Anchor

A fixed-position reference device with known coordinates that receives signals from mobile tags to determine positions. Forms the foundational infrastructure by establishing the coordinate system for tracking. Typically requires 4+ anchors for 2D positioning, optimally positioned in corners or elevated locations. Placement, density, and synchronization significantly impact system performance.

Fixed infrastructure device in positioning systems that serves as a reference point with known coordinates. In UWB RTLS specifically, anchors are synchronized receivers that measure signal arrival times from tags to calculate positions.

Typical industrial UWB anchors measure 15x15x5 cm, consume 5-12W power, and support 50-200 tag updates per second depending on configuration. Anchor placement requires clear line-of-sight to tags when possible, with typical mounting height of 3-6 meters on walls or columns. Each anchor covers 30-50 meter radius in industrial environments (less with obstacles). Minimum 4 anchors required for 3D positioning, 3 for 2D. Higher anchor density (6-10 per zone) improves accuracy through redundancy and better geometry. Cost typically $500-1500 per anchor unit. In BLE RTLS, the equivalent infrastructure device is called a gateway or scanner (cost $50-500, covering 20-50 meter radius, requiring no time synchronization). GNSS-based systems require no fixed anchors indoors but rely on satellite infrastructure outdoors, transitioning to anchor-based indoor systems at building boundaries in hybrid deployments.