I was testing the range of one of my RAK 811 evaluation boards with the included antenna, connecting through a RAK 7258 (also using the included antenna), and could only get a range of about 200 meters in a suburban area. I am operating on the US915 profile, ADR was off, and the DR 1.
In the Lorawan documentation, a DR of 1 corresponds to a SF of 9.
Looking at the uplinked frames, the RSSI was around -104 and the SNR was around 2 at 200m.
Is this typical? I noticed that previous topics note a range far greater than this and the documentation states a range of 2 km in dense urban areas.
How high was the gateway antenna, is it indoors, what sorts of buildings are around you, where in the world are you (actual town/city), where was the device, was it moving?
DR1 in my notes is actually SF11 but then I’m in the UK so I guess you must be in the US where DR1 = SF9.
If it’s not too painful to try, why not give another data rate a trial. And make like a snail and form a spiral from your gateway, it may be the spot you tested at just had the wrong characteristics for LoRa.
The gateway antenna is indoors on the second story of a building. The surrounding buildings are all two story homes. The device itself was with me.
I went on a walk and paused every so often to turn the portable power bank on and hit the reset button. I would wait for a small portion of time (about 20-30 seconds) and then continue with my walk.
The power bank I was using would shut off after a while. I assume because the device draws so little current that the power bank thinks nothing is using the power bank and thus shuts itself off. This is why I went through that process of turning it on and hitting the reset button every single time I stopped.
Yes, in the LoraWan specifications it states that DR1 is SF9 and DR0 is SF10 for US915. I’ve confirmed this by looking at the packet logger on my RAK 7258.
I set up a notification on my phone today for when Chirpstack events get stored on my database (tested and functioning), and set the DR to 0 for the device (also tested and functioning). I’ll try and test the range again today on a walk with this new setting.
Ok, just got back. It seems that the maximum range in which transmission was consistent was around 450 meters. It was tested in two different directions and both produced the same maximum range.
From what I remember reading online, with each subsequent increase in SF, the range doubles. This seems to correlate with the results I found, i.e. SF9 produced a range of about 200 m while SF10 produced a range of 400(ish)m. Unfortunately, while the Lorawan specification for US915 does have SF11 and SF12, they are on DR8 and DR9 and “must be implemented by end-devices and are reserved for future applications”.
However while re-reading these specifications I noticed that DR4 had a SF of 8 but had a different bandwidth (500 kHz) than DR 0-3 (125 kHz). This now has me wondering if the bandwidth has anything to do with range.
How do you test? Since the antennas are all omnidirectional antennas, the gateway must be placed at a certain vantage point, and then the ADR must be opened to connect.
I had the board with me while I walked and turned it on until I received a notification on my phone. If I didn’t receive a notification within a few minutes, that meant the board didn’t connect and I back tracked until I did receive a notification. If I did receive a notification I would walk some more and then repeat the process.
To my knowledge, ADR only serves to adjust the data rate to save battery. However since my tests were using the data rates with the largest range, I didn’t see it as necessary to enable.
I’ve also mentioned previously that the antenna of the gateway is on the second story of a building. Since I was using the included antenna for the node and the node was on my person, it was at the ground floor.
If it is at a window or on one side of the building, the rest of the building on three sides is going to reduce its reception. If you walk somewhere there is a building between you, on the ground, and the building with your gateway in, it will reduce reception. If you walk behind a building that is on the three poor reception sides of the gateway’s building, reception will be even worse.
There will be other factors at play, but the less obstacles the better. Is it at all possible to get the antenna on to the roof, preferably above it.
An alternative test is to find somewhere you can power the gateway where you can have a direct view to the device - maybe a friend with some open space next to it.
This is why I asked the question, awaiting answer:
because very often we look on Google Maps / Earth and have a much better idea of what challenges you face.
That makes sense. I guess my assumptions were too lofty when reading the specified range as being so high. I didn’t take into consideration that the signal could be impacted by buildings to that degree. (This technology isn’t magic)
Unfortunately, the gateway antenna is situated in a room with 4 walls inside a two story building and it is not possible to get it onto the roof. Nor do I have feasible way of testing a large amount of distance with line of sight.
Apologies, I thought you only needed a more general location (such as North America) for frequency and specification considerations. The gateway is situated in the area of 1928 Edgewood Avenue, Coquitlam, BC. The whole area is filled with 2 story homes and tall trees, which would (as you mentioned) lend to poor reception.
That will certainly reduce range, as we can presume there will be another set of walls or windows around this inside room. Coverage in the building should be good, but not so much outside of it. Certainly the line of trees to the west are going to impede coverage and the overhead power looks like a cats-cradle of RF fun.
If you can get yourself 12V (aka car battery or just a good size set of cells), you can setup the RAK7258 as a standalone LoRaWAN gateway & network+application server, use a cross-over ethernet cable in to you laptop and put it in Colony Farm Regional Park. Then send a friend with your device on a power pack to run up Eagle Mountain Trial Head.
With an external antenna a few feet above roof height, not withstanding the overhead power, you may find the range is transformed.
Could you tell me how you set the datarates and turn adr off? Is it by using AT commands or are you using it with arduino? Could you share the libraries and code used? I am having trouble some trouble. I use rak811 without a master mcu. I used MCCI Lorawan LMIC Library, No matter what I try I can’t turn off ADR.
I doubt that @AffilAcai will be able to answer your question because his last visit here in our forum was last August 22, 2020.
If you’ll use the standard AT command, it will be a straightforward process but you need to have an external MCU. If you are using MCCI LMIC Lorawan Stack, I strongly suggest that you check their github repo and forum for possible solutions to the issue you have with ADR. Our friends from MCCI are very accommodating in answering inquiries
