Communications is an extremely important aspect of surveillance and the various methods of communicating covertly by radio are covered. The different types of radio systems; covert microphones, earpieces and wires are explained together with different types of radio voice procedure and code systems.

• Types of communication equipment
• Mobile and handheld radios
• Antennas & frequencies
• Covert systems
• Radio security
• Brevity code systems
• Radio call signs and networks
• Voice procedure
• Spot Codes
• Encryption
• The click system