WO1995008906A1 - Digitally controlled analog cancellation system - Google Patents
Digitally controlled analog cancellation system Download PDFInfo
- Publication number
- WO1995008906A1 WO1995008906A1 PCT/US1994/009999 US9409999W WO9508906A1 WO 1995008906 A1 WO1995008906 A1 WO 1995008906A1 US 9409999 W US9409999 W US 9409999W WO 9508906 A1 WO9508906 A1 WO 9508906A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- noise
- analog
- noise canceling
- cancellation
- canceling
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/002—Damping circuit arrangements for transducers, e.g. motional feedback circuits
Definitions
- This invention relates to the use of a digital signal processor (DSP), or other microprocessor to control various adjustable parameters in an analog active cancellation system.
- DSP digital signal processor
- the adjustment of these parameters at calibration time of the system permits the parameters of the analog cancellation system to be matched to the characteristics of the other components used in the system. This adjustment would be necessary when the cancellation electronics are packaged separately from the rest of the cancellation system (e.g. the speakers, microphones, and external gain devices).
- the example application (used for illustrative purposes only), is a headset for emergency vehicles.
- this invention relates to any system that would use a digital means to control and adjust the system parameters of an analog cancellation system.
- the digital system consists of an active noise cancellation controller implementing the "Digital Virtual Earth" algorithm as described in U.S. Patent No.
- the digital syste consists of a general purpose microprocessor and associated input/output circuitry.
- Ti e analog cancellation electronics consist of a "NoiseBuster" circuit as described in a co-filed U.S. application on September 20, 1993, incorporated by reference herein. Setting of the parameters of the analog cancellation system could be accomplished manually in the factory by trained technical personnel using sophisticated instrumentation, but would not be possible for an average user. Further, preset factory values would preclude the separate packaging of the electronics and the rest of the system.
- Figure 1 is a block diagram of a dig i tally controlled analog filter building block.
- Figure 2 is a block diagram of a digitally controlled analog filter.
- Figure 3 is a block diagram of a hybrid noise canceling system.
- Figure 4 is a block diagram of a hybrid noise cancellation system showing the automatic gain setting.
- Figure 5 is a block diagram of a hybrid noise cancellation system showing the automatic equalization setting.
- a digitally controlled analog filter building block 10 consisting of a 16-bit shift register 11 connected to the serial port of the microprocessor 12 in the digital system, the output of which gets stored in a 16-bit latch 13.
- the lower (least significant) bits of this latch are used to set the resistance value of the low pass portion of the filter. This value varies as the digital value sent to the 8-bit C/A 14 is varied.
- the upper (most significant) bits of this latch are used to set the resistance value of the bandpass and highpass portion of the filter. These resistance values vary as the values sent to D/A 15 and D/A 16 vary.
- a complete analog filter is shown utilizing the building block described above (and shown in Figure 1).
- the complete filter 20 consists of the digitally controlled analog filter building block 10, with the gain of the system being adjusted by the two 8-bit D/A's 21 and 22.
- the loop gain determines the overall cancellation effectiveness of the system, it is the primary parameter of interest.
- the gain of the speaker can vary by as much as 2 dB between units, and the gain of the microphone up to 5 dB between units. The adjustment must therefore have a 10 dB range. If the desired cancellation effectiveness is 12 dB, a variation of 1 dB (20%) in the adjusted loop gain yields a variation of 3 dB in the cancellation effectiveness.
- this aspect of the present invention will be described with reference to the accompanying drawings.
- FIG 3 the combination of the digital system is shown combined with the analog cancellation electronics.
- the system uses an analog cancellation system 30 with microphone preamplifier 31, cancellation gain 32, equalizers 33, 34, and 35, output amplifier 36, and audio gain 37.
- System 30 is connected to controller 40 having analog to digital converter (A/D) and filter 41, microprocessor 42, parameter setting digital to analog converter (D/A) 43, and output D/A a filter 44.
- A/D analog to digital converter
- D/A parameter setting digital to analog converter
- a filter 44 output D/A a filter 44.
- predetermined output would be generated by the controller 40 and output through the D/A and filter 43 to the output amplifier 36 resulting in a calibration tone at the headset speaker 38.
- the resulting output f the residual microphone 39 due to the calibration signal would then be amplified by the microphone preamplifier 31, and the amplified signal would be used by the DVE controller to correctly adjust the cancellation gain 32.
- This cancellation gain 32 would be adjusted by the controller via the parameter setting D/A 43.
- this invention could be implemented with the analog cancellation electronics controlled by a DVE controller consisting of a DVE cancellation engine, an A/D to acquire the input samples, and a D/A to generate the output samples.
- a DVE controller consisting of a DVE cancellation engine, an A/D to acquire the input samples, and a D/A to generate the output samples.
- the locations of the poles and zeroes are determined by the values of the resistors, capacitors, and inductors in the circuit. Since the maximum stable cancellation at any particular loop gain is determined by the flatness and delay in the equalized loop, the ability to vary the frequency and damping of poles and zeroes in the filters of the equalizer greatly increases the effectiveness of the active noise cancellation system.
