RF detector is simply a radio frequency receiving device. It is designed to detect wireless signals that are being transmitted within a certain frequency range. A wireless hidden camera is designed to transmit video to a video receiver and some wireless transmitters are designed to transmit as far as 3 miles away while others can only be received one room away. So the stronger the signal being transmitted the easier it is for the bug detector to detect it. Some micro spy cameras are designed to output a very low signal making them very hard to detect.

Frequency Band Examples :
SIM Spy Ear (1MHz-470MHz), Telephone Listening Bug (50MHz-460MHz), Cell Phone Listening Bug (500MHz-2500MHz), Digital Audio Listening Bug (900MHz-1900MHz), Vehicle Tracker (900MHz-1900MHz), Pinhole Camera (700MHz-5800MHz), Encrypted Camera Surveillance (2400MHz-5800MHz), Gambling Cheat Equipment (130MHz-1900MHz) and Electronic Radiance Sources (4000MHz-6000MHz)
Monitor (1MHz–470MHz) Alert mode 1 4 indicator lights and “DiDi” voice
Telephone monitor (50MHz–460MHz) Alert mode 2 Vibration + 4 indicator lights
Mobile phone monitor(500MHz–2500MHz) No-voice, 4indicator lights and earphone Alert mode 3
Digital monitor (900MHz–1900MHz) detecting alert voice.
Car monitor (500MHz–1900MHz) Can play down or adjust high detecting Button
Car tracker (900MHz–1900MHz) sensitivity (You can locate pinhole camera adjusting
Pinhole camera (700MHz–5800MHz) as long as the detecting range is dwindled sensitivity
Encrypt camera (2400MHz–5800MHz) and sensitivity is played down).
Gambling fraudulent practices’ device No-voice vibration induction. (130MHz–1900MHz)
Wiring radiated source induction let it detect secretly in any special (4000MHz–6000MHz) location.