Laser audio preamplifier, volume control, and multiplexer

• US 7,657,041 B1
• Filed: 05/19/2005
• Issued: 02/02/2010
• Est. Priority Date: 05/19/2005
• Status: Expired due to Fees

• Current Assignee: Jimmy Ko
• Original Assignee: Jimmy Ko
• Inventors: Ko, Jimmy
• Primary Examiner(s): Mei; Xu
• Application Number:
  US11/132,770
• Time in Patent Office: 1,720 Days
• Field of Search: 381/77, 381/79, 381/111, 381/113, 381/116, 381/118, 381/120, 381/124, 359/337, 359/337.1, 359/337.13, 359/337.4, 359/285, 359/286, 398/25, 398/33, 398115-116, 398132-134, 398140-142
• US Class Current: 381/120
• CPC Class Codes: H03F 3/087 with IC amplifier blocks H03F3/085 takes precedence
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04S 7/30 Control circuits for electronic adaptation of the sound field

Abstract

A fiber optical audio preamplifier receives audio signals from an audio source, amplifies the audio signals, and transfers the signals to a power amplifier. The fiber optical audio preamplifier has at least one first signal converter. Each first signal converter acquires one audio signal from one audio source and converts the audio signal to a modulated light signal. At least one fiber optic volume control device that includes a variable optical attenuator that is connected to receive the modulated light signal. A control signal for sets an attenuation factor of the variable optical attenuator for attenuating the modulated light signal to control volume of the audio signal. One second signal converter is in communication with each fiber optic volume control device to receive the attenuated modulated light signal and demodulate the attenuated modulated light signal to recover the audio signal for transmission to the power amplifier.

Claims

1. A fiber optical analog signal preamplifier that receives at least one analog signal from a plurality of analog sources, amplify said analog signals and transmit said analog signals to a power amplifier, said fiber optical analog preamplifier comprising:

a plurality of first signal converters, each first signal converter acquiring said analog signal from each analog source and modulating a light signal to generate a modulated light signal;

a plurality of fiber optic amplitude control devices, each fiber optic amplitude control device comprising a variable optical attenuator connected to receive said modulated light signal from at least one of said first signal converters, said variable optical attenuator receiving a control signal for setting an attenuation factor of said variable optical attenuator to attenuate said modulated light signal to control amplitude of said analog signal; and

a plurality of second signal converters, said second signal converter in communication with said fiber optic amplitude control device to receive said attenuated modulated light signal and convert said attenuated modulated light signal to an electrical signal and from said electrical signal, recover said analog signal for transmission to said power amplifier; and

at least one multiplexer in communication with two or more of said first signal converters to receive said modulated light signals from each of said signals converters, said multiplexer receiving a first selection signal that selects which of said modulated light signals of the signal converters are to be transmitted to said fiber optic amplitude control device.

2. The fiber optical analog preamplifier of claim 1 further comprising:

at least one first analog connector, said first analog connector connected to receive said analog signal for transfer to said first signal converter.

3. The fiber optical analog preamplifier of claim 1 further comprising:

at least one second analog connector, said first analog connector connected to receive said demodulated analog signal for transfer to said power amplifier.

4. The fiber optical analog preamplifier of claim 1 further comprising:

at least one demultiplexer, each demultiplexer in communication with at least two of said fiber optic amplitude control devices to receive said attenuated modulated light signal from each of said fiber optic amplitude control devices, said de-multiplexer receiving a second selection signal that selects which of said second signal converters to which said attenuated modulated light signals from said fiber optic amplitude control device is to be transferred.

5. The fiber optical analog preamplifier of claim 4 further comprising:

a preamplifier controller in communication with said fiber optic amplitude control devices, said multiplexers, and said de-multiplexers to provide said control signal for transmitting said attenuation factor, said first selection signal for selecting said modulated signals, said second selection signal for selecting said second converter to which said attenuated modulated light signal is to be transferred.

6. The fiber optical analog preamplifier of claim 2 wherein said first analog connector is selected from a set of analog connectors consisting of an RCA audio connector, a BNC coaxial connector, and an XLR audio connector.

