Terminal anti-eavesdropping device
By setting up a connection module and an audio management module in the terminal anti-eavesdropping device, the audio control permissions of the external terminal are obtained and preset audio signals are transmitted, the problems of complex operation and the risk of eavesdropping are solved, and the anti-eavesdropping effect is achieved with convenient operation.
Patent Information
- Application Number
- CN202411692005.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-02-18
AI Technical Summary
The prior art is difficult to provide a terminal anti-eavesdropping device that is convenient to operate, so as to prevent the eavesdropping party from obtaining audio signals of the terminal's use environment through the terminal.
A terminal anti-eavesdropping device is designed, including a housing, a connection module and an audio management module. The connection module is used to establish a communication connection with an external terminal and obtain audio control permissions. The audio management module has built-in preset audio signals and transmits them to an external terminal through the connection module.
By simulating external microphone collection, the built-in preset audio signal is returned to prevent the eavesdropper from obtaining the audio signal, and the eavesdropping is prevented and easy to operate.
Smart Images
Figure CN119485117A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of anti-eavesdropping, in particular to a terminal anti-eavesdropping device. Background Art
[0002] With the rapid development of Internet technology and the increasing popularity of Internet terminals, people have entered the digital Internet era. At the same time, user privacy eavesdropping incidents based on Internet terminals occur from time to time. For example, the eavesdropper can activate the microphone of the terminal without the knowledge of the eavesdropped party through software installed in the terminal of the eavesdropped party, thereby achieving eavesdropping.
[0003] In the settings of the terminal's operating system, users can view the list of applications that access the device's microphone. If an application is found to have access to the microphone that should not be allowed, its permission should be revoked, and even the application should be considered for deletion. However, although the terminal's operating system provides a way to view the access rights of the device's built-in microphone and to turn it on / off, it is still a bit cumbersome and complicated for most users.
[0004] Therefore, it is necessary to provide a terminal anti-eavesdropping device that is easy to operate to prevent the eavesdropping party from obtaining the audio signal of the terminal usage environment through the terminal. Summary of the invention
[0005] The technical problem to be solved by the embodiments of the present invention is to provide a terminal anti-eavesdropping device that is easy to operate, so as to prevent an eavesdropping party from obtaining audio signals of the terminal usage environment through the terminal.
[0006] The present invention discloses a terminal anti-eavesdropping device, comprising a shell, a connection module and an audio management module arranged in the shell, the audio management module is connected to the connection module, the connection module is used to establish a communication connection with an external terminal to obtain the audio control authority of the external terminal, the audio management module is built with a preset audio signal, and the preset audio signal can be transmitted to the external terminal through the connection module.
[0007] Optionally, the preset audio signal is a disordered audio signal, an ordered audio signal or a blank audio signal.
[0008] Optionally, when the preset audio signal is a disordered audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate a random digital sequence with equal probability through a pseudo-random number generator, and output the random digital sequence directly as a waveform to output a first white noise as the disordered audio signal, or map the random digital sequence to a specific voltage or audio value, and output a second white noise as the disordered audio signal.
[0009] Optionally, when the preset audio signal is a disordered audio signal, the audio management module includes a main control chip and an audio signal generating circuit, the audio signal generating circuit includes a transistor, a resistor and a capacitor, the base of the transistor is grounded, the collector is suspended, the emitter is connected to one end of the resistor and one end of the capacitor, the other end of the resistor is connected to a power supply, and the other end of the capacitor is used to output a third white noise as the disordered audio signal, and the main control chip is connected to the connection module for controlling the connection module to transmit the disordered audio signal to an external terminal.
[0010] Optionally, the audio management module further includes a filter. When the audio management module includes a DSP chip, the filter is connected to the DSP chip, and the filter is used to filter the first white noise or the second white noise and then output corresponding colored noise as the disordered audio signal;
[0011] When the audio management module includes a main control chip and an audio signal generating circuit, the filter is connected to the other end of the capacitor, and the filter is used to filter the third white noise and then output corresponding colored noise as the disordered audio signal.
