Carrier Phase Detection for Radar Sensors Using Envelope Analysis
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Solution Overview
Problem
Existing radar detection systems face challenges in accurately detecting pulsed RF signals due to variations in signal amplitude, leading to reduced accuracy and increased noise interference, especially when dealing with sinusoidal bursts in expanded time ranging systems.
Innovation Solution
A detection system that includes a transmitter, receiver, and processor to detect the time-of-peak of the expanded time RF burst envelope within an analysis window, using a carrier phase detector to identify zero axis crossings of each sinewave cycle, thereby enhancing detection accuracy and immunity to noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed threshold detector is used to detect the first sinewave cycle crossing the threshold, then detection simplicity is improved, but detection accuracy deteriorates due to cycle jumps caused by amplitude variations
Solution Approach 1:
The patent introduces an envelope detector as an intermediary component that extracts the amplitude envelope from the sinusoidal burst. This envelope signal serves as a mediator between the raw RF signal and the threshold detector, providing a stable amplitude reference that is independent of carrier phase and frequency variations. The threshold detector then operates on this envelope signal rather than the raw sinusoidal signal, eliminating cycle jumps while maintaining detection simplicity.
2Reliability
If envelope detection techniques are used to detect the sinusoidal burst, then detection robustness to amplitude variations is improved, but detection accuracy deteriorates due to lower bandwidth and slower response
Solution Approach 1:
The patent segments the detection process into two independent functions: envelope detection for determining the analysis window timing, and zero-crossing detection for precise cycle identification. The envelope detector provides the temporal boundaries (analysis window) within which the high-precision zero-crossing detector operates. This segmentation allows each detector to optimize for its specific function without compromising the other.
Solution Approach 2:
The envelope detector acts as an intermediary that prepares the signal by defining the analysis window, which then enables the zero-crossing detector to operate at full precision. The envelope detection does not directly provide the final detection output but rather creates the conditions necessary for accurate zero-crossing detection by establishing the temporal context.
3Measurement precision
If the zero axis crossings of sinewaves are detected, then detection accuracy is improved due to fastest voltage rate of change, but detection complexity increases compared to envelope detection
Solution Approach 1:
The detection system is segmented into two functional blocks: an envelope detector for window generation and a zero-crossing detector for precise measurement. This segmentation isolates the complexity of zero-crossing detection to a specific module that operates only within the defined analysis window, rather than requiring the entire system to handle both envelope tracking and zero-crossing detection simultaneously.
Solution Approach 2:
The envelope detector performs preliminary action by establishing the analysis window before the zero-crossing detection occurs. This preliminary timing information reduces the search space for zero-crossing events, allowing the system to focus computational and hardware resources on detecting zero-crossings only within the relevant time window, thereby reducing overall complexity.
4Object-affected harmful factors
If a threshold detector with analysis window is used to gate noise outside the window, then noise immunity is improved, but detection accuracy deteriorates due to ambiguity of which cycle to detect
Solution Approach 1:
The patent segments the detection function into envelope detection for window definition and zero-crossing detection for cycle identification. Within the analysis window, the zero-crossing detector identifies specific sinusoidal cycles by detecting when the signal crosses zero voltage, providing unambiguous cycle identification even when multiple cycles are present in the window.
Solution Approach 2:
The envelope detector serves as an intermediary that provides timing context through the analysis window, while the zero-crossing detector acts as a secondary intermediary that identifies specific cycles within that window. This layered intermediary structure resolves the ambiguity of which cycle to detect by providing both temporal boundaries and cycle-specific identification.
Data Source
AI summary
A pulse detection system for expanded time radar, laser and TDR sensors detects specific cycles within bursts of cycles. A sensor transmits and receives short bursts of RF cycles. A transmit pulse detector triggers on a selected cycle of the detected transmit burst and starts a range counter. A receive detector triggers on a selected cycle within a received echo burst to stop the range counter, thereby indicating range. Cycle selection is enabled by an analysis window of time. The detection system can provide accuracies on the order of one picosecond and is well-suited to accurate ranging along an electromagnetic guide wire.