Radar Detection Using Segmented Pulse Sub-bands
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Solution Overview
Problem
Conventional radar systems face limitations in detecting close targets while maintaining constant distance resolution due to the issue of transmit blanking and the resulting blind zones, which restrict the usable range and sensitivity of the detection process.
Innovation Solution
A radar detection method that subdivides each pulse into N contiguous sub-pulses with specific carrier frequencies and modulation codes, allowing for compression and realignment of these sub-pulses to achieve consistent distance resolution across the entire range, using a combination function that adapts to different distance zones for signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pulse duration is increased to improve average power and detection range, then the detection range increases, but the blind zone distance increases due to emission blanking
Solution Approach 1:
The transmitted pulse is divided into N contiguous sub-pulses, each with a specific carrier frequency and modulation code. This segmentation allows the radar to process different portions of the pulse separately, enabling detection of echoes that arrive during the transmission period by identifying them as originating from distant targets rather than close targets.
Solution Approach 2:
The patent introduces frequency as an additional dimension for distinguishing target distances. By assigning different carrier frequencies to different sub-pulses, the system can differentiate between echoes from close targets (arriving during transmission) and distant targets (arriving after transmission), effectively eliminating the blind zone without reducing pulse duration.
2Length of stationary object
If the pulse duration is decreased to reduce blind zone distance, then the blind zone distance decreases, but the average power decreases and detection range is reduced
Solution Approach 1:
Instead of reducing overall pulse duration, the patent segments the pulse into multiple sub-pulses and uses frequency differentiation to extend the effective detection range. This maintains the total energy transmission while reducing the blind zone by allowing simultaneous transmission and reception through frequency-based echo identification.
Solution Approach 2:
The system changes the carrier frequency parameter across different sub-pulses, allowing the radar to identify echoes from distant targets that arrive during the transmission period. This parameter change enables the system to maintain long pulse durations for high average power while eliminating the blind zone problem.
3Measurement precision
If pulse compression is applied to improve distance resolution, then the distance resolution improves, but the blind zone problem worsens due to incomplete compression in the masked area
Solution Approach 1:
The pulse compression process is applied separately to each sub-pulse rather than to the entire pulse. This segmentation allows complete compression to be performed on unmasked portions while the masked portions are identified through frequency analysis, eliminating the incomplete compression problem that creates blind zones.
Solution Approach 2:
By using frequency as an additional dimension, the system can distinguish between masked and unmasked portions of the pulse. This allows the radar to perform complete pulse compression on all sub-pulses while using frequency information to identify which echoes correspond to distant targets that arrived during transmission, thereby eliminating blind zones while maintaining resolution.
4Use of energy by moving object
If the form factor is increased to improve average power ratio, then the average power to peak power ratio improves, but the eclipse in distance increases
Solution Approach 1:
The patent uses frequency as an additional dimension to distinguish between echoes from close and distant targets. By assigning different carrier frequencies to different sub-pulses, the system can identify and process echoes from distant targets that arrive during the transmission period, effectively eliminating the eclipse distance while maintaining a high form factor for improved average power ratio.
Data Source
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AI summary
The method utilizes a pulse radar waveform, one pulse (1) being subdivided into N contiguous sub-pulses (41, 42, 43, 44) each having its own carrier frequency (F1, F2, F3, F4) modulated according to a modulation code in a frequency band, N being greater than or equal to 2, said method comprising the following steps: - creating N reception channels by filtering, each suitable for one sub-pulse; - in each channel, carrying out a compression of said sub-pulse; - temporally realigning the compressed sub-pulses; the useful detected signal being obtained from the result of a combination function of the compressed signals realigned in N distance bins (c1i, c2i,..., cNi), one distance bin corresponding to each of the N pulse compressions, the combination function depending on the rank of the distance bin in which said function is applied, at least three distance zones being defined beforehand, the result of the combination function is: - the compressed signal of the last sub-pulse for the distance bins corresponding to the small distances zone; - the minimum of a function with amplitudes Ai of N compressions for the distance bins belonging to the medium distances zone; - the mean of a function of the amplitudes Ai of the N compressions for the distances bins belonging to the large distances zone; Ai being the amplitude of the compressed signal for the ith sub-pulse.