CN-121984637-A - Ultrasonic sound recording shielding method for multi-dimensional parameter cooperative modulation

Abstract

The invention provides an ultrasonic recording shielding method with multi-dimensional parameter cooperative modulation, which relates to the technical field of monitoring, and comprises the steps that a control unit outputs a control instruction to an ultrasonic signal generating unit, so that the ultrasonic signal generating unit consisting of a DDS1 and a DDS2 generates two paths of ultrasonic analog signals with heterogeneous modulation characteristics, the first path of ultrasonic analog signals execute parameter modulation in three dimensions of frequency, time sequence and phase, the second path of ultrasonic analog signals execute parameter modulation in waveform dimension, the two paths of ultrasonic analog signals are respectively input into a power amplifying unit for amplifying, then are converted into ultrasonic sound fields by two ultrasonic transducers, and the two paths of sound fields are radiated to a target area after being physically overlapped in the target area, so that the technical problems that in the prior art, the dimension of an interference signal is single, the regularity is too strong, and the interference signal is difficult to resist high-end recording equipment with a self-adaptive noise reduction function are solved.

Inventors

• QIN RUYI
• ZHANG LEIMING
• TANG SONGTAO
• ZHANG CHUANSHUO

Assignees

• 河南科技大学

Dates

Publication Date

20260505

Application Date

20260320

Claims (5)

1. 1. The ultrasonic sound recording shielding method for the multi-dimensional parameter cooperative modulation is characterized by comprising the following steps of: step 1, a control unit outputs a control instruction to an ultrasonic signal generating unit, so that an ultrasonic signal generating unit consisting of a DDS1 and a DDS2 generates two paths of ultrasonic analog signals with heterogeneous modulation characteristics; Implementing alternate control of scanning stage and silence stage, in which the working waveform of DDS1 is configured as triangular wave, and frequency step scanning is implemented according to set delay period, and at every frequency step point control unit a random phase control word is generated, randomly selecting any phase of 0 deg., 45 deg., 90 deg., 135 deg., 180 deg., 225 deg., 270 deg and 315 deg. and writing it into the phase register of DDS1 so as to implement one-time writing of phase register; the second ultrasonic module signal carries out parameter modulation of waveform dimension, namely switching DDS2 through a preset clock period to cooperatively output different waveform functions; And 2, respectively inputting two paths of ultrasonic analog signals with heterogeneous modulation characteristics into respective power amplifying units to amplify power, respectively driving two ultrasonic transducers to convert the two paths of ultrasonic analog signals into two paths of independent ultrasonic sound fields, and radiating the two paths of ultrasonic sound fields to a target area after physical superposition.
2. 2. The method of claim 1, wherein the silence period is a silence state in which the control unit sends a stop signal output command to the DDS 1.
3. 3. The method of claim 1, wherein the alternating control of the scan phase and the silence phase means that the scan phase is switched after the silence phase lasts for a set time, and the scan frequency value is reset and switched to the silence phase after the scan phase performs the step scan with the set number of frequencies.
4. 4. The ultrasonic sound recording shielding method for multi-dimensional parameter cooperative modulation of claim 1, wherein the method for generating the random phase control word by the control unit is characterized in that the rapid pseudo random number generation is realized through Xorshift algorithm arranged in the control unit, the control unit reads the current count value of a timer in the control unit, the current count value and a fixed constant are subjected to exclusive OR operation, and the operation result is used as an initial state seed of Xorshift algorithm.
5. 5. The ultrasonic sound recording shielding method of multi-dimensional parameter cooperative modulation as claimed in claim 1, wherein the method comprises the following steps: the different wave functions are triangular and sinusoidal.

Description

Ultrasonic sound recording shielding method for multi-dimensional parameter cooperative modulation Technical Field The invention relates to the technical field of monitoring, in particular to an ultrasonic sound recording shielding method with multi-dimensional parameter cooperative modulation. Background With the rapid development of information technology and mobile communication, smart phones have become an indispensable tool in people's daily lives. The mobile phone has the functions of a high-sensitivity microphone and a convenient recording, which brings convenience to users and brings serious information safety hidden trouble. In occasions requiring confidentiality, such as business negotiations, confidential meetings, judicial arbitration and the like, sensitive information can be leaked due to unauthorized mobile phone recording, so that serious economic loss and legal disputes are caused. The existing recording shielding technology mainly comprises a white noise interference method, an acoustic wave cancellation method, an electromagnetic interference method and the like. The white noise interference method masks effective voice information by emitting broadband noise in an audible range into the environment, but the method can seriously influence normal communication of field personnel and is difficult to widely apply in practical occasions. The acoustic wave cancellation method has the advantages of complex technology and high cost, needs to collect and process the sound signals in real time, and has high engineering realization difficulty. The electromagnetic interference method interferes with the recording device by transmitting electromagnetic signals in a specific frequency band, but the method involves the problem of electromagnetic compatibility, and can cause interference to other communication devices, and is strictly limited by laws and regulations. In recent years, recording interference methods based on ultrasonic waves have been attracting attention. The basic principle is that when the ultrasonic signal and the shielded voice signal act on the microphone together, new difference frequency and mixing frequency components can be generated in the audio frequency band due to the nonlinear effect of the microphone diaphragm and the amplifying circuit, so that the recorded content is interfered. However, the existing ultrasonic interference scheme has the defects of single interference frequency, fixed waveform, easy elimination of interference effect by the self-adaptive filtering algorithm of the recording equipment and the like. Particularly, by adopting a scheme of single fixed frequency or simple frequency sweep mode, the recording equipment can identify the regularity characteristic of the interference signal through frequency domain analysis and effectively inhibit the regularity characteristic, so that the shielding effect is greatly reduced. In addition, the existing ultrasonic sound recording interference device mostly adopts a single-channel signal generation scheme in hardware implementation, the signal generation mode is limited, and multi-mode and multi-waveform composite interference is difficult to realize. Meanwhile, the existing scheme lacks a flexible mode control mechanism, and cannot be quickly adjusted and optimized for different application scenes. Therefore, the prior art has the defects of single interference mode, weak anti-rule recognition capability, low hardware integration level and the like, and is difficult to meet the requirements of high-efficiency and reliable recording shielding in practical application. Disclosure of Invention In order to solve the technical problems, the invention provides an ultrasonic recording shielding method with multi-dimensional parameter cooperative modulation, which solves the technical problems of single interference signal dimension, strong regularity, difficulty in countering high-end recording equipment with self-adaptive noise reduction function and the like in the prior art. In order to achieve the technical aim, the adopted technical scheme is that the ultrasonic recording shielding method for the multi-dimensional parameter cooperative modulation comprises the following steps: step 1, a control unit outputs a control instruction to an ultrasonic signal generating unit, so that an ultrasonic signal generating unit consisting of a DDS1 and a DDS2 generates two paths of ultrasonic analog signals with heterogeneous modulation characteristics; Implementing alternate control of scanning stage and silence stage, in which the working waveform of DDS1 is configured as triangular wave, and frequency step scanning is implemented according to set delay period, and at every frequency step point control unit a random phase control word is generated, randomly selecting any phase of 0 deg., 45 deg., 90 deg., 135 deg., 180 deg., 225 deg., 270 deg and 315 deg. and writing it into the phase register of DDS1 so as to implement one-time