well I did some TTNmapper thing and it was a big supprise… not one lost packet in entire town, with device stuck in my motorcycle case behind.
for example… just one device did this
https://ttnmapper.org/special.php?node=ttgo_tbeam_new_zalemljen_direktno&date=2019-05-03&alldates=on&gateways=on
Wow, 14Km on SF7? What are the specs of the antennas at both the node and gateways?
Shengda SDBF1.4 on gateways … and that small 3-4cm black on ttgo t-beam.
Do you keep the TTN fair access policy in mind? Average airtime maximal 30 seconds a day. So for 30 second updates your transmission should be 30 / (24 * 60 * 2) = 30 / 2880 = 0.0104166 seconds max.
I’ll get that into consideration also. For now … it’s city wide network with only my 1 node that does power relay… … as time goes by and traffic increases I’ll surely add more fair time.
It would be better to design now with the limitations in mind. That way you do not run into nasty surprises later on. (Get a LoRa airtime calculator to see how much data you can transmit in 0.0104 seconds to see what I mean. Don’t forget LoRaWAN uses 13 bytes ‘overhead’)
The TTN fair access policy applies to every node, no matter how many nodes there might be in a certain area. (Why do I keep reading variations on ‘I am the only user so I don’t bother others and as such the rules do not apply to me’? When using TTN you should play by its rules.)
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What calculations have you done to ensure that your plan is;
A. Legal
B. Within the fair access policy of TTN
I think there a number of people, including me, who are struggling to comprehend what TTN mean by ‘fair access’. It seems that someone is allowed to run as many nodes as they like that comply with the ‘fair access policy’ but if one individual node exceeds the policy the owner is somehow a bad person. I don’t see the distinction between one device running a DC of 2% versus two devices running a DC of 1% each, because both are consuming the same airtime. Please explain.
tlu, I agree. plus the video and all that got me in lora promised whole bunch of things… like firmware updates over air that last for days… where was that fair access policy then. I whish there was one fair access policy with wifi back then ;D
Still I will do it fair from start, as much as I can.
LoRaTracker, it’s legal.
Fair is suggested and considered.
Interesting, are you able to share the calculations ?
O I thought about frequency and such. Like I said, I’m here to get advices on how to do it and what’s best practices. Calculations comes next. Surely if it’s not legal in 1 in 30sec it will be 40 or 60 … Don’t really care in this stage.
Probably best to to assume that a lot of messages will end up towards the SF12 end especially if the ‘public transport’ is in a City with few gateways.
A navigation payload at SF12 will take about 1.25seconds air time so around 24 messages a day. if that is enough to track the public transport then the project would be good to go.
The fair access policy is clear enough.
If you dont agree with the policy for TTN as a free to use system, then maybe look at alternatives.
LoRaTracker,
What do you mean when you ask “is it legal”. LoRa falls within the ISM band, as long as the “radio” falls within the specifications of the country its used.
Darkman, I see you’re using the TBeam too, great little tracker.
We use 3G trackers for buses, vehicles, trucks instead of LoRawan network.
We will have LoRa environmental sensors on the bus to measure temperature, humidity, air quality, UV light and upload the data 2-4 times daily.
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Trailers with 3G trackers. We will eventually add LoRawan environment sensors which are “peel and stick” installed, collecting env data along their routes.
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Do the transmissions, possibly at the worst case scenario, stick to the 1% duty cycle limit, common to most countries.
Which at SF12 would be a minimal position message around once every 125 seconds.
Ok, you meant fair access.
Er no, I meant legal.
Fair access and what is legal are different.
Got it. Thanks for sharing.
I see you’ve tested the SX1280, great to know Semtech makes a WIFI version for LoRa, will be a great fit with https://www.ui.com/products/#default
Indeed so, and whilst 2.4Ghz is shorter range, there are no duty cycle restrictions.
Unfortunatley the hardware interface to the SX1280 is completly different to the SX127x, so none of the software for TTN nodes or single channel gateways will work.
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