Recording interference prevention system and control method thereof

Abstract

The invention discloses a recording interference prevention system and a control method thereof, and the system comprises a controller which is used for controlling related components of the recording interference prevention system to work; the ultrasonic detection heads are connected with the controller, are arranged in an array and are used for capturing sound; the battery supplies power to the recording interference prevention system; and the power button is used for connecting a power supply and starting the system to work. The method has the beneficial effects that the voice signal is interfered through the random sound wave signal, so that the recording equipment can only record noise and cannot distinguish the voice. According to the invention, the mobile phone and the recording pen can be shielded, and the recording function of the wireless monitoring and monitoring camera can be interfered.

Description

Technical Field

[0001] The invention belongs to the technical field of information confidentiality and relates to a recording interference prevention system and a control method thereof. Background Art

[0002] Recording technology has been around for more than a hundred years, and has been widely used in all walks of life since its inception. With the continuous advancement of science and technology, recording technology has gradually been refurbished, from the initial magnetic recording to the later optical disc burning, and then to the current digital processing recording. In just a hundred years, recording technology has completed its transformation.

[0003] With the development of recording technology and the popularity of recording equipment, especially new recording equipment such as mobile phones and voice recorders, more and more criminals use various devices to conduct secret recording and eavesdropping activities, wantonly stealing and leaking personal privacy, corporate secrets, government agencies and even national security information, which has brought huge security risks to individuals, enterprises, government agencies and even our country's information security. The endless eavesdropping and recording incidents reflect the strong demand for anti-recording products in the current environment.

[0004] Anti-recording devices, also known as recording blockers or recording jammers, are often regarded as exclusive tools for professional occasions to prevent illegal recording, such as in business talks, confidential meetings or military occasions. In fact, they are gradually being integrated into the lives of ordinary people and becoming a powerful assistant in various conversation scenarios.

[0005] In the modern business environment, the protection of business secrets and customer privacy information is of vital importance. The emergence of anti-recording interference jammers provides companies with a better means of protection, by interfering with the work of recording equipment, thereby protecting the company's business secrets and customer privacy information. At present, the anti-recording interference technology uses white noise, but it has major defects. Summary of the invention

[0006] The purpose of the present invention is to address the problems existing in the current anti-recording interference devices, propose an anti-recording interference system and a control method thereof, and provide effective protection means for commercial secrets and personal privacy.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A recording interference prevention system, comprising:

[0009] A controller, used for controlling the operation of related components of the anti-recording interference system;

[0010] Ultrasonic detection heads, connected to the controller and arranged in an array, are used to capture sound;

[0011] Batteries, to power the anti-recording interference system;

[0012] The power button is used to connect the power supply and start the system.

[0013] The controller described in the present invention is a core single chip microcomputer.

[0014] The anti-recording interference system of the present invention includes single-machine arrangement, multi-machine networking and other arrangement modes.

[0015] The ultrasonic detection head of the present invention is divided into three arrangements: 90° arrangement, 270° arrangement and 360° arrangement.

[0016] The battery of the present invention is a rechargeable battery.

[0017] The battery power of the present invention is divided into four parts according to the voltage value. The first part is 15.2V-16.8V, which is three grids of power; the second part is 14V-15.2V, which is two grids of power; the third part is 13.4V-14V, which is one grid of power; and the fourth part is lower than 13.4V, which is a power shortage state and will automatically shut down.

[0018] A control method for an anti-recording interference system comprises the following steps:

[0019] Press the power button to power on the device. The controller controls the ultrasonic detection head to work. The ultrasonic detection head detects sound. When sound is detected, the system is triggered to work, that is, the ultrasonic probe is triggered to release ultrasonic waves to interfere with the recording process. If the ultrasonic detection head does not capture sound within a certain period of time, the machine enters standby mode.

[0020] The method for powering on the device of the present invention is: pulling up the PA3 pin of the single chip computer to turn on the shutdown circuit.

[0021] The two pins PA1 / PA2 of the microcontroller control the output of the ultrasonic detector.

[0022] The specific method for detecting sound of the present invention is as follows: PA0 of the single chip microcomputer is configured as ADC1 input channel 0, and the output is turned on when the ADC signal is higher than the threshold value through the differential signal amplified by AD8605.

[0023] The beneficial effect of the present invention is that the voice signal is interfered with by a random sound wave signal, so that the recording device can only record noise but cannot distinguish the voice. The present invention can not only shield mobile phones and voice recorders, but also interfere with the recording function of wireless monitoring and surveillance cameras. Portable anti-recording jammers are generally equipped with multiple ultrasonic transmitters, large-capacity batteries and remote controls. They are very convenient to use and can work without being noticed, without affecting the normal meeting or conversation environment at all. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of a 90° arrangement of an ultrasonic detector head according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a 270° arrangement of an ultrasonic detection head according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of a 360° arrangement of an ultrasonic detection head according to an embodiment of the present invention;

[0027] Figure 4 This is a control flow chart of the anti-recording interference system of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the invention in any way.

