Wireless camera or WiFi jammer?

Once, in ancient times, a cheap wireless camera was bought for strike-ball games in order to look at the enemy in different situations. However, in addition to its main action, a side effect was suddenly discovered ...



Descriptions on the websites of shops where you can buy such a kit are not very informative:

Wireless radio kit, color camera is designed for indoor installation, carrier frequency 2.4G transmitter power 50mW, receiving base for connecting to the monitor AV signal and two power supplies (for camera and base).

About the site of the manufacturer is not even talking. Just China.
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Specifications:
Model: RES LYD-208C 2.4G
Color analog in \ camera with sound ~ 380 TVL, wireless, without IR. Power + 8V.
The range of action with direct visibility to 100m (tested in practice).
Operating current: 100mA

Working channels of the camera (switch with 2 jumpers on the camera itself):
Channel 1 - 2.414 Ghz
Channel 2 - 2.432 Ghz
Channel 3 - 2.450 Ghz
Channel 4 - 2.468 Ghz

This baby quickly and efficiently puts any WiFi network with a lesion radius of up to 50m including walls and floors. Despite the fact that not all camera frequencies overlap WiFi frequencies, working on any of the 4 channels, the camera puts a wireless network at any of its frequencies. Where the camera is “missing” and the WiFi network is not falling, the data transmission rate is significantly reduced and so is not high. And it was not intended by the manufacturer as intentional harm. Just because of the cheapness of the assembly and parts, the frequency of the camera walks heavily in its range, thereby creating a noise that later leads to such results.

In the field, the “Krona” type battery lasts about 2 hours of work.

The price of a set is from 32 cu

Experiment

For the experiment, a car GPS navigator based on Windows CE 5.0 was used, with an analog video input as a video monitor. The picture from the camera is turned on automatically when a video signal appears on the A / V input.

Test bench:
- WiFi D-Link DIR 615 Rev C access point (with DD-WRT firmware), two omnidirectional antennas with a gain of 7dBi, transmit power of 100%.
- WiFi card in a laptop Intel Wifi Link 5100 AGN.

The access point works in Mixed mode (802.11b + 802.11g + 802.11n). Connected in 802.11n mode. Although it does not matter what.

The distance from the access point to the laptop <3m.

A brief video review of what is happening (available in HD ):


Also, this experiment was conducted in the office where there is no direct line of sight to the access point ~ 30m. The result exceeds all expectations. Laptops, smartphones, PDAs, etc. - all remain without WiFi.

There are similar cameras at 2.4 Ghz with a transmitter power as high as 1.5W. This also includes the so-called "Baby Monitor" \ "Baby Monitor" device.

Being installed in the office of competitors, or even in the corridor of the office center, somewhere in the depths of the suspended ceiling, it will deliver quite a few joyful minutes in search of malfunctioning WiFi networks. Especially where the wired ethernet network was not even in the project. Or your stairwell neighbor decided to set up video surveillance of his garage in the yard. And Wai-Fay points can be changed until blue in the face, until someone guesses to buy a “bug detector” \ “field detector”.

For reference, Wifi channels and frequencies

1. 2.412 Ghz
2. 2.417 Ghz
3. 2,422 Ghz
4. 2,427 Ghz
5. 2.432 Ghz
6. 2,437 Ghz
7. 2,442 Ghz
8. 2,447 Ghz
9. 2,452 Ghz
10. 2.457 Ghz
11. 2,462 Ghz
12. 2,467 Ghz
13. 2,472 Ghz
14. 2,484 Ghz

Red highlighted frequencies with almost 100% overlap. Although as I wrote above, it does not matter what.

Be careful and attentive. You should not save on the wires as when connected to a local network and when installing video surveillance.