[0012] Optionally, when the preset audio signal is a disordered audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate noise with specific statistical characteristics through a probability distribution function as the disordered audio signal.
[0013] Optionally, when the preset audio signal is a disordered audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate random noise as the disordered audio signal through an FFT inverse transform method or an inverse convolution method.
[0014] Optionally, when the preset audio signal is an ordered audio signal, the audio management module includes a DSP chip, and the DSP chip is used to pre-store a preset waveform sequence or audio, and control the preset waveform sequence or audio to be played sequentially or in a loop as the preset audio signal.
[0015] Optionally, when the preset audio signal is a blank audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate a data stream whose output values are all zero to form the blank audio signal.
[0016] Optionally, the connection module is a connector, which is used to be inserted into an external interface of an external terminal, and the connector is a Micro-USB connector, a Type-C connector, a Lighting connector, or a headphone plug;
[0017] Alternatively, the connection module is a remote communication connector, and the remote communication connector establishes a communication connection with an external terminal via a hotspot network, a cellular network, Bluetooth, WIFI or Star Flash.
[0018] Compared with the prior art, the terminal anti-eavesdropping device provided by the embodiment of the present invention has the following beneficial effects: by setting a connection module and an audio management module in the shell, the connection module can establish a communication connection with an external terminal to obtain the audio control authority of the external terminal; the audio management module has a built-in preset audio signal, and can transmit the built-in preset audio signal to the external terminal connected to it through the connection module; the terminal anti-eavesdropping device of the present application can convert the microphone collection inside the external terminal into an external microphone collection, and simulate the external microphone of the external terminal without setting a microphone to return the built-in preset audio signal to the external terminal, thereby preventing the eavesdropping party from obtaining the audio signal of the terminal usage environment through the external terminal, thereby achieving anti-eavesdropping and easy operation. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:
[0020] Figure 1 It is a structural block diagram of an embodiment of the terminal anti-eavesdropping device provided by the present invention;
[0021] Figure 2 It is a structural block diagram of another embodiment of the terminal anti-eavesdropping device provided by the present invention;
[0022] Figure 3 It is a structural block diagram of another embodiment of the terminal anti-eavesdropping device provided by the present invention.
[0023] The reference numerals in the figures are:
[0024] 110, connection module; 120, audio management module; 121, DSP chip; 122, audio signal generating circuit; 123, filter;
[0025] Q1, transistor; R1, resistor; C1, capacitor. DETAILED DESCRIPTION
[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.
[0027] The embodiment of the present invention provides a terminal anti-eavesdropping device, such as Figure 1As shown, the terminal anti-eavesdropping device includes a shell and a connection module 110 and an audio management module 120 arranged in the shell. The audio management module 110 is connected to the connection module 120. The connection module 110 is used to establish a communication connection with an external terminal to obtain the audio control authority of the external terminal. The audio management module 120 has a preset audio signal built in, and the preset audio signal can be transmitted to the external terminal through the connection module 110.
[0028] The present application sets a connection module 110 and an audio management module 120 in the shell. The connection module 110 can establish a communication connection with the external terminal to obtain the audio control authority of the external terminal. The audio management module 120 has a built-in preset audio signal and can transmit the built-in preset audio signal to the external terminal connected to it through the connection module 110. The terminal anti-eavesdropping device of the present application can convert the microphone collection inside the external terminal into external microphone collection, and simulate the external microphone of the external terminal without setting a microphone to return the built-in preset audio signal to the external terminal, thereby preventing the eavesdropping party from obtaining the audio signal of the terminal usage environment through the external terminal, thereby realizing anti-eavesdropping and easy operation.
