Adaptive ADC Sampling in Ranging Receivers for Lower Power
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Solution Overview
Problem
Existing active ranging systems face high power consumption due to high sampling rates required for long-range signal returns, which often digitize noise rather than useful signal, leading to increased power consumption and reduced battery life.
Innovation Solution
Implementing a ranging receiver with a time-variant sampling rate that increases when a return signal is detected and decreases as a function of time, using a comparator with a time-variant threshold and hysteresis to maintain the sampling rate, thereby reducing noise sampling and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high sampling rate is used to achieve high range resolution, then timing uncertainty is reduced, but power consumption increases due to digitizing noise at high data rate
Solution Approach 1:
The patent applies dynamics by making the ADC sampling rate variable rather than fixed. The sampling rate dynamically adjusts based on the detected signal strength and timing information. When a weak return signal is detected, the sampling rate increases to improve range resolution. When no signal is present, the sampling rate decreases to reduce power consumption. This dynamic adaptation resolves the contradiction between maintaining high measurement precision and reducing energy usage.
Solution Approach 2:
The patent changes the sampling rate parameter based on signal detection conditions. The system monitors the received signal strength and adjusts the ADC sampling rate accordingly. By changing this critical parameter dynamically, the system achieves high range resolution only when necessary (when signals are present) while consuming less power during idle periods, thus resolving the trade-off between measurement precision and power consumption.
2Measurement precision
If a high sampling rate is maintained for long-range signal returns, then timing uncertainty is reduced, but noise is digitized at high data rate increasing power consumption
Solution Approach 1:
The system dynamically adjusts the sampling rate based on the presence and strength of detected signals. When weak return signals from long-range objects are detected, the sampling rate increases to reduce timing uncertainty. When no signals are detected, the sampling rate decreases to minimize energy loss from digitizing noise. This dynamic behavior resolves the contradiction between maintaining timing precision and reducing energy waste.
Solution Approach 2:
The ranging receiver monitors its own received signal conditions and automatically adjusts its sampling rate accordingly. The system uses its detected signal strength information to control its own ADC operation, making self-service adjustments that optimize the balance between timing uncertainty and power consumption without external intervention.
3Reliability
If the sampling rate is increased to detect weak return signals, then detection capability is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic sampling rate adjustment where the ADC operates at high sampling rates only when weak return signals are detected, improving detection capability at those moments. During periods without detected signals, the sampling rate drops to low values, significantly reducing power consumption. This dynamic adaptation resolves the contradiction between maintaining high reliability for detecting weak signals and minimizing overall energy usage.
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 reduces power consumption, improves battery life, and enhances the ability to detect weak return signals without compromising range resolution, making it suitable for applications like LiDAR, sonar, and radar systems.
Implementation Method 1
an ADC, with a time-variant sampling rate, that converts the return signal from an analog domain to a digital domain
Implementation Method 2
a comparator having a time-variant threshold. This comparator may selectively change the sampling rate based at least in part on a comparison of a detection signal corresponding to the return signal and the time-variant threshold
Implementation Method 3
a matched filter that performs a correlation of the return signal and a target signal, and to provide the detection signal
Implementation Method 4
the comparator includes hysteresis and, after the sampling rate is increased to a higher sampling rate, the comparator may maintain the higher sampling rate for a time interval corresponding to the transmit signal
Data Source
AI summary
An integrated circuit may include a ranging receiver that includes an analog-to-digital converter (ADC) having a time-variant sampling or data rate. Notably, the sampling rate may be increased when a return signal is detected by the ranging receiver. For example, the return signal may be detected using a matched filter (such as a correlation of the return signal and a target signal) and a comparator having a time-variant threshold. The time-variant threshold may be decreased as a function of time after a transmit signal is output in order to track the channel response, such as a decrease in the return signal amplitude for objects at larger ranges. Alternatively or additionally, the sampling rate may be increased based at least in part on a predefined function (such as a closed-form expression or a stepwise function, e.g., a stairstep function) after the transmit signal is output.