Dynamic three-frequency and chord-pseudo-random pulse composite anti-recording interference equipment based on double-path DDS function

Abstract

This invention discloses a dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS functionality. Using the Zynq-7020 chip as its core, it comprises a control unit, a signal generation unit, a power amplification unit, and a human-machine interface unit. The signal generation unit is a dual-channel DDS module: the first channel generates three sets of cyclic triangular wave signals with an arithmetic frequency of 200Hz and a base frequency of 23kHz-23.5kHz; the second channel generates multi-dimensional pseudo-random triangular wave pulse signals of 23kHz-28kHz. The Zynq-7020 chip's PS and PL are configured via AXI-Lite communication. After the two signals are amplified by the power amplification unit, low-frequency difference-frequency interference is generated by leveraging the nonlinear distortion of the microphone in the recording device, constructing a highly complex nonlinear interference field within 3-5 meters. This invention offers diverse interference modes, strong noise reduction capabilities, and effectively shields mainstream mobile phones and various recording devices. Furthermore, it features a simple structure, convenient operation, and low power consumption, making it suitable for various scenarios such as confidential meetings and business negotiations.

Description

Technical Field

[0001] This invention relates to the field of recording jamming technology, specifically to a dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function. Background Technology

[0002] In scenarios such as confidential meetings, business negotiations, and private exchanges, the ubiquitous nature of various portable recording systems poses a serious threat to information security and personal privacy. Therefore, anti-recording interference devices have become an important carrier for information security protection.

[0003] In the existing technology, anti-recording interference devices are mainly divided into two categories: one is an interference system based on fixed-frequency ultrasonic waves, which interferes with the recording system through a single-frequency ultrasonic signal. However, the waveform is simple and the interference mode is fixed, making it easy to be targeted by recording noise reduction algorithms, resulting in poor interference effect. The other is an interference system based on simple random signals. Although randomization design is introduced, the random dimension is simple, and it does not utilize the nonlinear distortion characteristics of the recording system's microphone to achieve low-frequency difference frequency interference. The interference coverage is limited and the anti-noise reduction capability is weak.

[0004] Currently, SOC chips are configured with DDS IP cores to realize their functions, which not only have high-precision and fast switching generation of high-frequency signals, but also have 28-bit frequency resolution and 12-bit phase resolution, and support multiple waveform outputs such as sine wave, triangle wave, and square wave. However, there is currently no composite anti-recording interference device designed with dual-channel DDS function using FPGA. Based on this, this invention proposes a composite anti-recording interference device based on Zynq-7020 chip to realize dual-channel DDS function. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome existing defects and provide a dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function. It utilizes the DDS IP core of the PL section to construct a DDS module, generating arithmetic high-frequency signals and multi-dimensional pseudo-random pulse high-frequency signals. By leveraging the nonlinear distortion of the microphone in the recording system, it generates low-frequency difference frequency interference, covering the core audio pickup band of the recording system. Furthermore, it exhibits diverse interference modes and strong anti-noise reduction capabilities, achieving the generation of highly complex and highly random interference signals. This effectively circumvents the countermeasures of recording noise reduction algorithms, improves the anti-recording interference effect, and effectively solves the problems in the background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function, with Zynq-7020 chip as the core, including a control unit, a signal generation unit, a power amplification unit and a human-computer interaction unit;

[0007] The control unit, implemented by the PS section of the Zynq-7020, is responsible for the operation scheduling, parameter configuration and coordinated control of the two DDS modules, and sends control commands to the PL section through the AXI-Lite communication interface;

[0008] The signal generation unit utilizes the PL section of the Zynq-7020 to write a DDS programmable waveform generator IP core using Verilog HDL code, instantiates the DDS IP core to generate two DSS modules, and connects to the control unit via the AXI-Lite communication interface. It receives external control commands through the PS section of the Zynq-7020 and controls the two DDS modules in the PL section to stably output two triangular wave signals, supporting programmable adjustment of frequency, phase, duration, and silence time. The two triangular wave signals are superimposed and amplified by the power amplifier unit to form a composite interference field, which generates low-frequency difference frequency interference by utilizing the nonlinear distortion of the microphone in the recording system.

