Radio Network Range Finding Circuit Using Phase Measurement
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Solution Overview
Problem
Existing radio network communication methods, particularly those conforming to the IEEE 802.15.4 standard, face challenges in simultaneous transmission and reception and accurate range finding between nodes, which is essential for fault detection and movement tracking, due to limitations in multipath propagation and frequency synchronization.
Innovation Solution
A method and circuit for radio network nodes that initiate range finding by transmitting a Ranging Request Command, switching into a range finding mode, and using multiple frequency changes to measure phase values, allowing for accurate distance calculation while accounting for multipath propagation, with synchronized time windows and frequency adjustments to enhance precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transceiver conforms to IEEE 802.15.4 standard, then it can operate in radio networks with standardized communication, but it cannot simultaneously transmit and receive signals
Solution Approach 1:
The patent segments the communication process into distinct time slots: measurement slots for phase measurement and data slots for data transmission. This temporal segmentation allows the transceiver to alternate between receiving and transmitting modes, resolving the contradiction between standard compliance and simultaneous transmit-receive capability.
Solution Approach 2:
The patent implements dynamic slot allocation where the transceiver can switch between different operational modes (measurement mode and data mode) based on the current time slot. This dynamic behavior enables the system to overcome the static limitation of IEEE 802.15.4 transceivers that cannot simultaneously transmit and receive.
2Measurement precision
If phase measurement is performed for multiple frequencies to account for multipath propagation, then distance measurement precision is improved, but measurement time and complexity increase
Solution Approach 1:
The patent uses periodic phase measurements at multiple frequencies within structured time slots. By periodically switching between frequencies and using the periodic nature of sinusoidal signals, the system can extract distance information from phase differences while managing the time required for measurements.
Solution Approach 2:
The patent implements a feedback mechanism where phase measurement results from multiple frequencies are combined and processed to calculate distance. The system uses the phase differences obtained from different frequencies as feedback to resolve ambiguities and improve measurement precision, while the feedback loop manages the overall measurement time.
3Measurement precision
If frequency hopping is used to measure phase offset for multiple frequencies, then measurement accuracy is improved, but synchronization complexity increases
Solution Approach 1:
The patent introduces a synchronization protocol as an intermediary mechanism that coordinates frequency hopping between transmitter and receiver. This intermediary synchronization system manages the complexity by establishing clear rules for frequency switching and phase reference establishment, enabling accurate phase offset measurement without overwhelming synchronization complexity.
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 enables precise distance measurement and improved communication efficiency between nodes, reducing interference and enhancing the ability to track movements and detect faulty nodes within the radio network, while maintaining compliance with the IEEE 802.15.4 standard.
Implementation Method 1
the frequency is changed by frequency hopping in order to measure a phase offset for multiple different frequencies
Implementation Method 2
the phase locked loop is closed during reception and opened during transmission so that the receive signal and transmit signal have the same frequency. The phase of the local oscillator signal of the voltage controlled crystal oscillator is coherent with the received signal due to the synchronization by means of the PLL
Data Source
AI summary
A first node of a radio network initiates a mode for finding the range to a second node. The first node transmits to the second node, with the address of the second node, a range finding command, which switches the second node into the range finding mode and controls a sequence. The first node transmits in a transmission time window a first signal, which is received by the second node in an associated reception time window, a first phase value of the first signal being measured. The second node transmits in a transmission time window a second signal, which is received by the first node in an associated reception time window, a second phase value of the second signal being measured. The first frequency is changed by a frequency difference and the second frequency is changed by the frequency difference in a subsequent time window of the sequence.