and Leff is the effective number of past observations averaged in the clutter map defined as Leff=−2α α (2.63) For example, for Pf = 10−5 and a = 0.125, the clutter map loss is LCM = 1.8 dB since x = 5 and Leff = 15 for this case. |
ÓΰÎÈ 2!$!2 (!.$"//+ 4 0 +OCHANSKI - * 6ANDERHILL *6 :OLOTAREVSKY AND 4 &ARISS h,OW ILLUMINATION ANGLE BISTATIC SEA CLUTTER MEASUREMENTS AT 8 |
The screen properties ofimportance inthis connection arethe type ofdecay and themanner inwhich thelight intensity “builds up” under successive excitations. Toexamine their effects, consider first ascan which issoslow that either the limitations ofachievable persistence or therequirements offreedom from display confusion due totarget motion prevent appreciable storage ofinformation from one scan tothe next. Insuch acase, the averaging must bedone over asingle pulse group. |
Lin, H. Fang, E. Im, and U. |
This permits switching times of the order of microsecollds. Wticreas hysteresis was a nuisance to be tolerated in the Reggia-Spencer device, the latching phase shifter takes advantage of the hysteresis loop to produce the two discrete values of phase shift without the need for continuoi~s drive power. The toroid phase shifter is tiotirc~ciproc.rr1 in that the phase shift depends on the direction of propagation. |
PENSATE FOR LINEAR GAIN AND PHASE DEVIATIONS HOWEVER AS FOR THE CASE OF THE ,.! NONLINEARITIES DESCRIBED ABOVE COMPENSATION FOR NONLINEAR CHARACTERISTICS IS EITHER IMPRACTICAL OR IMPOSSIBLE WHEN THE CAUSE OF THE NONLINEAR DISTORTION IS OUTSIDE THE DIGITIZED BANDWIDTH %VALUATION ! THOROUGH EVALUATION OF ALL ELEMENTS OF THE RECEIVER IS NEC |
I. Skolnik (ed.), McGraw-Hill Book Co., N.Y., 1970. 64. |
ANTENNA SYSTEMS BECAUSE OF INTERNAL REFLECTIONS AND LEAKAGE THROUGH THE CIRCULATOR &IGURE SHOWS THE KIND OF SYSTEM THAT MAY BE USED TO MEASURE SCATTERING FROM WITHIN A VOLUME "Y DETERMINING THE SPECTRUM OF THE RETURN THE USER CAN ESTABLISH THE SCATTERING FROM DIFFERENT RANGES 4HIS SYSTEM HAS BEEN USED IN DETERMINING THE SOURCES OF SCATTER IN VEGETATION n AND SNOW 5LTRASONIC WAVES IN WATER CAN BE USED TO SIMULATE ELECTROMAGNETIC WAVES IN AIRn "ECAUSE OF THE DIFFERENCE IN VELOCITY OF PROPAGATION AN ACOUSTIC FREQUENCY OF -(Z CORRESPONDS WITH A WAVELENGTH OF MM 3UCH A WAVELENGTH IS OF A CONVENIENT SIZE FOR MANY MODELING MEASUREMENTS AND OF COURSE EQUIPMENT IN THE |
BASED 3!2 SYS |
23.23 Multiple Radar s ................................................. 23.24 Rapid Scanning ................................................. 23.25 Airborne and Space-Borne Radars .................... |
DAMENTAL TO THE CONSTRUCTION AND CIVIL ENGINEERING INDUSTRIES THE POLICE AND FORENSIC SECTORS SECURITYINTELLIGENCE FORCES AND ARCHAEOLOGICAL SURVEYS '02 HAS BEEN VERY SUCCESSFULLY USED IN FORENSIC INVESTIGATIONS 4HE MOST NOTORI |
vanKasteren, Ground-based X-band Radar Backscatter Measurements of Wheat, Barley and Oats , Wageningen NETHERLANDS: Center for Agrobiological Research, 1989. 130. B. |
2.1. We shall try, where possible, tomodify the radar equation tosuit the new circumstances, but itwill beour broader purpose todescribe, ifonly qualitatively, certain propagation phenomena peculiar tothemicrowave region, This isavast subject. Itincludes some exceedingly difficult problems inmathematical physics, notyetcompletely solved; itincludes topics inmeteorology; above all,since itinvolves the weather and the variegated features oflandscape and seascape never susceptible ofexact mathematical description, itincludes alarge collection ofobservations and experience, rarely easy tointerpret. |
Barton, Norwood, MA: Artech House, 1987. 17. R. |
73, pp. 312-324, February 1985. 10. |
