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Similarly, Cases 2 to 4 show conditions where the target's speed is 0.8, 0.6, and 0.4 times the radar's speed, in which case the target can be seen clear of sidelobe clutter over a region of up to ±78.5° relative to the target's velocity vector. Again, these conditions are for an assumed collision course. As is evident, the aspect angle of the target clear of sidelobe clutter is always forward of the beam aspect. |
Special-Purpose Reflectors. Several types of antennas are occasionally used for special purposes. One such antenna is the spherical reflector,34 which can be scanned over very wide angles with a small but fixed phase error known as spherical aberration. |
Remote Sens. 2016 ,8, 350. [CrossRef ] 42. |
, |
62. D. K. |
TheknownHarkercodesareshowninTable11.2.Thelongestisoflength13.Thisisa relatively lowvalueforapractical pulse-compression waveform. Whenalargerpulse compression ratioisdesired. someformofpseudorandom codeisusuallyused.Apopular technique isthegeneration ofalinearrecursive sequence usingashiftregisterwithfeedback. |
111. J. Worms, “Monopulse estimation and SLC configurations,” Proc. |
852-855, August, 1949. 52. Ruze, J.: Wide-angle Metal-plate Optics, Proc. |
The excess noise temperature is generally less than 50 K. 40 · Receiver protectors. Since the keep-alive in the TR is not usually energized when the radar is turned off, considerably more power is needed to break down the TR than when it is energized. |
RANGE PERFORMANCE IT TRANSMITS A FRAME OF PULSES WITH DIFFERING LENGTHS %ACH PULSE WITHIN THE FRAME IS OPTIMIZED TO COVER A SPECIFIED RANGE BRACKET /VERALL THE PULSE SEQUENCE COMPLETELY COVERS THE INSTRUMENTED RANGE AND ENSURES THAT THE )-/ SPECIFIED MINIMUM RANGE REQUIREMENT IS MET )N THE RECEIVER FRAMES ARE GROUPED INTO BLOCKS CALLED BURSTS 4HE DURATION OF A BURST IS APPROXIMATELY EQUAL TO THE TIME TAKEN FOR THE D" POINTS OF THE ANTENNA AZIMUTH BEAM TO SWEEP PAST A POINT TARGET CONSEQUENTLY THE NUMBER OF PULSES IN A BURST IS DIRECTLY RELATED TO THE INSTRUMENTED RANGE AND THE ANTENNA ROTATION RATE 4HE ECHOES RECEIVED DURING A BURST ARE PROCESSED BY A FILTER BANK TO EXTRACT THE RADIAL VELOCITIES OF TARGETS AND CLUTTER 7ITHIN THE DIGITAL SIGNAL PROCESSOR DETECTION THRESHOLDS FOR EACH OF THE FILTERS WITHIN THE BANK ARE CALCULATED ADAPTIVELY AIMING AT PROVIDING OPTIMUM CONTROL OF FALSE ALARMS WHILE MAXIMIZING CLUTTER SUPPRESSION AND TARGET DETECTION -ANUAL CONTROL OF THE THRESHOLDS IS ALSO PROVIDED TO BE COMPLIANT WITH )-/ REQUIREMENTS -ODERN FULLY SOLID |
CIENTLY 4HIS LACK IN HIGH PEAK POWER IS THE MAIN DISADVANTAGE OF THE SOLID |
It is sometimes convenient to divide an array into subarrays. For example, the AN/SPY-I AEGIS array utilizes 32 transmitting and 68 receiving subarrays of different sizes.81 One reason for dividing the transmitting array into subarrays is to provide a dis tributed transmitter. In the AEGIS array a separate high-power amplifier feeds each of the 32 transmitting subarrays. |
'Tlie noise No is measured over the linear portion of the receiver input-output characteristic, usually at the output of tlie IF amplifier before the nonlinear second detector. 'The receiver bandwidth Bn is that of tlie IF aniplifier in most receivers. The available gain G, is tlie ratio of the signal out So to the signal in Si, and kTo Bn is the input noise Ni in an ideal receiver. |
4HE RECEIVING SYSTEM IS DEFINED HERE TO EMBRACE ONLY THE RECEIVING ANTENNA ARRAY AND THE RECEIVERS THAT CONVERT THE ANTENNA OUTPUTS TO DISCRETE TIME SERIES USUALLY AT BASE |
Clampitt, L. L.: Microwave Radar Tubes at Raytheon, Electronic Progress, vol. 17, no. |