[0029] The audio control authority of the terminal refers to the authority of the terminal to obtain external audio signals. Specifically, when the terminal is not connected to an external device, the terminal uses the built-in microphone as the input source of the external audio signal. When the terminal is connected to the terminal anti-eavesdropping device, the connection module 110 of the terminal anti-eavesdropping device obtains the audio control authority of the terminal, and the terminal uses the terminal anti-eavesdropping device as the input source of the external audio signal. In this process, the terminal may automatically switch to the terminal anti-eavesdropping device as the input source after establishing a communication connection with the connection module 110, or prompt the user to manually set the switch. The terminal may be a terminal device such as a mobile phone, a tablet computer, or a smart bracelet.
[0030] In the embodiment of the present application, the preset audio signal is a disordered audio signal, an ordered audio signal or a blank audio signal.
[0031] A disordered audio signal is a random audio data. An ordered audio signal is an audio data that presents a certain pattern. A blank audio signal is a signal without sound or audio content, that is, a silent signal.
[0032] When the preset audio signal is a disordered audio signal, refer to Figure 2 The audio management module 120 includes a DSP chip 121, which is used to generate a random digital sequence with equal probability through a pseudo-random number generator, and directly output the random digital sequence as a waveform to output a first white noise as a disordered audio signal, or map the random digital sequence to a specific voltage or audio value, and output a second white noise as a disordered audio signal.
[0033] DSP (Digital Signal Processing) chip is a chip that can realize digital signal processing technology. The DSP chip 121 adopts Harvard structure with separate program and data, has a special hardware multiplier, widely adopts pipeline operation, and provides special DSP instructions, which can be used to quickly realize various digital signal processing algorithms. DSP chip 121 can specifically adopt SNC8X series chip.
[0034] The pseudo-random number generator generates a number series through a series of algorithms. These algorithms are usually based on the linear congruential method, the mixed linear congruential method, etc. These algorithms use an initial seed value and generate a series of pseudo-random numbers through a specific calculation process, that is, the random number sequence mentioned above. The random number sequence is directly output as a waveform to obtain the first white noise, which is simple and fast. The audio management module 120 can transmit the first white noise to the external terminal through the connection module 110, so as to simulate the external terminal receiving the first white noise through the external radio device.
[0035] The random number sequence generated by the pseudo-random number generator can be further mapped to a specific voltage or audio value through a preset rule to form a second white noise. The difference between the second white noise and the first white noise is that the probability distribution and power spectrum density are different, but both can be transmitted to an external terminal as an audio signal.
[0036] When the preset audio signal is a disordered audio signal, the embodiment of the present application provides another method for generating a disordered audio signal.
[0037] refer to Figure 3 The audio management module 120 includes an audio signal generating circuit 122, which includes a transistor Q1, a resistor R1 and a capacitor C1. The base of the transistor Q1 is grounded, the collector is suspended, the emitter is connected to one end of the resistor R1 and one end of the capacitor C1, the other end of the resistor R1 is connected to a power supply, and the other end of the capacitor C1 is connected to the connection module 110, which is used to output a third white noise as a disordered audio signal.
[0038] By reversely connecting the base-emitter PN junction of transistor Q1 to the circuit, the circuit generates a Zener voltage of about 5 volts, and uses this Zener breakdown phenomenon to generate white noise, without the need for complex circuits or expensive components. The circuit is relatively simple and low in cost. Moreover, white noise is generated by hardware circuits, which is not easily interfered by external factors, has high stability, and can provide real-time disordered audio signals. The power supply can be obtained through an external power supply, or obtained by taking power from an external terminal through the connection module 110.
[0039] refer to Figure 3The audio management module 120 also includes a filter 123. When the audio management module 120 includes a DSP chip 121, the filter 123 is connected to the DSP chip 121. The filter 123 is used to filter the first white noise or the second white noise and then output the corresponding colored noise as a disordered audio signal.
[0040] When the audio management module 120 includes the audio signal generating circuit 122 , the filter 123 is connected to the other end of the capacitor C1 , and the filter 123 is used to filter the third white noise and then output the corresponding colored noise as the disordered audio signal.
