CN107404560B - Wireless signal acquisition system for reducing false alarm rate of mobile phone detection - Google Patents
Wireless signal acquisition system for reducing false alarm rate of mobile phone detection Download PDFInfo
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- CN107404560B CN107404560B CN201710703345.7A CN201710703345A CN107404560B CN 107404560 B CN107404560 B CN 107404560B CN 201710703345 A CN201710703345 A CN 201710703345A CN 107404560 B CN107404560 B CN 107404560B
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Abstract
The invention discloses a wireless signal acquisition system for reducing the false alarm rate of mobile phone detection, which comprises an MCU (microprogrammed control Unit) controller, an ADC (analog to digital converter), a low-noise amplifier, a band-pass filter, an antenna matching circuit and an antenna, wherein the MCU controller is used for controlling the ADC converter to be connected with the low-noise amplifier; the antenna is used for sensing radio-frequency wireless signals of the mobile phone, the radio-frequency wireless signals are received through the antenna matching circuit, the radio-frequency wireless signals are amplified through the low-noise amplifier after being filtered by the receiving band-pass filter, the amplified signals are subjected to analog-to-digital conversion through the ADC and then are transmitted into the MCU to be subjected to FFT conversion, whether energy exists in sensitive frequency points or not is checked, and whether the mobile phone passes through the sensitive frequency points or not is judged. The invention obviously reduces the false alarm rate of the mobile phone, greatly reduces the workload of field maintenance personnel and obviously optimizes the user experience of the mobile phone detection system.
Description
Technical Field
The invention relates to the field of mobile phone detection, in particular to a wireless signal acquisition system for reducing the false alarm rate of mobile phone detection.
Background
At present, the mainstream technology of mobile phone detection comprises a coil technology, a weak magnetic field detection technology and a nonlinear joint detection technology, and the coil technology and the weak magnetic field detection technology are used more frequently.
The operating principle of the loop coil detector is summarized as follows: the mobile phone is designed according to the electromagnetic field coupling principle, when a current with a certain frequency passes through the annular coil, if a ferromagnetic substance is added to the cross section of the coil, the demagnetization effect of the coil eddy current is larger than the magnetization effect of the ferromagnetic substance, so that the equivalent inductance of the coil is obviously reduced, and the mobile phone achieves the detection purpose according to the principle by similar situations of adding the ferromagnetic substance. The detection technology principle is that a crystal oscillator generates 3.5-4.95M sine oscillation, a frequency divider divides the frequency into sine waves of about 7.8K, the sine waves are input into a door panel large coil to carry out electromagnetic wave transmission after power amplification is carried out on a triode and a coil, and the electromagnetic waves are respectively received by coils of detection areas in a door. After receiving, comparing the received signal with a reference signal, changing the output level of the acquisition card after the change is found, scanning the acquisition card data of each zone in 300 milliseconds by the CPU, judging whether metal and electronic products exist, judging the zone in which the zone is located, and outputting and displaying. In order to improve the detection sensitivity, the annular coil sensor can be arranged in a rhombic shape, an 8-shaped shape and the like. The recording equipment such as the mobile phone, the recording pen and the like comprises magnets, and the magnetic sensor is used for detecting the change of the magnetic field, so that the recording equipment such as the mobile phone, the recording pen and the like can be detected.
The weak magnetic field detection technology carries out mobile phone detection by detecting sudden change of a system magnetic field, and after ferromagnetic substances are magnetized by a geomagnetic field, the magnetic sensor can sense magnetic field change and convert the magnetic change into an electric signal when the ferromagnetic substances pass through the magnetic sensor array.
