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The frequency forreception and that fortransmis- sion arenearly the same; they arenot identical because ofthe different voltages and transit times involved atthetwo clifferen tlevels ofoperation. Figure 8.10 shows two readily realizable cycles ofvariation offrequency. SEC.87] INTERR~A TIONCODES 263 with time. |
J. A.: Large Radomes, chap. 5 of" Microwave Scanning Antennas, vol. |
However, in systems with large bandwidths (short compressed pulses), the timing jitter require - ments become significant and may require special clock regeneration circuitry at key system locations. Effect of Quantization Noise on Improvement Factor. Quantization noise, introduced in the A/D converter, limits the attainable MTI improvement factor. |
Steunou, E. Caubet, L. Phalippou, L. |
E 20 - 10 -Sparse woods Wooded hills 10 knots Wooded hills Seo echo Rain 40 knots Chaff 0'------'---'---'--'-_._~~---~~~~_._~~~--~-~--'--~~~ 0 001 01 1·0 10 c,11 = rms velocity spread, mis Figure 4.30 Plot of double-canceler clutter improvement factor [Eq. (4.26)] as a function of uv = rms velocity spread of the clutter. Parameter is the product of the pulse repetition frequency (/p) and the radar wavelength (,l). |
WIDTH WHICH IS P 4HE 3. IS THE VALUE AT THE CENTER OF THE BEAM AFTER 0 3WERLING Ú )%%% . |
Scan, conical) Connectors coaxial-line, 396 type N,397 Contrast ofPPI display (see PPI dis- plays, contrast of) Control (see Speed; Voltage; etc.) Controllers, 235 Corner reflector, 67 Cosecant-squared antenna (see Antenna, cosecant-squared) Counter, V.A.,80 Coupling, for coaxial line (see. Line, ‘coa;ial, coupling for) waveguide (see Waveguide, choke coupling for) Coverage, high, 50 low, 50 Coverage diagram, 54 Crest factor, 557 Cross section, ofaircraft, 76 experimental, 78 corner reflector, 67 cylinder, 66 effective receiving, 20 flatsheet, 65 propeller modulation of,76 radar, 21,63 scattering, ,21 from sphere, 64 segment ofsphere, 66 ofships, 80 CRT (seeCathode-ray tube) Crystal, converter-type, specifications of, 414 formixer, 412-414 noise temperature of,413 C-scope, 173 Cutparaboloid, 272 C-wradar systems (SeealsoRadar system, c-w) CXAM, 180 Cylindrical reflector, 276. 740 RADAR SYSTEM ENGINEERING D Dark-trace screens, 483 Dark-trace tube, 22o Data stabilization, 311–312 Data tramsmiesion, 283 potentiometers for, 487 variable condensers for, 489 variable transformers for, 487 autosyns, 487 resolvers, 487 selsyns, 487 synchros, 487 Data transmitter, angle, 48&492 D-creetorer, 503 Deck-tilt error (see Error, deck-tilt) Decoder, triple-pulse, 687 Delay line, characteristic impedance of, 671 folded mercury, 668 fused quartz, 669 laboratory type of,633 liquid, 667-669 mercury, design constants for, 670 supersonic, 667–672 Delay-line attenuation, 670 Delay-line circuits, 634 Delay-line driving circuits, 672 Delay-line end cells, 669 Delay-line signal circuits, 672-675 Delay-line trigger circuits, 67$677 degenerative, 675 regenerative, 676 Delaytank,liquid,669 Detection, aural,134 Detector, balanced, forMTI,666 second, 449 Dicke, R.H.,32 Diffraction cr08s8ecti0n, 69 DMraction phenomena atmedium wave- length, 715 Diode, biased, 504 charging, 383 Diode limiters, 504 Display, double-dot, 174 one-dimensional, 164–167 three-dimensional, 174175 two-dimensional, 167–174 pip-matching, 167 sector, 168 (See abo Indicator)Doppler effect, 125, 629 Doppler frequency, 128 Doppler system, bandwidth of,135 pulsed, 630 pulse-modulated, 150-157 range-measuring, 139-143 simple, 132–139 Double-dot display (see Display, double- dot) Double-tuned circuit, 446 DuBridge, L.A., 16 Duct, 56-58 Dueppel, 82 Duplexing, 407411 Dynamotors, 57%581 booster armature voltage regulation of, 560 dual-output, 579 triple-output, 