How to check the camera in the hotel?

The specific operation method of checking the camera in the hotel is as follows:

1, turn on the camera function of the mobile phone.

Turn off the lights in the room and close the curtains. Leave the room without light and in a dark state. The darker the room, the better the inspection status. Then turn on the camera function of the mobile phone, walk around the room, and check the dead angle, ceiling, TV, air conditioner and other places where pinhole cameras may be installed. If there is a pinhole camera, you will see a red dot on your mobile phone. The red dot is a camera.

Any camera needs to collect visible light to image, so you can find the camera according to the light reflected by the lens.

Shine a flashlight at each pinhole that looks like a hidden camera, and then observe the reflected light. The way to do this is to shine a flashlight on the front camera of a laptop or mobile phone and shake it back and forth. If you see this small color reflection and shake the flashlight, it will reflect a little; This is usually the lens reflection of the camera.

3. All cameras have an image sensor (CCD/CMOS), which needs a crystal oscillator to generate the clock and scan and image pixel by pixel (field clock) and line by line (line clock). The generators of these clocks will leak electromagnetic waves with a relatively fixed frequency. The line clock is 12MHz to 30MHz, and the field clock is 15.625kHz(PAL) and 15.750kHz(NTSC). The former can be detected by multi-band radio in short wave band. If there is no camera with electromagnetic shielding, you can hear the clock signal about half a meter.