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EP-4736472-A1 - METHODS FOR EXTRACTING A DESIRED SIGNAL FROM UNDESIRED SIGNALS USING STEREO AUDIO DEVICES

EP4736472A1EP 4736472 A1EP4736472 A1EP 4736472A1EP-4736472-A1

Abstract

A system and method for isolating a desired signal in the presence of undesired stereo audio signals, are presented. The disclosed embodiments provide a receiver that receives the desired and undesired signals and a modified bridge arrangement comprising a real branch having a fixed impedance level and a virtual branch having an adjustable impedance level. The combined desired and undesired signals are routed to the real branch to provide a first voltage signal and the undesired signal is routed to the virtual branch to provide a second voltage signal. The second impedance level of the virtual branch is dynamically adjusted to match the first impedance level of the real branch, such that a difference between the first and second voltage signals results in the cancellation of the undesired stereo audio signals such that the desired signal remains isolated.

Inventors

  • MENDES DA COSTA JUNIOR, Carlos Antonio
  • GEORGY, Mark George Azmy Beshay

Assignees

  • Ohmic Technologies Inc.

Dates

Publication Date
20260506
Application Date
20240629

Claims (20)

  1. 1. A system for isolating a desired signal for analysis within the presence of an undesired audio signal, comprising: a receiver configured to receive and forward the desired signal and the undesired audio signals; a bridge arrangement communicatively-coupled to the receiver and configured to receive and process the desired signal and the undesired audio signal, the bridge arrangement comprising a first branch containing a resistor-inductor segment having a first impedance level and a second branch containing an adjustable resistor-capacitor segment having an adjustable second impedance level; wherein, the desired and undesired signals are routed to the first branch to comprise a V p voltage signal and the undesired stereo signals are routed to the second branch to comprise a V n voltage signal; and wherein, the second impedance level of the second branch is dynamically adjusted to match the first impedance level of the first branch, such that a difference between the voltage signals Vp - Vn results in the cancellation of the undesired stereo audio signals such that the desired signal remains isolated for further processing.
  2. 2. The system of claim 1, wherein the resistor-inductor and the variable resistor-capacitor segments include an input one-way buffer to prevent reduction of the desired signal.
  3. 3. The system of claim 2, wherein the input one-way buffer comprises an amplifier.
  4. 4. The system of anyone of claims 1 to 3, wherein the dynamic adjustment of the variable resistor-capacitor segment is performed by a control loop comprising: a first voltage reference tone VREF and a second voltage reference tone VREF-90 orthogonal to the first reference tone, the first and second voltage reference tones VREF, VREF-90 corresponding to the Vp and Vn signal voltages; a subtractor element configured to determine the voltage difference Vp - Vn, amplify and forward the result of the amplified voltage difference signal; a first filter configured to isolate the amplified voltage difference Vp - Vn signal; a mixer arrangement configured to mix the isolated amplified voltage difference Vp - Vn signal with the first voltage reference tone VREF and a second voltage reference tone VREF-90 to determine in-phase and out-of-phase voltage signals; an in-phase feedback controller configured to receive the in-phase voltage signal and generate a feedback voltage signal Vr; and an out-of-phase feedback controller configured to receive the out-of-phase voltage signal and generate a feedback voltage signal Vi; wherein the feedback voltages signals Vr and Vi are forwarded to the variable resistorcapacitor segment to adjust the variable resistance values and match the first impedance level of the resistor-inductor segment to nullify the undesired audio signal and isolate the desired signal Vde sired-
  5. 5. The system of claim 4, further comprising an analog-to-digital converter (ADC) configured to digitize the desired signal Vdesired and forward the digital Vdesired values for further processing.