579 E Eagle (see AN/APQ-7 scanner) Eccles, W.H., 497 lIkcles-Jordan circuit, 497 Echo, from rain, 81 fluctuations of,83 reduction of,84 second time around, 117 from storm, 81 Eclipse, 559, 574 Effective height, ofship target, 80 Eicor Inc., 579 Eighth-power region, 51 Electromagnetic energy storage, 356 Electronic efficiency, ofmagnetron, 345 Electronic switches, 503–510 Electrostatic deflection ofbeam ofCRT (see Cathode-ray tube, electrostatic deflection of) Electrostatic energy storage, 356 Electrostatic focusing of CRT (see Cathode-ray tube, electrostatic fo- cusing of) Elsey, Howard M., 561 Emslie, A.G., 640, 645 Error, deck-tilt, 309 inaircraft, 311 E-scope, 173 Evans Signal Laboratory, 17. |
If the periods of the staggered waveforms have the relationship nl /TI = n2 /& = . = nN/TN, wherenl,n2, ..., n~ are integers, and if UB is equal to the first blind speed of a nonstaggered waveform with a MTJANDPULSE DOPPLER RADAR115 w1.0 V160.8- 0. ~0.6 .~0.4 0 di0.2n: 03/T, 4/T, 0 liT, 21T, rrequellcy (a) lO-w <I>6 0.8- 0. |
The use of a three-pulse canceler ahead of the fi1ter:bank eliminates stationary clutter and thereby reduces the dynamic range required 8 -pulse doppler Weighting filler bank and magnitude Zero velocity Clutter mop filter Mogni t ude .recursive filter Figure 427 Simple block diagram of the Moving Target Detector (MTD) signal processor. MTIANDPULSEDOPPLER RADAR127 4.7EXAMPLE OFANMTIRADAR PROCESSOR TheMovingTargetDetector (MTD)isanMTIradarprocessor originally developed bythe MITLincolnLahoratory fortheFAA'sAirportSurveillance Radars(ASR).42-44 TheASRisa medium range(60nmi)radarlocatedatmostmajorUnitedStatesairports.Itoperates atS band(2.7--2.9GHz)withapulsewidthoflessthan1ps,a1.4°azimuth beamwidth, anantenna rotation ratcoffrom12.5to15rpmdepending onthemodel,aprffrom700to1200Hz (1030Hztypical),andanaveragepoweroffrom400to600W.TheMTDprocessor employs severaltechniques fortheincreased detection ofmovingtargetsinclutier.Itsimplementation isbasedontheapplication ofdigitaltechnology. Itutilizesathree~pulse canceler followed by an8-pulseFFTdoppler filter-bank withweighting inthefrequency domaintoreducethefilter sidelobes, alternate prrstoeliminate blindspeeds,adaptive thresholds, andacluttermapthat isusedindetecting crossing targetswithzeroradialvelocity. |
The sampled spectra of the two portions of the signal do not over - lap; the sampled signal is not aliased. As will be described in more detail later in the chapter, this technique, bandpass sampling, is a powerful tool that allows a relatively high-frequency signal to be sampled by a relatively low-performance digitizer, which can result in considerable cost savings. Figure 25.6 a shows the spectrum of a more general complex signal of bandwidth B before sampling. |
73–78, July 1965. 14. A. |
SPEED APPLICATIONS THAN ))2 FILTERS WHICH TYPICALLY REQUIRE THE COMPU |
A proper blanking logic allows this signal to pass. Targets and/or jammers J situated in the sidelobes give small main but large auxiliary signals so that these targets are suppressed by the blanking logic. It is assumed that the gain GA of the auxiliary antenna is higher than the maximum gain Gsl of the sidelobes of the radar antenna. |
1957. 19. Ala kc. |
Howard, and A. M. King: Phenomena of Scintillation Noise in Radar Tracking Systems. |
ERATE TRANSMISSION OR RETRANSMISSION OF AMPLITUDE FREQUENCY PHASE OR OTHERWISE MODULATED INTERMITTENT #7 OR NOISE |
Headrick. R. W. |
(A further description as to why the log-FTC receiver is CF AR when the input is Rayleigh clutter is given m Sec. 13.8.) . 488 INTRODUCTION TO RADAR SYSTEMS Sea clutter has a Rayleigh pdf when the resolution is low. |
Equipment essentially like that just described has had agreat deal ofuse and initsfinal form has proved satisfactory. Anentire system using this method isdescribed inSec. 17.16. |
