Target detector and target detection method

Abstract

The present invention discloses a target detector and a target detection method, wherein the target detector comprises: a sound detection unit and an envelope detection unit, wherein the sound detection unit comprises a plurality of sound sensors for detecting audio signals around the target detector; the envelope detection unit is used to perform amplitude envelope feature processing on the audio signal detected by the sound detection unit and output an amplitude envelope signal, so that the target detector can judge whether there is voice around the target detector according to the amplitude envelope signal. The target detector and the target detection method provided by the present invention solve the problem that the target detection method in the prior art is too complicated.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a target detector and a target detection method. Background Art

[0002] In wireless sensor network (WSN) nodes, target detectors are mainly used to detect whether the audio signals around each node of the wireless sensor network are voices, that is, human speaking voices.

[0003] However, since the frequency of human speech is usually in the range of 300Hz to 3.4kHz, in order to facilitate the target detector to sample and process the audio signal, the sampling frequency usually needs to be greater than 6.8kHz, and the sampling time is at least more than 1 second. This causes the sampling data generated during the target detection process to occupy a large amount of memory and the signal processing requires a large amount of calculation, which ultimately makes the target detection too complicated.

[0004] It can be seen from the above that the target detection method in the prior art still has the defect of being too complicated. Summary of the invention

[0005] In order to solve the problem that the target detection method in the related art is too complicated, each embodiment of the present invention provides a target detector and a target detection method.

[0006] Wherein, the technical solution adopted by the present invention is:

[0007] In one embodiment of the present invention, a target detector includes: a sound detection unit and an envelope detection unit, wherein the sound detection unit includes a plurality of sound sensors for detecting audio signals around the target detector; the envelope detection unit is used to perform amplitude envelope feature processing on the audio signal detected by the sound detection unit and output an amplitude envelope signal, so that the target detector can determine whether there is voice around the target detector based on the amplitude envelope signal.

[0008] In another embodiment of the present invention, a target detection method includes: obtaining an amplitude envelope signal output by the above-mentioned target detector; when the amplitude envelope signal exceeds a warning threshold, calling an interrupt service program to determine whether there is voice around the target detector.

[0009] In the above technical solution, voice is taken as the target, and the high-frequency voice signal (300Hz~3.4kHz) is converted into a low-frequency voice envelope signal (less than 10Hz) through an envelope detection unit. This can not only reduce the sampling rate and reduce the memory occupied by the sampling data generated during the target detection process, thereby simplifying the target recognition algorithm during signal processing, but also greatly improve the target recognition speed without affecting the accuracy of target recognition.

[0010] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0012] Figure 1 The figure is a structural block diagram of a target detector according to an exemplary embodiment.

[0013] Figure 2 It is a structural block diagram of a sound detection unit according to an exemplary embodiment.

[0014] Figure 3 The figure is a structural block diagram of an envelope detection unit according to an exemplary embodiment.

[0015] Figure 4 The invention is a structural block diagram of a common-mode amplifier and a comparator according to an exemplary embodiment.

[0016] Figure 5 It is a structural block diagram of a sound excitation source according to an exemplary embodiment.

[0017] The above-mentioned drawings have shown clear embodiments of the present invention, which will be described in more detail hereinafter. These drawings and textual descriptions are not intended to limit the scope of the present invention in any way, but to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0018] Here, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples of devices and target detectors consistent with some aspects of the present invention as detailed in the appended claims.

[0019] See also Figure 1 In one embodiment, a target detector 100 includes: a sound detection unit 110 and an envelope detection unit 130 .

[0020] The sound detection unit 110 includes a plurality of sound sensors for detecting audio signals around the target detector. Optionally, voice, i.e., human voice, is used as the target of the target detector, that is, through the target detector, the audio signal detected around it can be further identified as voice, thereby judging whether there is human activity around it.

[0021] Preferably, the sound sensor comprises a microphone and a two-stage in-phase high-pass amplifier connected in sequence.

[0022] Specifically, Figure 2 As shown, the power supply SND_VCC, resistors R1 and R2 constitute the excitation source of the electret microphone MIC, and the capacitors C1 and C2 are used for power supply filtering; the resistors R3 and R4 are used as a voltage divider to provide a reference level for the single-power audio amplifier (SND_U1-1 / 2); the capacitor C3 and the resistors R3 and R4 constitute a DC isolation filter; the audio amplifier (SND_U1-1 / 2), the capacitor C5, the resistors R5 and R6 constitute a primary in-phase high-pass amplifier, and the capacitor C4 serves as a feedback compensation capacitor of the audio amplifier; the resistor R7 and the capacitor C6 constitute a first-order low-pass filter; the audio amplifier (SND_U1-2 / 2), the capacitor C8, the resistor R8 and R9 constitute a secondary in-phase high-pass amplifier, and the capacitor C7 serves as a feedback compensation capacitor.

