Bluetooth® (BT) is positioned as a short-range technology for personal area networks (PANs). In recent field tests, however, a Laird Technologies® engineer was able to send data via BT at an impressive range of over 1,000 meters.
The test was done with a pair of production BISM2 PA modules mounted on development boards, one a static (fixed) board and the other a mobile board:
- Static: Attached to a tripod and elevated above the ground. Powered via USB from a laptop that also was connected to the module’s UART via an RS232 cable.
- Mobile: Placed in the top pocket of a rucksack with its antennas facing those of the static module. Powered by four AA batteries.
Connected to the development board of the mobile module was a Garmin® Geko 201 GPS, which output positioning data. That data was sent from the mobile module to the static module using BT. The static module’s development board used the Ezurio® Terminal app to capture the data and log it to a text file.
The test procedure was as follows:
- Establish a connection between the two BT modules.
- Ensure that GPS positioning data from the mobile module is received by the static module and displayed on the laptop screen.
- Move the mobile module away from the static module until data is no longer received by the static module.
- Save the log file.
- Convert it to a KML file.
- Load the KML file into Google Earth for evaluation.
The KML file showed that data sent from the mobile module was received by the static module at 1,150 meters.
The test was carried out in conditions that were close to ideal, with good line of sight, minimal Wi-Fi® interference, no obstructions, and a very low data rate. Even so, the test results indicate that BT can be more than a PAN technology.