Method for directional sound propagation of interphone loudspeaker

Abstract

The invention relates to the related field of a wireless communication technology, in particular to a directional sound propagation method for an interphone loudspeaker, which realizes directional sound propagation, reduces noise pollution, has stronger confidentiality due to the fact that sound cannot be diffused all around, and realizes directional sound propagation of the interphone loudspeaker through an ultrasonic carrier modulation technology. According to the invention, sound directional propagation is realized on the basis of original hardware of a common interphone, the whole machine does not need to be reconstructed, the limitation that a traditional directional loudspeaker needs special hardware is broken through, the technical path is novel, and the realization cost of a directional propagation function is greatly reduced; and large-scale popularization and application of common interphones are facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless communication technology, in particular to a method for directional propagation of speaker sound of a walkie-talkie. BACKGROUND

[0002] The walkie-talkie is a kind of two-way communication equipment based on radio technology, which is used to realize instant voice communication, and can communicate without any network support, without generating call charges. The walkie-talkie is widely used in scenarios that require fast and direct communication, such as construction site dispatching, logistics management, security patrol, outdoor sports, etc. The speaker is one of the core components of the walkie-talkie, which is used to restore the received radio signal to sound for the user to listen to. The speaker directly determines the sound quality and call clarity of the walkie-talkie, especially in noisy environments.

[0003] The existing walkie-talkie has the problem of noise pollution when its speaker sound is omnidirectionally dispersed in the surrounding space. At the same time, when the user involves some private communication, the sound will be dispersed in all directions, which will easily spread these contents everywhere, making the walkie-talkie not strong in privacy. Although the existing counter public address intercom disclosed in the publication No. CN205883219U can also propagate sound directionally, it needs to use special hardware and reconstruct the whole walkie-talkie, which limits the popularization and use of ordinary walkie-talkies. SUMMARY

[0004] Therefore, in order to solve the above problems, the present application provides a method for directional propagation of speaker sound of a walkie-talkie.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme: a method for directional propagation of speaker sound of a walkie-talkie, comprising the following steps: S1, audio modulation: input 20Hz-20kHz audio signal, and synthesize the input audio signal with the carrier signal through the comparator, wherein when the audio instantaneous voltage is greater than the carrier voltage, output high level, otherwise output low level; S2, carrier modulation: configure the STM32 timer to be in PWM mode to generate a reference carrier signal, the carrier frequency range is 38-42kHz, and the frequency is adjusted in real time by ±2kHz according to the environmental temperature and humidity to compensate for air attenuation; S3, directional emission: adopt a piezoelectric ceramic unit with a resonant frequency of 40kHz±1% as the core transducer, and form a narrow sound beam through the acoustic structure of the reflector for directional propagation; S4, air demodulation: the ultrasonic wave is automatically demodulated in the process of propagation in the air due to the nonlinear effect, and audible sound waves are restored in the target area, while the sound pressure level outside the area is attenuated to the extent that the audible sound waves cannot be clearly perceived; Through the above steps, the sound wave propagation angle is controlled within a range of ±15°, and the propagation distance is ≤20 meters.

[0006] Preferably, the audio modulation step further comprises modulation depth control, that is, dynamically adjusting the audio gain so that the modulation depth is maintained at 30%-100%.

[0007] Preferably, the carrier modulation step selects a carrier frequency of 38-42 kHz to avoid common environmental noise interference.

[0008] Preferably, the core transducer uses a piezoelectric ceramic unit that supports high-power ultrasonic emission.

[0009] Preferably, the directional emission step uses a reflector designed to form a narrow sound beam with an angle within a range of ±15° to achieve the purpose of directional propagation.

[0010] Preferably, the air demodulation step relies on the nonlinear effect of ultrasonic waves in air propagation, which restores the original audio signal within a specific receiving area with a propagation distance of ≤20 meters.

