User Manual

INTRODUCTION

ACOUSTIC EAVESDROPPING

Thank you very much for purchasing the DNG-2300 digital noise generator. The DNG-2300 is

designed to prevent listening though devices that cannot be detected by conventional

countermeasures and installed around the perimeter of a room – wired wall microphones, contact

microphones, AC outlet transmitters and window systems based on the reflection of

laser/infrared/microwave beams. It is an excellent addition to high level countermeasures.

It is well-known that sound distributes though walls, doors, windows and other constructions. In

some materials sound travels even better than through air. For example, water is a good conductor

and a heating system can pass a conversation out of a room. Eavesdroppers take advantage of this

with the use of contact microphones. These microphones pick up the vibrations from the air ducts,

plumbing, structures, walls, windows, doors, floors, ceilings and more. The microphones may not

be in the same room as the conversation, but may be several floors or rooms away attached to a

pipe or other fixture.

The DNG-2300 can render these devices useless. It produces non-filterable acoustic noise which is

transferred to constructions by transducers and speakers. REI’s TRN-2000 is the recommended

transducer for use with the DNG-2300. It has optimal power parameters and can be set on different

types of surfaces. The TRN-2000 injects most of its power into surfaces while only a tiny part of

the noise gets inside a room. This does not force people to speak louder. The TRN-2000 transducer

can be supplied with adapters for mounting on walls, ceilings, windows, etc.

The speaker OMS-2000 can also be used with the DNG-2300. It does not inject the noise into the

surfaces but radiates it into surrounding space. The OMS-2000 is usually used in air ducts, ceiling

tiles, etc.

TRULY RANDOM NOISE

The DNG-2300 consists of 3 independent white noise digital generators. “White” means that the

noise is fully random and is equally distributed along the voice spectrum. This distribution

provides complete resistance against the filtering of a conversation. Another feature of white noise

is its unpredictability i.e. there is no method to wipe it out from a recorded conversation.

VOICE MASKING

Men’s and women’s voices consist of lots of frequencies simultaneously produced during speech.

These frequencies lie between 100 Hz and 6000 Hz. Listening devices usually have a narrower

range mostly because of size limitations, the scheme of the device and battery time. The DNG-

2300 has a range of 250-5000 Hz which is optimal to cover all types of voices and suppress all

listening devices.

OPERATION

The DNG-2300 uses a combination of transducers and speakers placed strategically throughout a

target area to create a blanket of masking noise that covers private conversations from

eavesdropping. Each transducer utilizes adapters for mounting to a variety of surfaces such as

walls, windows, ductworks, plumbing, etc. The three separate channels allow the user to tailor the

noise for separate materials, allowing greater flexibility and increased protection.