Multichannel Time-of-Flight Measurement Using FPGA Delay Lines
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Solution Overview
Problem
Existing multi-beam measurement devices for three-dimensional geometric capture face challenges with complex and costly design requirements, high energy consumption, and the need for multiple ADCs and evaluation units due to the complexity of time-of-flight distance measurement.
Innovation Solution
The implementation of a multi-beam measurement device with a programmable integrated circuit (PIC) that includes parallel delay lines with hundreds or thousands of delay elements, allowing for precise time measurement through fine measurement techniques and statistical analysis of delay elements, thereby reducing design complexity and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple ADCs and evaluation units are used for multi-channel time-of-flight measurement, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple time measurement channels into a single integrated evaluation unit that processes signals from multiple detectors simultaneously. This consolidation eliminates the need for separate ADCs and evaluation units for each channel, reducing device complexity while maintaining measurement precision through parallel processing capabilities within the unified unit.
Solution Approach 2:
The evaluation unit is designed with universal functionality to handle time measurement tasks across multiple channels. It incorporates multiple time-to-digital converters and processing capabilities that can universally evaluate signals from different detectors, replacing the need for channel-specific dedicated evaluation units.
2Measurement precision
If multiple ADCs are used for multi-channel measurement, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
By merging multiple evaluation functions into a single integrated unit that operates in parallel, the system reduces the total energy consumption compared to having separate ADCs and evaluation units for each channel. The unified architecture shares common resources such as clock signals, power supply regulation, and processing logic, thereby reducing cumulative energy usage while maintaining precision.
3Productivity
If multiple channels are implemented without sequential reading, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent implements multiple measurement channels with parallel signal processing within a single integrated evaluation unit. This allows simultaneous evaluation of signals from multiple detectors without requiring separate evaluation units for each channel, thereby maintaining high productivity while avoiding the complexity increase that would result from fully parallel independent units.
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 enables precise distance measurement with relaxed design requirements, reduced energy consumption, and simplified packaging, while maintaining high measurement accuracy and efficiency.
Implementation Method 1
emitting pulsed electromagnetic radiation, such as e.g. laser light, at a target to be measured and subsequently receiving an echo from said target as backscattering object
Implementation Method 2
the round-trip time of an emitted light pulse towards a target and back corresponds to the distance between the measuring device and the target to be measured
Data Source
Figure 1
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AI summary
The invention relates to a multi-beam distance measuring device (1, 1'), configured for timing the time-of-flight of transmission pulses (16) by using a programmable integrated circuit (6), e.g. a field-programmable gate array (FPGA), which has a plurality of parallel delay lines (7). Each delay line (7) has a plurality of delay elements (22), which sequentially propagate an input signal (200) of the respective delay line (7), wherein each of the delay elements (22) is configured to provide a binary output as a function of the input signal (200). Time measurement of a signal change of a return signal (8) is carried out by sampling binary outputs of a respective delay line (7) and simultaneous consideration of the sampled binary outputs at a certain point in time, by further taking into account individual time delays of the delay elements (22). The measurement device (1, 1') further comprises a reference generator (11) configured to generate a reference signal (12) having a known reference signal change, wherein the reference signal (12) is asynchronous to a sampling clock (24) driving the sampling of the binary outputs. A selector (13) is used to alternatingly feed individual ones of the delay lines (7) with the reference signal (12) instead of a return signal (8). By carrying out a statistical analysis of the sampled binary outputs that correspond to the reference signal (12) that propagated through a delay line (7) individual time delays of the delay elements (22) of this delay line (7) are determined, which individual time delays are taken into in the time measurement of the signal change when the delay line (7) is fed with one of the return signals (8).