- the digital system would produce a calibration signal to be used to adjust the system parameters of the analog cancellation system.
- predetermined output would be generated by the DVE controller 40 and output through the D/A and filter 44 to the output amplifier 36 resulting in a calibration tone at the headset speaker 38.
- the digital system would first set the two EQ2 equalization stages 34 and 35 for a flat response (since these two stages are strictly used to remove the effects of the analog cancellation electronics and the audio in from the feedback to the digital processor).
- the processor would then iteratively adjust the EQl equalization 33 to obtain the desired level of attenuation in the active band. At the same time, it would avoid a setting which would cause instability.
- This dynamic adjustment of the analog electronics ensures that the cancellation provided by that subsystem is optimized without the need for manual adjustment, and without the need for servicing.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE69434700T DE69434700T2 (en) | 1993-09-20 | 1994-09-02 | DIGITALLY CONTROLLED ANALOG DELETION SYSTEM |
EP94928558A EP0746959B1 (en) | 1993-09-20 | 1994-09-02 | Digitally controlled analog cancellation system |
JP50978595A JP3219770B2 (en) | 1993-09-20 | 1994-09-02 | Silencer |
CA002170026A CA2170026C (en) | 1993-09-20 | 1994-09-02 | Digitally controlled analog cancellation system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/123,928 | 1993-09-20 | ||
US08/123,928 US5440642A (en) | 1993-09-20 | 1993-09-20 | Analog noise cancellation system using digital optimizing of variable parameters |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995008906A1 true WO1995008906A1 (en) | 1995-03-30 |
Family
ID=22411756
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1994/009999 WO1995008906A1 (en) | 1993-09-20 | 1994-09-02 | Digitally controlled analog cancellation system |
Country Status (6)
Country | Link |
---|---|
US (1) | US5440642A (en) |
EP (1) | EP0746959B1 (en) |
JP (1) | JP3219770B2 (en) |
CA (1) | CA2170026C (en) |
DE (1) | DE69434700T2 (en) |
WO (1) | WO1995008906A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2182510A1 (en) * | 2008-10-31 | 2010-05-05 | Austriamicrosystems AG | Active noise control arrangement, active noise control headphone and calibration method |
Families Citing this family (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5732143A (en) | 1992-10-29 | 1998-03-24 | Andrea Electronics Corp. | Noise cancellation apparatus |
US6279099B1 (en) * | 1994-04-29 | 2001-08-21 | Sun Microsystems, Inc. | Central processing unit with integrated graphics functions |
US6278786B1 (en) | 1997-07-29 | 2001-08-21 | Telex Communications, Inc. | Active noise cancellation aircraft headset system |
US6249913B1 (en) | 1998-10-09 | 2001-06-19 | General Dynamics Ots (Aerospace), Inc. | Aircraft data management system |
US6363345B1 (en) | 1999-02-18 | 2002-03-26 | Andrea Electronics Corporation | System, method and apparatus for cancelling noise |
US6594367B1 (en) | 1999-10-25 | 2003-07-15 | Andrea Electronics Corporation | Super directional beamforming design and implementation |
US7016332B2 (en) * | 2000-12-05 | 2006-03-21 | Science Applications International Corporation | Method and system for a remote downlink transmitter for increasing the capacity of a multiple access interference limited spread-spectrum wireless network |
US7061891B1 (en) | 2001-02-02 | 2006-06-13 | Science Applications International Corporation | Method and system for a remote downlink transmitter for increasing the capacity and downlink capability of a multiple access interference limited spread-spectrum wireless network |
EP1386406A4 (en) | 2001-03-30 | 2009-06-03 | Science Applic Int Corp | Multistage reception of code division multiple access transmissions |
US7006461B2 (en) * | 2001-09-17 | 2006-02-28 | Science Applications International Corporation | Method and system for a channel selective repeater with capacity enhancement in a spread-spectrum wireless network |
CA2481629A1 (en) * | 2004-09-15 | 2006-03-15 | Dspfactory Ltd. | Method and system for active noise cancellation |
US7257040B2 (en) * | 2005-09-27 | 2007-08-14 | Macronix International Co., Ltd. | Fast pre-charge circuit and method of providing same for memory devices |
JP4892000B2 (en) * | 2005-09-29 | 2012-03-07 | 本田技研工業株式会社 | System to cancel motor and joint controller dynamics |
US20090136052A1 (en) * | 2007-11-27 | 2009-05-28 | David Clark Company Incorporated | Active Noise Cancellation Using a Predictive Approach |
TWI399101B (en) * | 2008-10-09 | 2013-06-11 | Mao Liang Liu | Acoustic equalizer and pre-calibration equipment |
