Pulse Radar Sampling Clocks Using Delay-Locked Loop
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Solution Overview
Problem
Conventional pulse radar systems face limitations in achieving high resolution due to their reliance on pulse width for distance determination and Signal to Noise Ratio (SNR) improvement, which restricts their ability to accurately detect and analyze targets with high precision.
Innovation Solution
A pulse radar apparatus utilizing a multi-stage Delay-Locked Loop (DLL) unit to generate and select sampling clocks with specific time delays, combined with a switch unit and analog-to-digital converter, allows for precise sampling and amplification of echo signals, enhancing resolution and SNR through the use of a low noise amplifier and capacitor-based hold device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional pulse radar receiver uses a single transmission pulse for distance determination, then the system structure is simple, but the distance resolution is limited by pulse width
Solution Approach 1:
The patent divides the pulse repetition period into multiple equal time intervals using a multi-stage DLL unit, creating multiple sampling clocks with different time delays. This segmentation of time allows the system to determine distance based on which time interval the echo signal falls into, achieving high resolution without requiring complex additional hardware.
Solution Approach 2:
The patent uses periodic transmission pulses at a pulse repetition frequency and generates sampling clocks by dividing the pulse repetition period. The periodic nature of the transmission and sampling allows the system to use time-of-flight measurement with multiple sampling points, improving distance resolution while maintaining a relatively simple system structure through regular, repeating operations.
2Measurement precision
If multiple transmission pulses are received to improve SNR, then the Signal to Noise Ratio increases, but the distance resolution remains limited by pulse width
Solution Approach 1:
The patent performs preliminary sampling of the echo signal at multiple time intervals determined by the DLL-generated sampling clocks. By pre-sampling the signal at these predetermined time points and selecting the appropriate sample based on which time interval the echo falls into, the system achieves high distance resolution without needing to process multiple pulses, thus maintaining good SNR while improving resolution.
3Measurement precision
If a conventional range gating method uses a delay element to sweep ranges, then the receiver can determine targets within specific ranges, but the resolution is still limited by pulse width
Solution Approach 1:
The patent replaces the conventional mechanical delay element with an electronic Delay-Locked Loop unit that generates multiple sampling clocks by dividing the pulse repetition period. This electronic approach eliminates the need for physical delay lines and associated switching mechanisms, achieving the same range sweeping function with higher precision and simpler overall structure.
Data Source
AI summary
A pulse radar apparatus is disclosed. The pulse radar apparatus includes a pulse generation unit, a receiver unit, a synchronization unit, and a switch unit. The pulse generation unit generates a pulse based on a transmission trigger signal having a transmission pulse repetition period, and sends the pulse to a target via a transmission antenna. The synchronization unit generates the transmission trigger signal using an external reference clock, provides the transmission trigger signal to the pulse generation unit, and generates a plurality of clock signals having a time delay with respect to the transmission pulse trigger signal using the external reference clock. The switch unit selects any one clock signal from the plurality of clock signals in response to an external selection signal, and provides the selected clock signal to a receiver unit which utilizes a sampler with provided sampling clocks.