E5-Mini Low Output Power

Products & Technology Wio Series
#1

Hi all,

I’ve been programming the E5-Mini using the STM32Cube IDE for LoRa purposes and I was noticing pretty terrible range. Doing some testing on with a spectrum analyser showed the power output was significantly below what was expected from the settings.
The board is advertised to have a tx power output of a max 20.8dBm @3.3V. My findings are (E-mini connected directly to spectrum analyser with changing the TX_OUTPUT_POWER settings) are:
Setting Power | Measured output power
14 & 15 = -77dB
16 = 3.7dB
17 = 5dB
18 = 7.4dB
…
21 = 10.8db
22-31 = ~6.6dB

I’m guessing the >21dB settings are hitting some sort of limit and have been capped at ~6.6dB actual output. 14dB (which is what the setup defaults to) and 15db are really shocking power outputs and I can’t think of a reason why.
As for the general low power I’m wondering if there’s any other low power settings crippling the power? Or is this a known problem of some sort?
Thanks for your help.

#2

What about the following 3 points?
Is the output of LoRa-E5 CW (unmodulated continuous output)? Is there impedance matching between LoRa-E5 and spectrum analyzer input? Can the spectrum analyzer accept an input of 22 dBm?

#3

There is impedance matching and the spectrum analyser is rated for +30dBm.
The output was not CW, it was using messages sent (Radio.Send)
I’ve just attempted to output in CW mode using Radio.SetTxContinuousWave(915000000,20,1), but I’m not getting an output from it.

#4

I tried to increase the output, but setting it above 14 dBm, the maximum value of the rules in my area, did not increase the output.
The output is not accurate because I am using an SDR dongle to observe it. And I am using Arduino and RadioLib library.

I checked the current during transmission.
As expected, the current did not increase above 13 dBm. It seems that the firmware may be protected for each country to which it is shipped.

4 dBm     66 mA
8         79
10        86
13        89
18        89
22        89