The logical extension from acoustic to electromagnetic methodology is a small step in comparison. ch18.indd 59 12/19/07 5:15:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. |
BASED RADARS FOR EXAMPLE 7 COMPARED TO K7 THE SPECTRUM INTERFERENCE LEVELS ARE MUCH REDUCED AND THEREFORE EXTENDED USE OF THIS TECHNOLOGY COULD RESULT IN BETTER USE OF THE 2& SPECTRUM !LSO THE HIGHLY CONTROLLED WAVEFORMS ARE EXPECTED TO CREATE LESS SPECTRAL NOISE THAN TYPICAL MAGNETRON |
SIDEBAND PHASE |
Matlt. Comp .. vol. |
BATIONS IN THE OCEANS MEAN SURFACE DUE TO SPATIAL VARIATIONS IN THE %ARTHS GRAVITY 4HE ORBIT SHOULD NOT REPEAT FOR ^ YEARS TO YIELD AN AVERAGE GROUND TRACK SPAC |
24.2 TERMINOLOGY EW is defined as a military action involving the use of EM energy to determine, exploit, reduce, or prevent radar use of the EM spectrum.8–11 The operational employ - ment of EW relies upon the capture of radar EM emissions using electronic intelli - gence (ELINT) devices, collating the information in support databases that are then used to interpret EM emission data, to understand the radar system functions, and to program reactions against the radar. EW is organized into two major categories: electronic warfare support measures (ESM) and ECM. Basically, the EW community takes as its job the degradation of radar capability. |
- - - - - . - - - - - - . (4n)'R ' Thus the echo from surface clutter varies inversely as the cube of the rang$ ratllcr than inversely as the fourth power as is the case for point targets. |
Thedynamic rangeofaradardisplay,whether PPI orA-scope, isfarlessthantherangeofecho-signal amplitudes thatcanbeexpected from clutter.Itisnecessary, therefore, tokeepthelargeclutterechoesfromsaturating thedisplay andpreventing thedetection ofwantedtargets.Echoesfromthevarioussourcesofclutter experienced byacivil-marine radarmightbe80dBgreaterthanreceivernoise.yetthereceiver mightonlybeabletodisplaywithoutsaturation signalsthatarelessthanabout20to25dB abovenoise.22Sensitivity timecontrol(STC),orsweptgain,iswidelyusedtoreducethe largeechoesfromclose-inclutter.STCisatimevariation ofthereceiver gain.Atth~endof thetransmission oftheradarpulsethereceiver gainismadelowsothatlargesignalsfrom nearbyclutterareattenuated. Echoesfromnearbytargetswillalsobeattenuated; butbecause oftheinversefourth-power variation ofsignalpowerwithrange,theywillusuallybelarge enoughtoexceedthethreshold andbedetected. Thereceivergainincreases withtimeuntil maximum sensitivity isobtained atrangesbeyondwhichclutterechoesareexpected. |
296-297 Fraunhofer region, antenna, 229 Frequency agility: ECCM, 548 for glint reduction, 170- 172 and sea echo, 485 Frequency diversity, 548 Frequency measurement accuracy, 407-408 Frequency modulated CW radar, 81-92 Frequency-scan arrays, 298-305 Frequency-scan radar. and pulse compression. 433 Fresnel region, antenna, 229 Fresnel zone plate, 523, 527 Gain. |
Patent no. 3,916,416. Oct. |
J. Spafford, “Optimum radar signal processing in clutter,” IEEE Trans. Information Theory , vol. |
A more threatening ECM against tracking radars is DECM. These threats require considerably less energy than noise jamming (a feature particularly important on tacti - cal aircraft, where available space is limited). Nevertheless, they are very effective in capturing and deceiving the range gate (with the RGPO technique), the velocity gate (with the VGPO technique), and the angle-tracking circuits. |
2.27b). The pencil beam is axially symmetric, or nearly so. Beamwidths of typical pencil-beam antennas may be of the order of a few degrees or less. |
PROPAGATION OF RADAR WAVES 453 Elcrntcd ducts. i\n example of propagation in elevated ducts is found in the "tradewin<l region" between the midoccan. high-pressure cells and the equatorial doldrums. |
