Radar Signal Self-Interference Cancellation via Phase Inversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Facilities that transmit and receive radar signals face difficulties in distinguishing incoming signals from their own transmitted signals due to signal masking, leading to reduced sensitivity and interference, especially at high power levels, which complicates the detection of small incoming pulses and introduces inner modulation noise.
Innovation Solution
A method involving a secondary signal with the same amplitude but a 180-degree phase difference is added to the primary signal before the detector, using voltage controlled attenuators and phase shifters, or by adjusting the path length, to cancel out the unwanted transmitted signal, allowing only incoming signals to reach the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the receiving antenna is placed close to the transmitting antenna for simultaneous transmission and reception, then the system can operate compactly and efficiently, but the receiving antenna picks up large signals from the transmitting antenna that mask incoming signals
Solution Approach 1:
The patent extracts the harmful self-generated signal from the receiving path by using a coupled circuit that taps into the transmitting antenna's signal source. This extracted signal is then processed separately through phase shifting and attenuation before being subtracted from the received signal, effectively removing the masking effect while preserving the ability to receive external signals
Solution Approach 2:
The patent applies preliminary anti-action by generating an inverted version of the transmitted signal before it reaches the receiver. The coupled circuit extracts the transmitted signal, applies a 180-degree phase shift, and combines it with the received signal in advance, preventing the self-generated signal from interfering with the detection of external signals
2Power
If high power transmitted signals are used to improve transmission range, then the radar can detect distant targets, but the detector's sensitivity is degraded and small incoming pulses cannot be detected
Solution Approach 1:
The patent converts the harmful high-power transmitted signal into a beneficial component by using it to generate the cancellation signal. The same high-power signal that causes masking is extracted, phase-shifted, and subtracted from the received signal, transforming the problem into a solution that enables detection of weak incoming pulses even when transmitting at high power
3Use of energy by moving object
If continuous wave transmission is used to improve power efficiency, then energy consumption is reduced, but inner modulation noise is generated that masks small input signals
Solution Approach 1:
The patent implements feedback by continuously monitoring the transmitted signal through the coupled circuit and using this information to generate the appropriate cancellation signal. The phase shifter and attenuator adjust the feedback signal in real-time to match the transmitted signal's characteristics, ensuring continuous suppression of self-generated signals and inner modulation noise throughout operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively blocks the reception of self-generated signals, enhancing the detection of small incoming pulses and reducing interference, thereby improving the sensitivity and accuracy of signal reception across a broad frequency range.
Implementation Method 1
transmit and receive signals, such as radar signals
Implementation Method 2
a signal which is derived from the same signal generator, or one synchronized with it in phase, frequency and amplitude is taken along a second path to the detector, with the signal taken via the secondary path arriving at the detector with the same amplitude as the signal arising from the primary path, but with a phase difference of 180 degrees, the two signals sum to zero
Data Source
AI summary
A method and apparatus which enables a facility or entity such as ships, airplanes, satellites, and land based sites, that transmits and receives radar signals to receive any incoming radar signal, or any electromagnetic signals in the frequency range of 1 Ghz-30 Ghz, while blocking reception of any signals generated by the facility or entity itself. The method comprises transmitting a primary signal from an rf generator; providing a second signal which is synchronized with the primary signal matching in both phase and amplitude, but with a phase difference of 180 degrees so that the two signals sum to zero. The second signal travels through a voltage controlled attenuator and thru a voltage controlled phase shifter. Combining in a combiner the second signal with a signal radiated by a transmitting antenna and received by a receiving antenna that connects into a transmission enabling mechanism, and then transmitting the combined signal to a detector apparatus.