Method and device for interfering passive wireless headphone by audio electromagnetic field

Abstract

The invention relates to a method and a device for interfering a passive wireless headphone by an audio electromagnetic field. Cheating in conventional large-scale exams is very difficult to prevent. The passive wireless headphone is directly driven by the audio electromagnetic field so as to send an interference signal to interfere the passive wireless headphone; the interference signal comprises ordered wave and noise which are sent simultaneously; the ordered wave is frequency-hopping positive / negative pulse wave, square wave and sine wave which are alternately sent; and the sine wave and the information transmitted by the passive wireless headphone produce beat frequency. The device for realizing the method comprises an audio and noise generating device, a power amplifier and a power coil, wherein the audio and noise generating device comprises a singlechip, a D / A conversion module, a filtering module, three input resistors, a comparator OP1 and an adder OP2; the output end of the adder OP2 is the output end of the audio and noise generating device. The method has the advantages of maturity, reliability, easy operation, and capability of directly utilizing an audio voice classroom or laboratory facility.

Description

technical field [0001] The invention belongs to the technical field of control, and relates to a method and a device for electromagnetic field interference to a passive wireless earphone, in particular to a method for interfering with and suppressing a miniature (or called invisible) audio wireless earphone as a cheating tool and an electromagnetic field generating device. Background technique [0002] The invisible wireless earphones on the market are composed of strong magnetic earplugs, audio amplifiers, collar-type electromagnetic field sending antenna coils, batteries and audio cables. With the advancement of technology, rare earth materials make the magnetic field of permanent magnet materials very strong, and the "passive rare earth earphones (earplugs)" produced have a smaller structure and better concealment. Except for special occasions such as broadcasting, they are often used by people. Use as a cheating tool. This type of "earphone" is passive, that is, it does...

AI Technical Summary

Problems solved by technology

3G mobile phones are in the emerging communication frequency band, and based on CDMA technology, the mobile phone jammers used in the early examination room did not contain 3G frequency bands, which attracted the attention of cheaters and related industry chains to 3G mobile phones

At present, even ordinary civil technology uses a large number of anti-interference code division multiple access (CDMA) technology, and it is necessary to increase the energy of the interference signal to suppress the transmission performance

The interference suppression performance is directly related to the spectrum energy density. The more frequency bands that need interference, the lower the spectrum energy that can be allocated, which directly reduces the prevention effect.

The coverage radius of commercially available mobile phone jammers is small, only 10-20 meters, which makes it very difficult to prevent cheating in large-scale exams

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