I am working in a project with a fleet of several fishing boats. I am measuring their locations with a GPS module and some other data with a set of sensors and a micro-controller. I would like to send this data in real-time over a radio frequency link to mainland.
- Ships could be located far away, around 100-400km.
- There is no GSM coverage.
- Satellite link should not be used.
I have evaluated using Xbee modules, however they are limited to line of sight and power limitations.
I have read that working in the MF/HF band, long ranges may be reached, specially using skywave propagation, in which the wave reflects with ionosphere. However I can not find commercial OEM modules on this frequencies to integrate with a micro-controller.
- Max distance for a ship from the coast is 80 nautical miles (148 km).
I was reading about sending digital data through VHF radios using APRS. According to Wikipedia:
Automatic Packet Reporting System (APRS) is an amateur radio-based system for real time digital communications of information of immediate value in the local area. Data can include GPS coordinates, weather station telemetry, text messages, announcements, queries, and other telemetry.
APRS uses 2m amateur band (142-148 MHz), which means that commercial amateur radios can be used after converting digital signals to audio tones by a Terminal Node Controller (TNC).
Do you think these distances can be achieved using APRS with handheld VHF radios?.