7.22 Significance of Aperture Matching ...................... 7.22 Effects of Mutual Coupling ................................. 7.23 Element Pattern ................................................. |
TO |
KD2 DTK2KVII II V2V2COS WHERE BOLD |
OR }[] W2% R DR |
DOMAIN CONVOLUTION ! GENERIC TIME |
M RESOLUTION HAVE BECOME THE NORM WITH SYSTEMS UNDER DEVELOPMENT OR ALREADY LAUNCHED BY AT LEAST SEVEN COUNTRIES !S EXPANDED IN THE APPROPRIATE SECTIONS OF THIS CHAPTER THE RANGE MEASUREMENT PRECISION OF SURFACE HEIGHT CHANGE IS NOW ON THE ORDER OF MILLIMETER PER YEAR AS ESTABLISHED BY TWO DIFFERENT CLASSES OF %ARTH |
(Also availahlc in ref. I.) 20. Headrick. |
12.17.—Circuit ofgeneral-purpose receiver.&-. 464 THE RECEIVING SYSTEM—RA DAR RECEIVERS [SEC. 12.10 control. |
(Subm~tted a Ohio State University Dissertation), U.S. Gov. Printing Office: 1974657-0171347. |
Thus there is no net gain in the detectability of desired targets. The only demand on the transmitter power is that it be great enough to cause the clutter power at the radar receiver to be large compared to receiver noise. If otherwise, Eq. |
58, pp. 543-550, April, 1970. 21. |
(b) SSN = 100.Ground Range (nmi) (b)Ground Range (nmi) (a) . Loss (dB) Frequency (MHz) or El. Angle (deg) Noise (dBW) Loss (dB) Frequency (MHz) or Ei. |
64 INTRODUCTION TO RADAR SYSTEMS Cumulative probability of detection. If the single scan probability of detection for a surveil- lance radar is P,, the probability of detecting a target at least once during N scans is called the cumulative probability of detection, and may be written The variation of P, with range might have to be taken into account when computing PC. The variation of range based on the cumulative probability of detection can be as the third power rather than the more usual fourth power variation based on the single scan probability.59 The cumulative probability has sometimes been proposed as a measure of the detectabi- lity of a radar rather than the single-scan probability of detection, which is more conservative. |
"!3%$ 2%-/4% 3%.3).' 2!$!23 £n°Ç 3EASAT 4HE GENERALLY ACKNOWLEDGED SPACE |
POLARIZED AND MUST TRANSMIT CIRCULAR POLARIZATION !S REVIEWED IN 3ECTION A DUAL |
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Hankins, T.H.; Eilek, J.A.; Jones, G. The Crab pulsar at centimetre wavelengths, II. Single pulse. |
Stuckey, “Activity control principles for automatic tracking algorithms,” in IEEE Radar 92 Conference , 1992, pp. 86–89. 41. |
no. 105, pp. 274-279, 1973. |
Adm. NTIA Rept . 83–127, July 1983. |
Themoredirective theantenna beamandthegreaterthe spacing between antennas, thegreaterwillbethe'isolation. Whentheantenna designer is restricted bythenatureoftheapplication, largeisolations maynotbepossible. Forexample, typicalisolations· between transmitting andreceiving antennas onmissiles mightbeabout 50dBatXband,70dBatKbandandaslowas20dBatLband.9Metallic baffles,aswellas absorbing material, placedbetween theantennas canprovideadditional isolation.10 Ithasbeenreported 11thatthe·isolationbetween twoX-bandhornantennas of22dB gaincanbeincreased fromanormal.value of70dBtoabout120dBbyseparating thetwo withasmoothsurfacecoveredbyasheetofradar-absorbing material andproviding screening ridgesattheedgesofthehorns.Acommonradome enclosing thetwoantennas shouldbe avoided sinceitlimitstheamountofisolation thatcanbeachieved.. |
STATE LINEAR &-#7 SYSTEMS nTHEIR PROMISE AND THEIR PROBLEMS v IN 0ROC )%%% )NT -IC #ONF !TLANTA '! PP n 2 - .ARAYANAN 9 8U 0 $ (OFFMEYER AND * / #URTIS h$ESIGN PERFORMANCE AND APPLICA |
