DDS-PLL Radar Synthesizer for Coherent Multi-Band Operation
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Solution Overview
Problem
Current radar systems are expensive and complex, often requiring a large number of semiconductor parts, making them costly and difficult to manufacture, while also lacking agility in operating across multiple frequency bands.
Innovation Solution
The use of direct digital synthesizer (DDS) circuitry driving phase-locked loop (PLL) circuitry to generate sinusoidal signals for both transmitter and receiver circuitry, allowing for the construction of radar systems that can operate in S-band and X-band frequencies with fewer and lower-cost components, utilizing a single clock source for increased coherence and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional radar systems use multiple independent oscillators and complex semiconductor parts, then they can achieve stable frequency generation, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent merges the transmitter oscillator and receiver local oscillator into a single phase-locked loop (PLL) system. The PLL generates a common output frequency that is distributed to both the transmitter circuitry and receiver circuitry, eliminating the need for separate oscillators. This consolidation reduces the number of semiconductor parts while maintaining frequency stability through the PLL's inherent feedback control mechanism.
Solution Approach 2:
The single PLL circuit serves multiple functions simultaneously: it generates the carrier frequency for transmission, provides the local oscillator signal for reception, and ensures frequency coherence between transmit and receive paths. This multi-functional approach replaces what traditionally required multiple dedicated oscillators, simplifying the overall system architecture.
2Adaptability or versatility
If radar systems are designed to operate in multiple frequency bands (S-band and X-band), then versatility is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs a dynamically reconfigurable PLL system where the division ratio and feedback path can be changed to operate at different frequency bands. By modifying the PLL configuration (such as changing the feedback divider value or switching feedback paths), the same basic circuit architecture can generate frequencies suitable for both S-band and X-band operations, eliminating the need for completely separate oscillator systems for each band.
Solution Approach 2:
The system achieves multi-band operation by changing key parameters of the PLL circuit, particularly the feedback division ratio and reference frequency. These parameter adjustments allow the same hardware architecture to generate different output frequencies, enabling the radar to switch between S-band and X-band modes without requiring fundamentally different circuit designs.
3Ease of operation
If separate oscillators are used for transmitter and receiver, then frequency independence is achieved, but measurement precision of Doppler effect deteriorates
Solution Approach 1:
The PLL incorporates a feedback mechanism that continuously monitors and corrects the output frequency to maintain precise locking to the reference. This feedback control ensures that the single oscillator provides coherent frequency references to both transmitter and receiver, enabling accurate Doppler measurements by eliminating frequency drift between separate oscillators while the PLL maintains the necessary frequency relationships.
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 approach enables the creation of high-performance radar systems at a lower cost, with reduced component count, capable of operating in multiple frequency bands, while maintaining performance comparable to more expensive systems, and improving the measurement of the Doppler effect for velocity determination.
Implementation Method 1
The DDS circuitry may be configured to deliver the DDS signal to drive phase-locked loop (PLL) circuitry of the synthesizer to generate a sinusoidal signal
Implementation Method 2
The frequency of the return signal is based on the velocity of the object because of the Doppler effect. The radar system may determine the change in frequency due to the Doppler effect by comparing the frequency of the return signal to the frequency of the radar signal
Data Source
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AI summary
In some examples, a radar system includes first direct digital synthesizer (DDS) circuitry and first phase-locked loop (PLL) circuitry configured to generate a first sinusoidal signal based on a first DDS signal generated by the first DDS circuitry. In some examples, the radar system further includes transmitter circuitry configured to generate a radar signal based on the first sinusoidal signal. In some examples, the radar system also includes one or more antennas configured to transmit the radar signal and receive a return signal based on the radar signal. In some examples, the radar system includes second DDS circuitry, second PLL circuitry configured to generate a second sinusoidal signal based on a second DDS signal generated by the second DDS circuitry, and receiver circuitry configured to process the return signal based on the second sinusoidal signal.