Abstract
The determination of position in a radiolocation system based on time-of-flight (TOF) estimation is closely related to time measurements in the transmitting and receiving nodes. In theory, TOF can be determined from the time of the transmission at the transmitting node and the time of reception at the receiving node. Such a concept implies that the clocks in the nodes are synchronized in time, and thus clearly the accuracy of range measurements is directly related to the accuracy of time synchronization. Such time synchronization can in turn be achieved by a node with a reference clock transmitting a signal which can be received by all the other nodes in the network. As fixed nodes have known positions, the TOF can be inferred from the distance between the nodes, assuming straight-line radio propagation.
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Notes
- 1.
This timing accuracy is based on a 10Â MHz radio bandwidth, high SNR (>40Â dB), and no multipath interference. The accuracy approximately scales inversely with the bandwidth.
- 2.
A pseudorange is by definition the required range plus an arbitrary constant.
- 3.
There will be small transient effects such as people walking in the vicinity of the base station. Installing the base stations high above head level will minimise these transient effects.
- 4.
- 5.
The model also is applicable to the LOS case, but with the bias parameter set to zero.
- 6.
See Appendix A for an introduction to Kalman filtering.
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Sharp, I., Yu, K. (2019). Time and Frequency Synchronization. In: Wireless Positioning: Principles and Practice. Navigation: Science and Technology. Springer, Singapore. https://doi.org/10.1007/978-981-10-8791-2_5
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DOI: https://doi.org/10.1007/978-981-10-8791-2_5
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