dave-in-nj:
You can get a topographical map of your area and then plot out line of sight for your links,as for LoRa distance, Andreas Spiess (the guy with the Swiss Accent) set a world record at 212 Km by using a balloon.
The 212km was a ground to ground record, from some high hills to a remote LoRa gateway, no balloon involved.
The ground to high altitude balloon record is 702km.
Ok sorry for not answering sooner! So, as you guys have seen, La Romaine is a big project. I am not on the dam building team however. we are scientists sampling and monitoring water quality as dams are being built. The team requires to sample at the target location you saw on the map, for a few days, and the wind is ofter too strong for boat navigation. The point of the windsensor project is to tell us before we get there if we wont be able to use the boat. We then need the device to run for 12 days on the battery. Its not actually made for sampling, really for efficiency. The dam company doesnt have precise windspeed at the location we are interested in, and if it does, it is unable to send the information every morning before we leave! For the 12 days, if the device can tell us the windspeed next to the entrance we use for the boat 2 or 3 times every morning, it is perfect for its purpose
Does anybody in your team have a ham radio (amateur radio) license? If yes, then that's the way to go.
You can cover hundreds of km without problems.
Or you use CB radio - no license needed, but still ranges between 20 - 80km possible, depending on antenna size and position.
The information you need to transmit is VERY simple (wind okay / wind too strong)
Probably you don't need to bother with packet radio / data transmission.
A simple morse code signal will be fine: Transmission pulses every second -> wind okay.
Transmission pulses every 2 seconds -> wind too strong.
Or transmit more information:
Beaufort wind speed-> pulses per 10 s
This signal can be received anywhere in the region and be interpreted by any listener without decoding equipment.
For power supply, just use a good old 12V car battery, and replace it with a charged one every time you go there.
The arduino would operate the PTT button of the radio transmitter. You could set up the arduino to broadcast ever hour for 10 minutes, or every 10 minutes for 1 minute. Or let it broadcast all the time, if battery power allows.
If you want to get really fancy, then you can connect the arduino also to the receiver, and transmit a "request" signal, which prompts the arduino to start transmitting.
Ham radio requires a huge power supply when compared to LoRa, especially if you want it to transmit continuously instead of just a few bytes every 10 minutes or so (average wind speed of the past 10 mins).
Also a human can pick up a morse type signal as long as it's at the very least 3 db above the noise level. LoRa can work well below noise levels, so you need a much stronger signal.
hydrocontrol:
Does anybody in your team have a ham radio (amateur radio) license? If yes, then that's the way to go.
You need to check the legality of that carefully.
Amateur radio licences are normally issued for amateur radio purposes, broadcasting 'messages' that are not intended for another radio amateur might not be legal.
srnet:
You need to check the legality of that carefully.Amateur radio licences are normally issued for amateur radio purposes, broadcasting 'messages' that are not intended for another radio amateur might not be legal.
I'm most sure you're right. One can't keep up the radio frequency continuously. But maybe one could send a 3 second message say every half an hour. Although it's a bit questionable.
JCSB:
Ok sorry for not answering sooner! So, as you guys have seen, La Romaine is a big project. I am not on the dam building team however. we are scientists sampling and monitoring water quality as dams are being built. The team requires to sample at the target location you saw on the map, for a few days, and the wind is ofter too strong for boat navigation. The point of the windsensor project is to tell us before we get there if we wont be able to use the boat. We then need the device to run for 12 days on the battery. Its not actually made for sampling, really for efficiency. The dam company doesnt have precise windspeed at the location we are interested in, and if it does, it is unable to send the information every morning before we leave! For the 12 days, if the device can tell us the windspeed next to the entrance we use for the boat 2 or 3 times every morning, it is perfect for its purpose
Since you are official you must have some leverage with the construction company and dam owner/operator. I would certainly talk over communications options with them, as they must have both mains power and existing coms links.
Your boat monitoring point is close to Centrale de la Romaine 2. If your battery based monitoring system could establish communications to that dam then from there you might have access to mains power and more options to back haul a signal to your lab.