Transmitting power of T-Beam and RAK4630

We tested T-Beam and RAK4630 as router, both with standard channel settings (Long Range / Slow, EU 868 MHz, same antenna configuration and location). T-Beam consumes approx. 100 mA while RAK4630 is much less, namely around 5-10 mA.

Our range tests showed, that the network is much better with the T-Beam as router than with the RAK4630. We would like to understand this observation. We assume that the transmitting power of the T-Beam is higher than the RAK4630 and would like to know, if there is an option to increase the transmitting power by changing a parameter (within legal limits)?

What version of the firmware? Which radio? There were recent radio power updates to the 1262 radio.

T-Beam: Type LILYGO® TTGO Meshtastic T-Beam V1.1 Drahtlose Modul für Arduino ESP32 LoRa EU868 mhz WiFi GPS NEO-6M Mit Oled-display, Firmware 1.2.63

RAK4630: WisBlock Base (RAK5005-O) plus WisBlock Core (RAK4631), EU868 , Firmware 1.2.59

1.2.59 with rak has the tx switch bug, update to 1.2.63 or newer

Ok, thanks, I will do the update and will check, if the transmission works better.

What is the transmission power of the two devices? Both supposed to use 25mW? In Germany under some conditions (duty cycle below 2.5% which seems to be ok for our network) it seems to be allowed to use up to 500mW in the band of 868 MHz. Is it possible to change a parameter to increase the transmission power?

The TX power could be adjusted by using the Meshtastic CLI:

Great, thanks. I updated the Rak4630 devices to FW 1.2.64 and will start the testing later today.

Concerning the TX power documentation: what is the standard setting? Is the “20” in the example 20 mW tranmission power? Or is it additional tranmission power gain? What are the limits for a particular device like the RAK4630? Seem’s like a cool feature to adjust.

It depends on the Lora chip, for SX1276 the max tx power could be 20dBm, and 22dBm for SX1262. For your RAK device, I think it comes with SX1262, thus you may set the tx power to 22 dBm.

Would you recommend to run the test first without changing the tx_power, since the 1.2.64 alone might have some positive impact?

I still have problems to read out the current tx_power settings, since with meshtastic --info there is no such information. Would be great, to learn, if there is a commend to get the current tx_power settings.

Yes, you may test first without changing TX power. I think this is what the new firmware fixed, its about the RF switch control. If the RF switch is not properly controlled, the RF signal cannot reach the antenna normally:

For reading back the tx_power, I haven’t found any relevant commands yet, but the default TX Power of current products is generally not the largest TX Power.

What exactly did you measure that showed the network was better on the RAK?

It was no quantitative measurement, but more a better impression of reach. We have several T-Beams running in villages close by, with the new firmware 1.2.64 some more T-Beams showed up in the list, which were not visible with 1.2.59.

Is it possible to get a quantitative measurement of the connection quality by writing down the SNR value for the node, observed from one reference node?