The receiver is open to reception of not only the desired signal but also all interfering signals within the receiver's bandwidth, which can prevent the receiver from processing the desired signal properly (Figure 8.1). Therefore, it is crucial for the receiver to have the ability to eliminate or reduce the effects of the interfering signals or jammers on the desired signal. These are divided into two groups, cosite and friendly jammers, which are often referred to as interferers, and unfriendly jammers that purposely jam the signal. The focus of this chapter is to address the types of unfriendly jammers and ways to mitigate their effect on the desired communication signal.

Chapter Contents:

• 8.1 Unfriendly jammers
• 8.1.1 Spot jammer
• 8.1.2 Barrage jammer
• 8.1.3 Continuous wave (CW) jammer
• 8.1.4 Repeater jammer
• 8.1.5 Cognitive jammer
• 8.1.6 Burst or pulsed jammer
• 8.1.7 Capturing the AGC
• 8.2 Techniques to reduce jammers
• 8.2.1 Burst clamp
• 8.2.2 Adaptive filter
• 8.2.2.1 Adaptive digital filter intuitive analysis
• 8.2.2.2 Basic adaptive filter
• 8.2.2.3 Least mean square algorithm
• 8.2.2.4 Analog/digital adaptive filter
• 8.2.2.5 Wideband ALE jammer suppressor adaptive filter
• 8.2.2.6 Simulation
• 8.2.2.7 Results
• 8.2.2.8 Amplitude and phase suppression results
• 8.2.3 Gram—Schmidt orthogonalizer
• 8.2.4 Basic GSO
• 8.2.5 Adaptive GSO implementation
• 8.3 Intercept receiver comparison
• 8.4 Summary
• 8.5 Problems
• Further reading

Inspec keywords: jamming; signal processing; radio receivers

Other keywords: communication signal; receiver bandwidth; jammers; interfering signals

Subjects: Signal processing and detection; Radio links and equipment; Electromagnetic compatibility and interference