ING THE EFFECT OF THE SURFACE REFLECTION 4HE NONCOHERENT VOLUME RETURN IS IRREDUCIBLE HOWEVER AND IS NOT INFLUENCED BY THE ORIENTATION OF THE COLUMN 4HE VOLUME RETURN OF SUITABLE FOAM COLUMN SUPPORT MATERIALS IS OF THE ORDER OF r |
Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 24.2 RADAR HANDBOOK 6x9 Handbook / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The chapter ends with an approach to the problem of evaluating the efficacy of ECCM and ECM techniques (Section 24.12). There is a lack of theory to properly quan - tify the endless battle between ECCM and ECM techniques. |
POINTING COMPUTATIONS ELECTRONIC DRIVERS AND PHASE SHIFTERS OR SWITCHES AND ALL THEIR INTERCONNECTIONS &REQUENT INDICATIONS THAT THE ANTENNA SYS |
The lag error, in this case, is dependent on many factors, including the accuracy of the value of angle sensitivity used to convert error voltages to angular error, the size of the previous tracking error, and the time interval between looks. FIGURE 9.15 (a) Closed-loop frequency-response characteristics of two servosystems and ( b) their corresponding time response to a step input ch09.indd 19 12/15/07 6:07:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. |
tures the range-tracking circuits. The deception signal is then progressively de- layed in the jammer by using an RF memory, thereby "walking" the range gate off the actual target (range-gate pull-off, or RGPO, technique). When the range gate is sufficiently removed from the actual target, the deception jammer is turned off, forcing the tracking radar into a target reacquisition mode.12 Another DECM technique is called inverse-gain jamming; it is used to capture the angle-tracking circuits of a conical-scan tracking radar.8 This technique re- peats a replica of the received signal with an induced amplitude modulation which is the inverse of the victim radar's combined transmitting and receiving antenna scan patterns. |
f- transmitter Tirn~ng signal r J. Average Range frequency --+ counter fo( l -flF Sidebond filter fo(tI -/I~ Figure 3.13 Block diagram of FM-CW radar using sideband superheterodyne receiver. ,/if:. |
Rutledge, N. Cheng, R. York, R. |
Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.10 RADAR HANDBOOK 6x9 Handbook / Radar Handbook / Skolnik / 148547-3 / Chapter 13 power, the vector sum of their contributions, added at a great distance as a function of q, is the radiation pattern E e eaj s j s( ) [( / )(/ )sin ( / (( /)siqq= +− 1 22 2 2 2 π λ π λ n n]q where q is measured from the broadside direction. Normalizing, to get unity ampli - tude when q = 0, and simplifying give Es a( ) cos s in q q = πλ (13.1) The absolute value of Ea (q ) is plotted in Figure 13.4 as a function of p (s/l) sin q. |
has had wide application. Historically, the early radar experimenters worked almost exclusively with continuous rather than pulsed transmissions (Sec. 1.5). |
10.10 RADAR HANDBOOK 6x9 Handbook / Radar Handbook / Skolnik / 148547-3 / Chapter 10 If a TWT using a coupled-cavity circuit is cathode-pulsed (Section 10.7), there is an instant during the rise and fall of voltage when the beam velocity becomes synchro - nous with the cutoff frequency (the so-called p mode) of the microwave circuit, and the tube can generate oscillations. These oscillations at the leading and trailing edges of the RF output pulse have a characteristic appearance on a power-time presentation that has given them the name rabbit ears . Only in rare cases has it been possible to sup - press these oscillations completely. |