15. Power in the Antenna Sidelobes. Airborne systems are limited in their ability to reject clutter due to the power returned by the antenna sidelobes. |
Grasso, “Improvement factor of a nonlinear MTI in point clutter,” IEEE Trans. , vol. AES-4, November 1968. |
(ALL $ # 3CHLERER ED -4) 2ADAR .ORWOOD -! !RTECH (OUSE )NC & 2 $ICKEY *R AND - - 3ANTA h&INAL REPORT ON ANTICLUTTER TECHNIQUES v 'ENERAL %LECTRIC #OMPANY 2EPT 2%-( -ARCH $ " !NDERSON h! MICROWAVE TECHNIQUE TO REDUCE PLATFORM MOTION AND SCANNING NOISE IN AIRBORNE MOVING TARGET RADAR v )2% 7%3#/. #ONV 2EC VOL PT PP n. ΰÎ{ 2!$!2 (!.$"//+ h&INAL ENGINEERING REPORT ON DISPLACED PHASE CENTER ANTENNA v VOL -ARCH VOLS AND !PRIL 'ENERAL %LECTRIC #OMPANY 3CHENECTADY .9 ( 5RKOWITZ h4HE EFFECT OF ANTENNA PATTERNS ON PERFORMANCE OF DUAL ANTENNA RADAR MOVING TARGET INDICATORS v )%%% 4RANS VOL !.% |
tion in) Aural detection (see Detection, aural) Automatic frequency control, 453457 (See .2s. AFC) Autosyns, 487 Azimuth-pulse removal, 695 B Back-bias, 459 Back bombardment ofmagnetron cath- ode (see Magnetron cathode, back bombardment of)Back-of-the-dish system (see System, back-of-the-dish) Baltzer, O.J.,80 Bandwidth, i-famplifier, 444 over-all, of cascaded double-tuned circuits, 448 ofcascaded single-tuned stages, 446 ofreceiver (see Receiver bandwidth) Bartelink, E.H.B.,449 Beacon, airborne, 246 azimuth width ofreply of,256 choice offrequency for, 260 fixed ground, 248 with ground radar, 609 interrogation of,252–260 interrogation coding of,263–264 frequency, 263 pulse length, 263 multiple pukes, 263 two-frequency interrogation, 264 overinterrogation of,265 portable, 249 radar, 27,243–270 general description of,243–246 useforcommunication, 244, 264 range performance of,254 reply coding of,264 gap coding, 264 range coding, 264 width coding, 264 side-lobe interrogation of,257 swept-frequency, 262 traffic capacity of,265–268 unsynchronized replies of,268 Beacon system, radar, 24&254 Beam shape, choice of,60@604 Beamwidth ofantenna, 20,271 Bell Telephone Laboratories, 291, 565, 664 Bendix Aviation, 578, 580 Blackmer, L.L,,221 Blind speeds, choice of,654 iuMT1, 650 Blocklng oscillator, 502 Boice, W.K., 560 Breit, G., 13 British Technical Mission, 15 Brush, high-altitude, for rotating ma- chines, 561 B-scope, 171 design of,52&532. B-scope, electrostatic, 528 magnetic, 528 Button, C.T.,578 c Cable, coaxial, 397 Carlson, J.F.,65 Cathode follower, 494 Cathode-ray tube, 47S486 deflection coil of,477 display projection of,219 electrostatic deflection of,476 electrostatic focusing of,476 magnetic deflection of,477 magnetic focusing of,476 types of,483 Cathode-ray tube screens, 479-483 cascade, 480 dark trace, 483 long-persistence, 480 supernormal buildup in,482 Cathode-ray tube swe~ps, delayed, 522 Cavities, resonant, 405-407 CH (see Home Chain) Chaff, 82 Chain, Home (see Home Chain, British) Channel, signal, 434 Chart projector, 215 Chokes, 397 Chu, L,J,,64 Circuit efficiency, ofmagnetron, 345 Cities, radar signals from, 101 Clamps, 503-508 switched, 505–508 Close control, 232–240 Clutter, 124–126 rain, 81 Clutter fluctuation, internal, 642–644 measured values of,643 when radar ismoving, 657 Clutter-noise, 651 CMH, 188 Coaxial-type mixer, 417 Coder, triple-pulse, 686 Coding (see Beacon, interrogation coding of) effectiveness of,688 ofpulses, 686 Coherence, ways ofproducing, between echo signals and reference signal, 635-638739 INDEX Coherent oscillator, 632 effect ofdetnning, 640 forMTI, 662-665 circuit design of,663 Combined plan and height systems, 192 Complex targets, 73,7$81 Component, r-f(see R-f components) Compound targets, 73,81 Computers, dead-reckoning, 215 Conical scan (se. |
