EP1941489A1 - Verfahren zum schätzen einer übertragungsfunktion mittels eines adaptiven algorithmus und eine vorrichtung zur durchführung des verfahrens - Google Patents
Verfahren zum schätzen einer übertragungsfunktion mittels eines adaptiven algorithmus und eine vorrichtung zur durchführung des verfahrensInfo
- Publication number
- EP1941489A1 EP1941489A1 EP06793981A EP06793981A EP1941489A1 EP 1941489 A1 EP1941489 A1 EP 1941489A1 EP 06793981 A EP06793981 A EP 06793981A EP 06793981 A EP06793981 A EP 06793981A EP 1941489 A1 EP1941489 A1 EP 1941489A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signal
- output signal
- estimated
- error signal
- filter unit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
- G10K11/17813—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
- G10K11/17817—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms between the output signals and the error signals, i.e. secondary path
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
- G10K11/17821—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the input signals only
- G10K11/17825—Error signals
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1783—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
- G10K11/17837—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions by retaining part of the ambient acoustic environment, e.g. speech or alarm signals that the user needs to hear
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17853—Methods, e.g. algorithms; Devices of the filter
- G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1787—General system configurations
- G10K11/17879—General system configurations using both a reference signal and an error signal
- G10K11/17881—General system configurations using both a reference signal and an error signal the reference signal being an acoustic signal, e.g. recorded with a microphone
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/30—Means
- G10K2210/301—Computational
- G10K2210/3023—Estimation of noise, e.g. on error signals
- G10K2210/30232—Transfer functions, e.g. impulse response
Definitions
- the present invention relates to a method according to the preamble of claim 1, an application of the method, a device for carrying out the method and a use of the device.
- Noise sources are increasingly perceived as an environmental impact and are considered to reduce the quality of life.
- noise reduction methods based on the principle of wave cancellation have already been proposed.
- ANC Active Noise Canceling
- the principle of Active Noise Canceling is based on the cancellation of sound waves due to interference. These interferences are generated by one or more electro-acoustic transducers, such as loudspeakers.
- the signal radiated by the electro-acoustic transducers is calculated by means of a suitable algorithm and continuously corrected.
- the basis for the calculation of the signal to be radiated by the electro-acoustic transducers is the information supplied by one or more sensors. These are on the one hand information about the nature of the signal to be minimized. For example, a microphone can be used for this purpose which detects the noise to be minimized. On the other hand, information about the remaining residual signal is needed. Again, microphones can be used.
- LMS Least Mean Square
- FxLMS FxLMS
- NLMS NLMS
- An algorithm for active noise reduction requires information from at least one sensor (for example a microphone), which determines the residual error - also referred to below as an error signal.
- another sensor is provided that provides information about the nature of the signal to be minimized.
- an adaptive noise reduction system requires one or more actuators (for example in the form of loudspeakers) to output the correction signal.
- the information from the sensors must be converted by an analog / digital converter into a suitable format. After being processed by the algorithm, the signal from a Digital / analog converter converted back and transmitted to the actuators.
- the present invention is therefore based on the object of specifying a method for the selective optimization of an adaptive algorithm which does not have the above disadvantages.
- the filter unit is for example of the type band stop, low pass or high pass.
- Bandstoppfilter (bandstop filter, notch filter, English: "notch filter”) are adequately described in the relevant literature.
- a bandstop filter is also referred to as a tunable bandstop filter. This can z. B. in the
- a method is provided which is particularly suitable for the selective optimization of adaptive algorithms, since signals desired by the method according to the invention can optionally be kept away from the adaptive process or be amplified. As a result, a targeted adaptability is obtained in an adaptive Ge Hursreduktionssystem.
- An embodiment of the present invention is that a frequency response in the filter unit is set such that the estimated transfer function deviates from the actual transfer function.
- a further embodiment variant of the present invention consists in that the condition for changing the signal (s) depends on the respective signal.
- Another embodiment of the present invention is that several signals are changed simultaneously using different conditions.