7. The fiber optical analog preamplifier of claim 3 wherein said second analog connector is selected from a set of analog connectors consisting of an RCA audio connector, a BNC coaxial connector, and an XLR audio connector.

8. The fiber optical analog preamplifier of claim 1 wherein each of the first signal converters comprises:

a modulator that receives said analog signal and converts it to a conversion current proportional to analog signal; and

an electron-to-light converter in communication with the modulator to receive said conversion current to generate said modulated light signal.

9. The fiber optical analog preamplifier of claim 7 wherein each of said electron-to-light converters is a light emitting diode or a laser diode.

10. The fiber optical analog preamplifier of claim 1 wherein each of said second signal converters comprises:

a light-to-electron converter to receive said attenuated modulated light signal and convert said attenuated modulated light signal to a current that varies with said modulated carrier signal;

a demodulator in communication with the light-to-electron converter to receive said current, said demodulator removing said carrier signal to reconvert said analog signal for transfer to said power amplifier.

11. The signal fiber optical analog preamplifier of claim 9 wherein each of the light-to-electron converter is selected from the group of light-to-electron converters consisting of photoresistors, phototransistors, and photodiodes.

12. The fiber optical analog preamplifier of claim 1 wherein said analog signal is an audio signal.

13. A fiber optical audio preamplifier that receives at least one audio signal from a plurality of audio source, amplify said audio signals and transmit said audio signals to a power amplifier, said fiber optical audio preamplifier comprising:

a plurality of first signal converters, each first signal converter acquiring one audio signal from one audio source and said audio signal modulating a light signal to generate a modulated light signal;

a plurality of fiber optic volume control device, each fiber optic volume control device comprising a variable optical attenuator connected to receive said modulated light signal from at least one of said first signals converters, said variable optical attenuator receiving a control signal for setting an attenuation factor of said variable optical attenuator to attenuate said modulated light signal to control volume of said audio signal; and

a plurality of second signal converters, each of said second signal converters in communication with one of said fiber optic volume control devices to receive said attenuated modulated light signal and demodulate and convert said attenuated modulated light signal to an electrical signal and from said electrical signal, recover said audio signal for transmission to said power amplifier; and

at least one multiplexer in communication with two or more of said first signal converters to receive said modulated light signals from each of said signals converters, said multiplexer receiving a first selection signal that selects which of said modulated light signals of the signal converters are to be transmitted to said fiber optic volume control device.

14. The fiber optical audio preamplifier of claim 13 further comprising:

at least one first audio connector, said first audio connector connected to receive said audio signal for transfer to said first signal converter.

15. The fiber optical audio preamplifier of claim 13 further comprising:

at least one second audio connector, said first audio connector connected to receive said demodulated audio signal for transfer to said power amplifier.

16. The fiber optical audio preamplifier of claim 13 further comprising:

at least one demultiplexer, each demultiplexer in communication with one of said fiber optic volume control devices to receive said attenuated modulated light signal from said fiber optic volume control devices, said de-multiplexer receiving a second selection signal that selects which of said second signal converters to which said attenuated modulated light signals from said fiber optic volume control device is to be transferred.

17. The fiber optical audio preamplifier of claim 16 further comprising:

a preamplifier controller in communication with each of said fiber optic volume control devices, said multiplexers, and said de-multiplexers to provide said control signal for transmitting said attenuation factor, said first selection signal for selecting said modulated signals, said second selection signal for selecting said second converter to which said attenuated modulated light signal is to be transferred.

18. The fiber optical audio preamplifier of claim 14 wherein said first audio connector is selected from a set of audio connectors consisting of an RCA audio connector, a BNC coaxial connector, and an XLR audio connector.

19. The fiber optical audio preamplifier of claim 15 wherein said second audio connector is selected from a set of audio connectors consisting of an RCA audio connector, a BNC coaxial connector, and an XLR audio connector.

20. The fiber optical audio preamplifier of claim 13 wherein each of the first signal converters comprises:

a modulator that receives said audio signal and converts it to a conversion current proportional to said audio signal; and

an electron-to-light converter in communication with the modulator to receive said conversion current to generate said modulated light signal.

