Payload with 7 instead of 11 bytes.

[designer2k2]

Hello,
this is a alternative payload with minimal information. As Lora is airtime limited and the Helium network charges per byte, it enables operating a mapper device at a lower cost.

The payload is 7 bytes. 6 bytes for lat/long is unchanged. Then only one byte for the altitude and satellite counts together.
This byte is 5 bits for altitude, counting from 0 to 31 with a step size of 150m. That gives a possible altitude to report from 0m up to 4650. Sufficient for most applications. The remaining 3 bit are for the satellite count, as 3 is the minimum for a 3D lock the value range goes from 3 to 10.

To distinguish between the formats i used the FPort byte, the decoder uses this to decide how to read the payload.

I am running this on a T-Beam 1.0 with Helium-IoT as LNS. Mapping works identically as with the original payload.

Greetings!

[Max-Plastix]

and the Helium network charges per byte

Is this a new cost? My understanding is that Helium charges DC per packet, not per byte. I haven't kept up with changes, but has the charge structure now favored smaller packets?

Separate FPort is a good idea, and maybe is a compatible an unobtrusive change.

[designer2k2]

Oh good catch, the price is constant from 0-24bytes, so this change will not make it cheaper! https://docs.helium.com/tokens/data-credit/#dc-and-iot

[designer2k2]

so with no price difference there is the airtime benefit left.
A 7 byte payload gives a intervall of 5,7s instead of a 6,2s intervall at 11bytes. Its not much but still a bit :-)

Airtime calculator: https://avbentem.github.io/airtime-calculator/ttn/eu868/7