[0023] Based on this, the signal gain of the sound sensor is about 230 times, and the bandwidth is limited to between 300Hz and 3400Hz.

[0024] The envelope detection unit 130 is used to perform amplitude envelope feature processing on the audio signal detected by the sound detection unit 110 and output an amplitude envelope signal, so that the target detector 100 can judge whether there is voice around the target detector 100 according to the amplitude envelope signal. Preferably, the envelope detection unit 130 includes an envelope detector.

[0025] Specifically, Figure 3 As shown, capacitor C1 and resistor R1 form a DC blocking filter; a single-power operational amplifier (SND_U2-1 / 2), a diode D, resistors R2, R3, R4, capacitor C2, and a Schottky diode SD form an envelope detector, whose charging time constant is τ1 = R2 × C2, and the discharging time constant is τ2 ≥ (R3 / / R4) × C2, and τ 2>> τ1. It should be noted that the main function of introducing the Schottky diode SD is to reduce the DC component of the amplitude envelope signal.

[0026] Here, based on the envelope detection unit, the high-frequency voice signal (300Hz~3.4kHz) is converted into a low-frequency voice envelope signal (less than 10Hz), which can not only reduce the sampling rate and reduce the memory occupied by the sampling data generated during the target detection process, thereby simplifying the target recognition algorithm during signal processing, but also greatly improve the target recognition speed without affecting the accuracy of target recognition.

[0027] It should be noted that in order to reduce the power consumption of the target detector, the electronic components in each embodiment of the present invention all adopt low-power devices, for example, the operational amplifier in this embodiment, which will not be repeated later, thereby realizing a target detector powered by a single lithium battery.

[0028] In one embodiment, the target detector further includes: a signal gain unit.

[0029] The signal gain unit includes an amplifier, so that the amplitude envelope signal passing through the amplifier can increase the signal gain. For example, the amplifier can be a common-phase amplifier or an inverting amplifier, which is not limited here.

[0030] Preferably, the amplifier is a common-mode amplifier. Figure 4 As shown, the common-mode amplifier can be composed of a low-power operational amplifier (SND_U2-2 / 2), resistors R1 and R2.

[0031] Here, the signal processing gain of the target detector is improved through the common-phase amplifier, which is more conducive to the detection of weak audio signals, and can effectively expand the effective range of the target detector, thereby realizing a target detector with a large effective range, and is conducive to improving the success rate of target detection and the environmental adaptability of the target detector.

[0032] In one embodiment, the target detector further includes: a signal gain adjustment unit.

[0033] The signal gain adjustment unit comprises a first digitally controlled potentiometer, which is connected between the output terminal and the reverse input terminal of the in-phase amplifier and is used to adjust the signal gain of the signal gain unit to the amplitude envelope signal.

[0034] Specifically, Figure 4 As shown, the signal gain adjustment unit is composed of a resistor R3 and a first digitally controlled potentiometer (SND_U3-1 / 2). The resistor R4 and the capacitor C1 form a first-order low-pass filter with a cut-off frequency less than 10 Hz.

[0035] Therefore, as the resistance value W1 of the first digitally controlled potentiometer is controlled and adjusted, the signal processing gain of the target detector is adjustable, which is beneficial to improving the accuracy of target detection.

[0036] It is explained here that the resistance value W1 of the first digitally controlled potentiometer can be controlled and adjusted by a processor disposed in the target detector, such as an ARM microprocessor or a CPU processor, and this embodiment does not limit this.

[0037] In one embodiment, the target detector further includes: an interrupt unit.

[0038] Wherein, the interrupt unit includes a comparator, the amplitude envelope signal is input from the reverse input terminal of the comparator, and when the amplitude envelope signal exceeds the warning threshold, the comparator outputs an interrupt signal; the warning threshold is input from the positive input terminal of the comparator.

[0039] With the generation of the interrupt signal, the interrupt service program is immediately started, and by continuously sampling and processing the amplitude envelope signal generated by the target detector, it is determined whether there is voice around the target detector, thereby realizing the target voice detection.

[0040] It should be understood that changes in environmental parameters or the environment itself will inevitably have an adverse effect on target detection, for example, causing the output state of the comparator to be erroneously flipped and a false alarm to occur, or causing the comparator to be insensitive to audio signals and a missed alarm to occur.

[0041] Therefore, it is necessary to compensate for the adverse effects caused by changes in environmental parameters or the environment itself. Furthermore, in one embodiment, the target detector further includes: a threshold adjustment unit.

[0042] Wherein, the threshold value adjustment unit comprises a second digitally controlled potentiometer, and the second digitally controlled potentiometer is connected to the positive input terminal of the comparator, so that the warning threshold value input to the comparator is adjustable.

