I’m new to IoT and TTN but I have set myself a big challenge for fun. I’m planning to build a model boat which will (hopefully!) go around the world.
The plan is to have a solar panel on the top and have it controlled by an internal Rasp Pi.
I thought it would be fun to be able to track it’s progress but the usual method of doing this through satellite communication is expensive and battery intensive.
My next thought is to search out open Lora Gateways as it travels around the world. If it finds one, it can check in, if not it caches the data locally until it can find a gateway and the it uploads the historic data too.
I guess my question is, do you think this is an option? I’ve read that Lora can reach 100’s of KM with line of sight, so there is a good chance that the signal will get far enough out to see for the boat to check in at some point.
I’ve never used Lora, or had a model boat before so any thoughts, ideas or suggestions would be greatly appreciated!
Yes, but thats when the transmitter is often at high altitude, several kms.
With the height of an antenna on a model boat at sea you might not get very far at all. To get even a few kms at sea you going to need gateways on very tall buildings close to the coast. Unfortunatly the Earth is very bendy.
There is also the very significant issue that the settings and frequency plans for TTN Gateways vary depending on where you are in the World, so some form of geofencing capabity is needed. And for the different frequency bands you would really need a sepearte LoRa module (and antenna) for each band.
Thanks for your response. I love your comment that the Earth is very bendy. You are right! No Flat Earthers here!
Please forgive my ignorant persistence…
From what you are saying the best I would expect is about a few km from a gateway if it was in the top of a building on the coast? I wonder if that’s worth the risk. The boat might come into range at some point.
With regards the frequency of the gateways, I had thought there may be an issue. I did notice that this Grove Lora module was capable of communicating on both the EU and US frequency so maybe this would overcome this issue?
I realise I may be clutching at straws here, but I’m trying to build this project on a tight budget and the jump from Lora up to satellite for hardware and comms costs is huge.
We have people sending High Altitude Balloons around the world trying to use LoRaWAN and making progress on each launch, so I guess one question is how many boats do you want to send out before you get the comms working reliably.
If you look at the maps of the gateways (home page of TTN plus http://ttnmapper.org) you’ll see that there is a lot of blue and only a few dots in some places.
Yes, I guess you are right - lots and lots of blue!
I’m slowly coming to the realisation that this projected is either going to turn in to a fun thought experiment or become significantly more expensive that I first anticipated!
Thanks for your input - back to the drawing board for me!
The advantage of satellite systems is that they work.
Most of the 868\915 modules will actually work on either frequency, but at reduced efficiency and range.
I would expect that you will only get contacts when within 2km to 5km of the coast, and only when there is a Gateway in that area. In a lot of places in the World there wont be a gateway in range.
Yes, the satellite would be best for a constant regular update.
I’m just trying to weigh up the risk of sending something out with only Lora in the hope that it might come into contact with a gateway at some point and be in range long enough to upload the historic cached data. I’m not really bothered about getting regular updates, I’d just like to see where it has been and maybe some other interesting info, but it’s pointless sending it out if I’m not going to get any updates at all. Writing the data locally while out of range then uploading when in range would be fine. I also have to consider that I don’t really want the boat to get too close to the shore in case it runs aground.
Having said all this, I haven’t a clue how I will even code the navigation system as the project is still in the very early information gathering stages!
Thanks again for your thoughts, it is really useful to get an expert opinion.
There is a formula about Line of sight calculation and if you add “1m” into it the reachable LOS is 3,6km. Not too much. Thats why ssailboats have the VHF antenna at the top of the mast ;-). So only baloon coverage or very close to land will help you transmitting your data unfortunately.
The situation is better than 1m. There maybe gateways on tall buildings near the coast, line of sight from the sea surface to a 100M tall building is ~36km. For example if one got within (say) 20km of New York I suspect there might be a reasonable chance of making a connection. You could plan your route to pass near big cities and/or known gateways on mountains etc.
If there is even a small swell near the craft then even that 1m may get lost! Plan on average height as 0m to allow for fact some time will be spent in troughs between wave peaks Then retry the formulae…(Obviously in heavy swell if craft at wave peak then you ‘may’ get suprisingly good range - but dont plan on it! )
Won’t the onboard accelerometer mean the uplink will occur at the bottom of the trough.
This is all rather academic as coverage along the coast for most of the world is non-existent and duty-cycle / FUP isn’t going to allow much in the way of catch up on data.
Would be better to put in an HF transmitter on morse …
Thanks so much for all your thoughts and feedback, it’s great to see that my question has sparked an interesting conversation and I appreciate all the responses.
They have given me a lot to think about. Maybe satellite comms with Lora backup.
I do like the idea of tracking the position on the wave and transmitting at the maximum height! I have yet to figure out the navigation system, how to track waypoints and avoid landfall, so this will add to my code requirements.
If you want a small vessel to roam the seven seas I’d image it carrying an AIS transceiver to stay clear of big vessels. Such an AIS transceiver would also broadcast your boats position to surrounding vessels, but this signal is also picked up by satellites and the position can be watched for free on many vessel trackers. See Automatic Identification System on Wikipedia (no link as my user is to new)
That’s a great idea which I didn’t know about, thanks!
I was aware of the AIS transceivers, but I wasn’t going to bother installing one in my boat since it will be under the minimum size requirement to necessitate one. I wasn’t aware that I would be able to do free satellite tracking if I did install one! I definitely need to do more reading into this hardware and how it would connect into the other devices in my boat.
I really appreciate you taking the time to have a Google about it for me and for providing the links. They were very interesting and have giving me lots of information about tracking my boat.
I still think it would be a good idea to install a Lora module due to it’s low cost and low power requirements and it would be a backup for gathering data from my boat and as you say I could plot costal gateways.
No one said that. Re-read the post, it was “the position can be watched for free on many vessel trackers”, you should find out if getting the signal through the receiver network is free before you embark on any great voyages.
Then retry the formulae…(Obviously in heavy swell if craft at wave peak then you ‘may’ get suprisingly good range - but dont plan on it! 
)
Detect the moment of near weightlessness/highest -ve G force and Tx immediately?! 