The parabola is well suited for microwave antennas because (I) any ray from the focus is reflected in a direction parallel to the axis of the paraboia atid (2) the distance traveled by any ray from the focus to the parabola and by reflection to a plane perpendicular to the parabola axis is independent of its path. Therefore a point source of energy located at the focus is converted into a plane wavefront of uniform phase. The basic parabolic contour has been used in a variety of configurations. |
Figure 15.3 shows thefindings ofamore recent (July 1945) survey covering 10-cm ship radars; itindi- cates that there had been nochange forthebetter. Such serious deficiencies inactual field radar performance emphasize the fact that the use oftest equipment tomeasure performance and to trace down thecauses ofimpaired performance had notbeen incorporated into routine maintenance practice formost radar sets atthe end ofthe 01Lo 10 20 30 40 Oedels below ratedperformance?%6* z ~4 2 22 0k o 10 20 30 40 Oeabels below rated performance FIG. 15.2.—Radar performance surveys, FIG. |
arid scan time is a constant. Eq. (2.57). |
Footnotes within Chapter V of SOLAS identify the recommended IMO perfor - mance standards with which the equipment should conform. IMO has had recom - mended radar performance standards2 since 1971, published as annexes to IMO Resolutions. However, by 1980, radar manufacturers were reporting difficulties because differing interpretations by national maritime administrations meant that radars had to be specifically designed to meet individual flag State requirements. |
P. D. Spudis, C. |
FIELD COMPONENTS PARALLEL AND PERPENDICULAR TO THE PLANE OF SCATTERING IN TERMS OF THE COMPONENTS OF THE INCI |
withinthelimitsoftheantenna coverage. The monostatic-radar signalincreases quiterapidlyasthetargetapproaches theradarbecauseof theinverserelationship between theechosignalPrandR4[Eq.(14.35)]. Thebistaticradar signalalso.increases aseitherendofthefenceisapproached sincetheechosignalisinversely proportiollal toDfD;[Eq.(14.36)]. |
468-480, April, 1969. 106. Konrad, T. |
Kim, “Remote sensing by radar,” in Wiley Encyclopedia of Electrical and Electronics Engineering Online , J. Webster (ed.), New York: John Wiley & Sons, Inc., 1999. 166. |
The factor F P includes the energy loss along the ionospheric path, the mismatch loss due to a change in polarization caused by the ionosphere, ionospheric focusing gain or loss, and losses due to the dynamic nature of the path.22•23 The receiver noise N0 includes the ambient noise radiated by natural sources (chiefly lightning discharges from around the world) as well as the combined interference from the many users of the HF band. It is the latter ,vhich generally determines system sensitivity at HF. The processing ·time T.: is included to emphasize that an 0TH radar is usually a doppler-processing radar that requires a dwell time of T, seconds if a frequency resolution of 1/T.: hertz is to be achieved. |
ÊÊ - 976 |
§S PULSE WITH PEAK POWER OF K7 TO PROVIDE A SINGLE |
Kerr, D. E. (ed.):" Propagation of Short Radio Waves," MIT Radiation Laboratory Series, vol. |
SEC. 13.20] RESOLUTION ANDCONTRAST 549 betaken as180. On arange sweep oflength Rnautical miles, the number ofradar pulse lengths resolvable inprinciple is12.2R/T, where 7 isthe pulse length inmicroseconds. |
ÓÈ°£{ 2!$!2 (!.$"//+ FROM THE %ARTHS SURFACE AND THE ATMOSPHERE IE FREE SPACE &REE SPACE IS DEFINED AS A REGION WHOSE PROPERTIES ARE ISOTROPIC HOMOGENEOUS AND LOSS |
