Hi Morse Micro team,
The maximum TX power of MM8108-EKH19 as mentioned in the datasheet is 26dBm
But when we check it via the webGUI it is limited to 22dBm.
I even tried to increase the TX power using “iw wlan0 set txpower fixed 2600”, but it is also limited to 22dBm.
Thanks,
Arti
Hi Arti,
26dBm is the maximum rating for the TX power of the chip itself.
In actual applications it’s got a few layers of constraints, firstly the SEM and EVM requirements of the 802.11ah, followed by the spectral requirements from your region’s regulatory body. The MCS has a role in determining the former two. There’s also insertion losses when you’re measuring externally.
Hi @michael.mccandless ,
Thank you for your input on this.
We are using MCS 2 with 2 Mhz bandwidth.
We are measuring the data from the GUI.
Which BCF file should we use to get the maximum power?
The BCF which will give you “maximum power” is the BCF that is right for your module, anything else is more than likely going to negatively impact your radio performance.
If you’re manually selecting a BCF, use the BCF that is named to match your module - eg bcf_mf15457.bin.
The bcf_boardtype_<id>.bin are usually installed as symbolic links to specific module BCFs to allow the driver to query the chip to determine which module it must load - as programmed by the module manufacturer.
I missed this bit. For an accurate confirmation of the power levels I would strongly recommend measuring the power with at least a spectrum analyzer or power meter. The value reported here is indicative, and can’t account for per-mcs configuration values. I left some detail in this post: Linux TX Power Max Reported Value for MM8108 - #2 by ajudge
How can we achieve the maximum power of the given module?
We have 2 modules one is the gateswork MM8108-M20 module which supports 28.5dbm , but we are getting 26dbm maximum power.
One is the MM8108 USB module which support 26dbm but we are getting 24 dbm maximum power.
Are you measuring the power as Arien suggested or relying on what iw/iwinfo reports?
I am relying on the iw iwinfo commands as I do not have appropriate spectrum analyser.
Also note, I have tried to change the “iw dev wlan0 set txpower fixed ” command. The result is reflected with iw info but only till 26dbm if i set 2700 the power still remaing 26.
Can you confirm which BCF I should use to get the maximum power with the M20 module?
Thanks
Also Can you share the TX power table for the latest M20 module. We would like to check at waht MCS settings and bandwidth we can acheieve the maximum power.
Thanks