[0009] The power amplification unit is used to superimpose and amplify the pulse waveforms generated by the two DDS modules in the Zynq-7020 PL section to form a composite waveform field, which drives the ultrasonic transducer to radiate interference signals outward.

[0010] The human-computer interaction unit is used for human-computer interaction and consists of a button input module and an LED indicator module. The button input module inputs operation commands, and the LED indicator module provides real-time feedback on the current start and stop status of the device.

[0011] Furthermore, after the device is powered on and reset, it sequentially completes peripheral initialization and generates a 100ms delay through an internal counter to ensure hardware stability. After initialization, the two DDS modules enter the reset state, the device goes into standby mode and detects key input. Upon triggering, it starts the dual-channel DDS signal generation and superposition interference process.

[0012] Furthermore, when the control unit is powered on and initialized, it reads the random count value of the on-chip counter and performs an XOR operation with a fixed constant. The result of the operation is used as the initial seed of the XorShift pseudo-random generator, ensuring that the phase modulation sequence generated each time it is powered on is different.

[0013] Furthermore, the control unit uses a main frequency of 100MHz and incorporates a pseudo-random number generation algorithm and a DDS frequency / phase control word calculation program. It calculates the 28-bit frequency control word of the DDS according to a formula and sends this frequency control word to the DDS waveform generation module to generate the required waveform signal. The calculation formula is as follows:

[0014] ;

[0015] in, Output interference frequency for the target. This is the external reference clock frequency for the DDS module. This is the fixed number of bits for the phase accumulator of the DDS module.

[0016] Furthermore, the three sets of triangular wave signals generated by the first DDS module have an initial frequency of 23kHz-23.5kHz, and the frequency of the subsequent two sets increases by 200Hz. The dwell time of each set of triangular waves is 3-6ms. The three sets of signals are cyclically output by utilizing the fast switching characteristics of DDS.

[0017] Furthermore, the high-frequency interference signal output by the first DDS module is three sets of triangular wave signals with equal arithmetic distribution, and the frequency generation formula is:

[0018] ;

[0019] in, The base frequency ranges from 23kHz to 23.5kHz. The frequency difference is fixed and is set to 200Hz.

[0020] Three sets of frequency signals are output cyclically, and the residence time formula for each set of signals is as follows:

[0021] ;

[0022] in, A random integer between 0 and 2. The value range is 3-6ms.

[0023] Furthermore, the second DDS module generates a multi-dimensional pseudo-random triangular wave pulse signal with a frequency range of 23kHz-28kHz, a phase that dynamically switches between 0°, 90°, 180°, and 270°, a pulse width of 100-500ms, and a randomized silence time of 50-150ms after the pulse signal runs continuously.

[0024] Furthermore, the high-frequency interference signal of the pseudo-random pulse interference mode output by the second DDS function is a triangular wave pulse signal with pseudo-random frequency, phase, and duration. The frequency generation formula is:

[0025] ;

[0026] in, =23kHz, =28kHz, Pseudo-random numbers ranging from 0 to 1;

[0027] The phase offset is controlled by the 12-bit phase register of the DDS module. The formula for the correspondence between the phase control word and the phase offset is as follows:

[0028] ;

[0029] in, , A pseudo-random integer between 0 and 3. The value can be 0. , , .

[0030] Furthermore, the pseudo-random pulse interference mode includes a pulse output phase and a silence phase, and the formulas for generating the pulse duration and silence time are as follows:

[0031] ;

[0032] ;

[0033] in, , Pseudo-random numbers between 0 and 1 The value range is 100-500ms. The value range is 50-150ms;

[0034] The duty cycle formula for pulse mode is:

[0035] ;

[0036] The duty cycle ranges from 40% to 90.9%.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows: This dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function has the following advantages:

[0038] 1. Combining the frequency synthesis characteristics of DDS IP core, two interference modes, namely arithmetic distribution pulse and pseudo-random pulse, are designed. Both are based on the nonlinear difference frequency principle of high frequency signals to achieve recording interference. The difference frequency signal can cover the core pickup band of the recording equipment and can effectively drown out the effective voice signal, with significant interference effect.