[0029] 1. Principle description:

[0030] The principle of noise reduction is mainly to generate some sound waves with equal amplitude and opposite phase to the noise to cancel each other out, thereby achieving the effect of eliminating noise and reducing noise.

[0031] The main feature of using ultrasound for recording shielding is that the noise generated is inaudible to human ears but can be recorded by recording equipment. The ultrasound emitted by the ultrasonic detector has good directivity. Using multiple probes to generate ultrasound at the same time can achieve the effect of long-distance recording shielding in a certain direction. However, if ultrasound is used directly to achieve the shielding function, the noise is easily filtered out when it reaches the hardware circuit of the recording equipment, so we need to use a 20Hz-20KHz noise signal as the fundamental wave and ultrasound as the carrier for modulation.

[0032] According to the principle of noise reduction, if you simply use an ultrasonic probe to modulate a normal noise (with an insufficient amplitude), it will be easily filtered out by the recording device. Therefore, the strategy we need to adopt is to generate a noise signal that can saturate the microphone amplitude of the recording device. When the microphone amplitude reaches saturation, it means that the noise has submerged the useful sound information, and the recording device software will only collect a single value with the highest amplitude, making it impossible to restore or generate a noise reduction signal.

[0033] 2. Theoretical Implementation

[0034] There are three main types of modulation methods, namely ASK, PSK, and FSK (amplitude modulation, phase modulation, and frequency modulation). Among them, ASK has 2ASK and SPWM modulation. Using 2ASK modulation can have a good shielding effect, but the noise it produces that can be heard by the human ear is also the largest. SPWM modulation is to use PWM to modulate a sine wave by changing the duty cycle. This modulation method has low noise and medium shielding effect. PSK is difficult to implement on a single-chip microcomputer and is generally not considered.

[0035] FSK has the best effect and less noise. It modulates a triangle wave, which is achieved by using a timer on the microcontroller to regularly adjust the PWM frequency.

[0036] 3. Control system

[0037] This control system is based on -M4 core microcontroller, using time slice polling for task management. The recording shielding algorithm uses FSK modulation, with a carrier frequency of 25KHz and a fundamental frequency of 92.5Hz. A timer is used to periodically change the PWM frequency so that the carrier frequency is swept within the range of 24KHz-26KHz, thereby generating 92.5Hz interference noise.

[0038] After the power button is pressed, the device is powered on, and the microcontroller pulls up PA3 to turn on the shutdown circuit. After that, releasing the power button will not cut off the power. To shut down, just pull the PA3 level low.

[0039] The two pins PA1 / PA2 control the ultrasonic output. These two pins are the PWM output channel 1 of the microcontroller TIMER15, which can generate complementary PWM waves and have configurable dead zones, making them suitable for controlling the motor driver chip TMI8140.

[0040] Human voice detection is configured as ADC1 input channel 0 through PA0. The differential signal amplified by AD8605 is used to determine if the ADC signal is higher than a certain threshold and then turn on the output.

[0041] PA4 is responsible for collecting battery voltage. Low-pass filtering has been done in the circuit, so the collected ADC value is relatively stable. The software processing only needs to increase the sampling time. Before conversion, the external voltage is judged by the internal reference voltage of the chip, and then the ADC value of ADC0 is converted into battery voltage using the converted external voltage. The battery power is divided into four parts by voltage value partitioning. The first is 15.2-16.8V, which is three grids; the second is 14-15.2V, which is two grids; the third is 13.4-14V, which is one grid; the fourth is below 13.4V, which is a power shortage state and will automatically shut down.

[0042] The four buttons are input through PB6, PB3, PA12, and PA11, and the GPIO is configured as internal pull-up, which reduces the use of pull-up resistors. The button driver uses a synchronous and asynchronous processing algorithm and adopts an event-driven approach; each button is connected using a static linked list, and the linked list is polled every 10ms. If a key event occurs, it is determined whether the user has registered a callback function for the corresponding event, and whether it is executed synchronously or asynchronously. If it is synchronous, it is executed immediately; if it is asynchronous, the corresponding callback function is marked and executed in idle time.

[0043] For example, after the MCU is powered on, by registering the long press callback of the power button, the power-on logic written in the long press callback will be executed.

[0044] After booting up, the power button can control the startup / standby state of the device by single-clicking. Before entering standby mode, we first unregister the single-click callbacks of the other three buttons to make them invalid during standby, and then re-register them after booting up. Using this button driver is more efficient and neater than traditional process-oriented button judgment.

[0045] The 433 module reads input through PA15 and PA8. Since its input is also transmitted through level, it can be abstracted as a key object, which can greatly reduce the difficulty of software writing.

[0046] The entire software uses a top-down modular design and is divided into modules such as application, business logic, driver, peripheral configuration, component, SDK, etc. Each module has a low degree of coupling, a high degree of closure, and clear logic, which facilitates secondary development and maintenance.

