Transceiver Circuit Phase Ranging with Continuous Oscillator
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Solution Overview
Problem
Existing distance measurement techniques between transceivers, particularly those using non-zero intermediate frequency receivers, face challenges in accurately calculating distances due to issues like multipath fading and phase incoherency, especially in Bluetooth Low Energy and IoT applications.
Innovation Solution
The proposed solution involves a transceiver circuit with a frequency synthesizer that generates oscillator signals at different working frequencies for each signal exchange, allowing for phase-based ranging by continuously maintaining the oscillator frequency throughout multiple signal exchanges, and using non-zero intermediate frequency receivers to mitigate errors from DC offsets and 1/f noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-based ranging techniques are used with non-zero intermediate frequency receivers, then distance measurement accuracy is improved, but phase incoherency and multipath fading errors occur
Solution Approach 1:
The patent applies preliminary action by establishing and maintaining a continuous oscillator signal at a fixed frequency before initiating the ranging measurement. The frequency synthesizer is configured to generate this reference oscillator signal in advance, ensuring phase coherence is preserved from the start of the measurement process. This pre-established continuous signal serves as a stable reference against which the reflected signal can be compared, preventing phase incoherency issues.
Solution Approach 2:
The patent uses an intermediary approach by introducing a continuous oscillator signal as a mediator between the transmitted and reflected signals. This intermediary reference signal, generated by the frequency synthesizer, provides a stable phase reference that mediates the comparison between outgoing and incoming signals, thereby maintaining phase coherence and reducing measurement errors caused by multipath fading.
2Reliability
If frequency switching is performed between signal exchanges, then measurement robustness is improved, but oscillator frequency stability may be compromised
Solution Approach 1:
The patent applies segmentation by dividing the frequency operation into distinct segments: a stable continuous oscillator segment for reference and separate frequency switching segments for actual signal exchanges. The frequency synthesizer maintains a continuous stable oscillator signal while allowing controlled frequency switching only during specific measurement phases. This segmentation isolates the stability-critical reference signal from the potentially disruptive frequency changes.
Solution Approach 2:
The patent implements dynamics by making the oscillator frequency adaptive rather than static. The frequency synthesizer dynamically adjusts the oscillator frequency based on the measurement phase - maintaining stability during reference signal generation and allowing controlled switching during active signal exchanges. This dynamic approach enables the system to balance between frequency stability and measurement robustness by optimizing the frequency behavior for each operational phase.
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 enhances the accuracy and reliability of distance measurements by reducing errors related to multipath fading and phase incoherency, improving performance in environments where traditional methods fail.
Implementation Method 1
a frequency synthesizer configured to generate an oscillator signal
Implementation Method 2
down convert the first reflection signal to a first intermediate frequency signal
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
A transceiver circuit is disclosed. The transceiver circuit includes an antenna, a receiver RF chain configured to receive a receiver RF signal from the antenna, a transmitter RF chain configured to transmit a transmitter RF signal to the antenna, a frequency synthesizer configured to generate an oscillator signal, and a controller configured to: before causing the transmitter RF chain to transmit a first initiation signal, and, before causing the receiver RF chain to receive the first reflection signal, cause the frequency synthesizer to generate the oscillator signal at a first working frequency; cause the transmitter RF chain to transmit, at the first working frequency, the first initiation signal to the antenna, wherein the first initiation signal is part of a first signal exchange; cause the receiver RF chain to receive the first reflection signal from the antenna at the first working frequency, wherein the first reflection signal is part of the first signal exchange; down convert the first reflection signal to a first intermediate frequency signal at a non-zero intermediate frequency; after causing the transmitter RF chain to transmit the first initiation signal, and, after causing the receiver RF chain to receive the first reflection signal, cause the frequency synthesizer to generate the oscillator signal at a second working frequency, wherein the second working frequency is not equal to the first working frequency; cause the frequency synthesizer to continuously generate the oscillator signal at the first working frequency until the causing of the frequency synthesizer to generate the oscillator signal at the second working frequency; and determine a range estimate to another transceiver circuit based on a phase of the first initiation signal and on a phase of the first reflection signal.