BORS IS THE BEST OVERALL MEASURE OF ARRAY PERFORMANCE OTHER THAN THE FULL ARRAY ITSELF )F A LARGE REFLECTION OCCURS AT SOME ANGLE OF SCAN IT CAN BE RECOGNIZED BY A NULL IN THE ELEMENT PATTERN 4HE SMALL ARRAY CAN ALSO PROVIDE DATA ON THE COUPLING BETWEEN ELEMENTS 4HIS DATA CAN BE USED TO CALCULATE THE VARIATION IN IMPEDANCE AS THE ARRAY IS SCANNED "OTH THESE TECHNIQUES WILL BE DISCUSSED LATER IN THIS SECTION %FFECTS OF -UTUAL #OUPLING 7HEN TWO ANTENNAS OR ELEMENTS ARE WIDELY SEPA |
With antennas that do not scan, the mismatch may often be tuned out by conventional techniques, prefer- ably at a point as close to the source of the mismatch as possible. In a scanning array the impedance of a radiating element varies as the array is scanned, and the matching problem is considerably more complicated. Unlike a conventional antenna, where mismatch affects only the level of the power radi- ated and not the shape of the pattern, spurious lobes in the scanning array may appear as a consequence of the mismatch. |
For two-delay cancelers, the stagger limitation is often comparable with the basic canceler capability without staggering. For three-delay cancelers, the stagger limitation usually predominates. Consider the transmitter pulse train and the canceler configurations shown in Figure 2.44. |
The SCR-584 could control an antiaircraft battery without the necessity for searchlights or optical angle tracking, In 1939 the Army developed the SCR-270, a long-range radar for early warning. The attack on Pearl Harbor in December, 1941, was detected by an SCR-270, one of six in Hawaii at the time.' (There were also 16 SCR-268s assigned to units in Honolulu.) But unfortunately, the true significance of the blips on the scope was not realized until after the bombs had fallen. A modified SCR-270 was also the first radar to detect echoes\ from the moon in 1946. |
These tubes were triodes or tetrodes designed lo minimize the transit-time effects and other problems of operating at VHF and UHF. 21 The potential applied to the control grid of the tube acts as a gate, or valve, to control the number of electrons traveling from the cathode to the anode, or plate. The variation of potential applied to the grid is imparted to the current traveling to the anode. |
15.24 RADAR HANDBOOK 6x9 Handbook / Radar Handbook / Skolnik / 148547-3 / Chapter 15 The production of sea clutter by rain falling on a “calm” surface in the absence of wind was also investigated by Hansen, with the results shown in Figure 15.17.69 A high-resolution X-band radar (40-ns pulse, 1° beamwidth), operating at a grazing angle of about 3°, viewed the backscatter from a fixed spot on the windless surface of Chesapeake Bay as the rain steadily increased from 0 to 6 mm/h. The cross sections for vertical and horizontal polarizations were quite different for low rain rates but tended to merge at a rain rate of about 6 mm/h. The magnitude of this splash cross section rose to a s 0 of about –40 dB, corresponding to highly averaged wind-induced cross sec - tions at this grazing angle for winds of about 10 kt. |
Notilit, R. S.: Reliability without Redundancy from a Radar Monopulse Receiver, Microwaves, vol. 6, pp. |
The ferrite diode limiter has fast recovery time (can be as low as several tens of nanoseconds), and if the power rating is not exceeded, the life should be essentially un- limited. The spike and flat leakage is low, but the insertion loss is usually higher and the package is generally longer and heavier than other receiver protectors. Except for the initial spike, the ferrite limiter is an absorptive device as compared to the gas-tube TR or the TR-limiter which are reflective. |
