Noise of all kinds limits ultimate detection performance for all electromagnetic sensor systems whether cosmic, UV, visible, IR, microwave or RF. Thermal noise is often thought of as the ultimate limitation on detection and tracking but often it is self-noise in a sensor system, which limits performance. Low-frequency systems with seemingly very low noise figures (NF) are often limited by sky noise from the residual of the “Big Bang,”from auroras and from what used to be called “Monkey Talk.”Great strides have been made in signal processing in the last 50 years. This is the result of dramatic improvements in signal processing hardware as well as a better theoretical understanding. In spite of this, many systems provide disappointing performance. The two main reasons for shortfalls are sensor signal processor self-noise and the physical world's continuing refusal to be normal (Gaussian). Although we have undreamed of device performance and number smashing today, we are inevitably forced by economics to limit hardware complexity that gives rise to significant self-noise. Noise and interference in the real world are “bursty,”“lumpy,”discrete, not stationary, anomalous and even malevolent! This chapter is an introduction to analog and digital signal processing self-noise analysis and heuristic means to control ill-behaved internal and external noise.

Chapter Contents:

• 5.1 Introduction
• 5.2 Noise and gain in signal selective networks [1]
• 5.3 Effects of processing order on dynamic range [1]
• 5.3.1 Pulse compression and beamforming
• 5.3.2 Scale factor changes, saturation and truncation
• 5.4 Noise in prefiltering [1]
• 5.4.1 Saturation and truncation introduced by prefiltering
• 5.4.2 Coefficient noise and stability of prefilters
• 5.5 Noise and signal response in narrowband filtering [1]
• 5.6 Transmitted noise sources
• 5.6.1 AESA unique noise contributions
• 5.7 Receiver noise sources
• 5.7.1 Thermal noise
• 5.7.2 Dynamic range and self-noise
• 5.7.3 Intermediate frequency analog processing
• 5.8 I/Q imbalance
• 5.9 A/D noise
• 5.9.1 Saturation, quantization and optimum signal level [1]
• 5.9.2 Aperture jitter
• 5.9.3 Other sources of noise in A/Ds
• 5.9.4 Advantages of A/D oversampling
• 5.10 Noise in digital signal processing systems [1]
• 5.10.1 Roundoff, saturation and truncation
• 5.10.2 Multiplier roundoff noise
• 5.11 Saturation and truncation during FFT processing
• 5.12 Self-noise performance of binary and polyphase codes
• 5.12.1 Other digital processing anomalous behavior
• 5.13 Noise-limited tracking [11]
• 5.13.1 Range tracking
• 5.13.2 Doppler tracking
• 5.13.3 Angle tracking
• References

Inspec keywords: radar interference; radar detection; radar tracking; thermal noise; radar signal processing

Other keywords: external noise; low-frequency systems; thermal noise; heuristic; electromagnetic sensor systems; sensor signal processor self-noise analysis; internal noise; digital signal processing; sky noise; noise figures; intercept systems; detection performance; Monkey Talk; time 50 year; big bang residual; device performance; signal processing

Subjects: Radar equipment, systems and applications; Signal detection; Electromagnetic compatibility and interference