[0011] Advantages of the present application: 1. The present application realizes directional propagation of sound, reduces noise pollution, and has stronger security for the interphone because sound does not disperse in all directions. The sound directional propagation is realized on the basis of the original hardware of the ordinary interphone through the ultrasonic carrier modulation technology, such as audio and carrier comparator synthesis, dynamic modulation depth control, etc., without the need to reconstruct the whole machine, breaking through the limitation of special hardware required by traditional directional speakers, and greatly reducing the implementation cost of directional propagation function, which is convenient for large-scale popularization and application of ordinary interphones.

[0012] 2. The present application realizes automatic demodulation by using the nonlinear effect of ultrasonic waves in air propagation, and restores audible sound waves without additional equipment at the receiving end, simplifying the implementation process of directional propagation, and being more practical compared with traditional directional technology which requires cooperation between the transmitting and receiving ends. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a working process schematic diagram of the present application. DETAILED DESCRIPTION

[0014] In order to further explain the technical scheme of the present application, the following specific embodiments are described in detail.

[0015] As shown in Figure 1 , the present application provides a method for directional propagation of sound of an interphone loudspeaker, comprising the following steps: S1, audio modulation: input 20Hz-20kHz audio signal to the original intercom, pre-process the input audio signal through the original audio amplification circuit of the intercom, and then combine the input audio signal with the carrier signal through a comparator, wherein high level is output when the instantaneous voltage of the audio signal is greater than the voltage of the carrier signal, and low level is output otherwise; S2, carrier modulation: configure the timer of the STM32 chip of the ordinary intercom, and adjust the timer to PWM mode to generate a reference carrier signal, the carrier frequency range is 38-42kHz, which is used to avoid common environmental noise interference, and the environmental temperature and humidity are collected through the temperature and humidity sensor in the intercom, and the frequency is adjusted in real time ±2kHz according to the environmental temperature and humidity to compensate for air attenuation; S3, directional emission: a piezoelectric ceramic unit with a resonance frequency of 40kHz±1% is used as the core transducer, the transducer is driven by the power amplification module of the original intercom, and a narrow sound beam is formed through the acoustic structure of the reflector for directional propagation; S4, air demodulation: ultrasonic waves are automatically demodulated due to nonlinear effects during propagation in air, and audible sound waves are restored in the target area, while the sound pressure level outside the area is attenuated to a level that cannot clearly perceive audible sound waves; Through the above steps, the sound propagation angle is controlled within ±15°, and the propagation distance is ≤20 meters; In the audio modulation step, the modulation depth control is also included, which is to dynamically adjust the audio gain, so as to ensure that the audio signal can fully modulate the carrier under different input intensities, thereby improving the clarity and restoration of the sound, so that the modulation depth is maintained at 30%-100%, thereby avoiding distortion and ensuring that the modulated signal is within a reasonable range; The core transducer uses a piezoelectric ceramic unit that supports high-power ultrasonic emission, which facilitates efficient energy conversion and precise frequency control; The reflector used in the directional emission step is designed to form a narrow sound beam with an angle within ±15°, so as to achieve the purpose of directional propagation; The air demodulation step relies on the nonlinear effect that occurs when ultrasonic waves propagate in air, which restores the original audio signal in a specific receiving area with a propagation distance of ≤20 meters, and the directional propagation is stronger; Specifically, according to the above-mentioned scheme of the present application, by using the core hardware of a common intercom, such as an STM32 master control, an audio interface, a power amplifier module, etc., only the loudspeaker is replaced by a piezoelectric ceramic unit, and a simple modification of adding a reflector cover of the adaptive shell is needed to realize the sound directional propagation function, and the power of the piezoelectric ceramic unit used is 1W-5W, combined with the ultrasonic carrier modulation technology (audio and carrier comparator synthesis, dynamic modulation depth control, etc.), without the need to redesign the whole machine, the cost required for the intercom to realize sound directional propagation is reduced, and the function upgrade of the intercom is realized. And by combining the piezoelectric ceramic transducer with a 40kHz±1% resonant frequency and the reflector acoustic structure, the sound propagation angle is strictly controlled within ±15°, and at the same time, the carrier frequency is dynamically compensated by the environment temperature and humidity, ensuring clear demodulation within 20 meters in the directional area, and the sound pressure level outside the area is attenuated to be imperceptible, meeting the actual needs of short-distance directional communication, and the ultrasonic wave is automatically demodulated when propagating in the air due to the nonlinear effect, without the need for additional equipment at the receiving end to restore audible sound waves in the target area, simplifying the implementation process of directional propagation, and the sound pressure level outside the area can be attenuated by up to 90%. By realizing directional propagation of sound, noise pollution is reduced, and the privacy leakage and environmental interference problems caused by sound diffusion of traditional intercoms are solved, and ordinary intercoms can also have stronger confidentiality.