- a further embodiment of the present invention is that the characteristics of the on the Error signal acting notch filter (filter unit) is selected from a number of predefined functions.
- the method according to the invention is particularly suitable for the selective processing of wanted signals in all adaptive systems.
- the subject of the present invention is a device which comprises the following features:
- an adaptive processing unit for determining an estimated output signal, wherein the adaptive processing unit is subjected to an input signal
- At least one filter unit in at least one of the following signal paths:
- a further embodiment variant comprises means for selecting the characteristic of the filter unit from a number of predefined functions for the error signal and for the estimated output signal.
- the filter unit has an adjustable characteristic.
- Device is that means for determining a level or an average power of a signal are provided, these means are operatively connected to the respective filter unit.
- a further embodiment variant of the device according to the invention consists in that the filter unit is contained in the signal path leading to the error signal.
- a further embodiment variant of the device according to the invention is that means for simultaneously changing a plurality of signals are present using different conditions.
- the device according to the invention is particularly suitable for active noise reduction, other uses are by no means excluded.
- the device according to the invention is particularly suitable for the selective processing of wanted signals in all adaptive systems.
- the present invention is based on
- Fig. 1 is a simplified block diagram of the inventive device in a schematic
- Fig. 2 shows a possible frequency response of a filter used in Fig. 1.
- Fig. 1 shows a block diagram of an embodiment of the present invention in a schematic representation. It is a so-called adaptive
- a sensor unit for example a microphone (not shown in FIG. 1), detects the input signal x to be minimized, which is supplied to a transmission path 1 with a transfer function H.
- the transfer function H describes the acoustic behavior of the space R. In addition to the acoustic behavior, H is also present in the transfer function
- the embodiment according to FIG. 1 further comprises a filter 3, which contains a model of the actual transfer function H, of an adaptive processing unit 4 and an addition unit 5, wherein the input signal x next to the microphone unit 1, as described above, both the filter 3 and the adaptive processing unit 4 is acted upon.
- a filter 3 which contains a model of the actual transfer function H, of an adaptive processing unit 4 and an addition unit 5, wherein the input signal x next to the microphone unit 1, as described above, both the filter 3 and the adaptive processing unit 4 is acted upon.
- an error signal e an actual output d of the transmission link 1 and an output y estimated by the filter 3 are added in the adding unit 5, the estimated output y being previously inverted to obtain the deviation of the two outputs d and y.
- the error signal e is applied via the filter ⁇ of the adaptive processing unit 4, which controls the filter 3 such that the error signal e is minimal.
- Fig. 1 corresponds to a system for active noise reduction. It is expressly stated that any number
- Microphone units and speaker units are conceivable without leaving the inventive principle. Also, other converter units are conceivable instead of the microphone units and / or the speaker units.
- “Secondary Path” which is used in active noise reduction systems to simulate system properties.
- “offline” modeling the characteristics of the system, including the room to be monitored, are determined by injecting white noise into the room and detecting it by a sensor - usually a microphone is used for this purpose.
- the signal path leading to the error signal e can now be modified, which is made possible with the aid of a filter unit 6 having a predeterminable frequency response.
- the frequency response of the filter unit 6 is chosen such that those frequency components are suppressed in the error signal e, which should not be eliminated in space 1. Conversely, those frequency components in the error signal e are not to be suppressed by the filter unit 6, which are as far as possible eliminated in the space 1, but at least greatly reduced.
- the configuration of the filter unit 6 then makes sense if either a certain noise needs to be amplified, and thus the active noise reduction system attenuates these frequencies better, or if certain frequencies are to be attenuated, thus making the active noise reduction system less sensitive to these frequencies.
- the engine noise in the vehicle interior is audible (at best, to an advantageous extent).
- the rolling noise of the wheels should be eliminated as possible.
- the frequency response of the filter unit 6 or its transfer function is selected such that the frequency ranges in which the engine noise is contained, are suppressed accordingly.