[0039] 2. The first pulse signal achieves "chord-like" difference frequency interference through the cyclic output of equal arithmetic frequencies, with comprehensive interference coverage and stable operation. The second pseudo-random pulse mode achieves randomization design from multiple dimensions such as frequency, phase, duration, and silence time, which can effectively avoid the targeted processing of recording noise reduction algorithms and has strong anti-noise reduction capabilities. The two modes are superimposed and amplified to form a composite interference field, which can be adapted to different anti-recording application scenarios.

[0040] 3. All interference signal generation formulas strictly follow the DDS IP core frequency synthesis principle to ensure high precision and fast switching characteristics of signal generation. In addition, the selection of triangular wave signals ensures high purity of the difference frequency signal, further improving the interference effect of the equipment.

[0041] 4. The equipment adopts a modular design with a simple overall structure; the human-machine interface adopts a single-button design, and the status indicator module is an LED indicator, which is convenient to operate and has clear status recognition; at the same time, a sleep mode is designed to effectively reduce the overall power consumption of the equipment. Attached Figure Description

[0042] Figure 1 This is a block diagram of the overall system architecture of the present invention;

[0043] Figure 2 This is a flowchart illustrating the operation of the present invention.

[0044] Figure 3 This is a flowchart of the dynamic three-frequency chord progression of the present invention;

[0045] Figure 4 This is a flowchart of the pseudo-random pulse of the present invention;

[0046] Figure 5 This is a dynamic three-frequency chord waveform analysis diagram of the present invention;

[0047] Figure 6 This is a pseudo-random pulse waveform analysis diagram of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Please see Figure 1-6 This embodiment provides a technical solution: a dynamic tri-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function, with Xilinx Zynq-7020 chip as the core, Zynq-7020 PL part instantiates DDS IP core, generates two channels of DDS dynamic tri-frequency chord and pseudo-random ultrasonic interference signals, and outputs the composite interference field after power amplification circuit to achieve signal shielding of devices such as mobile phones or recorders.

[0050] like Figure 1 As shown, Figure 1The diagram shows the overall system architecture of this invention, illustrating the hardware connections of the power supply, the Zynq-7020 chip PS / PL section, the dual-channel DDS IP core, the power amplification unit, the AXI-Lite communication interface, the human-machine interaction unit, and the signal superposition output. The device includes the following four functional units: control unit, signal generation unit, power amplification unit, and human-machine interaction unit.

[0051] The control unit, implemented by the PS section of Zynq-7020, is responsible for the operation scheduling, parameter configuration and coordinated control of the two DDS modules, and sends control commands to the PL section through the AXI-Lite communication interface;

[0052] The signal generation unit utilizes the PL section of the Zynq-7020 to write a DDS programmable waveform generator IP core using Verilog HDL code, instantiates the DDS IP core to generate two DSS modules, and connects to the control unit via the AXI-Lite communication interface. It receives external control commands through the PS section of the Zynq-7020 and controls the two DDS modules in the PL section to stably output two triangular wave signals, supporting programmable adjustment of frequency, phase, duration, and silence time. The two triangular wave signals are superimposed and amplified by the power amplifier unit to form a composite interference field, which generates low-frequency difference frequency interference by utilizing the nonlinear distortion of the microphone in the recording system.

[0053] The power amplification unit is used to superimpose and amplify the pulse waveforms generated by the two DDS modules in the Zynq-7020 PL section to form a composite waveform field, which drives the ultrasonic transducer to radiate interference signals outward.

[0054] The human-computer interaction unit, used for human-computer interaction, consists of a button input module and an LED indicator module. The button input module inputs operation commands, and the LED indicator module provides real-time feedback on the current start and stop status of the device. It has a simple structure, is easy to operate, and the LED indicator unit can provide real-time feedback on the current start and stop status of the device.

[0055] like Figure 2-6 As shown, Figure 2 The flowchart illustrates the operation of this invention, showing the workflow of device power-on, module initialization, status indication, interference mode activation, signal superposition interference, and button power-off.

[0056] Figure 3 This is a flowchart of the dynamic three-frequency chord mode of the present invention, which shows the process of generating the fundamental frequency, setting the frequency arithmetic progression, randomly generating the dwell time, signal output and power amplification in the three-frequency chord mode.

