Apparatus and method for level-dependent companding for wireless audio noise reduction
First Claim
Patent Images
1. A wireless audio noise reduction system providing wireless communication between an input source and an output device, the wireless audio noise reduction system comprising:
- an encoder comprising;
a variable compressor, the variable compressor receiving a signal derived from the input source through an input device, the variable compressor invoking compression operation above a first input threshold, the compression operation associated with a compression ratio greater than one to one;
a modulator connected to the variable compressor; and
a matching network connected to the modulator, the matching network coupled to a first antenna;
a decoder communicating with the encoder, the decoder comprising;
a signal detector, the signal detector'"'"'s input driven from a second antenna, the second antenna being in wireless communication with the first antenna; and
a variable expander connected to the signal detector, the variable expander invoking expanding operation above a second input threshold, the expanding operation having an expansion ratio greater than one to one.
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Abstract
Apparatus and method that mitigate the noise incurred on a wireless communications path between an encoder and a decoder of a wireless audio noise reduction system that utilizes frequency modulation (FM). The encoder includes a variable compressor that invokes compression whenever the input signal is above a first threshold level. The decoder includes a variable expander that invokes expansion whenever the received signal from the decoder is above a second threshold.
48 Citations
45 Claims
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1. A wireless audio noise reduction system providing wireless communication between an input source and an output device, the wireless audio noise reduction system comprising:
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an encoder comprising;
a variable compressor, the variable compressor receiving a signal derived from the input source through an input device, the variable compressor invoking compression operation above a first input threshold, the compression operation associated with a compression ratio greater than one to one;
a modulator connected to the variable compressor; and
a matching network connected to the modulator, the matching network coupled to a first antenna;
a decoder communicating with the encoder, the decoder comprising;
a signal detector, the signal detector'"'"'s input driven from a second antenna, the second antenna being in wireless communication with the first antenna; and
a variable expander connected to the signal detector, the variable expander invoking expanding operation above a second input threshold, the expanding operation having an expansion ratio greater than one to one. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 17)
a pre-emphasis circuit connected between the variable compressor and the input source.
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4. The wireless audio noise reduction system of claim 1, further comprising:
a high pass filter (HPF) connected between the variable compressor and the input source.
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5. The wireless audio noise reduction system of claim 1, wherein the compression ratio is between three to one and eight to one.
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7. The wireless audio noise reduction system of claim 1, wherein the variable compressor further comprising:
a bias offset circuit, the bias offset circuit reducing a bias difference of the RMS detector and the VCA.
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8. The wireless audio noise reduction system of claim 1, wherein the first antenna is integrated with the wireless audio noise reduction system.
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9. The wireless audio noise reduction system of claim 1, wherein the input device is integrated with the wireless audio noise reduction system.
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10. The wireless audio noise reduction system of claim 1, wherein the input device is selected from the group consisting of a microphone and a recording device.
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11. The wireless audio noise reduction system of claim 1, wherein the input device comprises at least one transducer.
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12. The wireless audio noise reduction system of claim 1, further comprising:
a de-emphasis circuit connected between the variable compressor and the output device.
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13. The wireless audio noise reduction system of claim 1, further comprising:
a low pass filter (LPF) connected between the variable expander and the signal detector.
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14. The wireless audio noise reduction system of claim 1, wherein the expansion ratio is between one to three and one to eight.
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17. The wireless audio noise reduction system of claim 1, wherein the second antenna is integrated with the wireless audio noise reduction system.
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6. A wireless audio noise reduction system providing wireless communication between an input source and an output device, the wireless audio noise reduction system comprising:
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an encoder comprising;
a variable compressor, the variable compressor receiving a signal derived from the input source through an input device, the variable compressor invoking compression operation above a first input threshold, the compression operation associated with a compression ratio greater than one to one, the variable compressor comprising;
a voltage controlled amplifier (VCA), the VCA'"'"'s input driven by the input source;
a root mean square (RMS) detector connected to the VCA; and
a compression ratio and threshold circuit connected to the RMS detector, the compression ratio and threshold circuit'"'"'s output affecting the VCA'"'"'s gain function;
a modulator connected to the variable compressor; and
a matching network connected to the modulator, the matching network coupled to a first antenna; and
a decoder communicating with the encoder, the decoder comprising;
a signal detector, the signal detector'"'"'s input driven from a second antenna, the second antenna being in wireless communication with the first antenna; and
a variable expander connected to the signal detector, the variable expander invoking expanding operation above a second input threshold, the expanding operation having an expansion ratio greater than one to one.
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15. A wireless audio noise reduction system providing wireless communication between an input source and an output device, the wireless audio noise reduction system comprising:
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an encoder comprising;
a variable compressor, the variable compressor receiving a signal derived from the input source through an input device, the variable compressor invoking compression operation above a first input threshold, the compression operation associated with a compression ratio greater than one to one;
a modulator connected to the variable compressor; and
a matching network connected to the modulator, the matching network coupled to a first antenna; and
a decoder communicating with the encoder, the decoder comprising;
a signal detector, the signal detector'"'"'s input driven from a second antenna, the second antenna being in wireless communication with the first antenna; and
a variable expander connected to the signal detector, the variable expander invoking expanding operation above a second input threshold, the expanding operation having an expansion ratio greater than one to one, the variable expander comprising;
a voltage controlled amplifier (VCA), the VCA'"'"'s input driven by the signal detector;
a root mean square (RMS) detector connected to the VCA; and
an expansion ratio and threshold circuit connected to the RMS detector, the expansion ratio and threshold circuit'"'"'s output affecting the VCA'"'"'s gain characteristics. - View Dependent Claims (16)
a bias offset circuit, the bias offset circuit reducing a bias difference of the RMS detector and the VCA.