  6. 6. The system of anyone of claims 1 to 3, wherein the dynamic adjustment of the variable resistor-capacitor segment is performed by a control structure comprising: a first voltage reference tone VREF corresponding to the V p and V n signal voltages; a subtractor element configured to determine the voltage difference V p - V n , and forward the result of the voltage difference signal; a first filter configured to isolate the voltage difference V p - V n signal; a phase and amplitude detector (PAD) configured to output a signal indicative of the phase and amplitude differences between the V p and V n signal voltages; and a look-up table configured to store the outputted phase and amplitude differences and output feedback voltages signals Vr and Vi; wherein the feedback voltages signals Vr and Vi are forwarded to the variable resistorcapacitor segment to adjust the variable resistance values and match the first impedance level of the resistor-inductor segment to nullify the undesired audio signal and isolate the desired signal Vde sired-
  7. 7. The system of claim 6, further comprising an analog-to-digital converter (ADC) configured to digitize the Vdesired signal and forward the digital Vdesired values for further processing.
  8. 8. The system of anyone of claims 1 to 7, wherein the configuration is implemented to operate as multi-band AC bridge (MBACB) for isolating the desired signal within a single frequency band- of-interest or across multiple frequency bands-of-interest.
  9. 9. The system of anyone of claims 1 to 3, wherein the dynamic adjustment of the variable resistor-capacitor segment is performed by a digital control structure comprising: a first voltage reference tone VREF corresponding to the V p and V n signal voltages; a second voltage signal Vin containing the VREF and the undesired signal; a first filter configured to filter the Vin voltage signal; a second filter configured to filter the V p voltage signal; an analog-to-digital converter (ADC) configured to digitize the Vin and V p signals into Vin and V p values, respectively; a digital adaptive filter comprising operating digital coefficients representative of impedance levels for the second branch, the digital adaptive filter configured to receive the Vin and V p values to generate a V n value that matches the V p value; a subtractor element configured to calculate the difference between the V p and Vn values to cancel the undesired signal Vundesired and isolate the desired signal Vdesired.
  10. 10. The system of claim 8, wherein the MBACB comprises: a right speaker channel containing: a right first branch voltage signal V P R representing the V p voltage signal for the right speaker channel; a right first branch fixed impedance level; a right second branch voltage signal VnR representing the V n voltage signal for the right speaker channel; and a right second branch adjustable impedance level; a left speaker channel containing: a left first branch voltage signal V P L representing the V p voltage signal for the left speaker channel; a left first branch fixed impedance level; a left second branch voltage signal VnL representing the Vn voltage signal for the left speaker channel; and a left second branch adjustable impedance level; wherein, the second branch impedance levels of the right and left speaker channels are dynamically adjusted to match the corresponding first branch impedance levels of the right and left speaker channels, and wherein, the VnR signal is subtracted from the V P R signal operation to cancel the right channel undesired signals and isolate the right channel desired signals and the VnL signal is subtracted from the V P L signal to cancel the left channel undesired signals and isolate the left channel desired signals.
  11. 11. A method for isolating a desired signal for analysis within the presence of an undesired audio signal, comprising: receiving, by a receiver, the desired signal and the undesired audio signals; receiving, by a bridge arrangement that is communicatively-coupled to the receiver, the desired signal and the undesired audio signals, the modified Maxwell-Wien Bridge arrangement comprising a first branch containing a resistor-inductor segment having a first impedance level and a second branch containing an adjustable resistor-capacitor segment having an adjustable second impedance level; routing the desired and undesired stereo signals to the first branch to comprise a V p voltage signal and routing the undesired stereo signal to the second branch to comprise a V n voltage signal; and dynamically adjusting, the second impedance level of the second branch to match the first impedance level of the first branch, such that a difference between the voltage signals V p - V n results in the cancellation of the undesired audio signal such that the desired signal remains isolated for further processing.
  12. 12. The method of claim 11, further comprising incorporating an input one-way buffer to the resistor-inductor and the variable resistor-capacitor segments to prevent reduction of the desired signal.
  13. 13. The method of claim 11 or 12, further comprising digitizing, by an analog-to-digital converter (ADC), the Vdesired signal and forward the digital Vdesired values for further processing.
