You are correct, I’ve been focused on the commercial use. So I’m wondering if you are using the community version what incentive we have to help you for free?
As to the “this might happen to another TTN user”, the short answer is, unlikely, because 300 nodes would be a huge community use - which is usually a mix of devices.
I’ve read every single post in the last two years and not come across a wholesale collapse of a deployment like this. Given that TTI have users with 10,000’s of devices on their Cloud offerings and given that if gateways stop hearing devices that’s usually something to do with the RF environment or the devices, and given that there aren’t any commands related to your issue and you say that the devices are heard when they are moved closer to a gateway, I’d be reasonably sure that there is something going on with your firmware.
Without knowing what the maximum range of one of these offline devices is (ie, bring it closer to a gateway until it is heard) and the subsequent RSSI & SNR figures and more info on the firmware - you have yet to answer @kersing’s question about the underlying version, who wrote it etc, I’m pressed to see how further help can be provided.
Thanks for this information. It means lots, may give a way to find exact issue.
Its Software RAK3172 Default AT Firmware. and My MCU didn’t send any command related to change of SF or Power or anything else, only send data to lorawan. (By default on startup ADR is enabled)
Excellent to know. Next question is of course if you have contacted RAK to see if they encountered this issue previously.
Something else to test is to use a fresh device with fresh battery and take it to the location of a previously working device that no longer works. That could tell you if the gateway(s) or the devices have issues.
Yes I already contact RAK, and they doesn’t seen any issues with RAK3172 devices.
As mentioned earlier, Tried to replace 4 device with fresh one (fresh battery), but not getting SNR and RSSI as get before in starting 18 days.
Also tried to replace gateway with new one, but it doesn’t help.
Have you investigated what has changed in the territory between the nodes and GW? A new building/shack/lorry parked in way….couple of years back had situation where nodes working fine for 8 months -then a local farmer gathered his harvests and suddenly we lost 12-15db….turns out a single bail of hay not a problem for <ghz LoRa, but a barn full…. Hummm! :scream just happened to be on line of sight to a couple of remote nodes….
Do you have the detailed uplink records that show all gateways and snr/rssi information for the early days? So you know for sure which gateway was reporting the best signal?
From 300 devices, only 25-30 (near by to gateways) data received. out of 4 I changed 1 gateway to new one, and other 3 gateway is same.
All gateway reports in decrease RSSI and SNR.
You could get a totally different device - perhaps just an off the shelf device - and deploy it to see what happens - then you’ll be able to differentiate between environmental or firmware issues.
IIRC the L-A consulted widely and selected a slightly lower range band than e.g.other EU868Mhz bands specifically to avoid such an issue and to squeeze in between avoiding mutual interference or need for expensive narrow band or steep roll off filters etc. you might reach out to the L-A to ask if they have started to accurate instances of poor implementation that might be indicative of a problem?
The often used dielectric bandpass-filter from Taoglas has an attenuation of only abt. 10dB at these frequencies.
Strong signals a few MHz under or above 868MHz can lead to an overload of the receiver-circuit. The receiver becomes deaf.
Every receiver has a signal-range it can handle, the difference between the lowest detectable signal and the highest signal it can withstand without distortion. This is called dynamic -range.
The signal a receiver sees at its input doesn’t only consist of the signal you want to receive (in-band), but it is a sum of all signals (voltages) comming from the antenna. If the out-band signals are very strong, they will overload the receiver-input.
Therefore you need means for selectivity to keep the out-band signals away from the receiver-input. The first part of this selection-chain can be the antenna, the second part are filters like the Taoglas dielectric bandpass-filters.
If you look at the datasheet of this bandpass-filters eg. DBP868UA you will see, that the attenuation of out-band signals that are only a few MHz away is rather low.
This is the reason why a receiver can become deaf because of out-band signals.