8.5 MTI Radar (Moving Target Indication) Moved or shifted targets can be detected in many ways and with many methods and partic u- larly due to: - Doppler shift - Range change from scan to scan - Direction change from scan to scan At first glance it is not therefore so necessary to integrate the elaborate Doppler signal p roc- essing. In practice is it however so that the echoes from moved targets are not received alone, but are rather surrounded by clutter, the echoes of all the reflecting objects found in the resol u- tion region. This clutter mostly masks the echoes of move d objects. |
Phaseinspace.Thistechniqueemploys asinglerellector witharatheruniquetypeoffeed.The effectofmultiple beamsisgenerated withthisfeed.butonlytworeceivers plusaphasedetector areneededtodetermine angular 10cation.3.\ 35Inordertoobtainwidecoverage inelevalion angleaparabolic-torus reflector isemployed ratherthanasectionofaparaboloid. Acurved pieceofwaveguide withradiating slotsactsasthefeed.Thetransmitter isfedintooneendof thewaveguide feedwhoseslotsarcdesigned toproduce anumber ofcontiguous beamsin elevation withamplitudes controlled soa~toproduce acosecant-squared radiation pattern. Onreception. |
SIGHT ,/3 CONSTRAINTS WHERE THE ,/3 IS DEFINED AS A LINE BETWEEN TRANSMIT AND RECEIVE ANTENNAS TANGENT TO THE %ARTHS SURFACE 3PECIFICALLY FOR A GIVEN TARGET TRANSMITTER AND RECEIVER ALTITUDES THE TARGET MUST SIMULTANEOUSLY BE WITHIN ,/3 TO BOTH THE TRANSMITTER AND RECEIVER SITES &OR A SMOOTH %ARTH MODEL THE ,/3 RANGE R 2 BETWEEN A RECEIVE ANTENNA OF ALTITUDE H2 AND TARGET OF ALTITUDE HT IS R2 H2 HT WHERE ALL UNITS ARE IN KILOMETERS 3IMILARLY THE ,/3 RANGE R4 BETWEEN A TRANSMIT ANTENNA OF ALTITUDE H4 AND TARGET OF ALTITUDE HT IS R4 H4 HT 4HUS TO PREVENT ,/3 TRUNCATION OF THE OVALS R2 q 22MAX AND R4 q 24MAX 4HESE EXPRESSIONS IGNORE BOTH DIFFRACTION AND MULTIPATH WHICH CAN SIGNIFICANTLY ALTER THESE RANGES SO THEY MUST BE CONSIDERED FIRST |
Delays and errors unavoidable inacomplicated scheme oftelling and plotting arelargely eliminated inasystem that combines theoperational organization with the radar equipment. Controllers who give instruc- tions toaircraft are able towork directly from the radar display and therefore have afarmore accurate and up-to-date appreciation ofthe situation than can beobtained from aplot, however well maintained it may be. This was eventually appreciated, and such systems have been put into very successful operation. |
,J Thereareotherfactorsbesidethenoisefigurewhichcaninfluence theselection ofa receiver front-end. Cost,burnout, anddynamic rangemustalsobeconsidered. Theselection of aparticular typeofreceiver front-end mightalsobeinfluenced byitsinstantaneous band width,tuningrange,phaseandamplitude stability, andanyspecialrequirements forcooling. |
WIND DIRECTIONS CAN ACCOUNT FOR THE OBSERVED BEHAVIOR OF THIS VERY LOW |
VIII At the same time as the development of ASV Mk. X, the 3 cm AN/APS-3 was alsomade available. This was a forward-looking ASV and was mainly fitted to Catalinas of Coastal Command as ASV Mk. |
/ |
The use of radar for ballistic missile defense has been of interest ever since the threat of ballistic missiles arose in the late 1950s. The longer ranges, high supersonic speeds, and the smaller target size of ballistic missiles make the problem challenging. There is no natural clutter problem in space as there is for defense against aircraft, but ballistic missiles can appear in the presence of a large number of extraneous con - fusion targets and other countermeasures that an attacker can launch to accompany the reentry vehicle carrying a warhead. |