The magnetic sensor can sense the change of a magnetic field, the magnetic field intensity collected by the sensor is mainly related to the distance and the direction from the sensor to a magnetic source, and the magnetic field intensity is as follows:
it can be seen that the key criteria are that the magnetic sensor requires high sensitivity and low noise floor, as shown in fig. 1:
the nonlinear node detector sends high-frequency fundamental waves (3.4-3.6GHz) of an S waveband to a target area or a target object through a transmitting end of the device, a receiving end captures second harmonic waves (7-7.5GHz) and third harmonic waves (10-10.6GHz) generated by the target object, and harmonic signals are analyzed and processed by using a fuzzy recognition algorithm and a self-learning algorithm in the field of artificial intelligence to give a harmonic change rule before and after fundamental wave transmission, so that the electronic device with the nonlinear node can be effectively recognized.
The nonlinear node technology has the defects of high difficulty, high cost, high false alarm rate and the like, is less in use, the mainstream equipment adopts coil detection and weak magnetic field detection technologies, both the coil detection technology and the weak magnetic field detection technology have the fatal defect that articles with high metal content such as a mobile phone, a watch, a belt buckle, a key and the like cannot be distinguished, the false alarm rate is high, field maintenance personnel cannot judge whether the alarm is a mobile phone alarm or an alarm such as a watch, a key, a belt buckle and the like, and the use effect is very poor.
Disclosure of Invention
The main disadvantages of the weak magnetic field detection technique are: the false alarm rate is high; susceptible to environmental magnetic fields. The prior art detects the existence of the mobile phone by detecting the sudden change of the magnetic field intensity, and belongs to the technology of weak magnetic field detection, so the magnetic field interference in the environment can influence the detection result, and the false alarm rate can be increased; watch, earphone, waistband etc. magnetic object all can lead to the sudden change in magnetic field, and prior art can't accurately distinguish cell-phone and other magnetic object through the sudden change of magnetic field intensity to lead to the wrong report.
Aiming at the technical problems, the invention aims to provide a method for reducing the false alarm rate of mobile phone detection, the invention adopts a magnetic sensor to collect array detection to detect that no magnetic field changes, judges that a non-magnetic object exists nearby, adopts a wireless collection system to collect radio frequency signals and carry out FFT conversion, checks whether sensitive frequency points have energy or not after conversion, adopts a magnetic sensor array to collect a sudden change magnetic field, carries out mobile phone alarm when the energy of the sensitive frequency points after the FFT of the wireless collection system exceeds a certain threshold value, and does not alarm when one of the two conditions is not met, so that the false alarm caused by keys, watches, belt buckles and the like can be avoided.
In order to realize the purpose, the invention is realized according to the following technical scheme:
a wireless signal acquisition system for reducing the false alarm rate of mobile phone detection is characterized by comprising an MCU controller, an ADC converter, a low noise amplifier, a band-pass filter, an antenna matching circuit and an antenna;
the antenna is used for sensing radio-frequency wireless signals of the mobile phone, the radio-frequency wireless signals are received through the antenna matching circuit, the radio-frequency wireless signals are amplified through the low-noise amplifier after being filtered by the receiving band-pass filter, the amplified signals are subjected to analog-to-digital conversion through the ADC and then are transmitted into the MCU to be subjected to FFT conversion, whether energy exists in sensitive frequency points or not is checked, and whether the mobile phone passes through the sensitive frequency points or not is judged.
In the above technical solution, the low noise amplifier adds a parallel resonant circuit on the collector, and the parallel resonant circuit includes an inductor and a capacitor.
In the technical scheme, the mobile phone detection device further comprises a magnetic sensor array system, the sensed radio-frequency wireless signals of the mobile phone and the infrared signals of other objects to be detected acquired by the magnetic sensor array system are simultaneously sent to the MCU controller for processing and analysis, and if the magnetic field has abnormal change and the sensitive frequency points after the radio-frequency wireless signals are subjected to FFT have energy, an alarm is triggered to display that the mobile phone is detected.
In the above technical scheme, the magnetic sensor array system is composed of a plurality of independent weak magnetic field acquisition systems, the weak magnetic field acquisition systems are arranged on two sides, and two rows of weak magnetic field acquisition systems are electrically connected by communication cables.
