Discussion about range and non-ACK protocol stack

Hey guys,

I am setting the stage here for a big picture question about reliability and true, real non-anecdotal RF range:

I’ve been a HAM since the early 90s and that was the golden age of packet. Aside from the AX.25 protocol I did a lot of APRS testing and I have to share a very disappointing observations from those days.

When using my ARPS tracker while driving around the broadcast is always a “beacon” type or non-AX.25 connection so basically best effort - best results. With a dense distribution of mountain top digipeaters here in the Bat Area and full 5W APRS tracker I only got around 50% of the packets pushed to the APRS network when compared with the locally stored log using an old Windows 2000 Toshiba laptop which logged all serial output of the tracker.

Mind you this was packet on 144MHz - far better propagation than 900MHz and let’s set aside the power issue alone. So then what is this expectation based upon that LoRa at 900MHz with a fraction of my 5W radio could achieve reliability and/or range given the same stack - non-ACK type of “beacon” broadcast?

The expectation of Lora is that it can provide 10-15 miles with line of sight. Has been proven in a lot of circumstances. This is being used every day at several locations, it is realistic and reliable.

Also using just the EU 14dB record distances of several hundred miles (over 400 miles). Not something you’ll see every day, but impressive non the less.

So no need to be pessimistic, Lora modulation is living up to expectations in every day deployments.

Have you tried the same tests you performed with LoRaWAN devices and gateways?

I am unsure what the question is really.

Range itself varies of course dependant on the environemnt and comparisons at ground level or in urban areas are difficult, there is no such thing as a standard urban area.

The only true range comparisions you can do, between LoRa and other technologies, are under line of sight conditions, mountain top to mountain top for instance. Typically LoRa will cover around 10 times the distance of other FSK based data systems, when compared on an equivalent data rate and transmission power. I did these comparsons (LoRa versus FSK) on a local 40km hilltop link at the end of 2014.

For TTN uses, power levels are resticted by regulation to typically 14dBm.


The question is not very clear indeed.

The introduction “sets the stage” for “big picture question about reliability and true range of LoRaWAN”.

But the actual question is:

"using my full 5W ARPS tracker while driving around … I only got around 50% of the packets pushed to the APRS network … So then what is this expectation based upon that LoRa at 900MHz? "

Nothing is mentioned or asked about range, only about expected reliability expressed in percentage of packages (messages) received.

If you drive around a metropolitan area like Gotham City (bat reference), LoRa results will be all over the place as every time you drive behind a big big building you reduce your line of sight - it’s the same problem your satnav will have, drive between two skyscrapers and all of a sudden Google Maps thinks you are on the pavement (or sidewalk as you’d say).

I personally don’t subscribe to the use of LoRaWAN for real time GPS tracking. It’s fine for asset tracking slow moving items on a site with a fence or crates/boxes/containers that end up stationary at the end of the journey when a device can confirm to a gateway that it’s arrived, but sucks for cars etc due to making connections to gateways and the size of the payload.

So I’d say reliability for tracking will vary between 0% and 100%, mostly in the “your mileage will vary” sort of way.

What is your actual application?

@descartes Hi you nailed it – the intended application is real time GPS tracking just like the APRS scenario. I suppose the proof will be in the pudding once I have some time to consolidate observations post COVID driving…

Useful information to have provided in the first post perhaps.

TTN is not suited to ‘real time’ GPS tracking. You have to account for the situation where your using long range mode, you cannot assume you will always be close to a gateway.

In those circumstances the fair access policy limits you to circa 24 location transmissions per day.

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