Audio rendering of an electromagnetic metal detection signal
AssigneeSarl Xplorer
InventorJean-Louis Vern
Life of this patent
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Abstract
A method includes compressing the dynamic range of the target detection signal so as to correspond to the desired dynamic range (60) of the audio signal (81) that is generated in order to acoustically render this detection signal to the user, so that the quietest signals are audible, the loudest signals do not cause hearing damage for the user, and that the sound volume is able to be perceived gradually for the intermediate-level signals. This avoids losing variations in the detection signal that are below the audibility threshold (63) and clipping them above a maximum hearing comfort threshold (64) in the corresponding audio signal (71) that would be generated according to the prior art.
Claims13
A method for generating an audio signal suitable for the acoustic rendering, to the user of a portable metal detection apparatus, using at least one electroacoustic transducer, of an electromagnetic target detection signal the amplitude of which may vary with a determined amplitude dynamic range, the method comprising the following steps:
- reducing the amplitude dynamic range of the detection signal so that it corresponds to a desired dynamic range of the audio signal, said amplitude dynamic range applied to the detection signal being the difference between the lowest amplitude and the highest amplitude of said detection signal;
- and
- generating the audio signal on the basis of the detection signal with the reduced dynamic range,
- wherein:
- reducing the dynamic range of the detection signal comprises:
- clipping the detection signal on the basis of a determined detection threshold;
- said clipping the detection signal comprising clipping said detection signal below the detection threshold;
- applying, to the clipped detection signal, an overall determined dynamic range compression rate, between 0 and 1, which depends on the ratio between the dynamic range of the detection signal and the desired dynamic range of the audio signal;
- and
- shifting the compressed detection signal so as to set a desired minimum level of the audio signal;
- and in that
- applying an overall dynamic range compression rate to the clipped detection signal comprises segmenting the dynamic range of the detection signal into a plurality of separate portions, and also applying respective local dynamic range modification rates to different portions of the clipped detection signal.
A non-transitory computer-readable storage medium, comprising:
- instructions for execution on a computer with a data processor, said data processor configured to generate an audio signal suitable for acoustic rendering, to a user of a portable metal detection apparatus, using at least one electroacoustic transducer, of an electromagnetic target detection signal the amplitude of which may vary with a determined amplitude dynamic range by:
- reducing the amplitude dynamic range of the detection signal so that it corresponds to a desired dynamic range of the audio signal, said amplitude dynamic range applied to the detection signal being the difference between the lowest amplitude and the highest amplitude of said detection signal;
- and
- generating the audio signal on the basis of the detection signal with the reduced dynamic range,
- wherein:
- reducing the dynamic range of the detection signal comprises:
- clipping the detection signal on the basis of a determined detection threshold;
- said clipping the detection signal comprising clipping said detection signal below the detection threshold;
- applying, to the clipped detection signal, an overall determined dynamic range compression rate, between 0 and 1, which depends on the ratio between the dynamic range of the detection signal and the desired dynamic range of the audio signal;
- and shifting the compressed detection signal so as to set a desired minimum level of the audio signal;
- and in that
- applying an overall dynamic range compression rate to the clipped detection signal comprises segmenting the dynamic range of the detection signal into a plurality of separate portions, and also applying respective local dynamic range modification rates to different portions of the clipped detection signal.
A portable metal detection apparatus comprising a non-transitory computer-readable storage medium, with instructions for execution on a computer with a data processor, said data processor configured to generate an audio signal suitable for acoustic rendering, to a user of a portable metal detection apparatus, using at least one electroacoustic transducer, of an electromagnetic target detection signal the amplitude of which may vary with a determined amplitude dynamic range by:
- reducing the amplitude dynamic range of the detection signal so that it corresponds to a desired dynamic range of the audio signal, said amplitude dynamic range applied to the detection signal being the difference between the lowest amplitude and the highest amplitude of said detection signal;
- and
- generating the audio signal on the basis of the detection signal with the reduced dynamic range,
- wherein:
- reducing the dynamic range of the detection signal comprises:
- clipping the detection signal on the basis of a determined detection threshold;
- said clipping the detection signal comprising clipping said detection signal below the detection threshold;
- applying, to the clipped detection signal, an overall determined dynamic range compression rate, between 0 and 1, which depends on the ratio between the dynamic range of the detection signal and the desired dynamic range of the audio signal;
- and
- shifting the compressed detection signal so as to set a desired minimum level of the audio signal;
- and in that
- applying an overall dynamic range compression rate to the clipped detection signal comprises segmenting the dynamic range of the detection signal into a plurality of separate portions, and also applying respective local dynamic range modification rates to different portions of the clipped detection signal.
Dependencies are inferred from the claim text.