Method and detector of loudspeaker diaphragm excursion
AssigneeAnalog Devices Global
InventorsRobert Adams, Kim Spetzler Berthelsen
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Abstract
The present invention relates in one aspect to a method of detecting diaphragm excursion of an electrodynamic loudspeaker. The method comprises steps of generating an audio signal for application to a voice coil of the electrodynamic loudspeaker and adding a high-frequency probe signal to the audio signal to generate a composite drive signal. The method further comprises a step of applying the composite drive signal to the voice coil through an output amplifier and detecting a modulation level of a probe signal current flowing through the voice coil.
Claims29
A method of detecting diaphragm excursion of an electrodynamic loudspeaker, comprising steps of:
- receiving a digital audio signal having a first sample rate,
- using an up-sampler and modulator circuit, up-sampling the digital audio signal to a greater second sample rate and adding a high-frequency probe signal to the up-sampled digital audio signal to generate a pulse-modulated composite drive signal, wherein the probe signal has a frequency that exceeds a Nyquist frequency of the received digital audio signal,
- applying the pulse-modulated composite drive signal to a voice coil of the electrodynamic speaker through an output amplifier,
- detecting a composite drive signal current flowing through the voice coil in response to the application of the pulse-modulated composite drive signal,
- detecting a modulation level of a probe signal current from the composite drive signal current, and
- identifying an excursion of a diaphragm of the loudspeaker based on the detected modulation level of the probe signal current.
A loudspeaker excursion detector for electrodynamic loudspeakers, comprising:
- an audio signal input for receipt of a digital audio signal supplied by an audio signal source,
- a probe signal source for generation of a high-frequency digital probe signal,
- an up-sampler and modulator circuit configured to up-sample the audio signal and then combine the up-sampled audio signal with the probe signal to provide a composite drive signal,
- an output amplifier configured to supply the composite drive signal at a pair of output terminals connectable to a voice coil of an electrodynamic loudspeaker,
- a current detector configured for detecting from the voice coil a composite drive signal current flowing through the voice coil in response to the application of the composite drive signal, and
- a modulation detector configured to determine a modulation level of a probe signal current of the composite drive signal current, wherein the modulation level indicates an excursion characteristic of a diaphragm of the electrodynamic loudspeaker.
Dependencies are inferred from the claim text.