Compared with the prior art, the invention has the following beneficial effects:
the invention obviously reduces the false alarm rate of the mobile phone, greatly reduces the workload of field maintenance personnel and obviously optimizes the user experience of the mobile phone detection system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a diagram illustrating the relationship between the noise intensity and the frequency of a sensor in the prior art;
FIG. 2 is a schematic diagram of a wireless signal acquisition system of the present invention;
FIG. 3 is a schematic diagram of a magnetic sensor array system topology according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention.
The current mainstream technology for mobile phone detection is a coil technology and a weak magnetic field detection technology, and compared with the coil technology, the weak magnetic field detection technology has the following advantages: the high-sensitivity/ultrahigh-sensitivity detection can be realized for a weak magnetic field; the passive detection is realized, no radiation exists, no harm is caused to a human body, and surrounding electronic equipment is not interfered; low power consumption and small volume; stable temperature performance, high reliability and nondestructive detection.
The main technical scheme of the weak magnetic field detection technology is as follows: the earth's magnetic field may approximate a dipole magnetic field, which is located at the earth's center, and the earth is wrapped in the earth's magnetic field. The magnetic axis of the geocentric dipole and the earth axis do not coincide and form a small angle theta of about 11.5 degrees. The poles of the dipoles are opposite to the north-south poles of the earth, with the north-magnetic pole Nm being near the north-geographical pole Ng and the south-magnetic pole Sm being near the south-geographical pole Sg, according to international definitions. The earth magnetic field is stable in a certain range, the intensity of the earth magnetic field is basically consistent in a range of several kilometers, sudden change can not occur, and only when the magnetic substance passes through or exists, local disturbance can be caused to the originally stable earth magnetic field, and the intensity of the magnetic field is locally sudden change. When magnetic objects such as mobile phones pass or exist, the magnetic field of the earth is interfered, the magnetic field intensity is changed, and the abrupt change of the magnetic field is detected by using an advanced magnetic sensor, so that the existence of the magnetic objects such as the mobile phones is detected.
FIG. 2 is a diagram of a wireless signal acquisition system for reducing false alarm rate of mobile phone detection according to the present invention, which is characterized by comprising an MCU controller, an ADC converter, a low noise amplifier, a band pass filter, an antenna matching circuit and an antenna;
the antenna is used for sensing radio-frequency wireless signals of the mobile phone, the radio-frequency wireless signals are received through the antenna matching circuit, the radio-frequency wireless signals are amplified through the low-noise amplifier after being filtered by the receiving band-pass filter, the amplified signals are subjected to analog-to-digital conversion through the ADC and then are transmitted into the MCU to be subjected to FFT conversion, whether energy exists in sensitive frequency points or not is checked, and whether the mobile phone passes through the sensitive frequency points or not is judged.
Bandpass filters allow only frequencies in a certain frequency band to pass through, and have a large attenuation for components above or below this frequency band, and are typically present in the front end of the amplifier. For example, only GSM is allowed: the band 935-960MHz or DCS-1805-1880 MHz enters the amplifier to obtain the pure RF signal. Table 1, table 2, and table 3 are three operators 2G, 3G, and 4G mobile communication frequency bands, respectively:
TABLE 1
| GSM900 frequency channel 1-124 | 890∽915MHz(25M)/935∽960MHz(25M) |
| GSM1800 or DCS1800 frequency channel 512-885 | 1710∽1785MHz(75M)/1805∽1880MHz(75M) |
| Chinese mobile GSM900 channel 1-94 | 890∽909MHz(19M)/935∽954MHz(19M) |
| Chinese mobile GSM1800 channel 512-559 | 1710∽1720MHz(10M)/1805∽1815MHz(10M) |
| China Unicom GSM900 channel 96-124 | 909∽915MHz(6M)/954∽960MHz(6M) |
| China Unicom GSM1800 channel 687-736 | 1745∽1755MHz(10M)/1840∽1850MHz(10M) |
| China telecom CDMA | 825∽835MHz(10M)/870∽880MHz(10M) |
TABLE 2
| China telecom CDMA2000 | 1920∽1935MHz(15M)/2110∽2125MHz(15M) |
| China mobile TD-SCDMA | 1880∽1900MHz(20M)/2010∽2025MHz(15M) |
| China Unicom WCDMA | 1940∽1955MHz(15M)/2130∽2145MHz(15M) |
TABLE 3
The low noise amplifier adds a parallel resonant loop on the collector, and the parallel resonant loop comprises an inductor and a capacitor. The low-noise amplifier is generally positioned at the front end of the ADC and mainly used for carrying out first-stage amplification on a received high-frequency signal so as to meet the amplitude requirement of the ADC on an input signal and improve the signal-to-noise ratio of a received signal; and selects the frequency band we need, which is also called frequency-selective network or resonant network.