[0047] 4. Recording Interference Algorithm

[0048] The recording interference algorithm uses FSK modulation with a carrier frequency of 25KHz and a fundamental frequency of 92.5Hz. The 25KHz ultrasonic wave entering the recording device will be filtered by its low-pass filter, thus forming 92.5Hz noise. The intensity of this noise needs to be large enough to maximize the amplitude of the microphone of the recording device, causing distortion of other sound signals.

[0049] However, the power cannot be continuously increased in order to increase the intensity of the interference noise, because the noise signal will be accompanied by harmonic noise. As the power increases, the intensity of some low-frequency harmonic noise audible to the human ear also increases, resulting in some unwanted sounds being heard when the device is used, which does not meet the application scenarios of the device's concealment.

[0050] The frequency of human speech is usually between 85 and 1100 Hz. Since the lower the frequency of sound waves, the farther they travel in the air, 92.5 Hz is a more reasonable frequency value. The center frequency of the carrier is 25 KHz. The timer is used to change the PWM frequency regularly so that the carrier frequency is swept within the range of 24 KHz-26 KHz. If the clock frequency of PWM is 1 MHZ, then to generate 25 KHz PWM, the cycle value is 1 MHz / 25 KHZ=400. Similarly, the cycle value of 26 KHz is: 384, and the cycle value of 24 KHz is: 416. Assuming that the clock frequency of the timer is 1 MHz, each time the timer is entered, the cycle value is ±1, then 64 interrupts need to be generated for a cycle from 384 to 416. To generate 92.5 Hz interference noise, the interrupt frequency of the timer is: 1 MHz / (64*92.5 Hz).

[0051] 5. Recording interference effect test:

[0052] Recording equipment: Place 2 smartphones (Android and Apple) in the room.

[0053] Location: The two smartphones were placed in locations where the noise energy was relatively high.

[0054] Recognition results: Two anti-recording jammers were used to identify the recordings and the lowest WER was selected as the result.

[0055] Noise-free condition: Test the condition where the power amplifier is turned on but no noise is emitted to verify the effect of noise on the recognition results.

[0056] Analysis of anti-recording results:

[0057] At locations with high noise energy, the recognition accuracy of both devices was less than 20%, indicating that they were able to effectively interfere with the recording.

[0058] Noise-free condition: In the noise-free condition, the recognition accuracy of both devices exceeded 90%, verifying the impact of noise on the recognition results.

[0059] in conclusion

[0060] The noise energy distribution meets the WHO recommended standards and is harmless to the human body. The anti-recording interference function can be effectively implemented to protect user privacy.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Those skilled in the art should understand that the specific implementation modes of the present invention may be modified or replaced by equivalents with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the pending claims.

Claims

1. A recording interference prevention system, characterized in that: include: A controller, used for controlling the operation of related components of the anti-recording interference system; Ultrasonic detection heads, connected to the controller and arranged in an array, are used to capture sound; Batteries, to power the anti-recording interference system; The power button is used to connect the power supply and start the system.

2. The anti-recording interference system according to claim 1, characterized in that: The controller is a core single chip microcomputer.

3. The anti-recording interference system according to claim 1, characterized in that: The anti-recording interference system includes single-machine arrangement, multi-machine networking and other arrangements.

4. The anti-recording interference system according to claim 1, characterized in that: The ultrasonic detection heads are divided into three arrangements: 90° arrangement, 270° arrangement and 360° arrangement.

5. The anti-recording interference system according to claim 1, characterized in that: The battery is a rechargeable battery.

6. The anti-recording interference system according to claim 1, characterized in that: The battery power is divided into four parts according to the voltage value. The first part is 15.2V-16.8V, which is three grids of power; the second part is 14V-15.2V, which is two grids of power; the third part is 13.4V-14V, which is one grid of power; and the fourth part is lower than 13.4V, which is a power shortage state and will automatically shut down.

7. A control method for an anti-recording interference system according to any one of claims 1 to 6, characterized in that: The following steps are involved: Press the power button to power on the device. The controller controls the ultrasonic detection head to work. The ultrasonic detection head detects sound. When sound is detected, the system is triggered to work, that is, the ultrasonic probe is triggered to release ultrasonic waves to interfere with the recording process. If the ultrasonic detection head does not capture sound within a certain period of time, the machine enters standby mode.

8. The control method of the anti-recording interference system according to claim 7, characterized in that: The method for powering on the device is: pull up the PA3 pin of the single chip computer to turn on the shutdown circuit.

9. The control method of the anti-recording interference system according to claim 7, characterized in that: The two pins PA1 / PA2 of the microcontroller control the output of the ultrasonic detector.

10. The control method of the anti-recording interference system according to claim 7, characterized in that: The specific method of detecting sound is: configure PA0 of the microcontroller as ADC1 input channel 0, and use the differential signal amplified by AD8605 to determine if the ADC signal is higher than the threshold and turn on the output.

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