246:, that is, the frequency of the carrier is varied within the pulse, much like the sound of a cricket chirping. When the pulse reflects off a target and returns to the receiver, the signal is processed to add a delay as a function of the frequency. This has the effect of "stacking" the pulse so it seems stronger, but shorter in duration, to further processors. The effect can increase the received signal strength to above that of noise jamming. Similarly, jamming pulses (used in deception jamming) will not typically have the same chirp, so will not benefit from the increase in signal strength.
36:
261:") may be used to rapidly switch the frequency of the transmitted energy, and receiving only that frequency during the receiving time window. This foils jammers which cannot detect this switch in frequency quickly enough or predict the next hop frequency, and switch their own jamming frequency accordingly during the receiving time window. The most advanced jamming techniques have a very wide and fast frequency range, and might possibly jam out an antijammer.
209:
Throughout its 20-year existence, the U.S. government developed and installed over 3,143 electronic counter-countermeasures to its array of weapons. There is also the BAMS Project, which was funded by the
Belgian government since 1982. This system, together with advanced microelectronics, also provided secure voice, data, and text communications under the most severe electronic warfare conditions.
330:
are able to home in directly on sources of radar jamming if the jamming is too powerful to allow them to find and track the target normally. This mode, called "home-on-jam", actually makes the missile's job easier. Some missile seekers actually target the enemy's radiation sources, and are therefore
192:
signals from other aircraft and send them back with random delays and other modifications in an attempt to confuse the opponent's radar set, making the 'blip' jump around wildly and become impossible to range. More powerful airborne radars means that it is possible to 'burn through' the jamming at
309:
Aside from power loss to the jammer, radar receivers can also benefit from using two or more antennas of differing polarization and comparing the signals received on each. This effect can effectively eliminate all jamming of the wrong polarization, although enough jamming may still obscure the
135:
Ever since electronics have been used in battle in an attempt to gain superiority over the enemy, effort has been spent on techniques to reduce the effectiveness of those electronics. More recently, sensors and weapons are being modified to deal with this threat. One of the most common types of
284:
can be effective from directions other than the direction the radar antenna is currently aimed. When jamming is strong enough, the radar receiver can detect it from a relatively low gain sidelobe. The radar, however, will process signals as if they were received in the main lobe. Therefore,
208:
Examples of electronic counter-countermeasures include the
American Big Crow program, which served as a Bear bomber and a standoff jammer. It was a modified Air Force NKC-135A and was built to provide capability and flexibility of conducting varied and precision electronic warfare experiments.
200:
for operation of the radar might be able to better discriminate between a moving target like an aircraft and an almost stationary target like a chaff bundle. The technology powering modern sensors and seekers allow all successful systems partly due to ECCM designed into them. Today, electronic
301:
can be used to filter out unwanted signals, such as jamming. If a jammer and receiver do not have the same polarization, the jamming signal will incur a loss that reduces its effectiveness. The four basic polarizations are linear horizontal, linear vertical, right-hand circular, and left-hand
193:
much greater ranges by overpowering the jamming energy with the actual radar returns. The
Germans were not really able to overcome the chaff spoofing very successfully and had to work around it (by guiding the aircraft to the target area and then having them visually acquire the targets).
229:
Sensor logic may be programmed to be able to recognize attempts at spoofing (e.g., aircraft dropping chaff during terminal homing phase) and ignore them. Even more sophisticated applications of ECCM might be to recognize the type of ECM being used, and be able to cancel out the signal.
289:
is used for a comparison signal. By comparing the signal strength as received by both the omnidirectional and the (directional) main antenna, signals can be identified that are not from the direction of interest. These signals are then ignored.
268:
in that it forces the jammer to spread its jamming power across multiple frequencies in the jammed system's frequency range, reducing its power in the actual frequency used by the equipment at any one time. The use of
339:. This makes the use of such ECM a difficult decision – it may serve to obscure an exact location from non-ARMs, but in doing so it must put the jamming vehicle at risk of being targeted and hit by ARMs.
184:
In perhaps the first example of ECCM, the
Germans increased their radio transmitter power in an attempt to 'burn through' or override the British jamming, which by necessity of the
188:
being airborne or further away produced weaker signals. This is still one of the primary methods of ECCM today. For example, modern airborne jammers are able to identify incoming
577:
553:
627:
318:
Another practice of ECCM is to program sensors or seekers to detect attempts at ECM and possibly even to take advantage of them. For example, some modern
171:
483:
458:
394:
57:
597:
358:
127:. A more detailed description defines it as the electronic warfare operations taken by a radar to offset the enemy's countermeasure.