- these noises are not taken into account in the adaptive setting in the adaptive processing unit 4, thus eliminating the elimination of these noises inside the car.
- the rolling-off noises which are to be completely eliminated must not be changed in the filter unit 6, because only in this way is it possible to eliminate as completely as possible the interior of the car.
- the engine noise a certain background noise, originating from the engine, is often desired in order to give the driver the impression of a powerful engine.
- the engine is no longer audible as possible, but rather the engine should be perceptible to the driver by means of the most advantageous possible acoustic impression.
- the invention is thus not limited to the ability to lower a level of noise by a certain amount in the car interior, but the noise that should be audible at least partially inside the car, can also be modified after a template, so that the sound inside the car as advantageous as possible (as powerful, low frequency or the like.) Is.
- the filter unit 6 can be set in advance to suppress these frequency components. Thus, there is no acoustic extinction inside the vehicle by the activity of the active noise reduction system.
- the present invention is not limited to the application in a vehicle.
- the invention also has a very desirable smoothing effect with rapid
- FIG. 2 shows a possible frequency response of a transfer function w of the filter unit 6. Accordingly, attenuation of the error signal e occurs in a first frequency range 8 and in a second frequency range
- Frequency range 10 is an increase of the error signal e. Accordingly, noises in the first frequency range 8 are not reduced by the active noise reduction system, while the noise in the second frequency range 10 is within the scope of the active Noise reduction system can be eliminated or at least reduced.
- the filter unit 6 is not contained in the signal path leading to the error signal e, but is contained in a signal path carrying the estimated output signal y or in a signal path carrying the actual output signal d.
- a plurality of filter units are provided, in all mentioned signal paths or in at least two of the mentioned signal paths.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Health & Medical Sciences (AREA)
- Audiology, Speech & Language Pathology (AREA)
- General Health & Medical Sciences (AREA)
- Signal Processing (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH17082005 | 2005-10-25 | ||
PCT/EP2006/067107 WO2007048692A1 (de) | 2005-10-25 | 2006-10-05 | Verfahren zum schätzen einer übertragungsfunktion mittels eines adaptiven algorithmus und eine vorrichtung zur durchführung des verfahrens |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1941489A1 true EP1941489A1 (de) | 2008-07-09 |
Family
ID=37560769
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP06793981A Withdrawn EP1941489A1 (de) | 2005-10-25 | 2006-10-05 | Verfahren zum schätzen einer übertragungsfunktion mittels eines adaptiven algorithmus und eine vorrichtung zur durchführung des verfahrens |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP1941489A1 (de) |
WO (1) | WO2007048692A1 (de) |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4473906A (en) * | 1980-12-05 | 1984-09-25 | Lord Corporation | Active acoustic attenuator |
JPH05134685A (ja) * | 1991-09-19 | 1993-05-28 | Toshiba Corp | 能動消音装置 |
DE19842804A1 (de) * | 1998-09-18 | 2000-03-23 | Deutsche Telekom Ag | Verfahren und Vorrichtung zur aktiven Geräuschminderung in offenen Telefonzellen |
-
2006
- 2006-10-05 WO PCT/EP2006/067107 patent/WO2007048692A1/de active Application Filing
- 2006-10-05 EP EP06793981A patent/EP1941489A1/de not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO2007048692A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2007048692A1 (de) | 2007-05-03 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
