Power at 1496 mW on powerup/reboot? [AC66U ASUSWRT-Merlin RT-AC66U_3.0.0.4]

[ml70]

Is the output of wl txpwr/1 reliable? Because on a new nvram cleared system right after boot it says:

ASUSWRT-Merlin RT-AC66U_3.0.0.4 Fri Nov 1 23:26:23 UTC 2013
admin@RT-AC66U:/tmp/home/root# wl txpwr
31.75 dBm = 1496 mw.
admin@RT-AC66U:/tmp/home/root# wl txpwr1
TxPower is 127 qdbm, 31.75 dbm, 1496 mW Override is Off

Wireless>Professional is set at 40 mW.

Only after executing wl txpwr1 -m 40, txpwr reports 40 mW.

 

[ml70]

Router rebooted after changing some settings, back at 1496. Always.

 

[Raptor]

Is the output of wl txpwr/1 reliable? Because on a new nvram cleared system right after boot it says:

ASUSWRT-Merlin RT-AC66U_3.0.0.4 Fri Nov 1 23:26:23 UTC 2013
admin@RT-AC66U:/tmp/home/root# wl txpwr
31.75 dBm = 1496 mw.
admin@RT-AC66U:/tmp/home/root# wl txpwr1
TxPower is 127 qdbm, 31.75 dbm, 1496 mW Override is Off

Wireless>Professional is set at 40 mW.

Only after executing wl txpwr1 -m 40, txpwr reports 40 mW.

Hi ml70! The router is not outputting 1496 mW. This is simply a user request for 31.75 dbm / 1496 mw. The router is going to give you the best that it can based in built in power output table in the wifi driver. The driver dynamically adjust the outpower based on the country code and the settings in the driver. It would be the same as me asking my car to go 1000 miles and hour. Its not going to give my that but it will give the best it can within its limitations. With a 80 mw setting the RT-AC66U has an output of around 250 mw. Just set it to the standard 80 mw and forget about it.

 

[ml70]

Thank you, was worried about my brain frying sitting near the router

 

[RMerlin]

This is probably an uninitialized variable inside the driver. It will show that weird value if you are using the default values.

 

[Smedley]

With a 80 mw setting the RT-AC66U has an output of around 250 mw.

With a 80 mw setting, why wouldn't the output be around 80 mw?

 

[Raptor]

With a 80 mw setting, why wouldn't the output be around 80 mw?

Hi Smedley! That must be some kind of inside joke at ASUS. The mW input into the transmit power field does not represent the actual mW output from the antenna's. The real output power of the router varies from 200 to 300 mW depending on the channel and the country you are in. All the real mW output numbers are detailed in the FCC documents. ASUS has to give the real radio transmit output numbers to the FCC before they can sell the router on the US market. Increasing the transmit power level really does not improve signal strength while it can be used to reduce output. A setting of 100 mW is really the maximum output setting and inputs from 100 to 200 mW do not change the real power output. I've tested this extensively in a large quiet room with RT-AC66U router and laptop. Inputs of 0 to 100 changed the transmit level while inputs from 100 to 200 mW yield no differences. The setting of 80 mW that Asus chose as default is almost the maximum output while likely helping to reduce RF noise. Some people want to reduce there wireless footprint and this adjustment can be used to reduce output power. Asus should really have a output control of 100, 80, 60, 40, 20 percent to avoid confusion like most manufactures. Most modern routers output between 150 and 400 mW.

 

[Smedley]

Hi Smedley! That must be some kind of inside joke at ASUS. The mW input into the transmit power field does not represent the actual mW output from the antenna's. The real output power of the router varies from 200 to 300 mW depending on the channel and the country you are in. All the real mW output numbers are detailed in the FCC documents. ASUS has to give the real radio transmit output numbers to the FCC before they can sell the router on the US market. Increasing the transmit power level really does not improve signal strength while it can be used to reduce output. A setting of 100 mW is really the maximum output setting and inputs from 100 to 200 mW do not change the real power output. I've tested this extensively in a large quiet room with RT-AC66U router and laptop. Inputs of 0 to 100 changed the transmit level while inputs from 100 to 200 mW yield no differences. The setting of 80 mW that Asus chose as default is almost the maximum output while likely helping to reduce RF noise. Some people want to reduce there wireless footprint and this adjustment can be used to reduce output power. Asus should really have a output control of 100, 80, 60, 40, 20 percent to avoid confusion like most manufactures. Most modern routers output between 150 and 400 mW.

Thanks for the explanation. I run mine with the Transmit Power set to 50 mw, so is that about half of the maximum output (whatever that is based on channel and country), or the whole thing non-linear?

 

[Raptor]

Thanks for the explanation. I run mine with the Transmit Power set to 50 mw, so is that about half of the maximum output (whatever that is based on channel and country), or the whole thing non-linear?

Hi Smedley! Its really non linear now. A few years ago it was more straight forward, set your power level and that what you got. Now Broadcom and the manufactures use a dynamically adjusting drivers and a power table. I think things like beam forming are taking even more power control out of our hands.

Example output from a Broadcom power table: All the number are dBm.
The driver at first request 31.75 dBM which is 1,496 mW (Not possible)
I think it is some Broadcom initialization setting.