US8085952B2 (en) * | 2008-11-22 | 2011-12-27 | Mao-Liang Liu | Combination equalizer and calibrator circuit assembly for audio system |
EP2259250A1 (en) | 2009-06-03 | 2010-12-08 | Nxp B.V. | Hybrid active noise reduction device for reducing environmental noise, method for determining an operational parameter of a hybrid active noise reduction device, and program element |
US9818394B2 (en) | 2009-11-30 | 2017-11-14 | Graeme Colin Fuller | Realisation of controller transfer function for active noise cancellation |
CN108452514A (en) * | 2017-02-18 | 2018-08-28 | 饶涛 | A kind of billiard table and application method |
CN112640485B (en) | 2018-08-02 | 2022-02-22 | 杜比实验室特许公司 | Automatic calibration of active noise control system |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4837832A (en) * | 1987-10-20 | 1989-06-06 | Sol Fanshel | Electronic hearing aid with gain control means for eliminating low frequency noise |
US5140640A (en) * | 1990-08-14 | 1992-08-18 | The Board Of Trustees Of The University Of Illinois | Noise cancellation system |
US5146505A (en) * | 1990-10-04 | 1992-09-08 | General Motors Corporation | Method for actively attenuating engine generated noise |
US5216721A (en) * | 1991-04-25 | 1993-06-01 | Nelson Industries, Inc. | Multi-channel active acoustic attenuation system |
US5259033A (en) * | 1989-08-30 | 1993-11-02 | Gn Danavox As | Hearing aid having compensation for acoustic feedback |
US5321759A (en) * | 1992-04-29 | 1994-06-14 | General Motors Corporation | Active noise control system for attenuating engine generated noise |
US5325437A (en) * | 1991-12-27 | 1994-06-28 | Nissan Motor Co., Ltd. | Apparatus for reducing noise in space applicable to vehicle compartment |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57135600A (en) * | 1981-02-17 | 1982-08-21 | Brother Ind Ltd | Listening device |
US4750207A (en) * | 1986-03-31 | 1988-06-07 | Siemens Hearing Instruments, Inc. | Hearing aid noise suppression system |
US5105377A (en) * | 1990-02-09 | 1992-04-14 | Noise Cancellation Technologies, Inc. | Digital virtual earth active cancellation system |
-
1993
- 1993-09-20 US US08/123,928 patent/US5440642A/en not_active Expired - Fee Related
-
1994
- 1994-09-02 WO PCT/US1994/009999 patent/WO1995008906A1/en active IP Right Grant
- 1994-09-02 EP EP94928558A patent/EP0746959B1/en not_active Expired - Lifetime
- 1994-09-02 DE DE69434700T patent/DE69434700T2/en not_active Expired - Fee Related
- 1994-09-02 CA CA002170026A patent/CA2170026C/en not_active Expired - Fee Related
- 1994-09-02 JP JP50978595A patent/JP3219770B2/en not_active Expired - Fee Related
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4837832A (en) * | 1987-10-20 | 1989-06-06 | Sol Fanshel | Electronic hearing aid with gain control means for eliminating low frequency noise |
US5259033A (en) * | 1989-08-30 | 1993-11-02 | Gn Danavox As | Hearing aid having compensation for acoustic feedback |
US5140640A (en) * | 1990-08-14 | 1992-08-18 | The Board Of Trustees Of The University Of Illinois | Noise cancellation system |
US5146505A (en) * | 1990-10-04 | 1992-09-08 | General Motors Corporation | Method for actively attenuating engine generated noise |
US5216721A (en) * | 1991-04-25 | 1993-06-01 | Nelson Industries, Inc. | Multi-channel active acoustic attenuation system |
US5325437A (en) * | 1991-12-27 | 1994-06-28 | Nissan Motor Co., Ltd. | Apparatus for reducing noise in space applicable to vehicle compartment |
US5321759A (en) * | 1992-04-29 | 1994-06-14 | General Motors Corporation | Active noise control system for attenuating engine generated noise |
Non-Patent Citations (1)
Title |
---|
See also references of EP0746959A4 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2182510A1 (en) * | 2008-10-31 | 2010-05-05 | Austriamicrosystems AG | Active noise control arrangement, active noise control headphone and calibration method |
WO2010049241A1 (en) * | 2008-10-31 | 2010-05-06 | Austriamicrosystems Ag | Active noise control arrangement, active noise control headphone and calibration method |
US9779714B2 (en) | 2008-10-31 | 2017-10-03 | Ams Ag | Active noise control arrangement, active noise control headphone and calibration method |
Also Published As
Publication number | Publication date |
---|---|
CA2170026A1 (en) | 1995-03-30 |
EP0746959A4 (en) | 2001-10-17 |
JP3219770B2 (en) | 2001-10-15 |
DE69434700T2 (en) | 2007-02-01 |
JPH08510105A (en) | 1996-10-22 |
EP0746959B1 (en) | 2006-04-12 |
CA2170026C (en) | 2001-01-16 |
DE69434700D1 (en) | 2006-05-24 |
US5440642A (en) | 1995-08-08 |
EP0746959A1 (en) | 1996-12-11 |
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