Digital Phase Offset Generation for Radar Target Simulation
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Solution Overview
Problem
Conventional radar systems face limitations in simulating target return signals due to phase shifting constraints, including limited phase step size, linearity, repeatability, and bandwidth, which lead to errors and require frequent calibration in multi-channel systems.
Innovation Solution
A super-heterodyne architecture utilizing a direct digital synthesizer (DDS) or digital-to-analog converter (DAC)-based local oscillator (LO) to impart precise phase offsets, eliminating the need for analog phase shifters and ensuring phase repeatability and accuracy to less than one-hundredth of a degree across large bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog phase shifters are used to simulate target return signals, then phase shifting capability is provided, but phase step size, linearity, repeatability, and bandwidth are limited
Solution Approach 1:
The patent replaces analog phase shifters with a digital signal processing approach using direct digital synthesis (DDS) and digital-to-analog conversion. The phase shifting function is implemented through digital code control of the DDS device, which generates local oscillator signals with precise phase control. This substitution eliminates the mechanical and analog limitations of traditional phase shifters, providing unlimited phase resolution and wider bandwidth capability.
Solution Approach 2:
The patent changes the control parameter from analog voltage to digital code for phase shifting. The DDS device accepts digital phase control words that directly determine the phase of the generated signal. This parameter change enables precise phase control with resolution determined by the digital word length, eliminating the coarse phase steps inherent in analog phase shifters.
2Ease of operation
If multiple coherent channels are used in legacy systems, then phase adjustment capability is provided, but device drift occurs across channels requiring frequent calibration
Solution Approach 1:
The patent merges the phase control function into a single digital processing domain for all channels. Multiple channels share a common reference clock and use synchronized DDS devices that are all controlled by digital codes from a central processor. This unified digital control architecture ensures that all channels maintain coherent phase relationships without drift, as the phase accuracy is determined by the digital clock reference rather than analog component tolerances.
Solution Approach 2:
The patent implements digital feedback control through the use of a common reference clock that synchronizes all DDS devices. The digital nature of the control system allows for precise timing synchronization and phase alignment across channels. Any phase deviations can be detected and corrected through digital signal processing, eliminating the need for frequent manual calibration required in analog multi-channel systems.
3Adaptability or versatility
If analog phase-varying components are used, then phase modulation is provided, but bandwidth is inherently limited and phase step resolution is coarse
Solution Approach 1:
The patent replaces analog phase modulation components with digital signal processing. The phase modulation is achieved by varying the digital phase control word input to the DDS device, which directly modulates the phase of the generated signal. This digital approach provides phase resolution determined by the number of bits in the phase control word, enabling extremely fine phase steps that are impossible to achieve with analog components.
Solution Approach 2:
The patent makes the phase control dynamic and programmable through digital means. The phase control word can be changed at will by the digital processor, allowing for dynamic phase modulation with arbitrary waveforms. The DDS device responds to digital input changes with corresponding phase changes in the output signal, providing real-time, programmable phase control without the bandwidth limitations of analog phase modulators.
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
This solution provides high phase and frequency modulation accuracy with minimal channel-to-channel variation, reducing the need for frequent calibration and enhancing the fidelity of simulated target return signals.
Implementation Method 1
a direct digital synthesized (DDS) or digital to analog converter (DAC)-based local oscillator (LO) to impart desired phase offsets
Implementation Method 2
combining the input target signal with an oscillator signal to generate a first output signal having a second frequency
Data Source
AI summary
Methods and apparatus for generating a target signal with desired phase shift information. In embodiments, a system receives an input target signal having a first frequency and combines the input target signal with an oscillator signal to generate a first output signal having a second frequency. The oscillator signal is generated using a digital component that imparts phase-shift information into the oscillator signal. The first output signal is combined with a fixed frequency oscillator signal to generate a second output signal corresponding to a signal reflected from a target.