DE102004026660B4 (de) | Aktives Geräuschsteuersystem | |
EP1853089B2 (de) | Verfahren zum Unterdrücken von Rückkopplungen und zur Spektralerweiterung bei Hörvorrichtungen | |
EP1912471B1 (de) | Verarbeitung eines Eingangssignals in einer Hörhilfe | |
DE102017129097B4 (de) | Schallmaskierungsvorrichtung, Fahrzeug und Schallmaskierungsverfahren | |
DE102013217367A1 (de) | Vorrichtung und verfahren zur raumselektiven audiowiedergabe | |
EP3375204B1 (de) | Audiosignalverarbeitung in einem fahrzeug | |
WO2006111039A1 (de) | Verfahren zur nachbildung eines secondary-path bei einem aktiven geräuschreduktionssystem | |
DE102006047983A1 (de) | Verarbeitung eines Eingangssignals in einem Hörgerät | |
DE112016004394B4 (de) | Heulunterdrückungsvorrichtung | |
DE3733983A1 (de) | Verfahren zum daempfen von stoerschall in von hoergeraeten uebertragenen schallsignalen | |
DE10242700B4 (de) | Rückkopplungskompensator in einem akustischen Verstärkungssystem, Hörhilfsgerät, Verfahren zur Rückkopplungskompensation und Anwendung des Verfahrens in einem Hörhilfsgerät | |
EP1406469B1 (de) | Rückkopplungskompensator in einem akustischen Verstärkungssystem, Hörhilfsgerät, Verfahren zur Rückkopplungskompensation und Anwendung des Verfahrens in einem Hörhilfsgerät | |
DE102019123971B4 (de) | Aktives lärmkompensationssystem und verfahren | |
EP1445761B1 (de) | Einrichtung und Verfahren zum Betrieb von sprachunterstützten Systemen in Kraftfahrzeugen | |
EP1649719B1 (de) | Einrichtung und verfahren zum betrieb von sprachunterstützten systemen in kraftfahrzeugen | |
EP3403260B1 (de) | Verfahren und vorrichtung zur aufbereitung eines verlustbehaftet komprimierten audiosignals | |
EP1077013A1 (de) | Verfahren und einrichtung zum betrieb von sprachunterstützten systemen in kraftfahrzeugen | |
WO2007036443A1 (de) | Verfahren zur aktiven geräuschverminderung und eine vorrichtung zur durchführung des verfahrens | |
EP1941489A1 (de) | Verfahren zum schätzen einer übertragungsfunktion mittels eines adaptiven algorithmus und eine vorrichtung zur durchführung des verfahrens | |
EP1351550A1 (de) | Verfahren zur Anpassung einer Signalverstärkung in einem Hörgerät sowie ein Hörgerät | |
DE102016001593A1 (de) | Verfahren zum Erzeugen eines Gegenschalls für eine Geräuschminderung in einem Kraftfahrzeug | |
EP1800400A1 (de) | Verfahren zur stabilisierung eines adaptiven algorithmus sowie eine vorrichtung zur durchführung des verfahrens | |
DE102022118019A1 (de) | Geräuschreduzierungssystem mit einer Kombinationseinheit, Verfahren zum Betreiben des Systems und Verwendung desselben | |
WO2007048815A2 (de) | Verfahren zur reduktion eines störsignals in einem raum sowie eine anwendung des verfahrens | |
EP4133476A1 (de) | Verfahren, vorrichtung, kopfhörer und computerprogramm zur aktiven störgeräuschunterdrückung |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20080506 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: EXAMINATION IS IN PROGRESS |
|
17Q | First examination report despatched |
Effective date: 20090113 |
|
19U | Interruption of proceedings before grant |
Effective date: 20081211 |
|
19W | Proceedings resumed before grant after interruption of proceedings |
Effective date: 20210601 |
|
PUAJ | Public notification under rule 129 epc |
Free format text: ORIGINAL CODE: 0009425 |
|
32PN | Public notification |
Free format text: MITTEILUNG GEMAESS REGEL 142 EPUE (WIEDERAUFNAHME DES VERFAHRENS NACH REGEL 142 (2) EPUE VOM 10.12.2020) |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: EXAMINATION IS IN PROGRESS |
|
PUAJ | Public notification under rule 129 epc |
Free format text: ORIGINAL CODE: 0009425 |
|
32PN | Public notification |
Free format text: FESTSTELLUNG EINES RECHTSVERLUSTS NACH REGEL 112(1) EPUE (EPA FORM 2524 VOM 13/07/2022) |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20211202 |