UWB Reader Clock Synchronization Using Master Pulse Time Slots
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Solution Overview
Problem
Real-time Ultra-Wide Band (UWB) locating systems face challenges in achieving precise synchronization among readers, which is critical for accurate location tracking but requires a simple, versatile, and cost-effective method.
Innovation Solution
The system employs a master UWB reader that transmits UWB pulses with a precise timing, allowing slave readers to adjust their clocks based on the received pulses, using techniques like CDMA or CSMA-CA, and utilizing software-based synchronization protocols like IEEE 1588 PTP or NTP for coarse synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional synchronization methods are used, then synchronization accuracy may be sufficient, but additional hardware resources and increased system complexity are required
Solution Approach 1:
The system enables readers to automatically synchronize their clocks using UWB pulses transmitted by a master reader. Each reader independently adjusts its own clock based on received pulses, eliminating the need for external synchronization hardware or centralized control mechanisms.
Solution Approach 2:
UWB pulses serve as an intermediary carrier for synchronization information. The master reader embeds timing information in UWB pulses, which slave readers receive and use to adjust their clocks, thereby transferring synchronization data through the existing communication medium without additional hardware.
2Measurement precision
If precise synchronization is achieved through complex methods, then location tracking accuracy improves, but system cost and complexity increase
Solution Approach 1:
The UWB pulse transmission system performs multiple functions: it simultaneously enables communication between readers and tags, and provides synchronization among readers. This multi-functionality eliminates the need for separate synchronization hardware or protocols, reducing system complexity while maintaining high location tracking accuracy.
Solution Approach 2:
The patent combines the synchronization function with the existing UWB communication function. Instead of implementing synchronization as a separate subsystem, it merges timing adjustment capabilities into the regular pulse transmission and reception process, thereby achieving precise location tracking without increasing overall system complexity.
3Reliability
If UWB pulses are transmitted with high power, then signal detection improves, but interference with other RF services increases
Solution Approach 1:
The system changes the power spectral density parameter of the transmitted signal by using ultra-wideband pulses with very short duration. This spreads the transmitted power over a very wide frequency range, resulting in extremely low power spectral density at any individual frequency, thereby enabling reliable signal detection without interfering with narrowband RF services.
Solution Approach 2:
The system uses periodic transmission of ultra-short UWB pulses instead of continuous wave transmission. This pulsed transmission pattern, combined with the wide bandwidth of each pulse, allows the signal to achieve sufficient detection reliability through time-energy concentration while maintaining low average power spectral density that does not interfere with other RF services.
Data Source
AI summary
In a UWB real time locating system, UWB readers (12) are synchronized by adjusting a clock of a UWB slave reader (12) until the UWB reader (12) receives each UWB pulse (34) of a sequence of UWB pulses (34) having a predetermined pulse period (Tp) and encoding a master UWB reader unique identifier at an expected time slot (35) within each predetermined pulse period (Tp), the expected time slot (35) being related to the distance between the UWB tag reader (12) and a master UWB reader (12).