[0041] By adding a filter 123 on the basis of white noise, the frequency components of the spectrum can be controlled. Different filters 123 will produce different types of color noise. For example, a low-pass filter 123 can be used to attenuate the high-frequency part of white noise, so that the frequency component is proportional to 1 / f, forming pink noise; a low-pass filter 123 is used to further increase the attenuation, so that the spectrum component is proportional to 1 / f2, the sound is deeper, forming brown noise or red noise; a high-pass filter is used to enhance the high-frequency part of white noise, so that the sound is biased towards high frequency, forming blue noise and purple noise. Low-pass filters and high-pass filters can use conventional technology, which will not be described here.
[0042] When the preset audio signal is a disordered audio signal, the embodiment of the present application provides another method for generating a disordered audio signal.
[0043] The audio management module 120 includes a DSP chip 121 , which is used to generate noise with specific statistical characteristics as a disordered audio signal through a probability distribution function.
[0044] The audio management module 120 can generate noises with different statistical characteristics through different probability distribution functions, which can better simulate the noise conditions in the real world. For example, a Gaussian distribution function can be used to generate a signal similar to white noise, which is more consistent with the statistical characteristics of actual noise, or a noise with specific statistical characteristics can be generated through different distribution functions such as Poisson distribution, exponential distribution, uniform distribution, etc., which is nonlinear noise. These noises can be transmitted to the external terminal as a preset audio signal and recognized and acquired by the external terminal.
[0045] When the preset audio signal is a disordered audio signal, the embodiment of the present application further provides another method for generating a disordered audio signal.
[0046] The audio management module 120 includes a DSP chip 121, and the DSP chip 121 is used to generate random noise as a disordered audio signal by using an inverse FFT transform method or an inverse convolution method.
[0047] The random noise is generated by the inverse transform method of FFT (Fast Fourier Transform), specifically, a set of random frequency domain data is generated, and then the generated frequency domain data is converted back to time domain data by inverse transform of FFT, so as to generate random noise with specific spectrum characteristics. By generating random noise by the inverse transform method of FFT, the spectrum of the noise signal can be operated in the frequency domain, the amplitude and phase information in the frequency domain can be adjusted, the frequency component of the noise can be controlled more flexibly, and different random noises with specific spectrum characteristics can be generated. Moreover, the inverse transform method of FFT can generate random noise more quickly and efficiently, and the timeliness is better.
[0048] The inverse convolution method is specifically to generate random noise with specific spectral characteristics by performing an inverse convolution operation on a specific signal. By generating random noise through the inverse convolution method, a noise signal with specific spectral characteristics can be generated by adjusting the spectral characteristics of the convolution kernel in the inverse convolution operation.
[0049] An ordered audio signal is a sound with a fixed regularity or pattern. When the preset audio signal is an ordered audio signal, an embodiment of the present application provides an embodiment for generating an ordered audio signal.
[0050] The audio management module 120 includes a DSP chip 121, which is used to pre-store a preset waveform sequence or audio, and control the preset waveform sequence or audio to be played sequentially or cyclically as a preset audio signal.
[0051] Specifically, the DSP chip 121 stores a predefined waveform sequence, and when necessary, controls the waveform sequence to be played in order to form an ordered audio signal, which is transmitted to an external terminal through the connection module 110 to be captured by the external terminal. Alternatively, the DSP chip 121 pre-stores a recorded audio file, which is read by an audio playback program preset in the DSP chip 121 and transmitted to the connection module 110, which is then transmitted to an external terminal by the connection module 110. The content of the audio file may be a song or a piece of music or a human voice or a natural sound or other sound, and its format may be WAV, MP3, etc. Alternatively, the DSP chip 121 pre-stores a pre-recorded audio sample, which is a periodic loop audio segment formed by pre-cutting, and controls its loop playback to generate regular sounds, and outputs audio such as drum sounds and beats.
