We’ve set up a number of gateways in our city, we have a GPS black box that sends it’s location over LoRa (ABP) and we’re trying to figure out just how far our coverage is able to reach.
What would be the best spreading factor and bandwidth settings for a node attached to the roof of a moving (50~70km/h) vehicle?
Suggest you read this;
Experimental Study of LoRa ModulationImmunity to Doppler Effect
And you will likley conclude there are no ‘best’ settings.
Of course at SF7 you can send the location packet more often, but it wont go as far as SF12.
Do appreciate that TTN is hardly ideal for tracking vehicles, you should perhaps assume that you will be sending at SF12 and thus fair access rules would limit you to say 20-25 location packets a day.
Why are you asking about changing the bandwidth, in most cases this is set at 125Khz by the gateway software ?
The limitation on the number of packets is less severe for a paid TTI account, however it is still 2-3 minutes between packets at SF12. If it is sufficient for your application, I would go for SF12 or SF11 at most. SF11 would cover your speed needs, but in my experience ‘most’ of times also SF12 manages such speeds. In any case, be ready to accept packet losses at any SF.