305:, a DC offset is an undesirable characteristic. It occurs in the capturing of sound, before it reaches the recorder, and is normally caused by defective or low-quality equipment. It results in an offset of the center of the recording waveform that can cause two main problems. Either the loudest parts of the signal will be clipped prematurely since the base of the waveform has been moved up, or inaudible low-frequency distortion will occur. Low-frequency distortion may not be audible in the initial recording, but if the waveform is resampled to a compressed or lossy digital format, such as an MP3, those corruptions may become audible.
412:
398:
36:
226:, for example, a network of resistors is used to apply a small amount of DC to the base terminal of the transistor. The AC signal is applied at the same terminal and is amplified. The bias network is designed to preserve the applied AC signal. Similarly, amplifiers using
281:. Bit errors can occur when a series of 1's create a DC level that charges the coupling capacitor, bringing the signal input down incorrectly to a 0-level. In order to avoid these kinds of bit errors, most
265:. For stored digital signals, subtracting the mean amplitude from each sample will remove the offset. Very low frequencies can look like DC bias but are called "slowly changing DC" or "baseline wander".
261:
capacitor can be used to block or remove it, leaving only the AC component on the other side. In signal processing terms, DC offset can be reduced in real-time by a
119:
234:
also have bias circuits. The operating point of an amplifier greatly affects its characteristics of distortion and efficiency;
557:
57:
488:
codes, as they are often called, have a long history and their application is certainly not confined to recording practice.
332:
526:
258:
242:
100:
504:
72:
430:
223:
245:
or other undesirable change in the operating point of an amplifier. An electrical DC bias will not pass through a
46:
379:
273:
DC-balanced signals are used in communications systems to prevent bit errors when passing through circuits with
435:
79:
53:
235:
227:
455:
363:
86:
290:
254:
348:
286:
68:
285:
are designed to produce DC-balanced signals. The most common classes of DC balanced line codes are
274:
193:
403:
336:
137:
133:
471:
340:
262:
320:
302:
218:
189:
551:
425:
417:
192:
voltage. In contrast, various other non-DC frequencies are analogous to superimposed
93:
459:
355:
344:
222:, the steady state current and voltage on the device when no signal is applied. In
316:
278:
246:
231:
141:
35:
397:
393:
359:
530:
411:
309:
282:
250:
17:
500:
375:
352:
165:
212:
In the design of electronic amplifier circuits, every active device has
213:
475:
383:
161:
29:
238:
are distinguished by the operating point set by the DC bias.
374:
The concept has been extended to any representation of a
168:. A waveform with zero mean or no DC bias is known as a
312:
was used in early tape recorders to reduce distortion.
460:"Performance Assessment of DC-Free Multimode Codes"
60:. Unsourced material may be challenged and removed.
378:and to two-dimensional transformations like the
241:DC offset is usually undesirable when it causes
27:Mean amplitude of a waveform in the time domain
8:
366:can be done solely by changing the DC bias.
315:A DC bias is applied to the control grid of
184:The term originates in electronics, where
120:Learn how and when to remove this message
196:(AC) voltages or currents, hence called
447:
7:
58:adding citations to reliable sources
464:IEEE Transactions on Communications
25:
410:
396:
34:
529:. Aikenamps.com. Archived from
507:from the original on 2016-08-23
45:needs additional citations for
351:(FM), the AC component is the
1:
347:is done with a DC bias. For
333:voltage-controlled oscillator
323:in order to regulate power.
501:"DC offset - Audacity Wiki"
574:
431:Root-mean-square amplitude
224:bipolar transistor biasing
380:discrete cosine transform
436:Root-mean-square voltage
228:field-effect transistors
370:Waveform representation
236:power amplifier classes
456:Kees Schouhamer Immink
364:Frequency-shift keying
291:paired-disparity codes
269:Communications systems
558:Electrical parameters
287:constant-weight codes
255:isolation transformer
349:frequency modulation
335:(VCO), such as in a
136:, when describing a
54:improve this article
339:, selection of the
327:Frequency selection
275:capacitive coupling
194:alternating current
527:"What Is Biasing?"
