Radar Distance Calculation Using Nonlinear Frequency Change
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Solution Overview
Problem
Conventional radar devices cannot calculate the distance to a target when the frequency of the beat signal exceeds the Nyquist frequency of the analog-to-digital converter, limiting their range.
Innovation Solution
A radar device with a radar signal generation unit producing nonlinearly changing frequency signals, a transmission and reception unit for sending and receiving signals, and a distance calculation unit that includes an amount-of-change calculator, absolute value calculator, and distance calculator to determine the target's distance from the beat signal's digital representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the radar device uses a conventional beat signal frequency measurement method, then the distance calculation is simple and direct, but the measurement range is limited by the Nyquist frequency
Solution Approach 1:
The patent changes the measurement parameter from direct beat signal frequency to the amount of change in beat signal frequency over time. By measuring how the frequency changes rather than the frequency itself, the system can determine distances beyond the Nyquist frequency limit, as the rate of change contains information about the original frequency without being constrained by folding effects
Solution Approach 2:
The patent transitions from measuring a single frequency value to measuring the temporal derivative (rate of change) of frequency. This dimensional shift from static frequency measurement to dynamic frequency change measurement enables the system to extract distance information that was previously inaccessible due to Nyquist frequency constraints
2Adaptability or versatility
If the radar device increases the beat signal frequency to measure farther targets, then the distance measurement range extends, but the frequency folds back at the Nyquist frequency causing measurement failure
Solution Approach 1:
The patent converts the harmful effect of frequency folding at the Nyquist frequency into a beneficial measurement method. Instead of avoiding high frequencies, the system measures the amount of change in frequency, which remains reliable even when the absolute frequency exceeds the Nyquist limit. The folding effect no longer corrupts the measurement because the rate of change is what matters, not the absolute value
3Ease of operation
If the radar device uses a linear frequency chirp signal, then the beat signal frequency directly corresponds to target distance, but the system cannot measure targets beyond the Nyquist frequency limit
Solution Approach 1:
The patent introduces dynamics into the frequency measurement process by measuring the time derivative of the beat signal frequency. Instead of a static frequency measurement, the system dynamically tracks how frequency changes over time, enabling distance measurements for targets at ranges that would cause the beat frequency to exceed the Nyquist limit
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
Enables the calculation of distances to targets beyond the range limited by the Nyquist frequency, effectively extending the radar device's measurement capabilities.
Implementation Method 1
transmits the radar signal generated by the radar signal generation unit as a reference wave, transmits the radar signal to a target, and receives a returning radar signal reflected from the target as a reflected wave
Implementation Method 2
detects a beat signal indicating a difference frequency between a frequency of the reference wave output from the radar signal generation unit and a frequency of the reflected wave received by the transmission and reception unit
Data Source
AI summary
The radar device is provided with a distance calculation unit that calculates a distance correspondence value corresponding to the distance to a target from a digital signal converted by a beat signal detection unit, and calculates the distance to the target from the distance correspondence value.