# &' " . ££°Îä 2!$!2 (!.$"//+ DESIGNER IN ORDER TO SATISFY THE 2& ELECTRICAL DC ELECTRICAL THERMAL AND RELIABILITY REQUIREMENTS 0ACKAGING OF --)# COMPONENTS INTO THE 42 MODULE MUST TAKE INTO CONSIDERATION MULTIPLE ELEMENTS AS THEY IMPACT THE ELECTRICAL PERFORMANCE 0OWER #ONDITIONING #ONSIDERATIONS 0ULSED TRANSMIT AMPLIFIERS CAN CONSUME VERY HIGH DC CURRENTS AND SPECIAL DESIGN ATTENTION MUST BE PAID TO PARASITIC INDUC |
MENTS REPORTED BY DIFFERENT INVESTIGATORS FOR EXACTLY THE SAME SET OF PARAMETERS 4HIS IS SEEN CLEARLY IN &IGURE A AND B WHICH COMPARES THE GRAZING |
Trunk The Johns Hopkins University Applied Physics Laboratory 7.1 INTRODUCTION As digital processing has increased in speed and digital hardware has decreased in cost and size, radars have become more and more automated, so that automatic detection and tracking (ADT) systems are associated with almost all but the simplest of radars. In this chapter, automatic detection, automatic tracking, and sensor integration techniques for surveillance radars are discussed. Included in the discussion are vari - ous noncoherent integrators that provide target enhancement, thresholding techniques for false alarms and target suppression, and algorithms for estimating target position and resolving targets. |
The problem isespecially acute onthe slower scans, partly because ofthe long time “between excitations and partly because the cascade screens areless efficient than those with less persistence. Inintensity-modulated displays thecharacteristics ofthescreen have important effects onthe signal-to-noise discernibility y. As has been pointed outinChap. |
The ground reflectivity has been assumed equal to the target reflectivity (this is quite a pessimistic assumption, because in many cases of practical interest, the target reflectivity is higher). A receiver thermal noise, 40 dB below the target return, has also been summed to the received signal. The ground echo is first can - celed, by using a two-element antenna and two time samples. |
By using the proposed method, we not only increase the number of images, but we can also retain the important information of the images. Some noise is still in the background, but concerning SAR images, that noise of the sea surface can be accepted. Because of the characteristics of SAR images, the angle of pictures may cause a lot of difference in CNN training than simple transposition. |
MONOPULSE RECEIVERS ARE DESCRIBED IN 3ECTION OF THE SECOND EDITION OF THIS HANDBOOK -ODERN RADAR SYSTEMS ARE MOSTLY DESIGNED TO MAXI |
Provide IF Limiters prior to A/D converters. MTI radars require that IF bandpass limiters exist prior to an A/D (analog/digital converter). The limiter prevents any clutter return from exceeding the dynamic range of the A/D. |
AMPLITUDE NOISE SOURCES CAN BE RESOLVED IF THEY ARE SEPARATED IN ANGLE BY K, IN RADIANS WHERE K IS THE WAVELENGTH AND , IS THE APERTURE LENGTH 7HEN THE INCIDENT WAVE IS RECEIVED WITH A HIGH *.2 AN ADAPTIVE ARRAY ANTENNA MAYIN PRINCIPLEACHIEVE A NARROWER ADAPTIVE BEAMWIDTH GIVING A SHARPER BEARING ESTIMATION OF THE INCIDENT WAVE )F ACCURATE STROBES OF THE JAM |
2. Human behavior is certainly less predictable than that of an electronic device. However, it appears that an operator's performance can be as good as that predicted for the ideal electronic threshold detector if the operator is well trained, motivated, alert, not fatigued, and the display is properly designed. |
HORIZON RADAR v #HAPTER IN 2ADAR (ANDBOOK - ) 3KOLNIK ED ND %D .EW 9ORK -C'RAW |
Another example is shown in Fig. 12.9. This is the small illuminated area for a narrow-beam, short-pulse system. |