404:Electronics portal
476:10.1109/26.558690
337:radio transmitter
138:periodic function
134:signal processing
130:
129:
122:
104:
16:(Redirected from
565:
542:
541:
539:
538:
522:
516:
515:
513:
512:
497:
491:
490:
452:
420:
415:
414:
406:
401:
400:
341:center frequency
321:power amplifiers
263:high-pass filter
253:; thus a simple
125:
118:
114:
111:
105:
103:
62:
38:
30:
21:
573:
572:
568:
567:
566:
564:
563:
562:
548:
547:
546:
545:
536:
534:
525:Randall Aiken.
524:
523:
519:
510:
508:
499:
498:
494:
454:
453:
449:
444:
416:
409:
402:
395:
392:
372:
329:
303:audio recording
299:
271:
219:operating point
210:
202:AC coefficients
182:
126:
115:
109:
106:
63:
61:
51:
39:
28:
23:
22:
15:
12:
11:
5:
571:
569:
561:
560:
550:
549:
544:
543:
517:
492:
470:(3): 293–299.
458:(March 1997).
446:
445:
443:
440:
439:
438:
433:
428:
422:
421:
407:
391:
388:
371:
368:
328:
325:
298:
295:
270:
267:
209:
206:
190:direct current
181:
178:
158:DC coefficient
128:
127:
42:
40:
33:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
570:
559:
556:
555:
553:
533:on 2012-02-13
532:
528:
521:
518:
506:
502:
496:
493:
489:
487:
483:
477:
473:
469:
465:
461:
457:
451:
448:
441:
437:
434:
432:
429:
427:
426:Phantom power
424:
423:
419:
418:Energy portal
413:
408:
405:
399:
394:
389:
387:
385:
381:
377:
369:
367:
365:
361:
357:
354:
350:
346:
342:
338:
334:
326:
324:
322:
318:
313:
311:
306:
304:
296:
294:
292:
288:
284:
280:
276:
268:
266:
264:
260:
256:
252:
248:
244:
239:
237:
233:
229:
225:
221:
220:
215:
207:
205:
203:
199:
198:AC components
195:
191:
187:
179:
177:
175:
171:
167:
164:value of the
163:
159:
155:
151:
147:
143:
139:
135:
124:
121:
113:
102:
99:
95:
92:
88:
85:
81:
78:
74:
71: –
70:
66:
65:Find sources:
59:
55:
49:
48:
43:This article
41:
37:
32:
31:
19:
535:. Retrieved
531:the original
520:
509:. Retrieved
495:
485:
481:
479:
467:
463:
450:
373:
356:audio signal
345:carrier wave
330:
317:vacuum tubes
314:
307:
300:
279:transformers
272:
259:series-wired
240:
232:vacuum tubes
217:
211:
208:Applications
201:
197:
188:refers to a
185:
183:
173:
169:
157:
153:
150:DC component
149:
145:
131:
116:
107:
97:
90:
83:
76:
64:
52:Please help
47:verification
44:
18:DC component
482:dc-balanced
360:subcarriers
247:transformer
216:to set its
170:DC balanced
142:time domain
110:August 2012
537:2012-08-16
511:2014-01-30
442:References
283:line codes
176:waveform.
80:newspapers
358:plus any
310:tape bias
251:capacitor
154:DC offset
69:"DC bias"
552:Category
505:Archived
390:See also
382:used in
376:waveform
353:baseband
243:clipping
166:waveform
486:dc-free
343:of the
214:biasing
174:DC free
160:is the
146:DC bias
140:in the
94:scholar
180:Origin
144:, the
96:
89:
82:
75:
67:
331:On a
308:A DC
297:Audio
156:, or
101:JSTOR
87:books
480:The
384:JPEG
289:and
162:mean
73:news
484:or
472:doi
362:.
319:in
301:In
277:or
257:or
249:or
230:or
200:or
172:or
132:In
56:by
554::
503:.
478:.
468:45
466:.
462:.
386:.
293:.
204:.
186:DC
152:,
148:,
540:.
514:.
474::
123:)
117:(
112:)
108:(
98:·
91:·
84:·
77:·
50:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
