Oh and I forgot to mention, if I do jumps of 20000 then my configuration gets accepted.
So I did that and it worked, but 1 frequency cannot be achieved with the jumps of 20000.
So I will go contact my supplier and Dragino now.
Much of your problem seems to be that you’re trying to do almost everything with only one of the two IF’s. You probably want to move the 866 MHz channels to the second radio and perhaps increase its tuned frequency towards their middle. But it may not be simple to get that implemented and there may be compromises, so figuring out what the people who dreamed it up went with is likely best for now.
You have three frequencies setup and working on the gateway. If you use single channel mode you can set what frequency the node will be on - so you can allocate three nodes to one frequency, three nodes to another and the final four to the last frequency.
As per the math above, if you have nodes taking 200ms to transmit once every 15 minutes, a single frequency can support 5 x 60 x 15 nodes (=4,500) if by some fantastic co-incidence they are all spread evenly over the 15 minutes.
Even if by some miracle you managed to turn them all on at exactly the same time, they will start to drift within the space of an hour. I have about 10 nodes permanently running spread over my own Arduino + RFM95 thing to a TTN Node to RAK nodes (various) and none of them could be regarded as a precision timebase - just silly little things like which cycle of data acquisition that means the ATmega has to setup a different ADC channel or the temperature of the node all induce nanosecond differences in timing that mean they all show a tiny drift in their precise check-in interval.
If you have yours set over a range of 14 to 16 minutes as my example and you turn them on, you may see the occasional collision in transmission, but it will be very random.
In this scheme, if you look at the logs and see that two nodes are transmitting uncomfortably close together, just cycle the power on one of them.
Alternatively, buy some nodes that support the IN frequency scheme properly.
Thank you @cstratton and @nmcc ,
I did as you suggested and set the nodes onto single channel mode.
It’s working great.
I just hope that by some coincidence the data does not become incorrect, because on its basis I am running another application and it’s purpose will become wrong.
My supplier doesn’t seem to have an idea what offsets and intermediate frequencies are, he replied to by email just by telling me the frequencies.
One final question. From a theoretical point of view, if I have 4 nodes on a single frequency transmitting every 1 minute, what is the change of error? They take about 1.3 seconds to transmit the data.
I most definitely do not and did not recommend single channel operation
My supplier doesn’t seem to have an idea what offsets and intermediate frequencies are, he replied to by email just by telling me the frequencies.
It would seem that your supplier is not really able to support making the product they have designed usable. In particular, they’ve not put you in contact with anyone who actually understands the engineering of its strategy for operation in your country.
Or perhaps they have no actual strategy and just wrote up some code in an afternoon to fulfill a request from the marketing department, without testing it as part of an actual LoRaWAN network.
That part I was referring to @nmcc .
This is a common practice in India. People are running business that they are not really qualified to. But I don’t blame them and they need to run those businesses as the extreme overpopulation has increased the demands for jobs. But yes, at the price of the quality of service / products.
I bought Dragino nodes and they forward all my queries to their Indian supplier (which I don’t want to name because even though they might be unqualified, they are good people and trying their best).
I asked him about the offsets and intermediate frequencies, even sent my config file because he probably is using some other gateway but he just sent me the list of frequencies I was supposed to use which he already gave me.
I don’t think he understood my question.
I didn’t recommend it but I accept by replying to your question about ‘is it safe’ that there is an implication that you could do as I suggested - but that is your choice to make based on the facts.
If your gateway is running properly for IN channels, then you will not inconvenience others.
If your application absolutely relies on every single transmission from the nodes to arrive, then LoRaWAN is not suitable as it’s not designed for that.
If your nodes are transmitting every minute, you will be in breach of the TTN fair use policy.
Having given two basic examples, perhaps you could figure out how many time slots there are, but first, I’d check to see what the gateway (either its logs or the TTN console) thinks is the actual transmission time - 1.3 seconds would be for a lower data rate with a large payload - and at 1.3 seconds you’d be restricted to around 1 an hour.
I don’t have a choice as I am no expert in radio frequencies and my supplier doesn’t know how to setup the configuration.
Maybe they have the type of gateway that accept any frequency they put into it.
Oh yes, it is. I don’t want to get in any legal trouble. Right now, I am using the default configuration on the gateway along with the node transmitting on the same default frequncies.
Oh. The thing is I am making 3 products.
But for the first one, I needed fast transmission of data, I was thinking about 5 seconds, but with ChirpStack (as I don’t want to abuse The Things Network policy) and neither do I want to transmit the data online.
So for this first application, I turn on the node, it transmits data every 5 seconds. After 3 minutes, I turn off the node and go home. Then use it again after a week or maybe a month perhaps depending upon when we get our next client.
The next two applications are not critical of the data. They will transmit every 1 hour and if sometimes data doesn’t arrive, it’s fine. They are just systems to check if everything is working in order.
I plan on using ChirpStack and I won’t be transmitting this data anywhere. It will stay on the Raspberry Pi itself.
Correct my mistakes if I am wrong anywhere above. 