Radar Device Doppler Sign Determination Using Dual-Channel Processing
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Solution Overview
Problem
Radar devices that only receive real signals face ambiguity in determining the sign of Doppler frequency and target angle, leading to uncertainty in whether a target is approaching or receding, and in the direction of the target angle, which is a limitation in both Doppler radar and digital beam forming systems.
Innovation Solution
A radar device configuration that includes an oscillator, transmitting and receiving antennas, a receiver, Fourier transform unit, spectral peak detecting unit, distance calculating unit, and distance determining unit, which generates and processes real received signals to determine the sign of Doppler frequency or target angle by using multiple transmission frequencies and performing Fourier transforms to extract peak complex signal values, allowing for accurate distance measurement and sign determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only a real received signal is obtained (single channel), then the number of components is reduced and cost is lowered, but the sign of the Doppler frequency becomes ambiguous and cannot determine whether the target is approaching or receding
Solution Approach 1:
The patent transitions from a single-channel real signal system to a dual-channel complex signal system by adding the Q-channel (quadrature phase component). This dimensional expansion allows the system to preserve phase information and determine the sign of Doppler frequency, resolving the ambiguity in target approach/recede detection while maintaining reasonable system complexity
Solution Approach 2:
The patent introduces a local wave (reference signal) as an intermediary that is mixed with the received wave in both I-channel and Q-channel. This local wave serves as a mediator to extract phase information through mixing operations, enabling the determination of Doppler frequency sign without requiring complex direct measurement of the received signal alone
2Device complexity
If only a real received signal is obtained (single channel), then the device configuration is simplified, but the sign of the target angle becomes ambiguous and cannot determine the direction of the incoming wave
Solution Approach 1:
The patent applies the same dual-channel complex signal approach to the digital beam forming system. By introducing the Q-channel component alongside the I-channel, the system gains the ability to determine the sign of target angle information through phase relationships, enabling direction determination while keeping the device configuration manageable through systematic signal processing
3Measurement precision
If two channels (I-channel and Q-channel) are used, then the sign of Doppler frequency can be determined accurately, but the number of components increases and cost rises
Solution Approach 1:
The patent merges the I-channel and Q-channel processing into a unified complex signal processing framework. By combining the in-phase and quadrature-phase components into a single complex received signal, the system achieves accurate Doppler frequency sign determination while streamlining the overall processing architecture, reducing redundant components, and optimizing the balance between measurement precision and device complexity
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 determination of the sign of Doppler frequency or target angle even with only real signals, reducing the number of components and cost while maintaining accurate measurement capabilities, thus overcoming the ambiguity in existing systems.
Implementation Method 1
an oscillator for generating the wave at a plurality of transmission frequencies
Implementation Method 2
a transmitting antenna for emitting the wave generated from the oscillator into the space
Implementation Method 3
a receiving antenna for receiving an incoming wave
Implementation Method 4
a receiver for detecting the received wave received by the receiving antenna to generate a real received signal
Implementation Method 5
a Fourier transform unit for performing a Fourier transform on the real received signal generated from the receiver
Implementation Method 6
a spectral peak detecting unit for receiving an input of a result of the Fourier transform from the Fourier transform unit to extract peak complex signal values of Doppler frequency or angle points at which an amplitude is maximum
Implementation Method 7
a distance calculating unit for storing the peak complex signal values from the spectral peak detecting unit, which are obtained by using the plurality of transmission frequencies, and for calculating a distance to the reflecting object based on the stored peak complex signal values
Data Source
AI summary
A radar device includes: an oscillator for generating a wave at a plurality of transmission frequencies; a transmitting antenna; a receiving antenna; a receiver for generating a real received signal; a Fourier transform unit for performing a Fourier transform on the real received signal in a time direction; a spectral peak detecting unit for receiving an input of a result of the Fourier transform to extract peak complex signal values of Doppler frequency points having a maximum amplitude; a distance calculating unit for storing the peak complex signal values and for calculating a distance to a reflecting object based on the stored peak complex signal values to output the obtained distance as a measured distance value; and a distance sign determining unit for determining validity of the measured distance value and for outputting the measured distance value and the Doppler frequency according to a result of determination.