In their classic book, Barton and Ward characterized angle-of-arrival errors for various antenna types, including interferometers. In this chapter, we focus on the effect of additive random noise on angle-of-arrival accuracy for several types of interferometers: monopulse interferometer, digital interferometer, orthogonal interferometer, amplitude interferometer, and bistatic interferometer. In each case, angle-of-arrival is computed as a difference in measurements and the error due to additive random noise affects each interferometer type differently. The basic angle accuracy equations are derived for each interferometer type for the case that noise is independent and identically distributed (IID) and for the case when it is not IID. For the monopulse and digital interferometer, the general case is considered where the noise error is neither independent nor identically distributed. These basic accuracy equations relate radar design parameters to angle accuracy and can be used to design interferometer architectures. For this chapter, we derive the accuracy equations assuming an interferometer that uses two antennas to measure angle in one dimension. The angle precision relationships presented in this chapter are derived from principles developed in Chapters 2, 3, and 4. In Chapter 7, we will consider interferometers with more than two antennas that are designed to estimate the two-dimensional angle-of-arrival.

Chapter Contents:

• 6.1 Monopulse Interferometry
• 6.1.1 Monopulse Interferometer Phase Sensitivity
• 6.1.2 Monopulse Beamwidth
• 6.1.3 Monopulse Interferometer Angle Error
• 6.1.4 Off-Axis Monopulse Error
• 6.2 Digital Interferometer Angle Error
• 6.2.1 Correlated and Nonidentically Distributed Error Effects
• 6.2.2 Impact of Baseline Errors
• 6.3 Transmit Interferometry
• 6.3.1 Correlated and Nonidentically Distributed Error Effects
• 6.4 Cramer-Rao Lower Bound Analysis
• 6.5 Amplitude Interferometer
• 6.6 Bistatic Interferometer
• 6.7 Differential Interferometry
• 6.8 Synthetic Aperture Radar Interferometry
• 6.8.1 SAR Interferometry Using Differentials
• 6.8.2 SAR Interferometry Using Angle-of-Arrival
• 6.8.3 SAR Interferometry Height Error
• 6.9 Cramer Rao Lower Bound for Time-of-Arrival
• 6.10 Coherent Phase Trilateration
• 6.10.1 Geometric Dilution of Precision
• 6.11 Summary of Interferometer Angle Precision
• References

Inspec keywords: radar interferometry

Other keywords: orthogonal interferometer; digital interferometer; monopulse interferometer; independent and identically distributed; amplitude interferometer; additive random noise; bistatic interferometer; angle-of-arrival errors; radar interferometer; radar design parameters; IID

Subjects: Radar equipment, systems and applications