Messages posted by: srnet

To test the long distance capability of the new LoRa transceivers the HABAXE2 Pico balloon tracker was designed, it and the receiver used an RFM98.

Pico trackers are often launched using just a 36” foil party balloon filled with Helium. Filled to the correct level, they will rise to around 8000M and float along at that altitude. The radio horizon at that altitude is 370KM, so you can expect line of sight conditions to this distance. In the UK we normally use FSK RTTY to report back on the tracker positions.

HABAXE2 was launched in January 2015, from Caerphilly Common, near Cardiff, UK. The tracker was last heard of just short of the Mediterranean coast having travelled just over 1000km.

The tracker had software that allowed requests to be sent to the balloon tracker, via LoRa of course, such that it would respond with a series of packets at a particular mode.
The receiving antenna was a 6dB gain vertical, the tracker antenna a 1/4 wave vertical.

Some results of tests were;

BW500Khz, SF7, CR4:8 (13700bps) packets at 7dbm/5mW received at 105KM
BW41.7khz, SF12, CR4:5 (98bps) packets at 2dbm/3mW received at 242KM
BW41.7khz, SF8, CR4:5 (1042bps) packets at 10dBm/10mW received at 269KM.

To give a more practical guide, if a power of 10dBm/10mW was used with simple ¼ wave wire antennas at each end, the expected range would be;

BW500Khz, SF7, CR4:8 (13700bps) = 74KM
BW41.7khz, SF12, CR4:5 (98bps) = 303KM
BW41.7khz, SF8, CR4:5 (1042bps) = 135KM