Somewhat higher transmitter power will beavailable atthelonger wavelengths. Atthetime ofthedevelopment described, perform- ance ofexisting components was better inthe 10-cm region than atany other wavelength suitable forthis application. 15.10. |
MATION IS TYPICALLY REQUIRED FOR MANY LARGE APERTURES 4HE TRANSFORMATIONS CAN RANGE FROM SIMPLE COLUMN BEAMFORMING TO OVERLAPPED SUBARRAYS TO BEAM |
G. V . Trunk and J. |
With FM -CW Radar the duration will be determined from the difference in frequency as received from the target and of the current transmitter. For the simple case of linear frequency modulation, referring to Figure 4.1, ∆ t is as fo l- lows: € Δt=ΔfT B⇒R=ΔfT 2Boc (4.2) Along with the analysis of the frequency difference ∆ f, with FM -CW Radar the range to reflecting objects can also be calculated from a Fourier transform of the complex frequency signal in the time domain. The unambiguous range of coverage is limited by th e pulse repetition frequency PRF = 1/Τ of the selection. |
148.Brennan, L.E.,I.S.Reed,andP.Swerling: Adaptive Arrays,Microware J.,vol.17,pp.4346,p.74, May,1974. 149.O'Donovan, P.L.,andA.W.Rudge:Adaptive Control ofaFlexible LinearArray,Electronin Letters,vol.9,pp.121-122, Mar.22,1973. 150.Gabriel, W.F.:Adaptive Arrays-An Introduction, Proc.IEEE,vol.64,pp.239-272, February, 1976. |
BER OF ZEROS CAN BE ALLOCATED DYNAMICALLY TO EITHER CLUTTER SOURCE AS A FUNCTION OF RANGE 4HIS LEADS TO A FULLY ADAPTIVE -4) IMPLEMENTATION USING A MORE COMPLEX ADAPTATION ALGORITHM AS DISCUSSED BELOW 3UCH AN ADAPTIVE -4) MAY PROVIDE A PERFORMANCE CLOSE TO THE OPTIMUM DISCUSSED IN 3ECTION )N ORDER TO ILLUSTRATE THE DIFFERENCE IN PERFORMANCE BETWEEN SUCH CANDIDATE -4) IMPLEMENTATIONS A SPECIFIC EXAMPLE IS CONSIDERED NEXT &OR THIS EXAMPLE LAND CLUTTER RETURNS ARE PRESENT AT ZERO DOPPLER WITH A NORMALIZED SPECTRAL SPREAD OF R F4 AND CHAFF RETURNS ARE PRESENT AT A NORMALIZED DOPPLER OFFSET OF FD4 WITH A NORMALIZED SPECTRAL SPREAD OF RF4 4HE POWER RATIO OF THE LAND CLUTTER TO THAT OF THE CHAFF IS DENOTED 1 D" 4HERMAL NOISE IS NOT CONSIDERED IN THIS EXAMPLE )N BOTH CASES THE TOTAL NUMBER OF FILTER ZEROS IS ASSUMED TO BE EQUAL TO &OR THE ADAPTIVE -4) WITH A FIXED ALLOCATION OF ZEROS TWO ZEROS ARE LOCATED AT ZERO DOPPLER AND THE REMAINING ZERO IS CENTERED ON THE CHAFF RETURNS )N THE OPTIMUM -4) THE ZERO LOCATIONS ARE CHOSEN SO THAT THAT OVERALL IMPROVEMENT FACTOR IS MAXIMIZED 4HE RESULTS OF THIS COMPARISON ARE PRESENTED IN &IGURE WHICH SHOWS THE IMPROVEMENT FACTOR FOR THE OPTIMUM AND THE ADAPTIVE -4) AS A FUNCTION OF THE POWER RATIO 1 D" 7HEN 1 IS SMALL SO THAT CHAFF RETURNS DOMINATE A SIGNIFICANT PERFORMANCE IMPROVEMENT CAN BE REALIZED BY USING ALL -4) FILTER ZEROS TO CANCEL THE CHAFF RETURNS 4HE PERFORMANCE DIFFERENCE FOR LARGE VALUES OF 1 IS A RESULT OF AN ASSUMPTION MADE THAT THE LOCATION OF THE THIRD ZERO REMAINS FIXED AT THE CHAFF DOPPLER FREQUENCY )N REALITY THE ADAPTIVE -4) WOULD MOVE &)'52% /PEN |
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However, ARM receiver sensitivity is affected by mismatching losses; accuracy in locating the victim radar is affected by the limited dimension of the ARM antenna. 24.5 OBJECTIVES AND TAXONOMY OF ECCM TECHNIQUES The primary objective of ECCM techniques when applied to a radar system is to allow the accomplishment of the radar intended mission while countering the effects of the enemy’s ECM. In greater detail, the benefits of using ECCM techniques may be summarized as follows: (1) prevention of radar saturation, (2) enhancement of the signal-to-jamming ratio, (3) discrimination of directional interference, (4) rejection of ch24.indd 8 12/19/07 6:00:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. |