The invention also comprises a magnetic sensor array system, simultaneously sends the sensed radio frequency wireless signal of the mobile phone and the infrared signal of other objects to be detected acquired by the magnetic sensor array system to the MCU controller for processing and analysis, and triggers an alarm if the magnetic field has abnormal change and the energy of the sensitive frequency point of the radio frequency wireless signal after FFT, and displays the detected mobile phone.
One embodiment of the invention: the system sends an acquisition command, the magnetic sensor array system acquires surrounding magnetic field signals and the wireless signal acquisition system acquires radio frequency signals, sensed radio frequency signals of the mobile phone and infrared signals of other objects to be detected acquired by the magnetic sensor array system are simultaneously sent to the MCU controller for processing and analysis, and if abnormal change occurs in the magnetic field and energy exists at sensitive frequency points after FFT of the radio frequency wireless signals, an alarm is triggered to display that the mobile phone is detected.
The magnetic sensor array system is composed of a plurality of independent weak magnetic field acquisition systems, the weak magnetic field acquisition systems are arranged on two sides, and two rows of weak magnetic field acquisition systems are electrically connected by communication cables, as shown in fig. 3.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (1)
1. A wireless signal acquisition system for reducing the false alarm rate of mobile phone detection is characterized by comprising an MCU controller, an ADC converter, a low noise amplifier, a band-pass filter, an antenna matching circuit and an antenna;
the antenna is used for sensing radio-frequency wireless signals of the mobile phone, the radio-frequency wireless signals are received through the antenna matching circuit, the radio-frequency wireless signals are filtered through the receiving band-pass filter and then amplified through the low-noise amplifier, the amplified signals are subjected to analog-to-digital conversion through the ADC and then transmitted into the MCU for FFT conversion, whether energy exists in sensitive frequency points or not is checked, and whether the mobile phone passes through the sensitive frequency points or not is judged;
the low noise amplifier adds a parallel resonant loop on a collector, and the parallel resonant loop comprises an inductor and a capacitor;
the magnetic sensor array system is used for simultaneously sending the sensed radio frequency wireless signals of the mobile phone and the infrared signals of other objects to be detected, which are acquired by the magnetic sensor array system, to the MCU controller for processing and analysis, and triggering alarm if the magnetic field has abnormal change and the energy exists in sensitive frequency points after the radio frequency wireless signals are subjected to FFT, so that the mobile phone detection is displayed;
the magnetic sensor array system is composed of a plurality of independent weak magnetic field acquisition systems, the weak magnetic field acquisition systems are arranged on two sides, and two rows of weak magnetic field acquisition systems are electrically connected through communication cables.
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| KR20060068733A (en) * | 2004-12-17 | 2006-06-21 | 유엔젤주식회사 | Prevention system of cheating conduct in the examination using short message of mobile terminal |
| CN104092505A (en) * | 2014-07-30 | 2014-10-08 | 厦门大学 | Method for detecting and recognizing activated mobile phones in examination room |
| CN104602268A (en) * | 2015-02-10 | 2015-05-06 | 武汉虹旭信息技术有限责任公司 | Terminal signal detecting equipment and method thereof based on GSM (global system for mobile communications) software radio |
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