Anyone know what these NVRAM settings do?

[Vexed]

1:mcsbw805glpo=0x88653320
1:mcsbw805ghpo=0x88653320
0:mcsbw402gpo=0x88653320
0:mcsbw202gpo=0x88653320
1:mcsbw405glpo=0x88653320
1:mcsbw405ghpo=0x88653320
1:mcsbw205gmpo=0x88653320
1:mcsbw205glpo=0x88653320
1:mcsbw805gmpo=0x88653320
1:mcsbw205ghpo=0x88653320
1:mcsbw405gmpo=0x88653320
1:mcsbw1605glpo=0
1:mcsbw1605gmpo=0
1:mcsbw1605ghpo=0
1:mcslr5glpo=0
1:mcslr5gmpo=0
1:mcslr5ghpo=0

# Power-Per-Rate settings:
#
# General notes on these settings:
# - real_max_power[chain, rate] = max_power[chain] - power_offset[rate]
#
# - The power offset is in units of 0.5dB.
# Note: Some offsets are signed offsets. Others are unsigned. Unless explicitly mentioned, offsets should be treated as unsigned.
#
# - 11n rates mcs8-mcs15, mcs16-mcs23, and mcs24-mcs31 will have the same power-per-rate offsets corresponding to mcs0-mcs7.
# In other words, the power-per-rate offsets on each chain are irrepsective of the number of streams
#
# - 11ac rates mcs0-mcs9 will have the same power-per-rate offsets on each chain irrespective of the number of streams
#
# - mcs32 uses the same power offsets as legacy 40Dup 6 Mbps
# mcsbw205glpo is the 5GHz band, low sub-band, 11a 6-54, 11n mcs0-23, 11ac mcs0-9, 20MHz BW, power offsets
# Nibble: 7 6 5 4 3 2 1 0
# --- --- --- --- --- --- --- ---------
# Offset for 11a rates: - - - 54 48 36 24 18,12,9,6
# Offset for 11n mcs rates: - - 7 6 5 4 3 2,1,0
# Offset for 11ac mcs rates: 9 8 7 6 5 4 3 2,1,0
#
# each offset is in half-dB steps of reduction from maxp5gb0a0/maxp5gb0a1/maxp5b0ga2
1:mcsbw205glpo=0x99753333

I accidentally found these settings while reading the man for the wl driver. They seem to be tied to the wl curppr setting command.

# wl curppr
Power/Rate Dump (in 1/4dB): Channel 1
20MHz:
CCK           0  0  0  0
CCK CDD 1x2   6  6  6  6
CCK CDD 1x3   9  9  9  9
OFDM          0  0  0  0  3  3  5  6
OFDM-CDD      6  6  6  6  6  6  6  6
1 Nsts 1 Tx   0  0  0  2  3  3  5  6  8  8
1 Nsts 2 Tx   6  6  6  6  6  6  6  6  8  8
1 Nsts 3 Tx   9  9  9  9  9  9  9  9  9  9
2 Nsts 2 Tx   6  6  6  6  6  6  6  6  8  8
2 Nsts 3 Tx   9  9  9  9  9  9  9  9  9  9
3 Nsts 3 Tx   9  9  9  9  9  9  9  9  9  9

The numbers in wl curppr all decrease if you set non-zero values to 0x00000000. This changes the numbers but I'm not sure it actually does anything.

# wl curppr
Power/Rate Dump (in 1/4dB): Channel 1
20MHz:
CCK           0  0  0  0
CCK CDD 1x2   2  2  2  2
CCK CDD 1x3   6  6  6  6
OFDM          0  0  0  0  3  3  5  6
OFDM-CDD      2  2  2  2  3  3  5  6
1 Nsts 1 Tx   0  0  0  0  0  0  0  0  0  0
1 Nsts 2 Tx   2  2  2  2  2  2  2  2  2  2
1 Nsts 3 Tx   6  6  6  6  6  6  6  6  6  6
2 Nsts 2 Tx   2  2  2  2  2  2  2  2  2  2
2 Nsts 3 Tx   6  6  6  6  6  6  6  6  6  6
3 Nsts 3 Tx   6  6  6  6  6  6  6  6  6  6

There are also these settings. I think it refers to "Specific absorption rate" but I couldn't find out if 18dBm and 15dBm corresponds to any jurisdictions, or what these settings did in the firmware.

# sar2g is the SAR limit for the 2.4GHz band
# value in in dBm
# Set 18dBm for 2.4GHz
1:sar2g=18
# sar5g is the SAR limit for the 5GHz band
# value is in dBm
# Set 15dBm for 5GHz
1:sar5g=15

 

[CrashXRu]

Most of the settings are chip calibration.

There are no 2 identical chips, all of them are checked at the factory and are adjusted in accordance with the requirements of power for data transmission and power consumption.

 

[gjf]

I am especially interested in SAR values.

Because it looks like sar2g=18 and sar5g=15 always in all routers - so

There are no 2 identical chips, all of them are checked at the factory and are adjusted in accordance with the requirements of power for data transmission and power consumption.

looks untrue.

These values come from CFE. There are some reports that sar2g=24 and sar5g=20 improve the signal slightly - but I really cannot understand why. Afaik "SAR" means "Specific Absorption Rate" - but what for? I don't understand and any ideas would be interesting.

 

[Make WiFi Great Again]

I believe (though maybe incorrectly so) that sar has to do with limiting radiation emissions as it pertains to humans. I think I know what you are trying to do and I hope you are on the right track. Pls, keep me informed if you get anywhere.

 

[Vexed]

I believe (though maybe incorrectly so) that sar has to do with limiting radiation emissions as it pertains to humans. I think I know what you are trying to do and I hope you are on the right track. Pls, keep me informed if you get anywhere.

@gjf
A bit of a late response, I forgot to follow up but I'm here.

If your router's maxp*ga* settings are already maxed out to 120, your router is in manufacturing mode, and you set all the non-zero mcsbw* values to 0x00000000 by writing them to the cfe...

The router dumps so much dirty RF into the air that your skin tingles if you stand close to it with almost no appreciable gain in wifi performance. Don't set your mcsbw* values to all zeroes is the lesson to be learned.