CAMO Surveillance Equipment
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ABOUT AUDIO SURVEILLANCE DEVICES
purpose of an audio surveillance device is to enable you to secretly listen into (and/or
record) conversations that take place at a particular location or on a particular
telephone line. These devices are divided into two main types ;
(a) Wireless i.e room and telephone transmitters (commonly referred to as "bugs").
(b) Wired devices i.e recorders, telecorders, wall contact microphones, wired microphones etc.
The hard wired devices are pretty self-explanatory, and their applications are obvious.
The transmitters that we supply fall into two main categories ;
(1) Free Oscillating VHF FM transmitters
(2) UHF Crystal Controlled transmitters
(1) Free Oscillating VHF FM transmitters are intended for general use, are cheap, small and ideal for simple monitoring over short ranges.
A characteristic of this type of equipment is that it is tuneable to different frequencies, and can be picked up on the receivers that we supply by tuning in to the specified frequency that the transmitter is set on (This signal can also be picked up by a scanner, provided the scanner has the ability to function on FM in the airband frequencies). However, this also means that the receiver and transmitter can "go off tune" over a period of time, and this is remedied by periodically fine tuning the receiver. The signal from this equipment does not have the penetrative power of the more expensive UHF equipment and signal strength and range can be reduced by buildings, power cables, obstacles etc. This equipment, when used under optimum conditions, gives good results and is used world wide by both private citizens and professional information gatherers, and is ideal (because of its relatively low cost) for use in situations where it may not be possible to retrieve the transmitter after the required information has been obtained.
(2) UHF Crystal Controlled transmitters give excellent penetrative power through obstacles and are set on dedicated, locked frequencies in the 300-460 Mhz frequencies. The advantage of this type of equipment is that there is no tuning required - once the transmitter is powered up, you simply switch on the dedicated receiver and listen - thats it ! (alternatively, the signal can be picked up on a radio scanner set to the required frequency). Because the frequency is stabilised by a crystal, there is no signal drift and therefore no retuning is required. UHF transmitters are also more efficient, and battery life is generally longer.
Irrespective of which type of transmitter is used, the received signal can be picked up and listened to in real time or recorded and listened to at a later stage, though naturally for unattended recordings, the UHF equipment will give more guaranteed results because of its signal stability. This may be important for professional use, but for more casual applications the VHF equipment may suffice.
A WORD ABOUT TRANSMITTING DISTANCES
The ranges that we quote in transmitter specifications are as realistic as possible, and reflect both average working ranges and maximum line-of-sight ranges i.e ideal unobstructed conditions.
It is impossible to guarantee transmitter ranges, due to the nature of RF - in some situations you will get close to the maximum stated range, while in others you will get far less (in built-up areas, areas spanned by power cables, mobile phone masts, naturally occuring obstructions etc.) The sensitivity and location of your receiver is also an important factor in increasing the signal quality and range - sometimes involving trial and error.
Another important point to consider is that if the transmitter is left connected to its power source (battery) for long lengths of time, as the battery level drops, so will the transmitter output power, and by consequence the transmitter range (always use good quality batteries, and change them when you notice the signal quality starting to deteriorate). We recommend that when siting your transmitter, that you should use the average transmit distance as a guide, and not depend on the maximum stated range.
Some suppliers of transmitters of this type quote very inflated range figures for their products, and the kindest thing that can be said about this is that they are being over-optimistic ; We feel that it is both misleading and unfair on the customer, and our ranges are arrived at by testing the equipment under a variety of different conditions in order to arrive at the specified result.
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