Aircraft Radar Composite Waveform Ground Clutter Detection
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Solution Overview
Problem
Current radar systems for detecting aerial targets, particularly for drones, face challenges in detecting moving objects against heavy ground clutter, especially at low altitudes, due to wide antenna beams and high secondary lobe levels, and existing solutions are not economically viable or adaptable for self-piloted aircraft.
Innovation Solution
A radar system that transmits a microwave wave with a double form, comprising sinusoidal waveforms of different frequencies, and uses differential phases to disambiguate distance and speed, optimizing waveform adaptation based on relative and absolute speeds, and employing beam forming for reception to enhance detection capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide-field antenna is used in transmission to achieve a very wide field of observation (±120° in azimuth and ±15° in elevation), then the field of observation is improved, but the level of secondary lobes increases which worsens the detection of moving objects against ground clutter
Solution Approach 1:
The patent changes the waveform parameter from conventional single-frequency or simple pulse to a composite waveform consisting of at least two sinusoids of different frequencies. This parameter change enables the radar to resolve targets from ground clutter through frequency discrimination while maintaining the wide-field antenna configuration, thus resolving the contradiction between wide observation field and clutter interference.
2Adaptability or versatility
If the aircraft altitude is reduced to operate in low-altitude environments, then the applicability to self-piloted aircraft is improved, but the detection becomes more complicated due to increased ground clutter
Solution Approach 1:
By using a composite waveform with multiple frequencies, the radar can differentiate between ground clutter and aerial targets through frequency analysis. This allows low-altitude operation with self-piloted aircraft while managing detection complexity through signal processing rather than requiring complex antenna systems or high altitude operation.
3Measurement precision
If conventional Doppler detection methods are used to separate targets from ground clutter, then target separation is achieved to some extent, but the detection performance deteriorates at low altitudes with wide beams and high secondary lobe levels
Solution Approach 1:
The patent merges frequency discrimination with Doppler detection by using a composite waveform of at least two sinusoids. This combination allows the radar to separate targets from ground clutter using both frequency and velocity information, improving reliability in low-altitude operations where conventional Doppler alone is insufficient.
4Reliability
If fighter aircraft radar modes (HFR, MFR, BFR) are applied to self-piloted aircraft, then target detection capability is maintained, but the cost and device complexity become unacceptable
Solution Approach 1:
The patent uses a composite waveform with at least two sinusoids of different frequencies, which provides target detection capability similar to complex fighter radar modes but with simpler implementation. This approach avoids the need for mechanical or electronic scanning while achieving reliable detection, thus reducing device complexity and cost for self-piloted aircraft applications.
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
The system effectively detects aircraft in flight, regardless of approach speeds, by optimizing radar resources and increasing target detection capabilities, particularly at low altitudes, while minimizing volume, weight, and cost.
Implementation Method 1
The detection is conventionally carried out by detection of the Doppler effect, which makes it possible to some extent to separate the targets from the ground clutter.
Implementation Method 2
a radar for the detection of aerial targets equipping an aircraft, for example a drone
Data Source
Figure 1~2
Figure 3
Figure 4a~4b
AI summary
Since the radar is carried by an aircraft, it includes means for emitting a microwave wave towards a target. This wave has a dual form: the first form, wave (45), is composed of at least two sinusoids (42, 43, 44) of different frequencies emitted simultaneously. The radar includes receiving circuits that receive the signals reflected by the target and analysis means that detect the target from the received signals. The second waveform is pulsed. The emitted waveform is a function of the relative velocity of the target with respect to the carrier and the absolute velocity of the carrier.