[0043] Specifically, Figure 4 As shown, the low-power comparator (SND_U4), the second digitally controlled potentiometer (SND_U3-2 / 2) and the resistor R5 constitute a comparator circuit with an adjustable warning threshold. Among them, the capacitor C2 is used to filter out the threshold level noise, and the resistor R6 and the LED light are used to display the output state of the comparator circuit.

[0044] Therefore, through the comparator circuit with adjustable warning threshold, the adverse effects caused by changes in environmental parameters or the environment itself are suppressed, so that the environmental adaptability of the target detector is effectively improved, and the false alarm probability and missed detection probability of the target detector can be effectively reduced.

[0045] It is worth mentioning that, in one embodiment, the single output signal received by the interrupt unit comes from one of the two signals output by the in-phase amplifier, such as Figure 4As shown, one of the signals is input by the inverting input terminal of the low-power comparator (SND_U4), and the other signal SND_AOUT output by the in-phase amplifier is directly transmitted to the analog-to-digital converter (MPU_ADC) of the ARM microprocessor, so that the ARM microprocessor can sample and process the amplitude envelope signal, thereby realizing the target voice detection.

[0046] In one embodiment, the signal gain adjustment unit is excited by a first sound excitation source, and the interruption unit is excited by a second sound excitation source.

[0047] Specifically, when the first sound excitation source is turned on, if the peak value of the amplitude envelope signal does not meet the preset requirements (such as the full scale of the analog-to-digital converter of the ARM microprocessor), the first digitally controlled potentiometer is adjusted to gradually increase the gain of the common-mode amplifier.

[0048] When the second sound excitation source is turned off, the warning threshold is set according to the peak value or the average amplitude value of the amplitude envelope signal. For example, 1.2 to 1.5 times the peak value or the average amplitude value of the single-channel output signal is used as the warning threshold.

[0049] The sound excitation source as an accessory to the target detector is described in detail below.

[0050] In one embodiment, the sound excitation source is generated by a multivibrator, a power amplifier and a speaker connected in sequence. Preferably, the multivibrator includes a timer (eg, a 555 timer).

[0051] Specifically, Figure 5 (a) is a schematic diagram of the DC power supply (5V / 3A) of the sound excitation source. Figure 5 (b) is a schematic diagram of the sound excitation source consisting of a low-power 555 timer (SND_U7), a power amplifier (SND_U8) and an 8Ω speaker.

[0052] like Figure 5 As shown in (a), the synchronous boost converter (SND_U6) is a turnable DC voltage regulator chip that can be powered by a single lithium battery. Capacitors C1 and C2 are used to filter the input-output voltage ripple of the DC voltage regulator chip; resistor R1 and inverter (SND_U5) constitute the synchronous boost converter on / off circuit, which is then controlled by an ARM microprocessor.

[0053] like Figure 5 As shown in (b), resistors R1, RW, R2, capacitors C1, C2 and low-power 555 timer (SND_U7) together form a multivibrator (frequency range: 330Hz≤f≤3400Hz). The oscillation frequency f of the multivibrator is determined by the following formula:

[0054]

[0055] The capacitor C2 is used to filter the threshold voltage ripple of the low power 555 timer (SND_U7).

[0056] The power amplifier (SND_U8) is used to increase the driving capability of the multivibrator; the AC coupling capacitor C3 is used to isolate the DC and output the AC signal.

[0057] Therefore, by timed activation of the sound excitation source, the false alarm probability and missed alarm probability of the target detector can be reduced, thereby effectively suppressing the adverse effects caused by changes in environmental parameters or the environment itself, thereby improving the environmental adaptability of the target detector.

[0058] The above contents are only preferred exemplary embodiments of the present invention and are not intended to limit the implementation scheme of the present invention. A person skilled in the art can easily make corresponding changes or modifications based on the main concept and spirit of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope required by the claims.