419:
79:
549:
622:
612:
592:
572:
170:
raid on July 24-25, 1943. Jamming also may have originated with the
British during World War II, when they began jamming
607:
162:
273:
techniques allow signals to be spread over a wide enough spectrum to make jamming of such a wideband signal difficult.
617:
602:
242:
technique is boosting the apparent signal strength as perceived by the radar receiver. The outgoing radar pulses are
50:
44:
137:
104:
61:
335:" (ARMs). The jamming in this case effectively becomes a beacon announcing the presence and location of the
286:
332:
302:
circular. The signal loss inherent in a cross polarized (transmitter different from receiver) pair is 3
365:
298:
202:
505:. Miami: History Office, Aeronautical Systems Center, Air Force Materiel Command. 1994. p. 96.
17:
353:
100:
479:
454:
415:
390:
285:
jamming can be seen in directions other than where the jammer is located. To combat this, an
258:
239:
578:
Camp Evans
Engineers develop World War II counter-measures with the help of Allen B. DuMont.
387:
An
Introduction to Electronic Warfare; from the First Jamming to Machine Learning Techniques
319:
270:
265:
149:
145:
103:
which includes a variety of practices which attempt to reduce or eliminate the effect of
412:
Operations
Analysis in the United States Army Eighth Air Force in World War II, Vol. 4
586:
348:
281:
221:
of sensors through techniques such as increasing power or improving discrimination):
185:
141:
124:
157:
550:"Russia surges ahead in radio-electronic warfare | Russia & India Report"
177:
communications. These efforts include the successful
British disruption of German
336:
323:
201:
warfare is composed of ECM, ECCM and, electronic reconnaissance/intelligent (
254:
178:
303:
218:
217:
The following are some examples of EPM (other than simply increasing the
197:
167:
112:
327:
120:
108:
243:
189:
174:
414:. Providence, R.I.: American Mathematical Society. p. 254.
519:. Fort Bliss, TX: US Army Air Defense School. 1974. p. 50.
451:
234:
Pulse compression by "chirping", or linear frequency modulation
29:
503:
Against the Wind: 90 Years of Flight Test in the Miami Valley
111:
aboard vehicles, ships and aircraft and weapons such as
476:
Air Warfare: an International Encyclopedia, Vol. 1, A-L
306:
for dissimilar types, and 17 dB for opposites.
196:Today, more powerful electronics with smarter
123:. In practice, EPM often means resistance to
8:
478:. Santa Barbara, CA: ABC-CLIO. p. 191.
453:. Santa Barbara, CA: ABC-CLIO. p. 138.
438:. Air Force Association. 2007. p. 68.
80:Learn how and when to remove this message
474:Boyne, Walter J.; Fopp, Michael (2002).
43:This article includes a list of general
377:
7:
497:
495:
385:Cheng, Chi-Hao; Tsui, James (2021).
359:Electronic warfare support measures
264:This method is also useful against
628:Electronic counter-countermeasures
93:Electronic counter-countermeasures
49:it lacks sufficient corresponding
25:
18:Electronic counter-countermeasures
449:Sterling, Christopher H. (2008).
160:, which Americans referred to as
34:
573:Raytheon ECCM-capable radio set
556:from the original on 2020-09-22
530:"BAMS Association Momentanee".
389:. Oxon: CRC Press. p. 47.
166:. It was first used during the
117:electronic protective measures
1:
410:McArthur, Charles W. (1990).
152:use of what they codenamed
148:. This originated with the
644:
598:Electronic countermeasures
238:One of the effects of the
181:navigational radio beams.
105:electronic countermeasures
27:Part of electronic warfare
213:Specific ECCM techniques
115:. ECCM is also known as
623:Radar signal processing
613:Military communications
593:Weapons countermeasures
333:anti-radiation missiles
287:omnidirectional antenna
64:more precise citations.