[0052] In other embodiments, the method for generating an ordered audio signal may also be: basic waveforms such as sine waves, square waves, triangle waves or sawtooth waves are pre-stored in the DSP chip 121, and a single frequency sound like the "beep" sound of an electronic watch is generated by fixing the frequency and waveform parameters, wherein single frequency sounds of different tones can be obtained by adjusting the frequency or amplitude, thereby forming an ordered audio signal.
[0053] When the preset audio signal is a blank audio signal, the audio management module 120 includes a DSP chip 121, and the DSP chip 121 is used to generate a data stream with all output values being zero, thereby forming a blank audio signal. The blank audio signal can also be transmitted to an external terminal through the connection module 110, and captured and recognized by the external terminal. The blank audio signal is generated by generating a data stream with all output values being zero, which is simple and effective, and the duration and intensity of the blank audio signal can be accurately controlled.
[0054] In this embodiment, the connection module 110 is a connector, which is used to be inserted into an external interface of an external terminal, and the connector is a Micro-USB connector, a Type-C connector, a Lighting connector, or a headphone plug.
[0055] When the connector is inserted into the external interface of the external terminal, a communication connection can be established with the external terminal to obtain the audio control permission of the external terminal. Different types of connectors have different ways of establishing a connection and communication with external terminals. The following uses a Type-C connector as an example and an external terminal as a mobile phone to explain the process of the terminal anti-eavesdropping device establishing a communication connection with a mobile phone through a Type-C connector to obtain the audio control permission of the external terminal:
[0056] The communication mechanism between the terminal anti-eavesdropping device and the mobile phone is implemented by the UAC (USB Audio Class) standard. The UAC standard is a USB communication protocol specifically for audio devices, which specifies communication methods such as audio transmission and control instructions. When the terminal anti-eavesdropping device is inserted into the Type-C interface of the mobile phone through the Type-C connector, the terminal anti-eavesdropping device can communicate with the mobile phone as an external sound card device to realize functions including microphones. The process of the terminal anti-eavesdropping device communicating with the mobile phone as an external sound card device is as follows:
[0057] (1)USB Audio Class standard support
[0058] Mobile phone operating systems (such as Android and iOS) support the USB Audio Class protocol. After the terminal anti-eavesdropping device is inserted into the mobile phone, the mobile phone operating system will detect whether the inserted device complies with the USB Audio Class specification.
[0059] (2) Device identification and initialization
[0060] When the terminal anti-eavesdropping device is connected to the mobile phone, USB communication begins to identify the device descriptor. The mobile phone will read the USB descriptor information of the inserted device, including the product ID (PID), vendor ID (VID), and the audio format and sampling rate supported by the device.
[0061] The phone will check whether the inserted device complies with the interface specification of USB Audio Class to ensure that the sound card can be initialized correctly.
[0062] (3) Enumerate audio interfaces
[0063] If the USB sound card meets the audio interface standard, the phone will enumerate the audio input and output interfaces through UAC, which includes the identification of the headphone output and microphone input ports.
[0064] In addition, the phone's operating system will automatically switch the audio output path to the terminal anti-eavesdropping device in the settings, rather than the phone's own speaker or microphone, which means that the terminal anti-eavesdropping device can obtain the phone's audio control permissions. Alternatively, the user can manually set the audio output path to automatically switch to the terminal anti-eavesdropping device.
[0065] (4) Audio Stream Transmission Mechanism
[0066] After the terminal anti-eavesdropping device obtains the audio control permission of the mobile phone, the transmission of the audio stream is carried out through the USB audio stream pipeline, and the connection module 110 of the terminal anti-eavesdropping device transmits the preset audio signal generated by the audio management module 120 to the mobile phone through the USB, and the preset audio signal is simulated as a microphone input stream input to the mobile phone. In the Android system, the microphone input stream will be assigned to the audio input called by the application (such as a recording or call application).
[0067] The transmission mode of the preset audio signal is an asynchronous mode, that is, the audio data is continuously transmitted between the endpoint of the device end (terminal anti-eavesdropping device) and the mobile phone through synchronous data packet exchange.
