Table Of Contents
Introduction
The most basic form of a bug is a sensitive microphone connected to an audio recording or listening device. A hidden voice recorder or dictaphone can be even considered as a crude bug. The common perception of a bug is that it's a tiny microphone that transmits an audio signal to a nearby receiver. There are also a few other types of covert listening devices that come under the description of "bug" too, and we'll cover most of these now.
A simple audio bug kit with a microphone extension lead up to 10 metres. A great kit to get started in electronics and spying.
This bug kit is available to buy at Maplin.co.uk.
Transmitting Bugs
When it comes to technology, transmitting bugs aren't particularly advanced. There are four major parts to a bug, namely a microphone, an amplifier, a radio frequency (RF) transmitter and a battery. The number of electronic components required to build a transmitting bug is related to the stability and transmission frequency of the bug.
The stability of a bug refers to how much resilience the bug has to changing its transmitting frequency when changes in the environment occur. Crude very high frequency (VHF) bugs will vary in frequency just by being near metal surfaces or getting a few degrees warmer.
Professional ultra high frequency (UHF) bugs will have components such as crystals to stablise the frequency and will be fixed at a precise frequency. The vast majority professionally constructed bugs are of the UHF type and use surface mounted technology (SMT) to create a very tiny device.
UHF designates a band of electromagnetic waves with frequencies between 300MHz and 3,000MHz (3GHz). VHF designates a band of frequencies between 30MHz to 300MHz. Transmitting bugs using UHF frequencies tend to be in the range of 300MHz to 500MHz. VHF bugs typically are in the range 88MHz to 108MHz (the public radio band in the UK) and 108MHz to 132MHz (otherwise known as the airband in the UK).
It's a myth that bugs have unlimited transmitting range. According to the laws of physics, the radio waves generated by the bug have infinite range, but the strength of the radio wave decreases exponentially. Therefore in practice, when using a standard receiver without any high gain or directional aerial, you are going to have a limited distance from the transmitter that you can receive a signal.
It's quite difficult to get hold of UHF or VHF bugs these days due to tight UK regulation for RF transmission equipment. On occasion you might be able to pick up some kit on eBay.
Telephone Taps
Telephone taps are devices that allow telephone conversations to be listened to or recorded without the users of the telephone line knowing. It's been known for the law enforcement agencies to dive into telephone exchange boxes to place listening devices. However, we'll focus on taps that can be connected within a residential or business premise.
A telephone tap might be a hardwired device connected to a tape recorder, or it might be a transmitting device. You can have parallel and series versions of both hardwired and transmitting devices. It's common for hardwired taps to be parallel devices and transmitting taps to be serial devices due to the complexity of the circuitry. The distinction between series and parallel is how they are connected to the phone line, and what they are capable of intercepting.
A series telephone tap involves inserting the phone tap between the actual telephone and telephone line. There are two wires that carry the audio signal in a telephone line in the UK, which are numbered 2 and 5. You need to disconnect one of these wires and connect it to one wire of the series bug. You need to connect the other wire of a series bug to where you disconnected the telephone wire. Essentially the electrical signal flows through the bugging device.
A parallel telephone tap is completely different and is installed without disconnecting any wires. You connect one wire of the parallel bugging device to wire 2 on the phone line, and the other wire to wire 5 on the phone line. So the parallel device is essentially peeking on the electrical signal flowing in the telephone line.
The advantages of series and parallel taps can be found on Spy Review in an article I wrote a while ago.
With the pervasiveness of mobile phones these days, there's not a great deal to be gained from bugging just a landline. However, bugging a mobile phone is incredibly difficult to do!
A compact telephone line recording lead that allows you to record phone conversations on to your standard voice recorder. The adaptor is approved for use on UK telephone lines and is compatible with any analog phone line. This lead can be used to record conversations from both wired and cordless telephones connected to the phone line.
This telephone recording lead is available to buy at Maplin.co.uk.
Spy phones
Spy phones are a relatively new creation and have been about since 2004. These fiendish devices exploit mobile phones by turning them into surveillance devices. Essentially a mobile phone is modified in hardware or software to allow someone to dial the mobile phone from a remote location and listen in using the built-in microphone. The phone is modified to answer automatically and without creating audio or video cues that the phone has answered the call.
The hardware modifications are based on making physical changes to the phone using a soldering iron. This might be removing lights, disabling the LCD screen and setting the phone to automatically answer. Hardware modifications are not so common now as software modifications are easier and more reliable.
The older software modifications made the phone look as if it was completely dead, just like the hardware modifications. The newer versions use the latest mobile phones and also give you features such as being able to relay SMS messages from that phone to your phone, and allow you to listen to conversations taking place on the target phone itself!
Legalities of Bugs and Bugging
Listening to someone's conversation without their consent is illegal in the UK. It is also illegal to use a RF transmitter without an appropriate licence in the UK. You will not be able to get a licence for any audio bugging device unless you work for the police or government secret services.
It is not currently illegal to own or buy a covert listening device. There are some cases in which it is illegal to sell covert listening devices that do not adhere to industry regulations. Talk about a minefield!