[0057] Figure 4This is a flowchart of the pseudo-random pulse mode in the pseudo-random pulse mode of the present invention, which shows the process of pseudo-random number generation, signal output, silent time switching, looping and power amplification in the pseudo-random pulse mode.

[0058] Figure 5 This is a dynamic three-frequency chord waveform analysis diagram in the three-frequency chord mode of the present invention, showing the complete chord waveform, triangle wave switching details, and the cyclic output timing of the three frequency signals;

[0059] Figure 6 This is a pseudo-random pulse waveform analysis diagram under the pseudo-random pulse mode of the present invention, showing the complete pseudo-random pulse waveform, triangular wave details, and pulse-silence duration timing.

[0060] Combination Figure 2-6 As shown, the operation flow of the dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function is as follows:

[0061] 1. Control unit initialization and power-on process

[0062] After the device is powered on and reset, each unit module sequentially completes the initialization display of LED indicators, configures the high and low levels of the button detection pins, and forms the initialization parameter configuration of the DDS module. After all peripherals are initialized, a 100ms delay is generated by counting with an internal counter to ensure the stability of the Zynq-7020 chip and peripheral circuit hardware after power-on. The control unit is implemented using the Zynq-7020PS part. Waveform generation is achieved by instantiating the DDS programmable waveform generator IP core written in Verilog code of the PL part to obtain two DDS waveform generation modules. The two DDS waveform generation modules realize the required functions under the parameter configuration of the control unit. The control unit sends control commands to the DDS modules through the AXI-Lite communication interface. In order to achieve a non-periodic and unpredictable phase modulation sequence, the control unit reads the random count value of the on-chip counter at power-on, performs an XOR operation with a fixed constant, and uses the result as the initial seed of the Xorshift pseudo-random generator to ensure that the phase modulation sequence generated each time it is powered on is different.

[0063] After the initialization process is completed, the LED indicator flashes three times in a cycle as a system ready sign. Then, the PS section outputs control commands to the two DDS modules respectively, controlling the DDS modules to enter the reset state, and the system enters standby mode, continuously detecting user key input, waiting to trigger the subsequent workflow.

[0064] 2. DDS waveform generation module in operation

[0065] (1) First DDS signal: arithmetic triangular wave pulse

[0066] The control unit uses a Zynq-7020 chip, which has a built-in pseudo-random number generation algorithm and a DDS module frequency / phase control word calculation program. It can calculate the 28-bit frequency control word of the DDS according to the following formula and send the frequency control word to the DDS waveform generation module to generate the required waveform signal:

[0067] ;

[0068] in, Output interference frequency for the target. This is the external reference clock frequency for the DDS module. The fixed number of bits for the phase accumulator of the DDS module;

[0069] The high-frequency interference signal output by the first DDS module consists of three sets of triangular wave signals with equal distribution. The frequency generation formula is as follows:

[0070] ;

[0071] in, The base frequency ranges from 23kHz to 23.5kHz. The frequency difference is fixed and is set to 200Hz.

[0072] Three sets of frequency signals are output cyclically, and the residence time formula for each set of signals is as follows:

[0073] ;

[0074] in, A random integer between 0 and 2. The value range is 3-6ms;

[0075] (2) Second DDS module signal: pseudo-random pulse signal

[0076] The high-frequency interference signal in the pseudo-random pulse interference mode output by the second DDS function is a triangular wave pulse signal with pseudo-random frequency, phase, and duration. The frequency generation formula is:

[0077] ;

[0078] in, =23kHz, =28kHz, Pseudo-random numbers ranging from 0 to 1;

[0079] The phase offset is controlled by the 12-bit phase register of the DDS module. The formula for the correspondence between the phase control word and the phase offset is as follows:

[0080] ;

[0081] in, , A pseudo-random integer between 0 and 3. The value can be 0. , , ;

[0082] The pseudo-random impulse interference mode includes a pulse output phase and a silence phase. The formulas for generating the pulse duration and silence time are as follows:

[0083] ;

[0084] ;

[0085] in, , Pseudo-random numbers between 0 and 1 The value range is 100-500ms. The value range is 50-150ms;

[0086] The duty cycle formula for pulse mode is:

[0087] ;

[0088] The duty cycle ranges from 40% to 90.9%.

