Adaptive Radar System Waveform Selection
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Solution Overview
Problem
Conventional radar level gauges in large storage tanks face accuracy issues due to multiple reflections and power limitations, leading to measurement uncertainty and errors, especially at longer distances and with products having low dielectric constants, and are restricted by regulatory power limits.
Innovation Solution
Adaptive multi-waveform radar systems with programmable transmitters and receivers that dynamically adjust power and waveform types to maintain high signal-to-noise ratio (SNR) and accuracy over long ranges, using waveforms like pulsed CW, LFM, SFCW, and FMCW, and incorporating power limiters to protect the receiver from saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high radar transmit power is used to improve measurement accuracy and extending measuring distance, then measurement accuracy and range are improved, but spectrum interference to other devices occurs and regulatory restrictions are violated
Solution Approach 1:
The radar system dynamically adjusts transmit power based on measured distance to the product surface. At longer distances, higher power is used to maintain signal-to-noise ratio, while at shorter distances power is reduced to avoid interference. This dynamic adaptation allows the system to maintain measurement accuracy across varying ranges while complying with regulatory power restrictions in different operating conditions.
2Object-affected harmful factors
If reduced radar transmit power is used to comply with regulatory restrictions, then spectrum interference is reduced, but measuring distance and signal-to-noise ratio are reduced
Solution Approach 1:
The system changes multiple parameters simultaneously to maintain measurement reliability under power restrictions: it adjusts waveform type (e.g., using FMCW or LFM waveforms with better processing gain), modifies pulse width, and applies signal processing techniques. These parameter changes allow the radar to achieve acceptable measurement reliability even with reduced transmit power by optimizing the overall signal detection capability.
3Measurement precision
If ultra-short radar pulses are used to improve measurement accuracy, then time resolution is improved, but power and measuring distance are reduced
Solution Approach 1:
The radar system uses periodic pulsed transmission with optimized pulse repetition frequency. By carefully selecting the pulse width and repetition rate, the system achieves sufficient time resolution for accurate level measurement while allowing adequate time for signal integration between pulses. This periodic action enables the accumulation of signal energy over multiple pulses, effectively increasing the average power without exceeding peak power limits.
4Length of stationary object
If longer pulse duration is used to increase power and measuring distance, then measuring distance is extended, but time resolution and measurement accuracy are degraded
Solution Approach 1:
The radar system segments the long pulse into multiple sub-pulses or uses chirp modulation (frequency modulation across the pulse duration). This segmentation allows the total pulse energy to be distributed over time in a structured way that maintains time resolution through correlation processing. The segmented structure enables long measuring distance while preserving the ability to resolve small time differences through signal processing of the segmented components.
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
The system achieves accurate level measurements with an SNR of at least 25 dB, ensuring reliable distance measurement and reducing errors, even at 100 meters, with improved reliability and accuracy across varying dielectric constants and power constraints.
Implementation Method 1
a transmitter coupled to a radar antenna which is positioned above the product (e.g., a liquid or solid) for emitting radar signals to the product
Implementation Method 2
The object or surface reflects part of the emitted radar signal/wave back in the direction of the antenna, which is received
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A pulsed radar method of sensing or measuring a product material in a storage tank. A plurality of waveform types are automatically selected based on a power limitation. The pulsed radar signal is transmitted by a programmable transmitter (190) to the product material, wherein the pulsed radar signal is reflected or scattered by the product material to provide a radar signal during an interval of time including a target signal. An initial gain or attenuation is automatically set for a programmable receiver (150). The programmable receiver receives the radar signal including the target signal during the interval of time, and the target signal is signal processed using a lower attenuation setting as compared to the initial gain or attenuation to determine at least one parameter associated with the product material. The transmitted and received radar signal can also be adjusted according to the measured SNR.