I searched for very long range wireless communications between two Arduinos, but can't find solutions. I don't live in USA, In my country there are regions, where GSM does not work. I want wireless communication approximately 500-1 000 KMs. What are options without GSM for that distance wireless communication(500-1000 KM)?

  • What do you want to send between them? How many bytes and how often? – Squats Sep 1 '17 at 7:40
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    I want to send text and voice, 4096 bytes in 1-5 seconds interval – Stackexchange User Sep 1 '17 at 7:48
  • Do you have a budget in mind for the initial build? Ongoing costs? – Squats Sep 1 '17 at 7:51
  • Satelite communication is expensive, but that can be used for voice and for short data messages. The short data messages are used for example by ships. Do you have a shortwave license for an extremely powerful transmitter ? As far as I know, everything else is illegal. – Jot Sep 1 '17 at 7:52
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    I don't have license, but I have budget. – Stackexchange User Sep 1 '17 at 8:02

Back in the old days, we used things called modems to connect computers across POTS.

old modems

Your country may not have GMS, but I bet you still have old land lines. In that case, you can use a land line + modem to connect the arduinos directly , no Internet involved, no ISP needed, no overhead, no lag, nothing. It's just one Arduino at each end of a very long cable. No TCP/IP needed, but you need your own protocol to keep data in sync and filter out errors. There is lot of well proven ones from the golden era of BBS.

I search Aliexpress, I didn't find any modem suitable for direct conection with Arduino, but there is a lot of USB modem like this:

USB Modem

I don't know if they can work with Arduino. I'm afraid that they are win-modem only.

What it really works with anything is a traditional modem, like this model from Multitech (not an endorsing):

Multitech modem

You will need a RS-232 level converter however, because RS-232's voltages can go up to 25V. The converter avoids you to deal with the peculiarities of the RS-232 standard and DB-9 connector.

RS232-TTL level converter

And a cable, of course.

You can develop and test your project using a null modem cable, to connect both Arduinos, a few meters apart, without need of a land line.


What are options without GSM for that distance wireless communication(500-1000 KM)?

1) use the internet;

2) use narrow band transmission, like qrp;

3) use relays;

4) use satellite phones;

5) use a high-powered lw transceivers.

6) ...


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