Beacons
Beacons receive Tag ID’s, transmitted by UHF signal, and then transmit that data back to the PC at Central Office via RS485 serial protocol. The data can be transmitted by a range of data links, such as conventional copper data cable (twisted pairs), fiber optic cable and radio modems. A combination of links may be integrated to carry both up-stream and down-stream data.
The Beacon enclosure (figure right) is made of 1.6mm stainless steel and protected against water and dust (IP66). Beacons require a 12 - 28V DC supply, and use a stubby quarter wave monopole antenna, attached by TNC connector. Three LED indicators, clearly visible from the front panel, display operational status.
A flashing red light (1 flash per sec.) indicates a HEARTBEAT, the presence of oscillations of the crystal oscillator on the beacon’s PCB (i.e. the Beacon is ‘alive’). Flashing yellow light represents a TAG READ, indicating that the beacon has received a signal from one or more Tags. And the flashing green light for COMMUNICATION indicates that the beacon’s stored data has been transmitted to the Central Office PC on its request.
TRACKER beacons can, as a minimum, reliably record 10 tags moving past in a vehicle at 40 km/h, and significantly more moving at lesser speeds.