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18. An encoder for transmitting on a wireless path from an input source to a decoder, the encoder provided an input signal from the input source, the encoder comprising:
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a variable compressor, the variable compressor receiving a signal from the input source through an input device, the variable compressor invoking compression operation above a first input threshold, the compression operation having a compression ratio greater than one to one;
a modulator connected to the variable compressor; and
a matching network connected to the modulator, the matching network coupled to the first antenna. - View Dependent Claims (19, 20, 21, 22, 25, 26, 27, 28)
a pre-emphasis circuit connected between the variable compressor and the input source.
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21. The encoder of claim 18, further comprising:
a high pass filter (HPF) connected between the variable compressor and the input source.
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22. The encoder of claim 18, wherein the compression ratio is between three to one and eight to one.
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25. The encoder of claim 18, wherein the first antenna is integrated with the encoder.
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26. The encoder of claim 18, wherein the input device is integrated with the encoder.
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27. The encoder of claim 18, wherein the input device is selected from the group consisting of a microphone and a recording device.
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28. The encoder of claim 18, wherein the input device comprises at least one transducer.
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23. An encoder for transmitting on a wireless path from an input source to a decoder, the encoder provided an input signal from the input source, the encoder comprising:
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a variable compressor, the variable compressor receiving a signal from the input source through an input device, the variable compressor invoking compression operation above a first input threshold, the compression operation having a compression ratio greater than one to one, the variable compressor comprising;
a voltage controlled amplifier (VCA), the VCA'"'"'s input driven by the input source;
a root mean square (RMS) detector connected to the VCA; and
a compression ratio and threshold circuit connected to the RMS detector, the compression ratio and threshold circuit'"'"'s output affecting the VCA'"'"'s gain function;
a modulator connected to the variable compressor; and
a matching network connected to the modulator, the matching network coupled to the first antenna. - View Dependent Claims (24)
a bias offset circuit, the bias offset circuit reducing a bias difference of the RMS detector and the VCA.
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29. A decoder for receiving a signal from an encoder on a wireless path, the decoder provided a received signal from the encoder, the decoder comprising:
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a signal detector, the signal detector'"'"'s input driven by the received signal from a second antenna; and
a variable expander connected to the signal detector, the variable expander invoking expanding operation above a second input threshold, the expanding operation having an expansion ratio greater than one to one, the variable expander'"'"'s output driving an output device. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
a de-emphasis circuit connected between the variable compressor and the output device.
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32. The decoder of claim 29, further comprising:
a low pass filter (LPF) connected between the variable expander and the signal detector.
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33. The decoder of claim 29, wherein the expansion ratio is between one to three and one to eight.
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34. The decoder of claim 29, wherein the variable expander comprises:
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a voltage controlled amplifier (VCA), the VCA'"'"'s input driven by the signal detector;
a root mean square (RMS) detector connected to the VCA; and
a expansion ratio and threshold circuit connected to the RMS detector, the expansion ratio and threshold circuit'"'"'s output affecting the VCA'"'"'s gain characteristics.
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35. The decoder of claim 34, wherein the variable expander further comprising:
a bias offset circuit, the bias offset circuit reducing a bias difference of the RMS detector and the VCA.
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36. The decoder of claim 29, wherein the second antenna is integrated with the decoder.
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37. A non-wireless audio noise reduction system providing communication over a transmission path from an input source and an output device, the non-wireless audio noise reduction system comprising:
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an encoder comprising;
a variable compressor, the variable compressor receiving a signal derived from the input source through an input device, the variable compressor invoking compression operation above a first input threshold, the compression operation associated with a compression ratio greater than one to one;
a modulator connected to the variable compressor; and
a matching network connected to the modulator, the matching network coupled to the transmission path;
a decoder communicating with the encoder, the decoder comprising;
a signal detector, the signal detector'"'"'s input driven from the transmission path; and
a variable expander connected to the signal detector, the variable expander invoking expanding operation above a second input threshold, the expanding operation having an expansion ratio greater than one to one.
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38. A method for encoding an input signal for transmission on a wireless path in order to support noise reduction associated with the wireless path, the method comprising the steps of:
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variably compressing the input signal in which compression operation is invoked above an input threshold in order to produce a processed signal;
frequency modulating the processed signal in order to produce a modulated signal;
transmitting the modulated signal through a first antenna. - View Dependent Claims (39)
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40. A method for encoding an input signal for transmission on a wireless path in order to support noise reduction associated with the wireless path, the method comprising the steps of:
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adjusting a voltage control input of a voltage controlled amplifier (VCA);
measuring a root mean square (RMS) value of a signal that is derived from the VCA'"'"'s output;
determining a compression ratio and a threshold, the compression ratio and the threshold affecting the VCA'"'"'s gain function;
frequency modulating the processed signal in order to produce a modulated signal;
transmitting the modulated signal through a first antenna; and
transmitting the modulated signal through a first antenna. - View Dependent Claims (41)
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42. A method for decoding a received frequency modulated signal that is received on a wireless path to support noise reduction on the wireless path, comprising the steps of:
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detecting the received signal, the received signal provided by a second antenna; and
variably expanding, in accordance with a signal level, a detected signal as provided by the step of detecting. - View Dependent Claims (43)
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44. A method for decoding a received frequency modulated signal that is received on a wireless path to support noise reduction on the wireless path, comprising the steps of:
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detecting the received signal, the received signal provided by a second antenna;
adjusting a voltage control input of a voltage controlled amplifier (VCA);
measuring a root mean square (RMS) value of a signal that is derived from the VCA'"'"'s output; and
determining an expansion ratio and a threshold, the expansion ratio and the threshold in order to affect the VCA'"'"'s gain function. - View Dependent Claims (45)
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Specification