[0068] (5) Automatic switching of the system
[0069] When the mobile phone detects the terminal anti-eavesdropping device, the system will automatically switch the audio output to the terminal anti-eavesdropping device.
[0070] The switching of audio input / output paths is done at the system level, so most applications (such as calls and recording applications) can seamlessly switch to the external USB sound card.
[0071] In another example, taking the connector as an earphone plug and the external terminal as a mobile phone as an example, the process of establishing a communication connection between the earphone plug and the mobile phone and obtaining the audio control permission of the external terminal is described:
[0072] The terminal anti-eavesdropping device is equivalent to simulating an ordinary round plug headset. The mechanism for establishing a communication connection with a mobile phone is the same as that for a round plug headset to establish a communication connection with a mobile phone, but the terminal anti-eavesdropping device does not have the function of collecting signals with a microphone. The process of inserting a round plug headset into a mobile phone and establishing a communication connection with the mobile phone is as follows:
[0073] When an ordinary round-plug headset (with a speaker and microphone) is plugged into the audio port of a mobile phone, the communication mechanism between the headset and the mobile phone is mainly the transmission and detection of analog signals, rather than digital signal communication like USB. The mobile phone switches the audio path by detecting the type of headset plug inserted, so that the headset and microphone can work normally. The following is the specific communication mechanism and process:
[0074] (1) Plug detection and type identification
[0075] The audio interface of a mobile phone is generally a four-section TRRS plug interface, the four sections are:
[0076] Tip(T): Left channel signal
[0077] Ring 1(R1): Right channel signal
[0078] Ring 2(R2): Ground
[0079] Sleeve(S): Microphone signal (for headphones with microphone)
[0080] When the earphone is plugged in, the phone identifies the plug type by detecting the resistance R1, capacitance C1 or voltage change of the internal circuit. If a standard TRRS interface is detected, the phone will switch the audio input / output to the external earphone and microphone. If the earphone plug has only three sections (TRS, i.e. earphones without a microphone), the phone will not enable the microphone function and only use the earphone output. The implementation method of the phone identifying the plug type by detecting the resistance R1, capacitance C1 or voltage change of the internal circuit is a conventional technology and will not be described in detail here.
[0081] (2) Audio routing switching
[0082] When the mobile phone detects that the earphone is plugged in, it will automatically switch the audio output path and transmit the audio signal to the left and right channels (T and R1) of the earphone. At the same time, the audio input path (i.e., microphone signal) is switched to the microphone input channel (S segment) of the earphone to receive the sound of the external microphone during calls or recordings. Because the terminal anti-eavesdropping device does not have a microphone, the audio management module 120 can generate a preset audio signal, which simulates the sound received by the external microphone.
[0083] (3) Audio signal transmission and communication mechanism
[0084] The sound signal generated by the headset microphone is transmitted to the mobile phone through the S segment of the plug. These signals are converted into digital signals by the ADC (analog-to-digital converter) of the mobile phone and then transmitted to the recording or call application. Because the terminal anti-eavesdropping device does not have a microphone, the audio management module 120 can generate a preset audio signal, which simulates the sound received as an external microphone, and the preset audio signal can be transmitted to the mobile phone through the S segment of the headset plug.
[0085] (4) Automatically switch audio routing and microphone use
[0086] The mobile phone system has an audio routing management mechanism. When headphones are inserted, the audio output automatically switches to the headphones instead of the mobile phone speakers.
[0087] If the headset has a microphone, the microphone input will also switch automatically. Usually, calling applications and recording applications will automatically use the headset microphone.
[0088] In another embodiment of the present application, the connection module 110 is a remote communication connector, and the remote communication connector establishes a communication connection with an external terminal through a hotspot network, a cellular network, Bluetooth or WIFI.
