There are usually two ways to block mobile phone signals:
One way is the same as the principle of CCTV, put the mobile phone into a metal mesh bag, in principle all electromagnetic waves will be shielded.
Another is that when you walk into an area, the mobile phone will have no signal. This is because there is an electromagnetic wave transmitter in the area. Its frequency is the same as that of the mobile phone. The signal it transmits interferes with the signal of the mobile phone.
At present, the mobile phone signal jammers on the market work according to the second method. In fact, the principle is very simple, but it is illegal to use this frequency band privately and cannot generate commercial value, but now schools have begun to use it to prevent cheating. Let's take a look at how it works.
1. The working principle of the mobile phone signal jammer: interfere with the downlink signal of the mobile phone
The specific schematic diagram:
When the mobile phone is working, it is within a certain frequency range. The mobile phone and the base station are connected by radio waves to complete the transmission of data and sound with a certain baud rate and modulation method. According to this communication principle, the mobile phone signal jammer scans from the low-end frequency of the forward channel to the high-end frequency at a certain speed during the working process. The scanning speed can cause garbled interference in the message signal received by the mobile phone, and the mobile phone cannot detect the normal data sent from the base station, so that the mobile phone cannot establish a connection with the base station. The mobile phone manifests as the phenomenon of searching the network, no signal, no service system, etc.
The popular explanation is: the principle of the mobile phone signal blocker is to block the downlink frequency of the base station signal;
Second, the specific realization of the function of the mobile phone signal jammer:
Common shielding range is: 10 meters; DC power supply: 5V.
3. Basic performance
At present, the performance parameters of most mobile phone signal jammers on the market are as follows:
Transmission frequency range: 860-960MHz1.800-1.990GHz
Transmit power: 1W±200mA
Ambient temperature: -20~55℃
Relative humidity: 30%~95%
Function frequency band: CDMA800, GSM900, DCS1800, PCS1900, PHS.
Control range: about 40 meters.
Fourth, the mobile phone signal blocker crack?
1. Mobile phone signal jammer cracking method 1: Number segment cracking method
The school uses an older signal blocker that can only block the old number segments of PHS, China Mobile, and China Unicom, such as the new Telecom Tianyi 186, China Unicom's Wo number segment, and China Mobile's TD-SCDMA equal number segment, which cannot be blocked. of!
Simply put, the China Unicom and Mobile number segments starting with 13 15 and all PHS number segments can be blocked! And those starting with 18 will not be blocked!
2. Band cracking method
Because the working principle of the school's blocker is to block the mobile phone by interfering with the mobile phone signal of the specified band, as long as the receiving and transmitting frequency of the mobile phone is modified, it can be prevented from being blocked. The blocker can only block the mobile phone signal of 900---1800MHZ, while the mobile phone The receiving and transmitting frequency of the mobile phone is 850-1900MHZ, which is much larger than the shielding range of the jammer, so as long as the receiving and transmitting frequency of the mobile phone is adjusted to the maximum in the mobile phone settings, the mobile phone signal can be received normally.
3,: wifi cracking method
This method has relatively high requirements on the mobile phone and the environment, but the effect is also the best and the most concealed.
After you have found and successfully connected to an available wireless network with your mobile phone, you can still surf the Internet even if the mobile phone has no signal and no traffic. At this time, if you want to find the answer you can't find, you can use Baidu. If you want to send the answer, you can use QQ. Row. A method of hypermetamorphosis.