[0016] The present application provides a method for directional propagation of intercom loudspeaker sound, which realizes directional propagation of sound, reduces noise pollution, and has stronger confidentiality of the intercom because the sound does not disperse in all directions, and realizes directional propagation of sound on the basis of the original hardware of an ordinary intercom through ultrasonic carrier modulation technology, i.e. audio and carrier comparator synthesis, dynamic modulation depth control, etc., without the need to reconstruct the whole machine, breaking through the limitation of traditional directional loudspeakers requiring special hardware, the technical path is novel, the implementation cost of directional propagation function is greatly reduced, and the application of ordinary intercoms is facilitated.

[0017] The above-mentioned only for the preferred examples of the present application, and not for limiting the present application, although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for directional propagation of sound from a walkie-talkie speaker, characterized in that: The following steps are involved: S1, audio modulation: input 20Hz-20kHz audio signal, and synthesize the input audio signal and carrier signal through the comparator. When the audio instantaneous voltage is greater than the carrier voltage, the output is high level, otherwise it outputs low level; S2, Carrier modulation: Configure the STM32 timer in PWM mode to generate a reference carrier signal with a carrier frequency range of 38-42kHz. The frequency is fine-tuned in real time by ±2kHz according to the ambient temperature and humidity to compensate for air attenuation. S3, Directional emission: A piezoelectric ceramic unit with a resonant frequency of 40kHz±1% is used as the core transducer, and a narrow sound beam is formed through the acoustic structure of the reflector for directional propagation; S4, air demodulation: Ultrasonic waves are automatically demodulated due to nonlinear effects during propagation in the air, restoring audible sound waves in the target area, while the sound pressure level outside the area is attenuated to the point where the audible sound waves cannot be clearly perceived; Through the above steps, the sound wave propagation angle is controlled within the range of ±15°, and the propagation distance is ≤20 meters.

2. The method for directional sound propagation of an intercom speaker according to claim 1, characterized in that: The audio modulation step also includes modulation depth control, which is to dynamically adjust the audio gain so that the modulation depth is maintained at 30%-100%.

3. The method for directional sound propagation of an intercom speaker according to claim 1, characterized in that: The carrier modulation step selects a 38-42 kHz carrier frequency to avoid common environmental noise interference.

4. The method for directional sound propagation of an intercom speaker according to claim 1, characterized in that: The core transducer adopts a piezoelectric ceramic unit that supports high-power ultrasonic emission.

5. The method for directional sound propagation of an intercom speaker according to claim 1, characterized in that: The reflective cover used in the directional emission step is designed to form a narrow sound beam with an angle within the range of ±15° to achieve the purpose of directional propagation.

6. The method for directional sound propagation of an intercom speaker according to claim 1, characterized in that: The air demodulation step relies on the nonlinear effect that occurs when ultrasonic waves propagate in the air. This nonlinear effect enables the ultrasonic waves to restore the original audio signal within a specific receiving area with a propagation distance of ≤20 meters.

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