Proof of Concept Achieved !!

A project log for Long Range Machine Control System

LoRa + ROS Full Duplex Peer to Peer Data Transceiver Array with Onboard High Precision Satellite Positioning

Capt. Flatus O'FlahertyCapt. Flatus O'Flaherty 08/01/2022 at 20:550 Comments

Yay ..... The system now has four LoRa modules sending data to another set of four modules in parallel!

In the previous update I had one module working at a spreading factor (SF) of 7 and bandwidth of 500 KHz transmitting every 5 seconds or so. Now I managed to ramp up the SF to 9 and pull down the bandwidth to 125 KHz, with a similar transmit time. Strangely, no parallel programming was required, even though the modules themselves run in parallel, which is a bit counter-intuitive. During testing, other than actually getting a GPS 'Fix',  I developed some simple indicators to check that the data was coherent such as detecting non - standard characters, checking for missing data chunks and measuring the time taken to transmit each chunk. The sleep time in the python script that performed the task of breaking the data down into chunks set the overall rate of the whole system and was simply the time recorded for each transmit divided by four. Having plenty of Blinkenlights available was useful and red LEDs were flashed on the receiver side every time a data chunk was missed - which was thankfully very rare!

The whole system could now be scaled up to get the maximum perfermance out of the LoRa modules ie a SF of 12 and this would required about 32 x 2 modules (SF 9 = 4 modules, SF 10 = 8 modules, SF 11 = 16 modules, SF 12 = 32 modules). However, it's getting to be expensive and for the time being tests out in the wild can be done with the current 2 x 4 set up. The next step is to sling the dog controller into a suitably sized enclosure and bolt it onto one of my robots ...... Hmmmmmn ..... which one will I choose ??