Development of a single LMS loop three channels analog adaptive co-site interference cancelling system

Area of Science:

• Electrical Engineering
• Signal Processing
• Radio Frequency (RF) Engineering

Background:

• Co-site interference poses a significant challenge for platforms like airplanes and satellites.
• Existing digital cancellation methods are insufficient for receiver front-end saturation caused by severe interference.
• Analog RF cancellation is crucial for addressing severe co-site interference before digital processing.

Purpose of the Study:

• To develop an analog adaptive co-site wideband interference cancellation system (AACWICS-3ch) that overcomes limitations of previous systems.
• To address the complexity issues associated with double LMS loops in existing analog adaptive co-site interference cancellation systems (AACICS).
• To investigate interference cancellation performance under antenna swaying conditions, a factor often overlooked.

Main Methods:

• Development of a 3-channel analog adaptive co-site wideband interference cancellation system (AACWICS-3ch) utilizing a single LMS loop per channel.
• Establishment and analysis of an equivalent model for the AACWICS-3ch to determine steady-state weight and interference cancellation ratio (ICR).
• In-depth analysis of the correlations between interference cancellation bandwidth, ICR, system gain, and antenna swing amplitude.

Main Results:

• The AACWICS-3ch demonstrates significantly enhanced interference cancellation performance compared to a 2-channel system (AACICS-2ch).
• Achieved a maximum improved ICR exceeding 30 dB.
• Successfully mitigated the complexity issues inherent in double LMS loop systems while increasing channel count.
• Validated performance improvements through both simulations and experimental tests, even under antenna swaying conditions.

Conclusions:

• The developed AACWICS-3ch offers a superior solution for analog RF co-site interference cancellation.
• The system effectively enhances interference cancellation bandwidth and ratio, particularly in dynamic environments with antenna sway.
• This approach provides a more practical and efficient method for mitigating severe co-site interference in various platforms.