To enhance the performance of location estimation in wireless positioning systems. the geometric dilution of precision (GDOP) is widely used as a criterion for selecting measurement units. Since GDOP represents the geometric effect on the relationship between measurement error and positioning determination error. the smallest GDOP of the measurement unit subset is usually chosen for p... https://www.roneverhart.com/Western-Digital-Ultrastar-DC-HC570-WUH722222ALE6L1-22TB-7-2K-RPM-SATA-6Gb-s-512e-SED-3-5in-Recertified-Hard-Drive/