21. The fiber optical audio preamplifier of claim 20 wherein said electron-to-light converter is a light emitting diode or a laser diode.

22. The fiber optical audio preamplifier of claim 13 wherein each of said second signal converters comprises:

a light-to-electron converter to receive said attenuated modulated light signal and convert said attenuated modulated light signal to a current that varies with said modulated carrier signal;

a demodulator in communication with the light-to-electron converter to receive said current, said demodulator removing said carrier signal to reconvert said audio signal for transfer to said power amplifier.

23. The signal fiber optical audio preamplifier of claim 22 wherein each of the light-to-electron converters is selected from the group of light-to-electron converters consisting of photoresistors, phototransistors, and photodiodes.

24. A method for optically preamplifying a plurality of one audio signals that are received from a plurality of audio sources, amplifying said audio signals and transmitting said audio signals to a power amplifier, said method for optically preamplifying audio signals comprising the steps of:

acquiring each of said audio signals from said audio sources;

modulating light signals with each of said audio signals to generate modulated light signals;

receiving a first selection signal containing a selection of said modulated light signals; and

selecting one said modulated light signals for optical adjustment of said volume;

optically adjusting volume of said selected audio signal by the steps of providing a variable optical attenuator,

connecting said variable optical attenuator to receive said modulated light signal, and

connecting said variable optical attenuator to receive a control signal for setting an attenuation factor of said variable optical attenuator to attenuate said modulated light signal to control volume of said audio signal;

converting said attenuated modulated light signal to a modulated carrier signal; and

demodulating said modulated carrier to recover said audio signal;

transmitting said demodulated audio signal to said power amplifier.

25. The method for optically preamplifying at least one audio signal of claim 24 wherein acquiring said audio signal comprises the step of:

providing at least one first audio connector, said first audio connector connected to acquire said audio signal.

26. The method for optically preamplifying at least one audio signal of claim 24 wherein acquiring said audio signal comprises the step of:

providing at least one second audio connector, said first audio connector connected to transmit said demodulated audio to said power amplifier.

27. The method for optically preamplifying at least one audio signal of claim 24 wherein converting said attenuated modulated light signal is accomplished by a second signal converter.

28. The method for optically preamplifying at least one audio signal of claim 24 further comprising the steps of:

receiving a second selection signal that selects which of said second signal converters to which said attenuated modulated light signals from said fiber optic volume control device is to be transferred; and

transferring said attenuated modulated light signal to a selected second signal converter based on said second selection signal.

29. The method for optically preamplifying at least one audio signal of claim 28 further comprising the step of:

generating said attenuation factor, said first selection signal for selecting said modulated signals, said second selection signal for selecting said second converter to which said attenuated modulated light signal is to be transferred.

30. The method for optically preamplifying at least one audio signal of claim 25 wherein said first audio connector is selected from a set of audio connectors consisting of an RCA audio connector, a BNC coaxial connector, and an XLR audio connector.

31. The method for optically preamplifying at least one audio signal of claim 26 wherein said second audio connector is selected from a set of audio connectors consisting of an RCA audio connector, a BNC coaxial connector, and an XLR audio connector.

32. The method for optically preamplifying at least one audio signal of claim 24 wherein converting each of said audio signals to modulated light signals is accomplished by a first signal converter, wherein said first signal converter comprises:

a modulator that receives said audio signal and converts it to a conversion current proportional to said analog signal; and

an electron-to-light converter in communication with the modulator to receive said conversion current to generate said modulated light signal.

33. The method for optically preamplifying at least one audio signal of claim 32 wherein said electron-to-light converter is a light emitting diode or a laser diode.

34. The method for optically preamplifying at least one audio signal of claim 27 wherein said second signal converter comprises:

a light-to-electron converter to receive said attenuated modulated light signal and convert said attenuated modulated light signal to a current that varies with said modulated carrier signal;

a demodulator in communication with the light-to-electron converter to receive said current, said demodulator removing said carrier signal to reconvert said audio signal for transfer to said power amplifier.

35. The method for optically preamplifying at least one audio signal of claim 34 wherein the light-to-electron converter is selected from the group of light-to-electron converters consisting of photoresistors, phototransistors, and photodiodes.