  14. 14. The method of anyone of claims 11 to 13, wherein the dynamic adjustment of the variable resistor-capacitor segment comprises: applying a first voltage reference tone VREF and a second voltage reference tone VREF-90 orthogonal to the first reference tone, the first and second voltage reference tones VREF, VREF-90 corresponding to the Vp and Vn signal voltages; determining a voltage difference Vp - Vn and amplifying the voltage difference result; isolating, by a first filter, the amplified voltage difference Vp - Vn signal; mixing the isolated amplified voltage difference Vp - Vn signal with the first voltage reference tone VREF and a second voltage reference tone VREF-90 to determine in-phase and out-of- phase voltage signals; receiving the in-phase voltage signal and generating a feedback voltage signal Vr; receive the out-of-phase voltage signal and generating a feedback voltage signal Vi; and forwarding the feedback voltages signals Vr and Vi to the variable resistor-capacitor segment and adjusting the variable resistance values to match the first impedance level of the resistor-inductor segment to nullify the undesired audio signal and isolate the desired signal.
  15. 15. The method of claim 14, further comprising digitizing the desired signal Vdesired and forwarding the digital Vdesired values for further processing.
  16. 16. The method of anyone of 11 to 13, wherein the dynamic adjustment of the variable resistorcapacitor segment comprises: applying a first voltage reference tone VREF corresponding to the V p and V n signal voltages; determining a voltage difference V p - V n ; isolating, by a first filter, the voltage difference V p - V n signal; outputting, by a phase and amplitude detector (PAD), a signal indicative of the phase and amplitude differences between the V p and V n signal voltages; storing, by a look-up table, the outputted phase and amplitude differences and outputting feedback voltages signals Vr and Vi; and forwarding, the feedback voltages signals Vr and Vi to the variable resistor-capacitor segment to adjust the variable resistance values and match the first impedance level of the resistorinductor segment to nullify the undesired audio signal and isolate the desired signal Vdesired.
  17. 17. The method of claim 16, further comprising digitizing the desired signal Vdesired and forwarding the digital Vdesired values for further processing.
  18. 18. The method of anyone of claims 11 to 17, further comprising implementing a multi-band AC bridge (MBACB) for isolating the desired signal within a single frequency band-of-interest or across multiple frequency bands-of-interest.
  19. 19. The method of anyone of 11 to 13, wherein the dynamic adjustment of the variable resistorcapacitor segment comprises: applying a first voltage reference tone VREF corresponding to the V p and V n signal voltages; applying a second voltage signal Vin containing the VREF and the undesired signal; filtering, by a first filter, the Vin voltage signal; filtering, by a second filter, the V p voltage signal; digitizing, by an analog-to-digital converter (ADC), the Vin and V p signals into Vin and V p digital values, respectively; receiving, by a digital adaptive filter, the Vin and V p digital values to generate a V n value that matches the V p value; calculating a difference between the V p and Vn values to cancel the undesired signal Vundesired and isolate the desired signal Vdesired.
  20. 20. The method of claim 18, wherein the implementation of the multi-band AC bridge (MBACB) comprises: implementing a right speaker channel comprising: providing a right first branch voltage signal V P R representing the V p voltage signal for the right speaker channel; providing a right first branch fixed impedance level; providing a right second branch voltage signal VnR representing the Vn voltage signal for the right speaker channel; and providing a right second branch adjustable impedance level; implementing a left speaker channel comprising: providing a left first branch voltage signal V P L representing the V p voltage signal for the left speaker channel; providing a left first branch fixed impedance level; providing a left second branch voltage signal VnL representing the V n voltage signal for the left speaker channel; and providing a left second branch adjustable impedance level; dynamically adjusting the second branch impedance levels of the right and left speaker channels to match the corresponding first branch impedance levels of the right and left speaker channels, and subtracting the VnR signal from the V P R signal to cancel the right channel undesired signals and isolate the right channel desired signals and subtracting the VnL signal from the V P L signal to cancel the left channel undesired signals and isolate the left channel desired signals.