[ CrossRef ] 27. Zhang, Z.; Wang, C.; Wang, M.; Wang, Z.; Zhang, H. Surface deformation monitoring in Zhengzhou city from 2014 to 2016 using time-series insar. |
PE-218-G PE-218-D 26 29–45 +25 +55 –45 +25 +55373 379 396 396 406 398 411 404 443 423 449 428 Over-all regulation ILeland IGECo, PE-21&C PE218-D Incps I76 Inpercent 17,0 i:.5 Alldata were taken atsealevel and with full rated load oninverter. The GE PE-218-D unit has acompensating resistor inseries with the field which accounts foritsslightly better regulation. Italso has an adjustable resist orwhich allows thefrequency tobevaried over arange ofapproximately 40cps. |
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The two final output devices and the eight driver devices are 100 W transistors capable of operating up to a 10% duty cycle over the 100-MHz bandwidth at collector efficiencies greater than 52%. Each module is air- cooled, and the measured efficiency is greater than 25% when the module is operating at an 8.2% average duty cycle. Module power gain is greater than 16 dB. |
1966. 55. Fried, W.R.: Doppler Navigation, chap. |
- 7ITH THE PROLIFERATION OF BALLISTIC MISSILES FUTURE SHIPBOARD RADAR SYSTEMS WILL PROB |
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A 9-bit A/D converter therefore has a maximum di:,cri mination of 1 out of 511 levels; or approximately 54 dB. (Equation (4.12) on the other hand, predicts 52.9 dB for 9-bit quantization.) In the above it was said that the addition of the Q channel removed the problem of reduced sensitivity due to blind phases. This is different than the blind speeds which occur when the pulse sampling appears at the same point in the doppler cycle at each sampling instant, as shown in Fig. |
-CO~PARISON OF THE Two PULSER TI-PES Characteristics Efficiency Pulse shape Impedance-matching Interpuke interval Voltage supply Change ofpulse dura- tion Time jitter Cmcuit complexity Effects ofchange in voltageHard-tube pulser Iwwer; more overhead power required fordriver, cathode heating, andfordissipation inswitch tube Better rectangular pulses l~ide range ofmismatch per- missible lIay be\-cry short, asforcod- ingbeacons (i.e.,<1psec) High-voltage supply usually necessary Easy; switching inlow-voltage circuit Somewhat easier toobtain negligible time jitter, i.e., <0.02 /see, than with line- type pulscr Greater, leading togreater difficulty inservicing Fordesign ha}-k gmaximum et%ciency, (AP/P) output = 6(AV/\’) input. Bysacri- ficing efficiency inthedesign, (AP/P) output =05(AV/~) input canbeobtainedLine-type plllser High, particularly rrben pUke- power output ishigh Poorer rectangular pulse, par- ticularly through pulse trans- former Smaller range ofmismatch per- missible (+20-30 percent). Pulse transformer ~villmatch anyload, butpower input to nonlinear load cannot be varied over awide range X[ust beseveral times the deionization time ofdischarge tube (i.e., >100psec) Low-voltage supply, particu- larly with inductance charg- ing Requires high-voltage switch- ingofnetwork High-power line-type pulsers with rotary-gap switch have inherently large time jitter. |
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CODE IN OR NEAR THE RADAR OPERATING BAND )N SOME CASES THE FREQUENCY CHANNEL IS RANDOMLY SELECTED AT THE FACTORY AND HARDWIRED INTO THE MISSILE &REQUENCY CHANNELS ARE TYPICALLY SELECTED OR COMMUNICATED TO THE RADAR IMMEDIATELY BEFORE LAUNCH )F THE DATA LINK FREQUENCY IS WELL BELOW THE RADAR BAND USUALLY A SMALL NUMBER OF RADIATORS AT THAT LOWER FREQUENCY ARE IMBEDDED IN THE RADAR APERTURE )F THE FREQUENCY IS CLOSE ENOUGH TO THE RADAR BAND THE RADAR APERTURE OR A SEGMENT OF THE APERTURE IS USED 2ADAR !PERTURE $ATALINKING (ISTORICALLY DATALINK FUNCTIONS EMBEDDED IN -&!2S HAVE BEEN USED FOR THE MIDCOURSE GUIDANCE OF MISSILES !N EMERGING APPLICA |
