Chirpstack-concentrator - RAK5146 - SX1303?


On Hardware support - ChirpStack open-source LoRaWAN® Network Server documentation it mentions the RAK5146 under the SX1302 chipset, but on RAK5146 Concentrator GPS Module for LoRaWAN Based on Semtech SX1303 LoRa LBT – RAKwireless Store it mentions it as SX1303.

I’m just wondering if that’s a small mistake in the docs, or if the RAK5146 got an upgrade :slight_smile:

Trying to build a gateway and want to check compatibility before ordering parts!

I have one. But there is a metal shield, so I cannot see the chip number inside.

There does not seem to be separate software for the SX1303, so I suppose this difference in model number does not matter much? I used the reference Semtech BasicStation and sx1302_hal (the HAL + UDP Packet Forwarder) projects with it, and it works.
I took the transmission power lookup tables and coefficients from global_conf.cfg of RAK’s RPi image.

If you know of the way to read the concentrator’s model, do let me know.

Thanks. That’s enough for me to order and try it :slight_smile:

On this topic, I want to say that while the stock software works, the transmission power lookup tables and coefficients are likely important. This seems to be a topic that is little discussed.

I believe these pieces of information need to come from the manufacturer, who did some calibration and certification of the complete device with the relevant authorities, who then certified that it operates within their regulations. Otherwise, transmitting at a certain power level might not actually be what you think it is.

I once had an experiment, whereby a Kerlink Wirnet iStation was exchanging messages with a RAK5146 via the 9th channel (the LoRa backhaul channel with fixed spreading factor). Both were transmitting between 8x floors, so the setup was not optimal.
At the beginning, I just used the reference software from Semtech. The result was slightly higher losses and worser RSSI in the direction of the RAK5146 → Kerlink.

That does make sense, considering that the gain setting near the maximum index, were set to the maximum values in RAK’s image. But the reference global_conf.cfg used lower gain settings.

I have updated the SX1302 header to SX1302/3. Note that the SX1302 and SX1303 chipsets share the same HAL. This is the reason why both SX1302 and SX1303 modules are found in the same table.