[0089] The following takes the example of establishing a communication connection between the remote communication connector and the external terminal via Bluetooth as an example, and describes the principle process of establishing a communication connection between the remote communication connector and the external terminal and obtaining the audio control authority of the external terminal as follows:
[0090] The terminal anti-eavesdropping device combines the wireless communication function to simulate a Bluetooth headset. The mechanism for establishing a communication connection with a mobile phone is the same as the mechanism for establishing a communication connection between a Bluetooth headset and a mobile phone. However, the terminal anti-eavesdropping device does not have a microphone and does not have a microphone function. The communication mechanism between the terminal anti-eavesdropping device and the mobile phone is based on the audio transmission protocol in the Bluetooth protocol stack. The working process of establishing a communication connection between a Bluetooth headset and a mobile phone and obtaining the audio control authority of the mobile phone is as follows:
[0091] After the Bluetooth headset is paired and connected to the mobile phone, the Bluetooth audio protocol is used to achieve two-way communication of audio signals, making it an external speaker and microphone for the mobile phone. Its main communication mechanism is based on the audio transmission protocol in the Bluetooth protocol stack, including A2DP and HFP / HSP protocols. The specific process is as follows:
[0092] (1) Bluetooth connection and pairing
[0093] When used for the first time, the mobile phone and Bluetooth headset will perform authentication and key exchange through Bluetooth pairing to establish a secure communication connection. After pairing is completed, the Bluetooth headset will be registered as an audio device by the mobile phone.
[0094] Pairing information between the phone and the headset, such as device address and encryption keys, is saved for quick and automatic connection in the future.
[0095] (2) Bluetooth protocol stack and audio protocol
[0096] After pairing is completed, the mobile phone and the headset transmit sound through different audio protocols in the Bluetooth protocol stack. The main protocols include A2DP (Advanced Audio Distribution Profile), HFP (Hands-Free Profile) and HSP (Headset Profile).
[0097] The A2DP protocol is a transmission protocol for high-quality stereo music, which is used to transmit audio streams (such as music, video audio) on the mobile phone to the headset. The A2DP protocol supports multiple encoding formats, including SBC (default), AAC, aptX, LDAC, etc. The mobile phone will select the appropriate encoding scheme based on the encoding format supported by the headset to optimize audio quality and transmission efficiency. The mobile phone encodes the audio data into a format that complies with A2DP, packages it into a Bluetooth data packet, and then transmits it to the headset via Bluetooth. After receiving the audio data, the headset decodes and plays it.
[0098] The HFP protocol and the HSP protocol are protocols mainly used for calls. The HFP protocol supports more control functions and higher audio quality, while HSP is a basic voice call protocol. The mobile phone transmits audio data to the headset through HFP / HSP, and receives audio input data from the headset microphone at the same time. Because the terminal anti-eavesdropping device does not have a microphone function, the terminal anti-eavesdropping device can transmit the preset audio signal to the mobile phone.
[0099] HFP / HSP usually uses CVSD encoding or mSBC encoding, which has a lower transmission bandwidth and is suitable for voice transmission.
[0100] (3) Audio routing switching and control
[0101] When a Bluetooth headset is connected to a mobile phone, the mobile phone operating system will automatically switch the audio route to the Bluetooth headset. At this time, the audio output path on the mobile phone will switch to Bluetooth instead of the mobile phone speaker.
[0102] If the Bluetooth headset supports a microphone, the audio input path of the mobile phone will also be switched to the headset microphone (implemented through the HFP / HSP protocol), which is suitable for calls or voice recording.
[0103] (4) Audio Data Transmission Mechanism
[0104] When audio data passes through Bluetooth headphones, it is encoded and compressed to reduce the amount of data. For example, A2DP transmission using SBC or AAC encoding can provide higher sound quality in limited bandwidth.
[0105] The audio data is divided into small packets and transmitted wirelessly via Bluetooth. At the receiving end (mobile phone), these packets are decoded and restored to analog audio signals.
