Low-noise driver and low-noise receiver for self-mix module

• US 10,334,359 B2
• Filed: 07/25/2016
• Issued: 06/25/2019
• Est. Priority Date: 07/26/2015
• Status: Active Grant

• Current Assignee: Vocalzoom Systems Ltd.
• Original Assignee: Vocalzoom Systems Ltd.
• Inventors: Fishman, Tal, Blumkin, Alexander, Ofek, Guy, Keydar, Eytan, Bakish, Tal
• Primary Examiner(s): Laekemariam, Yosef K
• Application Number:
  US15/511,642
• Publication Number:
  US 20180234761A1
• Time in Patent Office: 1,065 Days
• Field of Search: 381 13, 381 711, 381 731, 381 941, 381 945, 381119, 381317, 381355
• CPC Class Codes: G10L 21/0216 characterised by the method used for estimating noise
• CPC Class Codes: H04R 17/02 Microphones
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 23/008 using optical signals for detecting or generating sound
• CPC Class Codes: H04R 23/02 Transducers using more than one principle simultaneously
• CPC Class Codes: H04R 2410/05 Noise reduction with a separate noise microphone
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 2499/15 Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

Optical microphone, laser-based microphone, and laser microphone having reduced-noise components of low-noise components. A laser microphone comprises a laser-diode associated with a low-noise laser driver TX; and a photo-diode associated with a low-noise photo-diode receiver RX. The low-noise laser driver TX supplies a drive current which is a combination of a Direct Current component having a first bandwidth, and an attenuated version of an Alternating Current component having a second, different, bandwidth. Additionally or alternatively, the low-noise photo-diode receiver RX utilizes hardware-based demodulation of the analog signal, and operates to remove a Direct Current component of its output signal prior to digitization.

Claims

1. A system comprising:

a laser microphone comprising;

a self-mix interferometry unit, (i) to transmit via a laser transmitter at least one outgoing laser beam towards a human speaker, and (ii) to receive an optical feedback signal reflected from the human speaker, and (iii) to generate an optical self-mix signal by self-mixing interferometry of the at least one outgoing laser beam and the received optical feedback signal;

wherein the self-mix interferometry unit comprises a laser-diode and a photo-diode;

wherein the laser-diode is associated with a laser driver TX;

wherein the photo-diode is associated with a photodiode receiver;

wherein at least one of the laser driver TX and the photodiode receiver, implements integrally a mechanism for reducing noises;

wherein the laser driver TX comprises;

a Direct Current (DC) Digital-to-Analog Converter (DAC) to generate a Direct Current (DC) having a first bandwidth;

a Modulator DAC to separately generate an Alternating Current (AC) having a second, different, bandwidth;

wherein the laser driver TX generates a drive current to the laser-diode, by utilizing (i) said Direct Current having the first bandwidth, and also (ii) said Alternating Current having the second, different, bandwidth.

2. The system of claim 1,

wherein the laser driver TX comprises:

a summing unit to combine (i) said Direct Current having the first bandwidth, and (ii) said Alternating Current having the second, different, bandwidth;

wherein the laser driver TX utilizes output of said summing unit, to generate said drive current supplied to the laser-diode.

3. The system of claim 1,

wherein the laser driver TX comprises:

an attenuator to attenuate said Alternating Current and to produce attenuated Alternating Current;

a summing unit to combine (i) said Direct Current having the first bandwidth, and (ii) said attenuated Alternating Current having the second, different, bandwidth;

wherein the laser driver TX utilizes output of said summing unit, to generate said drive current supplied to the laser-diode.

4. The system of claim 1,

wherein the laser driver TX comprises:

an attenuator to attenuate said Alternating Current and to produce attenuated Alternating Current, wherein the attenuator comprises at least one of;

(I) a resistor, (II) an opposite-direction current;

a summing unit to combine (i) said Direct Current having the first bandwidth, and (ii) said attenuated Alternating Current having the second, different, bandwidth;

wherein the laser driver TX utilizes output of said summing unit, to generate said drive current supplied to the laser-diode.

5. The system of claim 1,

wherein the laser driver TX comprises:

an attenuator to attenuate said Alternating Current and to produce attenuated Alternating Current, wherein the attenuator comprises a cut filter;

a summing unit to combine (i) said Direct Current having the first bandwidth, and (ii) said attenuated Alternating Current having the second, different, bandwidth;

wherein the laser driver TX utilizes output of said summing unit, to generate said drive current supplied to the laser-diode.

6. The system of claim 1,

wherein the laser driver TX comprises:

an attenuator to attenuate said Alternating Current and to produce attenuated Alternating Current, wherein the attenuator comprises a cut filter;

a summing unit to combine (i) said Direct Current having the first bandwidth, and (ii) said attenuated Alternating Current having the second, different, bandwidth;

wherein said attenuator and said summing unit are an integrated unit;

wherein the laser driver TX utilizes output of said summing unit, to generate said drive current supplied to the laser-diode.

7. The system of claim 1,

wherein a ratio of (i) the first bandwidth of the Direct Current, to (ii) the second bandwidth of the Alternating Current, is smaller than 1/4.

