Pulse Doppler Radar Signal Processing for Ambiguous Velocity
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Solution Overview
Problem
Current radar systems face challenges in accurately measuring the position and speed of moving objects due to low signal-to-noise ratios and spectral resolution, particularly at low pulse repetition rates, leading to ambiguous Doppler shift determination and increased false hypothesis probabilities.
Innovation Solution
A pulse Doppler radar device with a filter that processes echo signals coherently across bursts in a variable window with different pulse repetition rates, combined with a detector for three-dimensional detection of local maxima, and a signal combiner to link multiple frequency channels for improved spectral information utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the pulse repetition rate is decreased to increase the unique range of the radar, then the maximum detectable range is improved, but the number of pulses per dwell decreases leading to low signal-to-noise ratio and low spectral resolution
Solution Approach 1:
The patent combines multiple frequency channels (first and second frequency channels) to form a composite signal spectrum. By merging the spectral information from multiple channels, the system achieves improved signal-to-noise ratio and spectral resolution without requiring an increased pulse repetition rate, thus maintaining the extended unique range while improving detection reliability.
2Length of stationary object
If the pulse repetition rate is decreased to increase the unique range, then the maximum detectable range is improved, but the spectral resolution relative to the pulse repetition rate decreases
Solution Approach 1:
The patent merges spectral information from multiple frequency channels to create a composite signal spectrum with enhanced spectral resolution. This combination allows the system to maintain low pulse repetition rates for extended range while achieving high spectral resolution through the aggregated frequency domain information from multiple channels.
3Length of stationary object
If the number of pulses per burst is reduced due to low pulse repetition rate, then the unique range is improved, but the detection reliability and ambiguity resolution accuracy decrease
Solution Approach 1:
The system combines signals from multiple frequency channels to form a composite spectrum that provides sufficient spectral information for reliable detection and ambiguity resolution. This merging approach compensates for the reduced number of pulses per burst by utilizing the complementary frequency domain information from multiple channels, thereby maintaining detection reliability despite lower pulse counts.
4Measurement precision
If multiple frequency channels are combined, then the spectral information utilization is improved, but the device complexity increases
Solution Approach 1:
The patent implements a multi-functional signal processing architecture where the same processing unit handles multiple frequency channels. The filter and detector are designed to process composite signals from multiple channels simultaneously, achieving universal functionality that improves spectral information utilization without proportionally increasing device complexity through dedicated separate processing paths for each channel.
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 enhances sensitivity to noise, increases the signal-to-noise ratio, and reduces false hypotheses, enabling more accurate and reliable measurement of target distance, azimuth, and speed, while suppressing secondary maxima and improving detection performance.
Implementation Method 1
Device and method for measuring position and velocity of an object, in particular a missile, using an airspace surveillance radar
Implementation Method 2
the Doppler shift of a target can only be determined ambiguously using a burst due to aliasing
Data Source
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Figure 3~4
AI summary
A device and a method for measuring the position and velocity of a moving object, in particular a missile, using an airspace surveillance radar, are described. A filter (10) and a detector (20) are used, wherein the filter (10) receives burst-wise echo signals of a predetermined frequency and processes the received echo signals coherently across bursts and within a variable window with different pulse repetition rates. The detector (20) performs three-dimensional detection of local maxima with respect to the distance, azimuth, and velocity of the moving object.