Millimeterwave Radar Sensor Phase Noise Reduction
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Solution Overview
Problem
Existing millimeterwave (MMW) radar systems for automotive, marine, and aviation applications face challenges with high phase noise and varying modulation characteristics due to complex frequency multiplication systems or overly simple direct modulation, leading to degraded performance and increased costs when scaling multiple sensors.
Innovation Solution
A system comprising a processor and multiple transceivers with a Dielectric Resonator Oscillator (DRO) and a Phase Locked Loop (PLL) component, along with a direct digital synthesizer (DDS), which provides stable frequency and low phase noise, allowing for centralized signal processing and coordinated sensor operation to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If frequency multiplication systems are used to generate MMW radar signals, then the radar can operate at higher frequencies, but phase noise increases significantly and modulation non-linearity is amplified
Solution Approach 1:
The frequency generation system is segmented into multiple stages: a stable reference oscillator (crystal oscillator) generates a low-phase-noise reference signal, which then feeds into a frequency synthesizer (PLL/DDS) that generates the final MMW signal. This segmentation allows each stage to optimize for its specific function, with the reference stage prioritizing stability and the synthesizer stage providing frequency flexibility without amplifying phase noise.
Solution Approach 2:
A phase-locked loop (PLL) or direct digital synthesizer (DDS) acts as an intermediary between the stable reference oscillator and the final MMW output. This intermediary device translates the stable, low-phase-noise reference frequency into the desired MMW frequency while maintaining low phase noise through precise frequency synthesis rather than multiplication, thereby mediating between stability requirements and frequency requirements.
2Reliability
If a directly modulated MMW VCO is used to avoid frequency multiplication, then phase noise is reduced, but the VCO becomes overly sensitive and non-linear due to circuit effects, temperature, and object movement
Solution Approach 1:
Instead of directly modulating a VCO, the system uses a phase-locked loop or direct digital synthesizer to generate the modulation signal, which then drives a clean VCO. The PLL/DDS acts as a buffer that copies the stable reference frequency characteristics while providing the necessary modulation, isolating the final VCO from direct modulation non-linearities and environmental sensitivities.
Solution Approach 2:
The phase-locked loop or direct digital synthesizer serves as an intermediary between the modulation source and the VCO. This intermediary provides a clean, stable frequency reference that drives the VCO through a controlled path, preventing direct modulation non-linearities from affecting the final output while maintaining phase noise performance.
3Adaptability or versatility
If multiple complete radar systems are added to provide distributed sensor functions, then coverage and functionality improve, but system complexity and cost increase significantly
Solution Approach 1:
A single centralized radar system is designed with universal functionality to perform multiple tasks that would traditionally require separate systems. The radar can detect, track, and classify various targets (vehicles, pedestrians, animals) and provide multiple functions (adaptive cruise control, anti-collision, parking assistance, marine threat detection) through a single integrated platform, eliminating the need for multiple dedicated radar systems.
Solution Approach 2:
The system merges previously separate radar functions into a single integrated platform. Multiple radar modules or antenna elements are combined within one system, sharing common signal processing, pulse generation, and data fusion capabilities. This consolidation reduces overall system complexity while maintaining distributed sensor coverage through multiple antenna elements or modules that communicate with a centralized processing unit.
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 achieves low-cost, low-phase-noise MMW radar sensors with accurate modulation, scalable for multiple sensors using a common control and signal processing system, reducing costs, power consumption, volume, and weight while maintaining performance.
Implementation Method 1
translating an operating frequency to Microwave or millimeterwave (MMW) range by mixing it with an 'open loop' oscillator that operates at MMW frequencies that offers frequency stability over time, temperature and vibration, such as a Dielectric Resonator Oscillator (DRO)
Implementation Method 2
The transceivers include receive and transmit electronics that are in signal communication with the corresponding antenna for outputting radar signals. The transmit electronics include a voltage controlled oscillator (VCO), a dielectric resonator oscillator (DRO), a phase locked loop (PLL) component and a direct digital synthesizer (DDS).
Implementation Method 3
The transmit electronics include a voltage controlled oscillator (VCO), a dielectric resonator oscillator (DRO), a phase locked loop (PLL) component and a direct digital synthesizer (DDS).
Implementation Method 4
The transmit electronics include a voltage controlled oscillator (VCO), a dielectric resonator oscillator (DRO), a phase locked loop (PLL) component and a direct digital synthesizer (DDS).
Implementation Method 5
The transceivers and/or antennas of the transceivers are located at various points around the vehicle. The transceivers include receive and transmit electronics that are in signal communication with the corresponding antenna for outputting radar signals.
Implementation Method 6
The receive electronics receive from the antenna any radar reflections corresponding to the outputted radar signals
Data Source
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AI summary
A radar sensor system and method for vehicles. An example radar system includes a processor (22), a plurality of transceivers having antcnna(c) (24). The antenna of the transceivers are located at various points around the vehicle. The transceivers include receive and transmit electronics that are in signal communication with the corresponding antenna. The transmit electronics output radar signals via the antenna. The transmit electronics include a voltage controlled oscillator (VCO), a dielectric resonator oscillator (DRO), a phase locked loop (PLL) component and a direct digital synthesizer (DDS). The receive electronics receive from the antenna any radar reflections corresponding to the outputted radar signals and send signals associated with the radar reflections to the processor. The processor generates output signals based on the signals received from the plurality of transceivers.