Multi-Frequency Range Estimation Using N-Dimensional Phase Space
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Solution Overview
Problem
Current range estimation methods using multi-frequency signals face limitations in unambiguous range and signal-to-noise ratio, especially over large distances, due to frequency differences and noise interference.
Innovation Solution
A method and device that transmit a multi-frequency signal comprising a primary and two secondary frequencies, determining phase differences in an N-dimensional phase space to select a candidate range estimate based on distance from unique associated points, thereby filtering out ambiguous estimates and improving signal-to-noise ratio without direct averaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single secondary frequency is used in multi-frequency ranging, then the system complexity is reduced, but the unambiguous range is limited to λ1 = c/2(f1 - f0)
Solution Approach 1:
The patent divides the frequency spectrum into multiple secondary frequencies (f1, f2, ..., fN) instead of using a single secondary frequency. Each frequency provides an independent phase measurement, and the combination of multiple measurements extends the unambiguous range beyond what any single frequency could achieve alone.
Solution Approach 2:
The patent transitions from one-dimensional range measurement (single frequency) to N-dimensional phase space measurement (multiple frequencies). By measuring phase differences across N different frequency pairs, the system creates an N-dimensional measurement space where the unambiguous range is extended to the least common multiple of individual unambiguous ranges.
2Length of stationary object
If the frequency difference between primary and secondary frequencies is decreased to increase unambiguous range, then the unambiguous range increases, but the range measurement becomes very noisy
Solution Approach 1:
The patent combines measurements from multiple frequency pairs to achieve both extended unambiguous range and improved measurement precision. By merging N independent phase measurements into a unified N-dimensional measurement vector, the system simultaneously extends the unambiguous range while averaging out noise through the combined information.
Solution Approach 2:
The patent changes the measurement parameters by using multiple frequency differences simultaneously rather than relying on a single frequency pair. This allows the system to select frequency combinations that provide both large unambiguous range and good signal-to-noise ratio, optimizing both parameters through parameter selection.
3Measurement precision
If the frequency difference between primary and secondary frequencies is increased to reduce noise, then the signal-to-noise ratio improves, but the unambiguous range decreases
Solution Approach 1:
The patent segments the frequency spectrum into multiple secondary frequencies with different frequency differences from the primary frequency. This allows the system to use frequency pairs with larger frequency differences (for better SNR) while combining multiple such measurements to recover the extended unambiguous range that would be lost with any single frequency pair.
4Length of stationary object
If multiple frequencies are used to extend unambiguous range, then the unambiguous range increases, but the device complexity increases due to filtering requirements
Solution Approach 1:
The patent employs a universal filtering approach where a single set of bandpass filters handles all frequency components (primary frequency f0 and all secondary frequencies f1, f2, ..., fN). This multi-functional filter bank simultaneously separates all frequency components needed for the N-dimensional phase measurement, reducing overall system complexity compared to having separate filtering paths for each frequency pair.
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 increases the unambiguous range and precision of range estimation while reducing the risk of selecting ambiguous ranges and enhancing signal-to-noise ratio by utilizing information from multiple phase differences.
Implementation Method 1
transmitting a first signal towards the object, wherein the first signal comprises at least a primary frequency (F0), a first frequency (F1), and a second frequency (F2); receiving a reflected echo signal reflected from the object comprising at least the primary frequency (F0'), the first frequency (F1'), and the second frequency (F2')
Implementation Method 2
determining a measured point (MP) in an N-dimensional phase space comprising at least a first phase coordinate representing the phase difference between the phase of the first frequency (F1') and the phase of the primary frequency (F0') in the received reflected echo signal
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3~4
AI summary
Disclosed is a method for estimating the range to an object, the method comprising: transmitting a first signal towards the object; receiving a reflected echo signal reflected from the object; and determining a measured point (MP) in an N-dimensional phase space. The range to the object is estimated by selecting a candidate range estimate from a plurality of candidate range estimates, each candidate range estimate in the unambiguous range R having an unique associated point in the N-dimensional phase space positioned on range lines, and wherein a candidate range estimate is selected dependent on the distance from its unique associated point in the N- dimensional phase space to the measured point (MP), so that a single range estimate is generated using information from at least two measured phase differences without directly averaging ambiguous range estimates.