[0089] 3. Coordinated superposition of two signals and construction of interference field

[0090] Both DDS modules output triangular wave interference signals, with their output amplitude based on the full-amplitude output voltage of the Zynq 7020 chip. The actual output state of the signal is determined by the output phase of the final DDS module.

[0091] The two DDS modules generate an arithmetic distribution triangular wave pulse signal and a pseudo-random triangular wave pulse signal, respectively. After the basic generation is completed, the two signals are superimposed. The superimposed composite signal is sent to the power amplification unit for power amplification. Finally, a highly complex and highly random nonlinear anti-recording interference field is constructed in the target area of ​​the device to effectively interfere with the recording equipment.

[0092] The working principle of this invention, a dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function, is as follows:

[0093] This composite anti-recording interference device uses the Xilinx Zynq-7020 ARM+FPGA heterogeneous SoC chip as its core. It relies on dual-channel DDS technology to generate two high-frequency triangular wave interference signals and utilizes the nonlinear distortion characteristics of the recording device's microphone to generate low-frequency difference frequency interference. By superimposing the two signals, a highly complex and highly random nonlinear interference field is constructed, achieving comprehensive coverage of the recording device's core audio pickup band. Ultimately, this prevents the recording device from effectively acquiring and reproducing voice signals. The core principles of this invention include DDS signal generation, nonlinear difference frequency interference, and dual-channel signal synergistic superposition, as detailed below:

[0094] 1. High-frequency signal generation of DDS IP core

[0095] This invention instantiates two DDS IP cores in the PL section of the Zynq-7020 chip as signal generation units for high-frequency interference signals, and realizes high-precision, fast-switching triangular wave signal generation according to the basic principle of DDS frequency synthesis.

[0096] Using 100MHz as the external reference clock, the control module, written in Verilog code in the PS section of the chip, calculates the 28-bit frequency control word and the 12-bit phase control word according to the preset formula, and sends the parameters to the DDS IP core in the PL section through the AXI-Lite high-speed communication interface.

[0097] The DDS IP core accumulates the frequency control word through a phase accumulator, and combines the phase control word offset adjustment to convert the digital phase information into a triangular wave digital waveform, and finally outputs an analog high-frequency triangular wave signal through the PL section.

[0098] Leveraging the 28-bit frequency resolution and 12-bit phase resolution of the DDS IP core, high-precision adjustment of the frequency and phase of interference signals is achieved. At the same time, its fast switching characteristics are utilized to complete the cyclic output of multi-frequency signals and dynamic adjustment of parameters, providing a foundation for subsequent composite interference.

[0099] 2. Nonlinear distortion and low-frequency difference of microphones in recording equipment

[0100] The interference signal output by this invention is a high-frequency ultrasonic signal of 23kHz-28kHz. This frequency band is beyond the range of human hearing, but the microphone sensor of the recording device can capture this frequency band signal. Moreover, the piezoelectric conversion characteristics of the microphone have natural nonlinear distortion. This invention utilizes this physical characteristic to achieve recording interference.

[0101] When a single or multiple high-frequency interference signals are captured by the microphone of a recording device, their nonlinear conversion process generates a low-frequency difference signal. The frequency of the difference signal is equal to the frequency difference between the high-frequency signals.

[0102] The first DDS module generates an arithmetic high-frequency triangular wave signal, which, after nonlinear distortion, produces a fixed low-frequency difference signal that covers the core pickup band of the recording equipment (human voice 200Hz-4kHz). The second pseudo-random high-frequency signal generates a random low-frequency difference signal. The superposition of the two types of difference signals directly overwhelms the original speech signal, making it impossible for the recording equipment to distinguish between valid speech and interference signals. The triangular wave signal is used as the interference waveform. Compared with sine waves and square waves, the difference signal generated after nonlinear distortion has higher purity and more uniform interference coverage, further improving the overwhelming effect on the speech signal.

