Method and apparatus to evaluate audio equipment for dynamic distortions and or differential phase and or frequency modulation effects
OwnerRonald Quaninventor
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Abstract
A system is provided to analyze distortion in an electronic or electromechanical device, which may include testing with one or more modulated signals and/or with one or more demodulators. In one embodiment a change in pitch (or frequency) is measured at an output of the device. One or more signals from a demodulator output may be measured for an amplitude, noise, phase, aliasing, spurious signal, and/or frequency modulation effect.
Claims17
A method for measuring induced spurious signal, induced noise, or missing sideband signal from an audio device, wherein the audio device includes an input terminal and an output terminal, comprising:
- coupling to the input of the audio device a test signal comprising a modulated signal wherein the modulated signal includes a first modulating signal, a first carrier signal, and wherein the first carrier signal is modulated by the first modulating signal;
- the modulated signal having a first frequency variation of the first carrier signal, wherein the first frequency variation of the first carrier signal is determined by the first modulating signal;
- further comprising the modulated signal or test signal includes one or more sideband signals;
- further comprising the modulated signal or test signal includes a folded frequency sideband signal;
- coupling an output signal from the output terminal of the audio device to an input terminal of a measurement system wherein the measurement system includes spectrum analysis and/or distortion analysis to measure for the induced spurious signal, missing sideband signal, and/or induced noise from the output signal of the audio device;
- wherein the audio device comprises a digital audio device, a signal processing device, and/or a device including data compression;
- wherein the data compression included in the digital audio device provides an unwanted amplitude modulation effect on the output signal of the audio device.
A method for measuring induced spurious signal, missing sideband signal, or induced noise from an audio device, wherein the audio device includes an input terminal and an output terminal, comprising:
- coupling to the input of the audio device a test signal comprising a modulated signal wherein the modulated signal includes a first modulating signal, a first carrier signal, and wherein the first carrier signal is modulated by the first modulating signal;
- the modulated signal having a first frequency variation of the first carrier signal, wherein the first frequency variation of the first carrier signal is determined by the first modulating signal;
- further comprising the modulated signal or test signal includes one or more sideband signals;
- further comprising the modulated signal or test signal includes a folded frequency sideband signal;
- coupling an output signal from the output terminal of the audio device to an input terminal of a measurement system wherein the measurement system includes spectrum analysis and/or distortion analysis to measure for the induced spurious signal, missing sideband signal, and/or induced noise from the output signal of the audio device;
- wherein the audio device comprises a digital audio device, a signal processing device, and/or a device including data compression;
- wherein the test signal includes a frequency modulated signal and wherein the output signal of the audio device includes a data compression effect which induces a spurious output signal, a missing sideband output signal, and/or induces an output noise signal.
A method for measuring induced spurious signal, missing sideband signal, or induced noise from an audio device, wherein the audio device includes an input terminal and an output terminal, comprising:
- coupling to the input of the audio device a test signal comprising a modulated signal wherein the modulated signal includes a first modulating signal, a first carrier signal, and wherein the first carrier signal is modulated by the first modulating signal;
- the modulated signal having a first frequency variation of the first carrier signal, wherein the first frequency variation of the first carrier signal is determined by the first modulating signal;
- further comprising the modulated signal or test signal includes one or more sideband signals;
- further comprising the modulated signal or test signal includes a folded frequency sideband signal;
- coupling an output signal from the output terminal of the audio device to an input terminal of a measurement system wherein the measurement system includes spectrum analysis and/or distortion analysis to measure for the induced spurious signal and/or induced noise from the output signal of the audio device;
- wherein the audio device comprises a digital audio device, a signal processing device, and/or a device including data compression;
- further comprising the output signal of the audio device is coupled to an input terminal of a first demodulator and whereby the first demodulator includes an output terminal to provide a first demodulator output signal, wherein the first demodulator output signal is measured for distortion, noise, effect from the missing sideband signal, or spurious signal.
A method for providing a test signal for measuring a spurious sideband signal or missing sideband signals from a device under test with a test signal generator wherein the device under test includes an input terminal and an output terminal, comprising:
- the test signal generator comprising multiple tones including a first tone and a second tone;
- the device under test includes data compression;
- coupling the test generator to the input terminal of the device under test, wherein the output terminal of the device under test provides an output signal which includes a spurious sideband signal associated with one of the multiple tones provided by the test signal generator;
- wherein an amplitude of the spurious sideband or a number of the missing sideband signals is dependent on an amount of data compression in the device under test.
Dependencies are inferred from the claim text.