This loss in integration efficiency is caused by the nonlinear action of the second detector, which converts some of the signal energy to noise energy in the rectification process. (2.30)THERADAR EQUATION 29 change insignal-to-noise ratioismuchgreaterthanthisforagivenchangeindetection probahility, asdiscusscd inSec.2.8.)/\lso,thesignal-to-noise ratiorequired fordetection is notasensitive function ofthefalse-alarm time.Forexample, aradarwithaI-MHzbandwidth requires asignal-to-noise ratioof14.7dBfora0.90probability ofdetection andaIS-min false-alarm limc.IfIhcfalsc-alarm limewereincreased fromISminto24h,thesignal-to-noise ratiowouldheincreascd to15.4dB.Ifthefalse-alarm timewereashighasIyear,therequired signal-tn-lloise ratiowouldhe16.2dB. 2.6INTEGRATION OFRADAR PULSES Therclatiollship hetwecn thesiglwl-to-IJOisc ratio,theprobability ofdetection, andtheproh abilitynffalsealarmasgivclIinFig.2.7appliesforasinglepulscQnly. |
thelosses incurred inpropagating millimeter wavelengths through fog,haze,andsmokeislessthanat infrared orvisiblewavelengths. Another example whereaparticular property ofmillimeter-wave radarhasbothfavor ableandunfavorable aspectsisthatofthedoppler frequency shift.ItwasshowninSec.3.1 thatthedoppler frequency shiftwasproportional tathecarrier(rf)frequency. Thisresultsin moreaccurate relative-velocity measurements withmillimeter wavelengths thanatlower frequencies. |
HOP PROPAGATION CAN REACH GREATER RANGES &)'52% 4HE VARIATION OF THE MONTHLY MEDIAN SUNSPOT NUMBER SINCE THE YEAR OF THE FIRST OPERA |
K-SVD: An Algorithm for Designing Overcomplete Dictionaries for Sparse Representation. IEEE T rans. Signal Process. |
In the real data scenario, the rheological parameters of a stretch of highway (namely, the Lungui Highway in Foshan, China) are obtained, and the time-series subsidence over the period of June 2014 to December 2015 is investigated using TerraSAR X imagery. 2. Time-Series Modeling Considering Rheological Parameters2.1. |
vol.10.pp.RR-95.February. 1978.SeealsosametitleandauthorinIEEEEASCON '76 Record, pp.30-Ato30-H. 96.Trunk.G.V..andJ.D.Wilson: TrackInitiation inaDenseDetection Environment, NavalResearch Lanoratory (Washington. |
If the radar frequency were 10 GHz, PRF 1 kHz, and ground speed 580 kt, the notch would have to be held within 0.29 kt or 0.005 Vg. Because of these requirements and the width of the platform-motion spectrum, stag - ger PRF systems must be chosen primarily on the basis of maintaining the stopband rather than flattening the passband. Similarly, higher-order delay-line filters (with or without feedback) are synthesized on the basis of stopband rejection. |
10.5 SAW transducer types, (a) Dispersive output, (b) Both input and output dispersive, (c) Dispersive reflections. traverse the crystal length. Figure 10.5c shows a reflection-array-compression (RAC) approach10 which essentially doubles the achievable pulse length for the same crystal length. |
Itisthen possible touselonger persistence without blurring. However, since observation ofthefrozen display is usually part ofthe“tracking” operation which controls theremoval ofthemotion, thepersistence must notbesolong thatitreduces theeaseofdetecting small changes intarget position.. SEC. |
The rms noise power at the output is smaller than the peak power from a point target by the factor BT. A detection threshold is set somewhere within this range of possible amplitude to allow point targets that are larger than the background to be detected. This dispersive CFAR may be placed either before or after the matched Alter. |
FERING ONLY BY LESS THAN D" OVER WIDE RANGES OF 0$ 0FA AND N L "ECAUSE THE SIGNAL RETURN OF A SCANNING RADAR IS MODULATED BY THE ANTENNA PATTERN TO MAXIMIZE THE 3. WHEN INTEGRATING A LARGE NUMBER OF PULSES WITH NO WEIGHTING IE !I ONLY OF THE PULSES BETWEEN THE HALF |
#OUNTERMEASURES .ORWOOD -! !RTECH (OUSE )NC 3PECIAL )SSUE ON ELECTRONIC WARFARE )%% 0ROC VOL PT & NO PP n *UNE 7 ! $AVIS h0RINCIPLES OF ELECTRONIC WARFARE 2ADAR AND %7 v -ICROWAVE * VOL PP n n &EBRUARY , " 6AN "RUNT 4HE 'LOSSARY OF %LECTRONIC 7ARFARE $UNN ,ORING 6! %7 %NGINEERING )NC $EPARTMENT OF $EFENSE *OINT #HIEFS OF 3TAFF $ICTIONARY OF -ILITARY AND !SSOCIATED 4ERMS *#3 0UB |
