Quality of the observations, which is significantly affected by cycle slips, is a key factor affecting the positioning results in the high precision positioning. Traditional observation data error detection algorithms always miss some special data error combinations, which is also called the ''blind detection spots'' problem. For solving the problem, a complementary symmetric geometry-free (CSGF) method is proposed, which makes the detection of cycle slips more comprehensive and accurate. However, when the observation sampling interval becomes larger, the channel state cannot be seen as a constant which reduces the successful detection probability of the cycle slips. Then, a CSGF second-order differential model is further proposed to deal with this problem. The experimental results show that the proposed model significantly improves the accuracy of cycle slip detection even with long sampling interval. The results also indicate that the accuracy and convergence speed of the positioning solution are significantly improved than other schemes. INDEX TERMS High precision positioning, cycle slips, blind detection spots, CSGF-SD.
Terahertz (THz) all-dielectric metasurfaces made of high-index and low-loss resonators have attracted more and more attention due to their versatile properties. However, the all-dielectric metasurfaces in THz suffer from limited bandwidth and low tunability. Meanwhile, they are usually fabricated on flat and rigid substrates, and consequently their applications are restricted. Here, a simple approach is proposed and experimentally demonstrated to obtain a flexible and tunable THz all-dielectric metasurface. In this metasurface, micro ceramic spheres (ZrO) are embedded in a ferroelectric (strontium titanate) / elastomer (polydimethylsiloxane) composite. It is shown that the Mie resonances in micro ceramic spheres can be thermally and reversibly tuned resulting from the temperature dependent permittivity of the ferroelectric / PDMS composite. This metasurface characterized by flexibility and tunability is expected to have a more extensive application in active THz devices.
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