RTLS Signal Spectrum
Real-Time Location Systems (RTLS) leverage a variety of signal types across the electromagnetic spectrum to accurately track and locate objects or individuals within a defined space. The choice of signal directly impacts the system’s accuracy, reliability, and applicability to different environments. The diagram below is an overview of the RTLS signal spectrum, highlighting the characteristics and applications of various signal types used in RTLS technologies.
Wide Range RTLS Signal Technologies
The RTLS signal spectrum encompasses a wide range of technologies, each with its strengths and limitations. Understanding these can help organizations select the most appropriate RTLS solution for their specific needs, balancing accuracy, cost, and environmental considerations to achieve optimal tracking performance.
- Power Spectral Density (PSD): Represents how power is distributed with frequency in a signal. In wireless communications, it helps identify the bandwidth and power level of different technologies.
- Noise Floor: The level of background noise in a system without any intentional transmission. It sets the baseline below which a signal cannot be detected.
- FCC Limit: Regulatory limits set by the FCC to prevent interference between different communication systems. These limits define the maximum power levels across the frequency spectrum.
Signal Technologies Frequencies
- GPS: Operates in the L1 (1575.42 MHz) and L2 (1227.60 MHz) bands with very narrow bandwidths. GPS signals are typically below the noise floor and require sophisticated receivers to decode effectively.
- PCS: Utilizes frequencies in the 1850 to 1990 MHz range. PCS bands are allocated for cellular phone systems in North America and are characterized by higher power levels to ensure reliable communication.
- Bluetooth: Operates in the 2.4 GHz ISM band, with a relatively low power level and narrow bandwidth. Bluetooth’s PSD is designed to minimize interference with other devices in the same band.
- WiFi (IEEE 802.11b): Also in the 2.4 GHz ISM band, WiFi signals have higher power levels and wider bandwidths than Bluetooth to support higher data rates. The PSD shows distinct peaks for each channel used by WiFi.
- UWB Spectrum: Spans a wide range of frequencies, typically from 3.1 to 10.6 GHz, with very low power spectral density. This allows UWB to coexist with other signals without causing interference, as indicated by its PSD spread across a broad spectrum.
In the above diagram, each technology’s signal is plotted as a function of frequency versus power. The Noise Floor is a baseline with a constant value across frequencies. The FCC limit is a cap, indicating the maximum allowed power spectral density for each band.
RTLS in Healthcare
To learn more and compare Real-time Location Systems in Healthcare settings read our article about various real-time location system options.