D" WITH A PROBABILITY OF DETERMINE THE REQUIRED PROBABILITY ON ANY ONE GIVEN SIDELOBE 0 ; SIDELOBES D"= 4HEN |
SPECIFIC CONSTRAINTS ON FREQUENCY IN ADDITION TO PROPAGATION CON |
showed slant range. On H 2S Mk. II and ASV Mk. |
Decker, J. J. Sojka, and R. |
ch20.indd 62 12/20/07 1:17:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. |
Detailed Design ofthe AN/APS-10.-With these major design decisions taken, thedetailed components design oftheAN/APS-10 remained. No attempt will bemade todiscuss the many interacting decisions that determined the design ofthe components ofthe set; FIG,159.-Units ofAN/APS-10. only thefinal result will bepresented, and anattempt made torationalize itinterms ofthe considerations ofSec. |
SHIFTER CONFIGURATIONS AFTER , 3TARK ET AL A SWITCHED |
The A/D converter has been, in the past, one of the critical parts of the MTI signal processor. It must operate at a speed high enough to preserve the information content of the radar signal, and the number of bits into which it quantizes the signal must be sufficient for the precision required. The number of bits in the AID converter determines the maximum inl- provement factor the MTI radar can achie~e.~.~~.'~ Generally the AID converter is designed to cover the peak excursion of the phase detector output. |
The angle-error detector, assumed to be a product detector, has an output ld = *!icose where \e\ is the magnitude of the angle error voltage. Phases are adjusted to pro- vide O or 180° on a point-source target. The resultant is "l= ±4il Complex targets can cause other phase relations as a part of the angle scintilla- tion phenomenon.3 The above error voltage proportional to the ratio of the dif- ference signal divided by the sum signal is the desired angle-error-detector out- put, giving a constant angle error sensitivity.3 With limited AGC bandwidth, some rapid signal fluctuations modulate \e\9 but the long-time-average angle sensitivity is constant. |
TO |
P. McGarty, “Maximum-likelihood detection of unresolved targets and multipath,” IEEE Trans ., vol. AES-10, pp. |
OF |
If the compression rate is high, the consistency is more obvious. However, by applying the proposed approach, reconstruction is performed through multi-channel joint sparsity, so as to ensure that the scattering points are at the same pixel of the images from different channels, which is more favorable for extraction of target height information. T able 5. |
Angle noise causes a change with time in the apparent location of the target with respect to a reference point on the target. This reference point is usually chosen as the center of “gravity ” of the reflectivity distribution along the target coordinate of interest. The center of gravity is the long-time-averaged track - ing angle on a target. |
MAP MODE 4HE RESULT IS LARGER DOPPLER BANDWIDTH HENCE ENHANCED AZIMUTH RESOLU |
TION HAS ITS OWN UNIQUE IMPLICATIONS FOR SYSTEM DESIGN 4HE HIGHLIGHTS ARE REVIEWED IN THE FOLLOWING PARAGRAPHS 3EA |
PS-32, pp. 1109–1118, June 2004. 12. |
( / ) Ai i (16.23 b) where Ai and qi are constants that differ for the near-vertical and midrange regions. Figure 16.23 shows an example of this variation. No theory gives exactly this result, ch16.indd 29 12/19/07 4:55:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. |
Under these assumptions a reduction of up to 20 dB can be achieved. The creation of a stealth object with materials adapted to the free -space wave- impedance, according to Equation (11.26), offers no advantages for loss- less materials, since only the phase velocity in the mat e- rial is lowered. Additionally would the material still have to absorb, since otherwise a refle c- tion takes place on the other side. |