I want to preface this with an apology for my lack of knowledge on the subject.
I'm working on a high altitude balloon experiment and my team and I need to be able to trigger an emergency cut down sequence at 5 km with a clear line of sight. We'll be using Our Arduino to trigger a relay circuit that will put current through a piece of nichrome wire, cutting the tether to the balloon. All we will need to do is send a brief signal to the balloon to tell it to initiate this sequence if it is deemed necessary. We have a HAM Radio that (I believe) will be sending a 433 mhz signal.
No one in my team is familiar with radio communication systems and because of the timeline we are on I ended up ordering both a HAMShield and an Adafruit RFM69HCW to try to make sure we could eliminate the lead time of ordering a second part if what we ordered was infeasible for the task we needed it for.
So this leads me to a few questions:
Are either of the transceivers we ordered a viable option to receive and decode our signal at 5 km?
How will the Arduino interpret this decoded signal, a number?
With the HAM radio, how do we code our signal. Say we want the Arduino to initiate a cutdown if it receives "1234" from the ground station.
Will this operation be as simple as getting our transceiver receiving and decoding our signal, having the Arduino read the decoded signal which we can then have it follow the procedure we code in?
Thanks for all of the help, and again I apologize if this comes across as a dumb question.
Unless you are a licensed Radio Amateur you shouldn't be using the band for your stated purposes.
Much better to use 433MHz ISM free licenced modules or 868MHz (900MHz in US). There a quite a few to choose from, however 5km is a lot to ask unless you use a small yagi, which then contravenes the ISM specs.
Edit: Ok seems you are thinking of using an LoRa Module so I think you are confused with ham radio and the fact that 433 is a ham band.
tasmod:
Unless you are a licensed Radio Amateur you shouldn't be using the band for your stated purposes.
Much better to use 433MHz ISM free licenced modules or 868MHz. There a quite a few to choose from, however 5km is a lot to ask unless you use a small yagi, which then contravenes the ISM specs.
The professor we are working with has an Amateur Radio License, so that isn't a concern.
We did order the following modules in the hopes we could use one of them:
To answer your question. With the HAMshield at 1W output you should easily accomplish your goal with just a whip antenna.
With 1W from a handheld transceiver on voice I achieve 10km easily from inside my living room. ( I talk to a ham friend across a river from me, which is 20km by road over the bridge)
433 mhz AKA 70 CM is a ham band of a sort. the first thing: it's a shared allocation, Government & DoD have priority. Amateurs are secondary, and there is a huge chunk of Part 15. Part 15 has to yield to licensed amateurs, licensed amateurs have to yield to Feds. as a licensed amateur I get to put real antennas on Part 15 devices.
For ground to high altitude balloon, where you normally have good line of sight, then most FSK data modules such as RFM22, RFM69 etc are good for around 40km @ 100mW, there is absolutly no need for higher power.
LoRa modules will go at least 10 times further than that, or cover the same 40km with around 2mW.
The person using\launching the transmitter need an Amateur license .................