[0103] 3. First-channel DDS: Dynamic tri-frequency chord interference

[0104] The first DDS module generates three sets of triangular wave high-frequency signals with equal frequency distribution to achieve "chord-like" difference frequency interference. The core of this is fixed equal frequency distribution, random dwell time, and cyclic output, which allows the low-frequency difference frequency signal to form a continuous and stable interference coverage.

[0105] The first group of signals is generated based on a fundamental frequency of 23kHz-23.5kHz. The second and third groups of signals are generated by increasing the fundamental frequency by 200Hz in turn. The three groups of signals form a high-frequency combination with a fixed frequency difference.

[0106] By utilizing the fast switching characteristics of DDS, a random dwell time of 3-6ms is allocated to each group of signals, and the three groups of signals are cyclically output to avoid the solidification of interference signal patterns.

[0107] After the three sets of equal high-frequency signals are nonlinearly distorted by the microphone, they generate low-frequency difference signals with corresponding fixed differences, forming a continuous low-frequency interference field in the form of "chords". This field fully covers the high-sensitivity pickup band of the recording equipment, thus achieving basic submersion of the speech signal.

[0108] 4. Second-channel DDS: Multi-dimensional pseudo-random pulse interference

[0109] The second DDS module generates a high-frequency triangular wave pulse signal with four dimensions of randomization: frequency, phase, duration, and silence time. This generates pseudo-random pulse interference. The four-dimensional randomization design can effectively avoid the targeted filtering and feature recognition of recording noise reduction algorithms.

[0110] Frequency random: High-frequency signals are dynamically generated in the range of 23kHz-28kHz using a pseudo-random algorithm, without a fixed frequency pattern;

[0111] Phase randomization: The phase dynamically switches between 0°, 90°, 180°, and 270°, precisely controlled by a 12-bit phase register, so that the signal waveform has no fixed phase characteristics;

[0112] Random duration: The effective output time of the pulse signal is randomly generated within the range of 100-500ms;

[0113] Random silence time: After continuous output of the pulse signal, a silence period of 50-150ms is randomly entered, and the signal output stops, further improving the unpredictability of the signal;

[0114] The four-dimensional randomized high-frequency pulse signal, after nonlinear distortion, generates a random low-frequency difference signal with no fixed pattern. This makes it impossible for recording noise reduction algorithms to extract the characteristics of the interference signal and to separate the interference signal from the speech signal through filtering, noise reduction, and other methods, thus greatly improving the device's anti-noise reduction capability.

[0115] 5. Dual-channel signal superposition to construct a nonlinear composite interference field.

[0116] This invention superimposes the energy of the first "chord-type" interference signal and the second pseudo-random pulse interference signal, amplifies them through a power amplifier circuit, and drives an ultrasonic transducer to construct a highly complex and highly random nonlinear composite interference field within an effective radius of 3-5 meters, achieving an interference effect of 1+1>2.

[0117] The first signal provides continuous and stable full-band basic coverage, while the second signal provides random and irregular noise reduction enhancement. When the two signals are superimposed, the recording device cannot avoid basic difference frequency interference in the frequency domain, nor can it eliminate random difference frequency interference through algorithms.

[0118] The superimposed composite high-frequency signal, after being nonlinearly distorted by the microphone, produces a low-frequency difference signal that is not simply the sum of two difference signals, but rather forms a more complex nonlinear mixed difference signal, further increasing the signal analysis difficulty of the recording equipment.

[0119] The power amplification unit boosts the power of the superimposed composite signal, driving the ultrasonic transducer to convert the electrical signal into a sound wave signal, forming a uniform and comprehensive interference sound field in the target area, ensuring that all recording devices in the area can be effectively interfered with.

[0120] In summary, this invention deeply integrates DDS signal generation technology, microphone nonlinear distortion difference frequency principle, and multi-dimensional pseudo-randomization design. By constructing a highly complex composite interference field through the collaborative superposition of dual signals, it not only achieves comprehensive coverage of the core audio pickup band of the recording equipment, but also effectively avoids the countermeasures of recording noise reduction algorithms. Ultimately, it achieves efficient and stable shielding of various recording equipment within its effective range.

