758:(MTI) radar reduces the impact of blind velocity by using redundant detectors that introduce a compensating reverse phase shift undoes the phase shift caused by Doppler from reflector motion. This is also improved by using 3 or more pulses with staggering pulse intervals.
36:
Moving objects cause a phase-shift within the transmit pulse that produces signal cancellation. This phenomenon also has detrimental effect on moving target indicator systems, where the detection scheme subtracts signals received from two or more transmit pulses.
433:
216:
618:
709:
623:
The blind range for a specific PRF is an integer multiple of the distance between transmit pulses, which is when the reflected pulse arrives at the same time as when the transmitter fires.
254:
61:
This occurs when the radial velocity of the target induces a phase shift near 360 degree within the reflected pulse, which induces signal cancellation in the receiver.
461:
Scalloping happens in a two PRF detection scenario when target velocity produces a blind velocity for one PRF while the target is at the blind range of the other PRF.
748:
Intra-pulse scalloping is improved by shortening the transmit pulse or by modulating the transmit pulse. This can include frequency or phase shifting associated with
70:
470:
464:
The blind velocity for a specific pulse repetition frequency (PRF) is an integer multiple of the following, which causes the signal to have zero doppler.
245:
Scalloping occurs when the radial velocity of the reflector induces an integer multiple of a 360 degree phase shift between two or more transmit pulses.
629:
737:
This system would fail to detect reflections at 50 km and 100 km that are moving 600 km/s or 1,200 km/s.
740:
It would also fail to detect reflections at 37.5 km and 75 km that are moving 450 km/s or 900 km/s.
248:
Radar scalloping for MTI radar begins to become a concern when the radial velocity is greater than the following value.
428:{\displaystyle Velocity>0.5\times \left({\frac {C}{2\times PeriodBetweenPulses\times TransmitFrequency}}\right)}
454:
involves blind velocities created by the clutter rejection filter. A two PRF detection schemes will have
765:
439:
720:
An L-Band transmitter using a 3 kHz and 4 kHz PRF pair has the following characteristics.
717:
These detection gaps are filled in by using three or more alternating PRF in the detection scheme.
755:
211:{\displaystyle Velocity>\left({\frac {C}{2\times TransmitFrequency\times PulseWidth}}\right)}
613:{\displaystyle Blind\ Velocity=\left({\frac {C\times PRF}{2\times Transmit\ Frequency}}\right)}
8:
761:
451:
64:
Intra-pulse radar scalloping begins to become a concern above the following velocity.
749:
714:
This leaves a series of detection gaps at discrete velocity and range combinations.
26:
phenomenon that reduces sensitivity for certain distance and velocity combinations.
221:
Scalloping occurs at 150 km/s for an L-band radar with a 1 microsecond pulse.
780:
774:
458:
with a pattern of discrete ranges, each of which has a blind velocity.
442:
of 1kHz (10m/s to 20m/s, 25m/s to 35m/s, 40m/s to 50m/s, and so on).
733:
4 kHz blind velocities are 600 km/s, 1,200 km/s, ...
438:
This occurs near multiples of 15 m/s for an L-Band radar with
704:{\displaystyle Blind\ Range=\left({\frac {C}{2\times PRF}}\right)}
727:
3 kHz blind velocities are 450 km/s, 900 km/s, ...
23:
229:
Inter-pulse radar scalloping involves two types of systems.
29:
The name is derived from the appearance of areas that are
730:
4 kHz blind ranges are 37.5 km, 75 km, ...
724:
3 kHz blind ranges are 50 km, 100 km, ...
632:
473:
257:
73:
45:There are two different types of radar scalloping.
703:
612:
427:
210:
772:
764:systems compensate using 3 or more different
33:of graphs that indicate radar sensitivity.
743:
240:
224:
56:
773:
445:
13:
14:
792:
1:
40:
7:
10:
797:
766:pulse repetition frequency
440:pulse repetition frequency
768:in the detection scheme.