8. The system of claim 1,

wherein a ratio of (i) the first bandwidth of the Direct Current, to (ii) the second bandwidth of the Alternating Current, is smaller than 1/8.

9. The system of claim 1,

wherein the first bandwidth of the Direct Current is in the range of 3.80 to 4.40 KHz;

and

wherein the second bandwidth of the Alternating Current is in the range of 42 to 46 KHz.

10. The system of claim 1,

wherein the first bandwidth of the Direct Current is in the range of 3.0 to 5.0 KHz;

and

wherein the second bandwidth of the Alternating Current is in the range of 69 to 76 KHz.

11. The system of claim 2,

wherein a ratio of (i) the first bandwidth of the Direct Current, to (ii) the second bandwidth of the attenuated Alternating Current, is smaller than 1/5.

12. The system of claim 2,

wherein a ratio of (i) the first bandwidth of the Direct Current, to (ii) the second bandwidth of the attenuated Alternating Current, is smaller than 1/9.

13. The system of claim 2,

wherein the first bandwidth of the Direct Current is in the range of 3.75 to 4.50 KHz;

and

wherein the second bandwidth of the attenuated Alternating Current is in the range of 41 to 47 KHz.

14. The system of claim 2,

wherein the attenuator comprises a Low Pass Filter (LPF) that provides an attenuation factor of:

15. The system of claim 2,

wherein the attenuator comprises a Low Pass Filter (LPF) that provides an attenuation factor of:

H(n)

wherein harmonies in a Fourier expansion of the required signal are F(n),

wherein “

n”

is the number of harmony;

wherein an input node of the LPF receives an input having harmonies according to the following formula;

A(n)=F(n)/H(n)

wherein the harmonies at an output node of the LPF correspond to the required signal A(n).

16. The system of claim 1,

wherein the photo-diode receiver comprises a hardware demodulation unit to perform hardware-based signal demodulation prior to Analog-to-Digital Conversion (ADC).

18. The system of claim 1,

wherein the photo-diode receiver comprises a Direct Current (DC) cancellation unit to remove a Direct Current component of an output signal of said photo-diode receiver, by utilizing a current source with opposite direction prior to performing Trans-Impedance Amplification (TIA).

19. The system of claim 1,

wherein the photo-diode receiver comprises a Direct Current (DC) cancellation unit to remove a Direct Current component of an output signal of said photo-diode receiver, by utilizing a resistor, prior to performing Trans-Impedance Amplification (TIA).

20. The system of claim 1,

wherein the photo-diode receiver comprises a Trans-Impedance Amplification (TIA) unit to amplify a signal that consists of (i) self-mixed signal component, and (ii) modulation component, wherein said signal already excludes any Direct Current (DC) component prior to entering said Trans-Impedance Amplification (TIA) unit.

22. The system of claim 1,

wherein the laser driver TX comprises:

a summing unit to combine (i) said Direct Current having the first bandwidth, and (ii) said Alternating Current having the second, different, bandwidth;

wherein the laser driver TX utilizes output of said summing unit, to generate said drive current supplied to the laser-diode;

wherein the photo-diode receiver comprises a Direct Current (DC) cancellation unit to remove a Direct Current component of an output signal of said photo-diode receiver prior to performing Trans-Impedance Amplification (TIA).

23. The system of claim 1, further comprising at least one acoustic microphone;

wherein the system is a hybrid acoustic-and-optical sensor.

17. A system comprising:

a laser microphone comprising;

a self-mix interferometry unit, (i) to transmit via a laser transmitter at least one outgoing laser beam towards a human speaker, and (ii) to receive an optical feedback signal reflected from the human speaker, and (iii) to generate an optical self-mix signal by self-mixing interferometry of the at least one outgoing laser beam and the received optical feedback signal;

wherein the self-mix interferometry unit comprises a laser-diode and a photo-diode;

wherein the laser-diode is associated with a laser driver TX;

wherein the photo-diode is associated with a photodiode receiver;

wherein at least one of the laser driver TX and the photodiode receiver, implements integrally a mechanism for reducing noises;

wherein the photo-diode receiver comprises a Direct Current (DC) cancellation unit to remove a Direct Current component of an output signal of said photo-diode receiver.

24. The system of claim 17, further comprising at least one acoustic microphone;

wherein the system is a hybrid acoustic-and-optical sensor which is comprised in a device selected from the group consisting of;

a laptop computer, a smartphone, a tablet, a portable electronic device, a vehicular audio system.

21. A system comprising:

a laser microphone comprising;

a self-mix interferometry unit, (i) to transmit via a laser transmitter at least one outgoing laser beam towards a human speaker, and (ii) to receive an optical feedback signal reflected from the human speaker, and (iii) to generate an optical self-mix signal by self-mixing interferometry of the at least one outgoing laser beam and the received optical feedback signal;

wherein the self-mix interferometry unit comprises a laser-diode and a photo-diode;

wherein the laser-diode is associated with a laser driver TX;

wherein the photo-diode is associated with a photodiode receiver;

wherein at least one of the laser driver TX and the photodiode receiver, implements integrally a mechanism for reducing noises;

wherein the photo-diode receiver removes a Direct Current component of an output signal of said photo-diode receiver, prior to digitization of said output signal.