[aprssig] LoRa GPS tracking

Dana Myers k6jq at comcast.net
Tue Sep 6 11:48:19 EDT 2022

On 9/6/2022 7:52 AM, Scott Howard wrote:

> Of course with the caveats that Helium is encrypted, not
> licensed amateur radio, and costs fractional pennies per packet (for
> better or worse).

Indeed. I think these will be the key non-technical concerns among
radio amateurs (along with the proprietary nature of LoRa modulation,
though radio silicon is available from multiple sources - I'm partial to

> First a, a distinction: LoRa is just the physical and link layers (and
> can be used as licensed amateur radio when operating at higher powers,
> at least in the US). LoRaWAN is the network layer added on top of the
> LoRa link layer (it is encrypted and generally thought to be
> incompatible with licensed amateur radio).

Making LoRaWAN compatible with amateur radio appears to primarily
mean "circumventing LoRaWAN security". It's an interesting thought but
it's a non-starter in terms of leveraging broad LoRaWAN infrastructure.

> 1) You can implement the APRS network as a whole just using LoRa as
> the physical and network layers (kind of like how HF implements APRS
> using a different physical layer than VHF APRS). Justin KD8IAY's link
> is a great example of LoRa implementation of the APRS network (with
> digipeating and igates). This approach is not LoRaWAN, but is in the
> spirit of amateur radio in that the network is entirely over-the-air
> and unencrypted (there's some whitening and proprietary encoding, but
> it's open to anyone listening):
> https://github.com/sh123/esp32_loraprs
> There's also at least one other project for trackers and igates:
> https://github.com/lora-aprs
> That can be used for licensed amateur operation when used with higher
> powers (although, like with APRS, more power doesn't necessarily mean
> better). These implementations are basically the APRS network, just
> not using VHF AX.25 (i.e., not using the physical and link layers that
> VHF APRS uses). However, this isn't exactly what you are asking.

I was sure I was not alone in implementing APRS-over-LoRa several years
back. I've probably lost the details now, but I did gateway some 915MHz
APRS onto APRS-IS. At the time I was thinking about LoRa exactly as you

> 2) You can use LoRaWAN instead of the APRS network (no digipeating nor
> explicit igate hardware). This is actually just using APRS at the
> highest levels (application/presentation) and using completely
> different physical, link, and network layers.

This is, in fact, what I'm contemplating now.

[ APRS-IS / LoRaWAN brokering discussion]

I'd also mention class A vs class C, but, Helium doesn't support class C
(yet) so I won't delve into detail. I'll just say that one characteristic of
LoRaWAN is that downlinks to mobile devices occur immediately after
an uplink is received from a mobile device. This surely influences messaging.

> This does bring up another question: if the future of APRS is actually
> messaging between devices on different networks (e.g., VHF, HF, LoRa,
> & several LoRaWANs), it's crucial that there is some specification
> about how all these networks interact (what Steve Dimse K4HG points
> out).

Bingo, this is the truly interesting discussion (and independent of LoRaWAN).

> the key might be to spend energy that allows all these innovations to be
> interoperable.


Thank you, Scott.

Dana  K6JQ

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