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202:) methods are used to produce stereophonic audio. Modulated subcarriers of the type used in FM broadcasting are impractical for AM broadcast due to the relatively narrow signal bandwidth allocated for a given AM signal. On standard AM broadcast radios, the entire 9 kHz to 10 kHz allocated bandwidth of the AM signal may be used for audio.
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of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broadcast. There is no physical difference between a carrier and a subcarrier; the
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or microwave channel for the audio channels of a video feed. There are usually at frequencies of 5.8, 6.2, or 6.8 MHz (the video carrier usually resides below 5 MHz on a satellite transponder or microwave relay). Extra subcarriers are sometimes transmitted at around 7 or 8 MHz for
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is a system with which broadcasters can multiply the speed of data transmission in the FM channel by using further normal RDS subcarriers, shifted into the higher frequencies of the FM multiplex. The extra RDS subcarriers are placed in the upper empty part of the multiplex spectrum and carry the
423:
subcarrier (57 kHz) allows FM radios to display what station they are on, pick another frequency on the same network or with the same format, scroll brief messages like station slogans, news, weather, or traffic—even activate pagers or remote billboards. It can also broadcast
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for the blind, which reads articles in local newspapers and sometimes magazines. The vision-impaired can request a special radio, permanently tuned to receive audio on a particular subcarrier frequency (usually 67 kHz or 92 kHz), from a particular FM station.
516:, often located in a difficult-to-access area at the top of a mountain. A station's engineer can carry a decoder around with them and know anything that's wrong, as long as the station is on the air and they are within range. This is the essence of a
225:
as the subcarriers. A black and white TV simply ignores the extra information, as it has no decoder for it. To reduce the bandwidth of the color subcarriers, they are filtered to remove higher frequencies. This is made possible by the fact that the
308:
to be separated in the receiver. The mono audio component of the transmitted signal is in a separate carrier and not integral to the video component. In wired video connections,
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388:
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the L+R and L−R signals, it adds the two signals ( + = 2L) to get the left channel and subtracts ( − = 2R) to get the right channel. Rather than having a
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manner. Removing other analog subcarriers (such as stereo) increases either the audio quality or channels available, the latter making it possible to send non-audio
273:
for the vision-impaired, and bilingual programs), and yet a third hidden one for the studio to communicate with reporters or technicians in the field (or for a
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than in color. In addition, only blue and red are transmitted, with green being determined by subtracting the other two from the luminance and taking the
130:"sub" implies that it has been derived from a carrier, which has been amplitude modulated by a steady signal and has a constant frequency relation to it.
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places the chrominance and luminance signals on separate wires to eliminate subcarrier crosstalk and enhance the signal bandwidth and strength (picture
265:
uses subcarriers on the video that can also carry three audio channels, including one for stereo (same left-minus-right method as for FM), another for
145:, which takes the left channel and "subtracts" the right channel from it — essentially by hooking up the right-channel wires backward (reversing
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used this service to cause people's radio sets to switch over to adverts for commercial vehicles during the morning and evening rush hours
991:
340:
on FM subcarriers. The fidelity of the subcarrier audio was limited compared to the primary FM radio audio channel. The United States
741:
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is also added at a 9% modulation to trigger radios to decode the stereo subcarrier, making FM stereo fully compatible with mono.
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retains the integrated subcarrier signal structure found in the transmitted baseband signal, while
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extra audio (such as radio stations) or low-to-medium-speed data. This is referred to as
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in the FM signal, which is joined at 2% modulation with the mono left+right audio (which
146:
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82:
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along with it, such as album covers, song lyrics, artist info, concert data, and more.
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extra data payload. xRDS has no fixed frequencies for the additional 57 kHz carriers.
432:" name ALERT to automatically trigger radios to tune in for emergency info, even if a
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communications rely on subcarriers transmitted with the video carrier on a satellite
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530:(STLs), not only are the broadcast station's subcarriers transmitted, but other
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Services like these and others on broadcast FM subcarriers are referred to as a
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stations frequently rely on this system. An upgraded version is built into
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149:) and then joining left and reversed-right. The result is modulated with
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978:
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474:, and other devices. Many of the subcarriers were from stations owned by
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156:, more correctly called sum and difference modulation or SDM, at 38
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Many stations use subcarriers for internal purposes, such as getting
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use different subcarrier frequencies, in addition to differences in
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596:-based system), where audio and video data are packaged together (
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results from the state gaming commission via the same technology.
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547:, is also possible over subcarriers, though its role is limited.
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used subcarriers to transmit traffic, gas prices, movie times,
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Stereo broadcasting is made possible by using a subcarrier on
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site to talk back to the studio), or any other use a
49:. Unsourced material may be challenged and removed.
492:subcarriers to transmit digital radio in a fully
179:, the 19 kHz pilot tone provides an in-phase
1253:
436:is playing. While it never really caught on in
683:
656:FM Receiver with subcarrier decoding circuit
662:Chrominance subcarrier phase control system
690:
676:
16:Sideband of a radio frequency carrier wave
503:
336:and similar services were transmitted to
164:50 Hz ~ 15 kHz). A 19 kHz
109:Learn how and when to remove this message
402:
221:part as the main signal, and the color
1254:
1068:
671:
47:adding citations to reliable sources
18:
614:Subsidiary Communications Authority
381:Subsidiary Communications Authority
13:
1069:
550:
363:FM stations in the US (especially
14:
1273:
649:
580:This is now mostly superseded by
342:Federal Communications Commission
214:signals are transmitted with the
1224:
383:(SCA) service by the FCC in the
323:
183:used to reconstruct the missing
23:
34:needs additional citations for
1164:Error detection and correction
664:; United States Patent 3974520
658:; United States Patent 4476581
632:
478:. The technology was known as
398:
1:
625:
428:messages, and has a station "
205:
187:from the 38 kHz signal.
