Non line of sight radio and arduino uno

Question

I've been using a pair of arduino uno and nrf24l01 and found it wasn't really suitable due to low range when it comes to obstacles.

Essentially I'd like to use it in country areas where it would ideally transmit through dense trees and over hills at around 500 meters.

I've spotted the SI4432 and the sx1272 (which seems ideal but it doesn't seem popular despite it's high NLOS range capabilities?)

I was just wondering if anyone had any recommendations on which would be the best radio module to try? Any help would be really appreciated. Many thanks in advance.

• CharlieHanson: Which country are you in, oduffy?
• oduffy: Hi chaaarlie2, I'm in England
• CharlieHanson: Then check out www.rfsolutions.co.uk, and their BRAVO transceiver modules.

Answer 1

General rule is, the lower the frequency, the longer the range (but lower bandwidth). So both should have a better range at 433Mhz and 137MHz instead of the 2.4Ghz of the NRF. Antennas also affect the range.

The "over the hills" part I think will be problematic. The RF won't be able to penetrate through the hill. So the signal has to bounce of the ionosphere to get over the hill, which is to long a distance. So you probably have to have some kind of repeater on top of the hill to accomplish this.

• Chris Stratton: Not sure I would agree with the proposed frequency vs. range rule. It is true that the ionosphere is more often reflective at lower frequencies (it's most basic characterization model being a "maximum usable frequency") but that will be more a source or interference than propagation here. And there are bands where vegetation and atmospheric moisture absorb more. But generally I'd look at trying to build a digital repeater or mesh network around one of the already digital-packet-oriented chipsets, even at 2.4 GHz.
• CharlieHanson: @ChrisStratton Frequency vs Range is proved in the Friis equation (too complex to add in comments!) but is observerd by playing around with an online calculator such as random-science-tools.com/electronics/friis.htm .
• Chris Stratton: @chaaarlie2 - that has essentially no application in terrestrial settings, such as this question.
• CharlieHanson: @ChrisStratton on what grounds?
• Chris Stratton: Here on earth, the grounds are curved, bumpy, and prickly with stuff - those facts dominate.

Answer 2

Since you already have the uno+nrf24 working, it might be worth trying a better nrf24 module before trashing the work you've already done. You can buy nrf24 modules with an integrated LNA, PA, and external antenna port. Just do a search for NRF24L01+LNA+PA. You can find them on amazon for < 10ドル and usually come with an external antenna.

• oduffy: Thanks Curtis, I do have one of the NRF24L01 with an aerials (pages.ebay.com/messages/page_not_responding.html). However, am I right in thinking that one doesn't have the LNA and PA circuits on?
• curtis: @oduffy yes, some nrf24's have an external antenna but no LNA/PA.
• oduffy: Great, thanks, I'll buy a pair and see how I get on.
• curtis: @oduffy Come back and add your results when you're done. This is a common topic and others would be interested. A quick search brings up some comparisons other people have done between different nrf24 modules... Like this. hallard.me/nrf24l01-real-life-range-test
• oduffy: I will do, I'll write something up once I've done some tests