756:Moving target indicator
744:Compensation Strategies
241:Moving Target Indicator
233:Moving Target Indicator
705:
614:
429:
225:Inter-pulse Scalloping
212:
57:Intra-pulse Scalloping
706:
615:
430:
213:
630:
471:
255:
71:
762:Pulse-Doppler radar
452:pulse-Doppler radar
446:Pulse-Doppler Radar
236:Pulse-Doppler Radar
701:
610:
425:
208:
750:pulse compression
695:
650:
604:
575:
491:
419:
202:
788:
710:
708:
707:
702:
700:
696:
694:
674:
648:
619:
617:
616:
611:
609:
605:
603:
573:
541:
524:
489:
434:
432:
431:
426:
424:
420:
418:
296:
217:
215:
214:
209:
207:
203:
201:
106:
16:Radar phenomenon
796:
795:
791:
790:
789:
787:
786:
785:
771:
770:
746:
678:
673:
669:
631:
628:
627:
542:
525:
523:
519:
472:
469:
468:
450:Scalloping for
448:
300:
295:
291:
256:
253:
252:
243:
227:
110:
105:
101:
72:
69:
68:
59:
43:
17:
12:
11:
5:
794:
784:
783:
745:
742:
735:
734:
731:
728:
725:
712:
711:
699:
693:
690:
687:
684:
681:
677:
672:
668:
665:
662:
659:
656:
653:
647:
644:
641:
638:
635:
621:
620:
608:
602:
599:
596:
593:
590:
587:
584:
581:
578:
572:
569:
566:
563:
560:
557:
554:
551:
548:
545:
540:
537:
534:
531:
528:
522:
518:
515:
512:
509:
506:
503:
500:
497:
494:
488:
485:
482:
479:
476:
456:detection gaps
447:
444:
436:
435:
423:
417:
414:
411:
408:
405:
402:
399:
396:
393:
390:
387:
384:
381:
378:
375:
372:
369:
366:
363:
360:
357:
354:
351:
348:
345:
342:
339:
336:
333:
330:
327:
324:
321:
318:
315:
312:
309:
306:
303:
299:
294:
290:
287:
284:
281:
278:
275:
272:
269:
266:
263:
260:
242:
239:
238:
237:
234:
226:
223:
219:
218:
206:
200:
197:
194:
191:
188:
185:
182:
179:
176:
173:
170:
167:
164:
161:
158:
155:
152:
149:
146:
143:
140:
137:
134:
131:
128:
125:
122:
119:
116:
113:
109:
104:
100:
97:
94:
91:
88:
85:
82:
79:
76:
58:
55:
54:
53:
50:
42:
39:
15:
9:
6:
4:
3:
2:
793:
782:
779:
778:
776:
769:
767:
763:
759:
757:
753:
751:
741:
738:
732:
729:
726:
723:
722:
721:
718:
715:
697:
691:
688:
685:
682:
679:
675:
670:
666:
663:
660:
657:
654:
651:
645:
642:
639:
636:
633:
626:
625:
624:
606:
600:
597:
594:
591:
588:
585:
582:
579:
576:
570:
567:
564:
561:
558:
555:
552:
549:
546:
543:
538:
535:
532:
529:
526:
520:
516:
513:
510:
507:
504:
501:
498:
495:
492:
486:
483:
480:
477:
474:
467:
466:
465:
462:
459:
457:
453:
443:
441:
421:
415:
412:
409:
406:
403:
400:
397:
394:
391:
388:
385:
382:
379:
376:
373:
370:
367:
364:
361:
358:
355:
352:
349:
346:
343:
340:
337:
334:
331:
328:
325:
322:
319:
316:
313:
310:
307:
304:
301:
297:
292:
288:
285:
282:
279:
276:
273:
270:
267:
264:
261:
258:
251:
250:
249:
246:
235:
232:
231:
230:
222:
204:
198:
195:
192:
189:
186:
183:
180:
177:
174:
171:
168:
165:
162:
159:
156:
153:
150:
147:
144:
141:
138:
135:
132:
129:
126:
123:
120:
117:
114:
111:
107:
102:
98:
95:
92:
89:
86:
83:
80:
77:
74:
67:
66:
65:
62:
51:
48:
47:
46:
38:
34:
32:
27:
25:
21:
760:
754:
747:
739:
736:
719:
716:
713:
622:
463:
460:
455:
449:
437:
247:
244:
228:
220:
63:
60:
44:
35:
30:
28:
19:
18:
52:Inter-pulse
49:Intra-pulse
31:scooped out
41:Definition
20:Scalloping
683:×
547:×
530:×
365:×
305:×
289:×
169:×
115:×
775:Category
649:
574:
490:
781:Radar
24:radar
22:is a
283:>
99:>
286:0.5
777::
752:.
698:)
692:F
689:R
686:P
680:2
676:C
671:(
667:=
664:e
661:g
658:n
655:a
652:R
646:d
643:n
640:i
637:l
634:B
607:)
601:y
598:c
595:n
592:e
589:u
586:q
583:e
580:r
577:F
571:t
568:i
565:m
562:s
559:n
556:a
553:r
550:T
544:2
539:F
536:R
533:P
527:C
521:(
517:=
514:y
511:t
508:i
505:c
502:o
499:l
496:e
493:V
487:d
484:n
481:i
478:l
475:B
422:)
416:y
413:c
410:n
407:e
404:u
401:q
398:e
395:r
392:F
389:t
386:i
383:m
380:s
377:n
374:a
371:r
368:T
362:s
359:e
356:s
353:l
350:u
347:P
344:n
341:e
338:e
335:w
332:t
329:e
326:B
323:d
320:o
317:i
314:r
311:e
308:P
302:2
298:C
293:(
280:y
277:t
274:i
271:c
268:o
265:l
262:e
259:V
205:)
199:h
196:t
193:d
190:i
187:W
184:e
181:s
178:l
175:u
172:P
166:y
163:c
160:n
157:e
154:u
151:q
148:e
145:r
142:F
139:t
136:i
133:m
130:s
127:n
124:a
121:r
118:T
112:2
108:C
103:(
96:y
93:t
90:i
87:c
84:o
81:l
78:e
75:V
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.