[0106] (5) Automatic connection after pairing
[0107] Since the mobile phone saves the pairing information, once the Bluetooth headset is turned on and enters the connection mode, the mobile phone will automatically reconnect. The terminal anti-eavesdropping device can be provided with a switch button connected to the audio management module 120, and the switch button is used to turn on the terminal anti-eavesdropping device. After the user uses the switch button to turn on the terminal anti-eavesdropping device, the terminal anti-eavesdropping device enters the connection mode and automatically reconnects to the mobile phone via Bluetooth. After each successful connection, the audio route will automatically switch to the terminal anti-eavesdropping device, and the user does not need to manually select the audio output path.
[0108] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present invention.
Claims
1. A terminal anti-eavesdropping device, characterized in that: It includes a shell and a connection module and an audio management module arranged in the shell. The audio management module is connected to the connection module. The connection module is used to establish a communication connection with an external terminal to obtain the audio control authority of the external terminal. The audio management module has a built-in preset audio signal and can transmit the preset audio signal to the external terminal through the connection module.
2. The terminal anti-eavesdropping device according to claim 1, characterized in that: The preset audio signal is a disordered audio signal, an ordered audio signal or a blank audio signal.
3. The terminal anti-eavesdropping device according to claim 2, characterized in that: When the preset audio signal is a disordered audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate a random digital sequence with equal probability through a pseudo-random number generator, and directly output the random digital sequence as a waveform to output a first white noise as the disordered audio signal, or map the random digital sequence to a specific voltage or audio value, and output a second white noise as the disordered audio signal.
4. The terminal anti-eavesdropping device according to claim 2, characterized in that: When the preset audio signal is a disordered audio signal, the audio management module includes a main control chip and an audio signal generating circuit, the audio signal generating circuit includes a transistor, a resistor and a capacitor, the base of the transistor is grounded, the collector is suspended, the emitter is connected to one end of the resistor and one end of the capacitor, the other end of the resistor is connected to a power supply, and the other end of the capacitor is used to output a third white noise as the disordered audio signal, and the main control chip is connected to the connection module to control the connection module to transmit the disordered audio signal to an external terminal.
5. The terminal anti-eavesdropping device according to claim 3 or 4, characterized in that: The audio management module further includes a filter. When the audio management module includes a DSP chip, the filter is connected to the DSP chip. The filter is used to filter the first white noise or the second white noise and then output corresponding colored noise as the disordered audio signal. When the audio management module includes a main control chip and an audio signal generating circuit, the filter is connected to the other end of the capacitor, and the filter is used to filter the third white noise and then output corresponding colored noise as the disordered audio signal.
6. The terminal anti-eavesdropping device according to claim 2, characterized in that: When the preset audio signal is a disordered audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate noise with specific statistical characteristics through a probability distribution function as the disordered audio signal.
7. The terminal anti-eavesdropping device according to claim 2, characterized in that: When the preset audio signal is a disordered audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate random noise as the disordered audio signal through an FFT inverse transform method or an inverse convolution method.
8. The terminal anti-eavesdropping device according to claim 2, characterized in that: When the preset audio signal is an ordered audio signal, the audio management module includes a DSP chip, which is used to pre-store a preset waveform sequence or audio, and control the preset waveform sequence or audio to be played sequentially or in a loop as the preset audio signal.
9. The terminal anti-eavesdropping device according to claim 2, characterized in that: When the preset audio signal is a blank audio signal, the audio management module includes a DSP chip, and the DSP chip is used to generate a data stream with all output values being zero to form the blank audio signal.
10. The terminal anti-eavesdropping device according to claim 1, characterized in that: The connection module is a connector, which is used to be inserted into an external interface of an external terminal, and the connector is a Micro-USB connector, a Type-C connector, a Lighting connector, or a headphone plug; Alternatively, the connection module is a remote communication connector, and the remote communication connector establishes a communication connection with an external terminal via a hotspot network, a cellular network, Bluetooth, WIFI or Star Flash.