Claims

1. An object detector, It is characterized in that include: Sound detection unit and envelope detection unit, wherein, The sound detection unit includes a plurality of sound sensors for detecting audio signals around the target detector; The envelope detection unit is used to perform amplitude envelope feature processing on the audio signal detected by the sound detection unit and output an amplitude envelope signal, so that the target detector can judge whether there is voice around the target detector according to the amplitude envelope signal; the envelope detection unit includes an envelope detector; Specifically, capacitor C1-1 and resistor R1-1 form a DC blocking filter; single-power operational amplifier SND_U2-1 / 2, diode D, resistors R2-1, R3-1, R4-1, capacitor C2-1 and Schottky diode SD form an envelope detector, whose charging time constant is , the discharge time constant is , and there is ; The sound sensor comprises a microphone and a two-stage in-phase high-pass amplifier connected in sequence; Specifically, the power supply SND_VCC, the resistors R1-2 and R2-2 constitute the excitation source of the electret microphone MIC, and the capacitors C1-2 and C2-2 are used for power supply filtering; the resistors R3-2 and R4-2 are used as a voltage divider to provide a reference level for the single-power audio amplifier SND_U1-1 / 2; the capacitor C3-2 and the resistors R3-2 and R4-2 constitute a DC isolation filter; the audio amplifier SND_U1-1 / 2, the capacitor C5-2, the resistor R5-2 and R6-2 constitute a primary in-phase high-pass amplifier, and the capacitor C4-2 serves as a feedback compensation capacitor of the audio amplifier; the resistor R7-2 and the capacitor C6-2 constitute a first-order low-pass filter; the audio amplifier SND_U1-2 / 2, the capacitor C8-2, the resistor R8-2 and R9-2 constitute a secondary in-phase high-pass amplifier, and the capacitor C7-2 serves as a feedback compensation capacitor; The target detector further comprises: a signal gain unit, wherein the signal gain unit comprises an amplifier, so that the amplitude envelope signal passing through the amplifier can increase the signal gain; The amplifier is a common-phase amplifier; the common-phase amplifier can be composed of a low-power operational amplifier SND_U2-2 / 2, resistors R1-3, R2-3; The target detector further comprises: a signal gain adjustment unit, the signal gain adjustment unit comprising a first digitally controlled potentiometer, the first digitally controlled potentiometer being connected between the output terminal and the reverse input terminal of the in-phase amplifier and being used for adjusting the signal gain of the in-phase amplifier to the amplitude envelope signal; The signal gain adjustment unit is excited by the first sound excitation source. When the first sound excitation source is turned on, if the peak value of the amplitude envelope signal does not meet the preset requirements, the first digitally controlled potentiometer is adjusted to gradually increase the gain of the common-mode amplifier; the signal gain adjustment unit is composed of a resistor R3-3 and a first digitally controlled potentiometer SND_U3-1 / 2; wherein the resistor R4-3 and the capacitor C1-3 form a first-order low-pass filter with a cut-off frequency less than 10Hz; the resistance value W1 of the first digitally controlled potentiometer is controlled and adjusted by a processor arranged in the target detector by an ARM microprocessor or a CPU processor; The target detector further includes: an interrupt unit, the interrupt unit includes a comparator, the amplitude envelope signal is input from the reverse input terminal of the comparator, and when the amplitude envelope signal exceeds the warning threshold, the comparator outputs an interrupt signal; the warning threshold is input from the positive input terminal of the comparator; the single-channel output signal received by the interrupt unit comes from one of the two-channel signals output by the common-mode amplifier, the one-channel signal is input from the reverse input terminal of the low-power comparator SND_U4, and the other channel signal SND_AOUT output by the common-mode amplifier is directly transmitted to the analog-to-digital converter MPU_ADC of the ARM microprocessor; The target detector further comprises: a threshold value adjustment unit, the threshold value adjustment unit comprising a second digitally controlled potentiometer, the second digitally controlled potentiometer being connected to the positive input terminal of the comparator so that the warning threshold value input to the comparator is adjustable; Specifically, the low-power comparator SND_U4, the second digitally controlled potentiometer SND_U3-2 / 2 and the resistor R5-3 constitute a comparator circuit with an adjustable warning threshold; wherein the capacitor C2-3 is used to filter out the threshold level noise, and the resistor R6-3 and the LED light are used to display the output state of the comparator circuit; The interruption unit is excited by a second sound excitation source, and when the second sound excitation source is turned off, the warning threshold is set according to the peak value or the amplitude average value of the amplitude envelope signal; The second sound excitation source is generated by a multivibrator, a power amplifier and a speaker connected in sequence; the multivibrator includes a 555 timer; Specifically, it consists of a low-power 555 timer SND_U7, a power amplifier SND_U8 and The sound excitation source constituted by the loudspeaker; The synchronous boost converter SND_U6 is a DC voltage regulator chip that can be turned off and can be powered by a single lithium battery. The capacitors C1-4 and C2-4 are used to filter the input-output voltage ripple of the DC voltage regulator chip. The resistors R1-4 and the inverter SND_U5 form a synchronous boost converter on / off circuit, which is then controlled by an ARM microprocessor. Resistors R1-5, RW, R2-5 and capacitors C1-5, C2-5 and low-power 555 timer SND_U7 together form a multivibrator with a frequency range of: , the oscillation frequency f of the multivibrator will be determined by the following formula: ； Among them, capacitor C2-5 is used to filter the threshold voltage ripple of the low-power 555 timer SND_U7; The power amplifier SND_U8 is used to increase the driving capability of the multivibrator; the AC coupling capacitor C3-5 is used to isolate the DC and output the AC signal.

2. A target detection method, It is characterized in that The method comprises: Acquire an amplitude envelope signal output by the target detector according to claim 1; When the amplitude envelope signal exceeds the warning threshold, an interrupt service program is called to determine whether there is voice around the target detector.

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