Lora Range Test
April 23, 2017 9 Comments
Lora Pager
Aright So I designed those awesome Lora pagers mentioned in my previous post based off some SX1276 modules. How far can they really go? Here’s a graph with a quick test to find out. Red line represents the Lora module broadcasting its GPS position back to the base-station. Blue line represents my phone’s GPS record (to show where I was actually driving). Yellow thumbtacks represent base station. Unfortunately my apartment is at a low altitude with roads on giant dirt hills around the base station: this killed range testing in most directions. Be sure to check out my Lora development boards that use the same radio
4.27 miles! yellow line represents base station to tag largest distance
Remember that this is with a 5dbi antenna on the base station located on the second floor of my apartment, and a free 2-3dBi antenna on the GPS tab sticking out of the sunroof on my car. Transmission power was 20dB. Zooming into that largest distance:
Zoom into the industrial area from previous image — Found the line of sight path!
Not bad for the pager’s 13mm! bad antenna. Definitely blows every other 100mW radio <10$ I’ve tested out of the water. It’s also awesome that it can sleep for only a couple microamps which brings the whole pager to ~50uA when on standby.
Pager with gps attached in car
How to do this on your own: save the pager’s Lat,Long in csv format then upload to gpsVisualizer and export as google earth (kmz format). For the phone use Geo Tracker (android) to record positions then share as a kmz and email yourself the kmz file. Then just open both files in google earth. I couldn’t figure out how to open these files in google earth for web browser, it’s very easy with the full install.
About Moser
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Nice test! Yeah you got most of the distance to the horizon. Assuming your 2nd floor apartment is about 20 ft in the air your radio horizon is about 5.5 miles.
http://www.ringbell.co.uk/info/hdist.htm
My own project used 2-FSK (CC430) and when we range tested at 400mW we parked one base station on a cliff by the ocean about 65 feet in the air (Palos Verdes, CA). Promptly forgot the radio horizon was about 10 miles at that altitude and the link dropped out almost exactly at 10 miles driving along the coast. When we realized what had happened I continued driving north towards Malibu and got to the Malibu hills (Pepperdine University) and was able to get about 600 feet above the ocean increasing my radio horizon to about 30 miles. This worked and we easily got 24 miles on 400mW with one good base station antenna and the mobile radio using a OK rubber duck antenna.
Get your project any decent height off the ground and I’d bet you’d see a much longer link!
Hey hello!
Nice work I’m doing something similar will share when code is better as I have the full stack including mqtt, nodejs and mongodb for storing all the incoming packets!
I’m using a hoperf Rfm95w and I’m only getting about 900mts (it’s a big dense urban area so that might be the limit for this radios)
Did you used the library Radiohead or did you use a different one? If a different one would you mind sharing the URL to it if its open source?
Thank!
I’m using radiohead. The RFM are just re-badged chips — it’s actually an sx1276 chip on the module. Look at semtech’s lora link budget calculator and set the registers appropriately, that’s how you’ll get max range.
Hi, nice work! I want to do something similair but I was actually curious what Spreading Factor and Bandwith you used. Could you shed some light on that? A higher SF should provide a higher range.
Also, since the node was on you car. Were all messages transmitted while driving? Did you take the Doppler effect in account? http://journals.sagepub.com/doi/full/10.1177/1550147717699412
This is related to the SF since a higher SF is more sensitive to the Doppler effect according to the above study.
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