Radar Apparatus Switching Frequency Detection Circuit
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Solution Overview
Problem
Conventional spread spectrum radar systems require complex circuit configurations to convert detection signals into alternating current (AC) signals, making it difficult to achieve simple AC signal output and accurate distance measurement.
Innovation Solution
A radar apparatus with a transmission section, delay device, reception section, switch control section, and switching frequency detection section, which transmits spectrum-spread signals, despreads reflected waves, and calculates distance based on detected switching frequencies, allowing for simple AC signal output without the need for complex circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional methods are used to convert detection signal into AC signal by giving data signal to spread code, then AC signal output is achieved, but circuit configuration becomes complex and large capacity memory is required
Solution Approach 1:
The patent extracts the data signal from the spread code generation process and applies it separately to modulate the transmission signal. This separates the AC signal generation function from the spread code generation, simplifying the circuit configuration while maintaining AC signal output capability.
Solution Approach 2:
The patent divides the signal processing into separate functional blocks: spread code generation, transmission signal modulation, and detection signal processing. This segmentation allows AC signal output to be achieved through coordinated operation of simplified individual blocks rather than a complex integrated system.
2Measurement precision
If spread code frequency is increased to obtain distance resolution, then distance measurement accuracy is improved, but mechanism for generating spread code becomes complex and large capacity memory is necessary
Solution Approach 1:
The patent uses a delay device to create a time-delayed copy of the spread code rather than generating high-frequency spread code directly. This copying approach maintains distance resolution capability while avoiding the complexity of high-frequency spread code generation mechanisms and large capacity memory.
Solution Approach 2:
The patent transitions from resolving distance through high-frequency temporal variations to resolving distance through time delay measurement of correlated signals. This dimensional change from frequency-domain to time-domain processing simplifies the spread code generation mechanism while maintaining measurement precision.
3Adaptability or versatility
If bandwidth of filter circuit at rear stage is widened to detect Doppler signal, then Doppler detection capability is achieved, but S/N ratio is lowered
Solution Approach 1:
The patent uses correlation detection with the delayed spread code to selectively amplify the desired signal component while suppressing noise and interfering signals. This feedback-like correlation process enables Doppler signal detection within a narrower bandwidth, maintaining S/N ratio while achieving Doppler detection capability.
Data Source
AI summary
A radar apparatus includes a transmission section, a delay device, a reception section, a switch control section, a switching frequency detection section, and a relative distance calculation section. The transmission section transmits a signal wave, which is spectrum spread by using a spread code. The delay device gives delay to the spread code. The reception section receives a wave reflected by an object and spectrum despreads the reflected wave with using the delayed spread code to output a despread signal. The switch control section switches at a switching frequency an operation of at least one of the transmission section, the reception section, and the delay device. The switching frequency detection section detects the switching frequency from the despread signal. The relative distance calculation section calculates a distance to the object based on a detection result provided by the switching frequency detection section and an amount of the delay.