Description

METHODS FOR EXTRACTING A DESIRED SIGNAL FROM UNDESIRED SIGNALS USING STEREO AUDIO DEVICES CROSS-REFERENCE TO RELATED APPLICATIONS [01] The present application claims priority to United States Provisional Patent Application No. 63/524,528, filed Jun. 30, 2023 entitled “Methods for Signal Extraction Using Stereo Audio Devices”, which is incorporated by reference herein in its entirety. BACKGROUND [02] Stereo audio devices are electronic devices that produce sound from two or more separate channels, providing a more immersive and realistic listening experience. The use of stereo audio has become prevalent in various fields, including music, movies, gaming, and virtual reality. Stereo audio devices rely on the principle of binaural hearing, which refers to the ability of the human ear to localize sound based on differences in the time and intensity of sound waves that reach each ear. By using two or more separate channels, stereo audio devices can replicate this effect, creating the impression of sounds coming from different directions and distances. For example, stereo audio devices include headphones and hearing aids. [03] First, headphones have been a popular audio accessory for decades, primarily used for personal audio entertainment such as music, podcasts, and audiobooks. However, in recent years, advancements in technology have led to the integration of additional features and functionalities, turning headphones into a versatile multi-purpose device. [04] One of the advancements in headphones technology is noise cancellation. Broadly, noise cancellation headphones are designed to reduce external noise, providing an immersive audio experience. This technology has become increasingly popular in recent years, particularly for users in noisy environments such as commuters or office workers. Another advancement in headphones technology is the integration of voice assistants such as Alexa™ and Siri™. With this feature, users can interact with their headphones to perform tasks such as making phone calls, sending messages, setting reminders, and more, all through voice commands. In addition to audio playback and voice assistance, headphones can also incorporate health monitoring functionalities. This technology allows the headphones to monitor and track the user's body/health metrics such as heartbeats, breathing rates/patterns, tapping, blood pressure, and even perform user authentication/identification with the use of echo signals for example, to enable users to maintain an active and healthy lifestyle. [05] Second, hearing aids are small electronic devices worn in or behind the ear to amplify sound. Over the years, hearing aid technology has undergone advancements, resulting in a wide range of devices with different features and functionalities. [06] One of the advancements in hearing aid technology is the miniaturization of components, making hearing aids smaller and more discreet. Additionally, hearing aids have become more “intelligent” and can adapt to different sound environments, adjusting the sound output to match the user's specific needs. For example, some hearing aids can reduce background noise or enhance speech sounds, making conversations easier to follow. Another feature of modern hearing aids is connectivity. Hearing aids can now connect wirelessly to smartphones, televisions, and other audio devices, allowing users to stream audio directly to their hearing aids. This feature makes it easier for users to listen to phone calls, music, or television without the need for external speakers or headphones. Additionally, many hearing aids now come with rechargeable batteries, eliminating the need to replace disposable batteries frequently. This feature is not only more convenient but also more environmentally friendly. SUMMARY [07] Developers have devised methods and devices for overcoming at least some drawbacks present in prior art solutions. [08] Developers have realized that adding new features and functionalities to stereo audio devices, such as headphones, for example, comes at a cost. This extra cost is often related to at least one of power consumption, price, and size. This is due to the need for integration of specialized sensors because headphones drivers are used as an output device, where an electrical signal is converted to an audio signal. Nonetheless, headphones drivers can simultaneously be used as an output and an input device, thus eliminating the need for extra sensors to enable, for example, the previously mentioned features. [09] In at least some embodiments of the present technology, there are provided methods and systems to turn regular headphones, headsets, earbuds, and/or hearing aids into “smart” devices, without the addition of extra sensors, to enable features, such as, but not limited to, user authentication, touch gesture control, and the extraction of biometric data. At least some methods and systems may allow enabling stereo music output while also providing the fe