60·61 The linearly polarized beam radiated by a ftat, two-dimensional array of spirals may be scanned by rotating the individual spiral antenna elements. One degree of mechanical rotation corresponds to a phase change of one electrical degree. No additional phase-shifting devices are required. |
Table 7.6gives the de finition for the Douglas sea states, usually used in radar. Much more discussion can be found in [ 6]. The minimum detectable signal is determined by the received signal, clutter and noise levels associated with a given target position in the radar beam, combined with Figure 7.4. |
AXIS CHARACTERISTICS OF THE PARABOLOIDAL REFLECTOR v .AVAL 2ES ,AB 2EPT ! 7 2UDGE AND . ! !DATIA h/FFSET PARABOLIC REFLECTOR ANTENNAS ! REVIEW v 0ROCEEDINGS )%%% VOL NO PP n $ECEMBER $ ' +IELSY h0ARABOLIC CYLINDER AERIALS v 7IRELESS %NG VOL PP n -ARCH 2 , &ANTE ET AL h! PARABOLIC CYLINDER ANTENNA WITH VERY LOW SIDELOBES v )%%% 4RANS VOL !0 |
Equation (2.27) is sometimes called the Rice probability-density function. The probability that the signal will be detected (which is the probability of detection) is the same as the probability that the enve]ope R will exceed the predetermined thresho]d VT. The . |
SIGNAL % FIELD IS ACCOMPLISHED INDEPENDENTLY OF THE DIFFERENCE |
One portion ofthetimer generates a square wave (Waveform b,Fig. 12”1)which performs this function and usually finds other applications within thetimer. Ifthedisplay includes arange sweep, asisnearly always thecase, the timer generates the waveform that ultimately produces it. |
fault location, data recording arid simulations; and the e.uecitrille nraiiagement of the radar by assigning priorities to the various tasks and how tliey should be performed so as to achieve a corilprotnise betweer1 tlie required radar actions and the resources available in the radar and cornputer. 111 addition, tlie computer provides the means whereby an operator can niani~ally intcr act with tlie radar Beam-steering computer. Although a single general-purpose cornputer can be used to perform all ttie computatiotis and control required for a phased-array radar, it is often desirable to utilize a separate, special-purpose computer for beam steering. |
/\teach range interval the detector integrates n pulses, where n is the number . 184 INTRODUCTION TO RADAR SYSTEMS of pulses expected to be returned from a target as the antenna scans past. The integrated pulses are compared with a threshold to indicate the presence or absence of a target. |
TUDE XI CAN BE OBTAINED USING A LINEAR SQUARE |
The course on which this book is based is a proven method for introducing the student to the subject of electronic systems. It integrates and applies the basic concepts found in the student's other courses and permits the inclusion of material important to the practice of electrical engineering not usually found in the traditional curriculum. Instructors of engineering courses like to use texts that contain a variety of problems that can be assigned to students. |
Lab. Rept. 7349, December 1971. |
2. Probabilistic Data Association (PDA) Another alternative is the probabilistic data association (PDA) algorithm62,63,64 where no attempt is made to assign tracks to detections, but instead, tracks are updated with all the nearby detections— weighted by the perceived probability of the track being the correct association. Because PDA relies on erroneous associations essentially “averaging out,” it is most effective when tracks are far enough apart that nearby detections originate from spatially random noise or clutter exclusively and when the tracking gains are small (i.e., when the tracking index gtrack is small). |
............. 7 SIGNAL MONITORING ................................ ................................ |