366:Wartime reserve mode
107:(ECM) on electronic
608:Military technology
618:Missile technology
603:Electronic warfare
517:Air Defense Trends
436:Air Force Magazine
354:Electronic warfare
322:missiles like the
119:(EPM), chiefly in
101:electronic warfare
485:978-1-57607-345-2
460:978-1-85109-732-6
396:978-87-7022-435-2
277:Sidelobe blanking
259:frequency hopping
250:Frequency hopping
240:pulse compression
150:Royal Air Force's
90:
89:
82:
16:(Redirected from
635:
565:
564:
562:
561:
546:
540:
539:
527:
521:
520:
513:
507:
506:
499:
490:
489:
471:
465:
464:
446:
440:
439:
432:
426:
425:
407:
401:
400:
382:
314:Radiation homing
85:
78:
74:
71:
65:
60:this article by
51:inline citations
38:
37:
30:
21:
643:
642:
638:
637:
636:
634:
633:
632:
583:
582:
569:
568:
559:
557:
548:
547:
543:
529:
528:
524:
515:
514:
510:
501:
500:
493:
486:
473:
472:
468:
461:
448:
447:
443:
434:
433:
429:
422:
409:
408:
404:
397:
384:
383:
379:
374:
345:
320:fire-and-forget
316:
310:actual signal.
296:
279:
271:spread-spectrum
266:barrage jamming
252:
236:
227:
215:
133:
99:) is a part of
86:
75:
69:
66:
56:Please help to
55:
39:
35:
28:
23:
22:
15:
12:
11:
5:
641:
639:
631:
630:
625:
620:
615:
610:
605:
600:
595:
585:
584:
581:
580:
575:
567:
566:
541:
522:
508:
491:
484:
466:
459:
441:
427:
420:
402:
395:
376:
375:
373:
370:
369:
368:
363:
362:
361:
351:
344:
341:
315:
312:
295:
292:
278:
275:
251:
248:
235:
232:
226:
223:
214:
211:
205:) activities.
132:
129:
88:
87:
42:
40:
33:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
640:
629:
626:
624:
621:
619:
616:
614:
611:
609:
606:
604:
601:
599:
596:
594:
591:
590:
588:
579:
576:
574:
571:
570:
555:
551:
545:
542:
537:
533:
526:
523:
518:
512:
509:
504:
498:
496:
492:
487:
481:
477:
470:
467:
462:
456:
452:
445:
442:
437:
431:
428:
423:
421:0-8218-0158-9
417:
413:
406:
403:
398:
392:
388:
381:
378:
371:
367:
364:
360:
357:
356:
355:
352:
350:
347:
346:
342:
340:
338:
334:
329:
325:
321:
313:
311:
307:
305:
300:
293:
291:
288:
283:
282:Radar jamming
276:
274:
272:
267:
262:
260:
256:
249:
247:
245:
241:
233:
231:
225:ECM detection
224:
222:
220:
212:
210:
206:
204:
199:
194:
191:
187:
182:
180:
176:
173:
169:
165:
164:
159:
155:
151:
147:
143:
142:radar jamming
139:
130:
128:
126:
122:
118:
114:
110:
106:
102:
98:
94:
84:
81:
73:
63:
59:
53:
52:
46:
41:
32:
31:
19:
558:. Retrieved
544:
538:: 128. 1995.
535:
531:
525:
516:
511:
502:
475:
469:
450:
444:
435:
430:
411:
405:
386:
380:
317:
308:
299:Polarization
297:
294:Polarization
280:
263:
253:
237:
228:
216:
207:
195:
183:
161:
158:World War II
153:
134:
116:
96:
92:
91:
76:
70:January 2013
67:
48:
337:transmitter
324:Vympel R-77
62:introducing
587:Categories
560:2015-12-22
372:References
257:agility ("
45:references
255:Frequency
179:Luftwaffe
554:Archived
343:See also
331:called "
326:and the
219:fidelity
198:software
146:spoofing
113:missiles
532:Signals
349:Jamming
244:chirped
168:Hamburg
156:during
131:History
125:jamming
109:sensors
58:improve
482:
457:
418:
393:
328:AMRAAM
186:jammer
172:German
154:Window
121:Europe
47:, but
203:ELINT
190:radar
175:radio
163:chaff
480:ISBN
455:ISBN
416:ISBN
391:ISBN
97:ECCM
144:or
140:is
138:ECM
589::
552:.
536:49
534:.
494:^
304:dB
563:.
488:.
463:.
424:.
399:.
95:(
83:)
77:(
72:)
68:(
54:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.