Power Control: On, HW
Current channel: 11
BSS channel: 11
BSS Local Max: 30.0 dBm
BSS Local Constraint: 0.0 dB
User Target: 31.75 dBm
SROM antgain: 2G: 0.0 dB, 5G: 0.0 dB

Regulatory Limits:
CCK : 30.0
CCK CDD 1x2 : 30.0
CCK CDD 1x3 : 30.0
Legacy OFDM 20MHz SISO : 30.0
Legacy OFDM 20MHz CDD : 30.0
MCS 0-7 20MHz 1 Tx : 16.50
MCS 0-7 20MHz 2 Tx : 14.0
MCS 0-7 20MHz 3 Tx : 14.0
MCS 8-15 20MHz 2 Tx : 14.0
MCS 8-15 20MHz 3 Tx : 14.0
MCS 16-23 20MHz 3 Tx : 14.0
Legacy OFDM 40MHz SISO : 0.0
Legacy OFDM 40MHz CDD : 0.0
MCS 0-7 40MHz 1 Tx : 0.0
MCS 0-7 40MHz 2 Tx : 0.0
MCS 0-7 40MHz 3 Tx : 0.0
MCS 8-15 40MHz 2 Tx : 0.0
MCS 8-15 40MHz 3 Tx : 0.0
MCS 16-23 40MHz 3 Tx : 0.0
MCS 32 : 0.0
20UL CCK : 30.0
20UL CCK CDD 1x2 : 30.0
20UL CCK CDD 1x3 : 30.0
20UL Legacy OFDM : 30.0
20UL Legacy OFDM CDD : 30.0
MCS 0-7 20UL 1 Tx : 16.50
MCS 0-7 20UL 2 Tx : 14.0
MCS 0-7 20UL 3 Tx : 14.0
MCS 8-15 20UL 2 Tx : 14.0
MCS 8-15 20UL 3 Tx : 14.0
MCS 16-23 20UL 3 Tx : 14.0

Board Limits:
CCK : 23.50
CCK CDD 1x2 : 23.50
CCK CDD 1x3 : 23.50
Legacy OFDM 20MHz SISO : 22.50
Legacy OFDM 20MHz CDD : 22.50
MCS 0-7 20MHz 1 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 0-7 20MHz 2 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 0-7 20MHz 3 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 8-15 20MHz 2 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 8-15 20MHz 3 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 16-23 20MHz 3 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
Legacy OFDM 40MHz SISO : 20.50
Legacy OFDM 40MHz CDD : 20.50
MCS 0-7 40MHz 1 Tx : 20.50 20.50 20.50 20.50 17.50 17.50 17.50 17.50
MCS 0-7 40MHz 2 Tx : 20.50 20.50 20.50 20.50 17.50 17.50 17.50 17.50
MCS 0-7 40MHz 3 Tx : 20.50 20.50 20.50 20.50 17.50 17.50 17.50 17.50
MCS 8-15 40MHz 2 Tx : 20.50 20.50 20.50 20.50 17.50 17.50 17.50 17.50
MCS 8-15 40MHz 3 Tx : 20.50 20.50 20.50 20.50 17.50 17.50 17.50 17.50
MCS 16-23 40MHz 3 Tx : 20.50 20.50 20.50 20.50 17.50 17.50 17.50 17.50
MCS 32 : 20.50
20UL CCK : 23.50
20UL CCK CDD 1x2 : 23.50
20UL CCK CDD 1x3 : 23.50
20UL Legacy OFDM : 22.50
20UL Legacy OFDM CDD : 22.50
MCS 0-7 20UL 1 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 0-7 20UL 2 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 0-7 20UL 3 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 8-15 20UL 2 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 8-15 20UL 3 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50
MCS 16-23 20UL 3 Tx : 22.50 22.50 22.50 22.50 22.50 20.50 19.0 17.50

Power Target:
CCK : 22.0
CCK CDD 1x2 : 22.0
CCK CDD 1x3 : 22.0
Legacy OFDM 20MHz SISO : 21.0
Legacy OFDM 20MHz CDD : 21.0
MCS 0-7 20MHz 1 Tx : 15.0
MCS 0-7 20MHz 2 Tx : 12.50
MCS 0-7 20MHz 3 Tx : 12.50
MCS 8-15 20MHz 2 Tx : 12.50
MCS 8-15 20MHz 3 Tx : 12.50
MCS 16-23 20MHz 3 Tx : 12.50
Legacy OFDM 40MHz SISO : 0.0
Legacy OFDM 40MHz CDD : 0.0
MCS 0-7 40MHz 1 Tx : 0.0
MCS 0-7 40MHz 2 Tx : 0.0
MCS 0-7 40MHz 3 Tx : 0.0
MCS 8-15 40MHz 2 Tx : 0.0
MCS 8-15 40MHz 3 Tx : 0.0
MCS 16-23 40MHz 3 Tx : 0.0
MCS 32 : 0.0
20UL CCK : 0.0
20UL CCK CDD 1x2 : 0.0
20UL CCK CDD 1x3 : 0.0
20UL Legacy OFDM : 0.0
20UL Legacy OFDM CDD : 0.0
MCS 0-7 20UL 1 Tx : 0.0
MCS 0-7 20UL 2 Tx : 0.0
MCS 0-7 20UL 3 Tx : 0.0
MCS 8-15 20UL 2 Tx : 0.0
MCS 8-15 20UL 3 Tx : 0.0
MCS 16-23 20UL 3 Tx : 0.0

Maximum Power Target among all rates: 22.0 22.0 22.0
Rate index with Maximum Power Target: 0 0 0
Last adjusted est. power : 22.25 22.0 22.0

My router is now transmitting at 22.0 dBm
22 dBm is 158.489 mW