575:multiple channel per carrier
252:broadcast television systems
133:
7:
1237:Comparison of radio systems
607:
488:on FM uses dozens of small
10:
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1210:International broadcasting
1179:FM extended band in Brazil
361:non-commercial educational
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911:
876:
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466:and other information to
367:stations affiliated with
289:might see fit. (See also
271:descriptive video service
230:sees much more detail in
528:studio/transmitter links
1189:Shortwave relay station
1088:Audio signal processing
561:and terrestrial analog
521:transmitter/studio link
1083:Audio data compression
541:Interruptible foldback
504:Telemetry and foldback
412:
1262:Broadcast engineering
1184:Multipath propagation
1007:MPEG-1 Audio Layer II
877:Frequency allocations
752:Frequency allocations
602:MPEG transport stream
406:
373:radio reading service
267:second audio programs
1137:Technical (emission)
559:satellite television
470:navigation devices,
261:For the audio part,
194:, different analog (
43:improve this article
545:remote broadcasting
512:back from a remote
344:(FCC) also allowed
638:The radio station
494:in-band on-channel
413:
407:Subcarries in the
300:In RF-transmitted
279:broadcast engineer
171:Once the receiver
151:suppressed carrier
1249:
1248:
1245:
1244:
1169:FM broadcast band
1076:Technical (audio)
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972:
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338:department stores
320:and brightness).
210:Likewise, analog
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118:
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93:
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1231:Radio portal
1229:
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1205:History of radio
1149:AM expanded band
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949:Commercial radio
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181:reference signal
177:local oscillator
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912:Digital systems
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822:Digital systems
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551:MCPC satellites
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346:betting parlors
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310:composite video
302:composite video
216:black and white
208:
198:) and digital (
192:AM broadcasting
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1123:Kahn-Hazeltine
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1070:Related topics
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650:External links
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600:) in a single
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476:Clear Channel
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446:digital radio
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438:North America
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385:United States
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352:state to get
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324:Private audio
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99:December 2006
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88:
84:
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63:
60: –
59:
55:
54:Find sources:
48:
44:
38:
37:
32:This article
30:
26:
21:
20:
1222:
1021:
706:broadcasting
634:
579:
554:
539:
526:On wireless
525:
507:
484:
472:wristwatches
458:Until 2012,
457:
450:
414:
378:
365:public radio
358:
354:horse racing
327:
306:demodulation
299:
281:at a remote
260:
209:
189:
185:carrier wave
170:
137:
122:
120:
105:
96:
86:
79:
72:
65:
58:"Subcarrier"
53:
41:Please help
36:verification
33:
1154:Cable radio
1097:Technical (
857:DVB-T2 Lite
713:Terrestrial
598:multiplexed
592:or another
570:transponder
514:transmitter
399:Datacasting
283:transmitter
250:) Various
223:chrominance
173:demodulates
1036:DirectBand
1022:Subcarrier
724:modulation
626:References
582:digital TV
480:DirectBand
460:MSN Direct
391:(CRTC) in
287:TV station
275:technician
206:Television
166:pilot tone
123:subcarrier
69:newspapers
1099:AM stereo
958:Sirius XM
951:providers
870:Satellite
584:(usually
563:microwave
537:as well.
510:telemetry
330:satellite
318:sharpness
295:A2 Stereo
269:(such as
236:remainder
228:human eye
219:luminance
196:AM stereo
134:FM stereo
1256:Category
1198:Cultural
1128:Magnavox
1101:formats)
1051:SCA/SCMO
1046:RDS/RBDS
849:HD Radio
839:DRM/DRM+
834:DAB/DAB+
640:Heart FM
608:See also
577:(MCPC).
535:commands
518:wireless
498:metadata
442:European
350:New York
256:encoding
238:. (See:
232:contrast
200:HD Radio
147:polarity
143:stations
140:FM radio
127:sideband
1024:signals
992:AMR-WB+
844:FMeXtra
486:FMeXtra
464:weather
328:Before
314:S-Video
83:scholar
1118:Harris
1113:C-QUAM
1002:HE-AAC
979:Codecs
963:Canada
929:DVB-SH
903:S band
898:L band
884:C band
808:L band
699:Analog
594:MPEG-2
590:DVB-S2
556:Analog
430:format
411:scheme
393:Canada
162:ranges
85:
78:
71:
64:
56:
1108:Belar
934:S-DMB
924:DAB-S
829:CAM-D
742:COFDM
721:Radio
616:(SCA)
586:DVB-S
566:relay
490:COFDM
409:OFDMA
359:Many
334:Muzak
291:NICAM
248:YPbPr
244:YCbCr
125:is a
90:JSTOR
76:books
1056:DARC
1031:AMSS
1012:DRA+
893:band
802:high
701:and
620:xRDS
452:xRDS
421:RBDS
415:The
190:For
62:news
1041:PAD
997:HDC
987:AAC
939:SDR
919:ADR
853:CDR
812:UHF
798:mid
794:low
790:VHF
468:GPS
426:EAS
417:RDS
369:NPR
348:in
297:.)
277:or
263:MTS
240:YIQ
158:kHz
45:by
1258::
800:/
796:/
784:HF
780:SW
774:MF
770:MW
764:LF
760:LW
737:FM
732:AM
604:.
588:,
523:.
482:.
448:.
440:,
434:CD
395:.
332:,
293:,
258:.
246:,
242:,
212:TV
154:AM
121:A
891:u
889:K
814:)
810:(
804:)
792:(
786:)
782:(
776:)
772:(
766:)
762:(
691:e
684:t
677:v
419:/
112:)
106:(
101:)
97:(
87:·
80:·
73:·
66:·
39:.
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