Arduino as repeater, for TX that is underground

Hello to arduino Forum.
Have a question to you guru-guys. Got interested in Arduino as repeater.

So the situation is: I have 4 arduinos- each with switches , that will send the message of switches setup, and NFR nrf24l01 ( simply lets call them TX1,2,3,4).
And I have 1 Arduino_RX ( same NRF24l01).

Arduino TX1 & TX2 are located in the basement ( 4 meters bellow ground floor) of the warehouse 50 meters away from TX3, TX4 , which are also at other underground basement.
Thus I can not have " direct communication" of the TX_1,2 or the TX_3,4 to Arduino_RX.

Basically I need repeater. maybe even 2 of them.
I have begun watching this:

Can anyone tell me if you done it?
How you did it?
What steps dd you do?
I have 5 arduinos with NRF that I can play with.
Just need to know the “milestones” at the way
Thank you

For the physical situation that you describe 2.4GHz wireless is probably not suitable. You will probably get better results with lower frequency wireless - for example 433MHz. And LoRa is reputed to work very reliably if you are content with a low data rate.

You could try the RF24 Network library provided each nRF24 can communicate with one other - but you will need to do some experiments.


Hello, Thank you for reply -
I will buy and give it a try to 433 modules ( again according to youtube and ebay ) they are easy to use and cheap.
My primary question is how do I make the repeater out arduino+ RF module.
Back in the day I made repeaters in the army - from 2 Radios, they had to be with different TX and RX frequencies...
I know that in Ham radio it is possible as well ..

But that was all audio and 2 frequencies that repeater had to work on.
I wonder if anyone built arduino based repeater with 1 or 2 modules required.

If you need a repeater Arduino then I would arrange for it to act as Master and send a request for data to SlaveA and when it gets the reply it would send the data on to SlaveB. That way they can all use the same frequency without risk of data collisions.

But, if you get the 433MHz units you may not need a repeater.


Are you we talking about these modules - in these tutorial?

What is the effective range for them?

Or do you need special antena?
After I read this:

For 433 MHz, the optimum end-to-end distance of the balanced dipole is 32 cm, using AWG#14 copper wire.

Are you we talking about these modules - in these tutorial?
Arduino Tutorial: 433Mhz Wireless modules basic setup and example using DHT22 temperature sensor. - YouTube
What is the effective range for them?

When you provide links in a post, make the links clickable, people are more likley to take a look and provide answers.

Like this, in answer to your question on effective range of the modules, see here;

Answer at about 0:52.

Also note that you need to check what is legal in your country, you may not be able to use those modules where you are.

Thank you so much sir
Much appreciated
I will see what could be done and report here
Thanks for heads up of the link
I sure did pressed Enter- Perhaps I should try harder :slight_smile:
Thank you again