AXIS RADAR v IN )NT 2ADAR #ONF 2EC PP n. 42!#+).' 2!$!2 °{ ) $ /LIN AND & $ 1UEEN h$YNAMIC MEASUREMENT OF RADAR C ROSS SECTION v 0ROC )%%% VOL PP n !UGUST * ( $UNN $ $ (OWARD AND ! - +ING h0HENOMENA OF SCINTILLATION NOISE IN RADAR |
30, pp. 729–737, May–June 1995. 57. |
ISTICS OF A RADAR CAN BE EXPLOITED AS %##- TECHNIQUES IN TWO WAYS &IRST THE CROSS |
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65. D. K. |
VELOCITY PRODUCT 4ABLE THE ANTENNA AREA NEEDS TO BE ONLY ^ M TO SATISFY THE MINIMUM AREA CONSTRAINT %Q 4HESE RADARS ARE INDEED LOW MASS AT ABOUT KG AND KG RESPECTIVELY INCLUDING IN EACH CASE THEIR ANTENNA ! MAJOR OBJECTIVE FOR BOTH OF THESE RADARS IS TO LOOK FOR EVIDENCE OF ICE DEPOSITS IN THE PERMANENTLY SHADOWED AREAS OF THE -OONS POLAR REGIONS 4HIS REQUIRES THAT THEY MUST MEASURE THE CIRCULAR POLARIZATION RATIO #02 (ENCE THEY TRANSMIT CIRCULAR POLARIZATION AND THEY ARE DUAL |
CATION &IGURE ILLUSTRATES THE MOST COMMON OF THESE REFLECTORS EACH OF WHICH IS DESCRIBED IN SOME DETAIL IN THE FOLLOWING SUBSECTIONS 4HE PARABOLOID IN &IGURE A COLLIMATES RADIATION FROM A FEED AT THE FOCUS INTO A PENCIL BEAM PROVIDING HIGH GAIN AND MINIMUM BEAMWIDTH 4HE PARABOLIC CYLINDER IN &IGURE B PERFORMS THIS COLLIMA |
Army has used the method extensively innavigating across the Alps. One difficulty inherent in the use ofradar pilotage over mountainous terrain isillustrated in Fig. 3-K). |
It acts as a digital pllase sliifter if the drive currents are digital. A digital-to-analog conversion is rcrlrlircd to transliite the digital control-signal generated by the array computer to a form that car1 set tlic I1u.u-drive pliase sliifter. *I'lic lengtli of the toroid is generally 111ade 15 to 20 percent greater thari normal to allow for some shrinkage of the total available increment of rnagtietizatio~i due to telnperature changes. |
Rem. Sens. , vol. |
, &IGURE DEFINES THE GEOMETRY FOR BISTATIC DOPPLER WHEN THE TARGET TRANSMITTER AND RECEIVER ARE MOVING 4HE TARGET HAS A VELOCITY VECTOR OF MAGNITUDE 6 AND ASPECT ANGLE C REFERENCED TO THE BISTATIC BISECTOR 4HE TRANSMITTER AND RECEIVER HAVE VELOCITY VECTORS OF MAGNITUDE 6 4 AND 62 AND ASPECT ANGLES C 4 AND C 2 RESPECTIVELY REFERENCED TO THE NORTH COORDINATE SYSTEM OF &IGURE !LL VECTORS ARE PROJECTIONS OF THE THREE |
T ectonophysics 2016 ,691, 271–281. [ CrossRef ] 9. Garcia, A.J.; Bakon, M.; Martinez, R.; Marchamalo, M. |
The other region of interest is that which lies just heyond the interference region below the radar line of sight and is the diffraction. or the shadow. region. |
The improvement factor of a noncoherent MTI will not, in general, be as good as can be obtained with a coherent MTI tliat employs a reference oscillator (coho). The reference signal in the noncoherent case is tlie clutter itself, which will not be as stable as a reference oscillator because of tlie finite width of the clutter spectrum caused by its own internal motions. If a nonlinear IF ariiplifier is used, it will also limit the improvement factor that can be achieved. |
9 of" Mechanical Engineering in Radar and Communications," C. J. Richards (ed.). |
The significant difference between this MTI configuration and that of Fig. 4. lh is the manner in which the reference signal is generated. |
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