The device is supplied with a remote control which allows turning the jammer on and off at a distance of up to 10 m (33 ft). BDA-4 is a stationary device powered only by 110/220V mains which ensures the maximum power of jamming interference.

Ultrasound combined with audible frequency. Now ultrasonic interference consists of two frequencies simultaneously: ultrasound (frequency range is over 20 kHz) and acoustic sound (frequency range is 18-19 kHz) with speech-like noise that not only jams microphones but overloads them. Dictaphones can’t record sounds and only receive interference transmitted. The interference signal forms not immediately, but in the air, approximately 40-60 cm (1.3-2.0 ft) from the transducers, when the frequencies overlap each other, forming a dense and powerful interference.

White noise mode. It is an indispensable model for negotiations when all parties are aware of the jammer operating. This mode provides 100% protection from eavesdropping. This product mixes your words with the noise signal that comes out of its transducers and covers a fairly large frequency range with numerous reflections in a room, which causes a "shock" to any dictaphone.

Anybody, even a non-professional can use the jammer. All you need to do is point the transducers in a direction of an expected location of recording devices and turn it on via the remote control. You can make your protection more reliable by activating the speech-like interference using a rotary knob on the back of the device’s housing.

It is important to realize that jamming is more effective in small rooms because of numerous reflections of the waves (interference). If you use only one device, it is recommended to stand behind it. If there are several devices operating and the room’s height does not exceed 3.5 m (11 ft), you may stand anywhere. Ultrasound spreads with maximum efficiency only within 10 m (33 ft). 

Specifications

Dimensions 180 х 165 х 110 mm (7.0 x 6.5 x 4.3 in)
Weight 2 kg (4.4 lb)
Power 110/220 V network
Power consumption No more than 0.7 A
Sound pressure at 1m (3.3ft) Not less than 125 dB
Range optimal — up to 2 m (7 ft), maximal — up to 7 m (23 ft)
Jamming method Ultrasonic interference + acoustic interference at 18-19 kHz frequency + acoustic speech-like interference
Remote control action range up to 10 m (33 ft)