[0121] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function, characterized in that: Based on the Zynq-7020 chip, it includes a control unit, a signal generation unit, a power amplification unit, and a human-machine interaction unit; The control unit, implemented by the PS section of the Zynq-7020, is responsible for the operation scheduling, parameter configuration and coordinated control of the two DDS modules, and sends control commands to the PL section through the AXI-Lite communication interface; The signal generation unit utilizes the PL section of the Zynq-7020 to write a DDS programmable waveform generator IP core using Verilog HDL code, instantiates the DDS IP core to generate two DSS modules, and connects to the control unit via the AXI-Lite communication interface. It receives external control commands through the PS section of the Zynq-7020 and controls the two DDS modules in the PL section to stably output two triangular wave signals, supporting programmable adjustment of frequency, phase, duration, and silence time. The two triangular wave signals are superimposed and amplified by the power amplifier unit to form a composite interference field, which generates low-frequency difference frequency interference by utilizing the nonlinear distortion of the microphone in the recording system. The power amplification unit is used to superimpose and amplify the pulse waveforms generated by the two DDS modules in the Zynq-7020 PL section to form a composite waveform field, which drives the ultrasonic transducer to radiate interference signals outward. The human-computer interaction unit is used for human-computer interaction.

2. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 1, characterized in that: When the control unit is powered on and initialized, it reads the random count value of the on-chip counter and performs an XOR operation with a fixed constant. The result of the operation is used as the initial seed of the XorShift pseudo-random generator, ensuring that the phase modulation sequence generated each time it is powered on is different.

3. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 2, characterized in that: The control unit uses 100MHz as its main frequency and has a built-in pseudo-random number generation algorithm and DDS frequency / phase control word calculation program. It calculates the 28-bit frequency control word of DDS according to the calculation formula and sends the frequency control word to the DDS waveform generation module to generate the required waveform signal. The calculation formula is: ； in, Output interference frequency for the target. This is the external reference clock frequency for the DDS module. This is the fixed number of bits for the phase accumulator of the DDS module.

4. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 1, characterized in that: The first DDS module generates three sets of triangular wave signals with an initial frequency of 23kHz-23.5kHz. The frequency of the next two sets increases by 200Hz. The dwell time of each set of triangular waves is 3-6ms. The fast switching characteristics of DDS are used to realize the cyclic output of the three sets of signals.

5. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 4, characterized in that: The high-frequency interference signal output by the first DDS module consists of three sets of triangular wave signals with equal arithmetic distribution. The frequency generation formula is as follows: ； in, The base frequency ranges from 23kHz to 23.5kHz. The frequency difference is fixed and is set to 200Hz. Three sets of frequency signals are output cyclically, and the residence time formula for each set of signals is as follows: ； in, A random integer between 0 and 2. The value range is 3-6ms.

6. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 1, characterized in that: The second DDS module generates a multi-dimensional pseudo-random triangular wave pulse signal with a frequency range of 23kHz-28kHz, a phase that dynamically switches between 0°, 90°, 180°, and 270°, a pulse width of 100-500ms, and a randomized silence time of 50-150ms after continuous operation of the pulse signal.

7. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 6, characterized in that: The high-frequency interference signal of the pseudo-random pulse interference mode output by the second DDS function is a triangular wave pulse signal with pseudo-random frequency, phase, and duration. The frequency generation formula is: ； in, =23kHz, =28kHz, Pseudo-random numbers ranging from 0 to 1; The phase offset is controlled by the 12-bit phase register of the DDS module. The formula for the correspondence between the phase control word and the phase offset is as follows: ； in, , A pseudo-random integer between 0 and 3. The value can be 0. , , .

8. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 7, characterized in that: The pseudo-random pulse interference mode includes a pulse output phase and a silence phase, and the formulas for generating the pulse duration and silence time are as follows: ； ； in, , Pseudo-random numbers between 0 and 1 The value range is 100-500ms. The value range is 50-150ms; The duty cycle formula for pulse mode is: ； The duty cycle ranges from 40% to 90.9%.

9. The dynamic three-frequency chord and pseudo-random pulse composite anti-recording interference device based on dual-channel DDS function according to claim 1, characterized in that: The human-computer interaction unit consists of a button input module and an LED indicator module. The button input module inputs operation commands, and the LED indicator module provides real-time feedback on the current start and stop status of the device.

Images