Finding hardware default transmit power

Discussion in 'Tomato Firmware' started by schnappi, Oct 2, 2017.

  1. schnappi

    schnappi Networkin' Nut Member

    Hi toastman, shibby, and koitsu,

    Always been a toastman build person but just to be fair put shibby builds half of Tomato routers/ access points today (since had to reset NVRAM to solve issue anyways). Also in a decision not taken lightly enabled to anonymous usage reporting because trust Tomato (everyone else takes information without asking why not give information to someone that like when they do ask?).

    In going through all the shibby settings went through wifi settings and again saw transmit power that really has two good options (understand doesn't really matter after reading toastman's posts on this a while back). Either 0 for hardware default or Tomato default of 42. How does one find the hardware default transmit power for a device, or alternatively if anyone knows it off top of head for RT-N66U?
  2. schnappi

    schnappi Networkin' Nut Member

    Just saw that Koitsu gave up on tomato, Toastman is MIA, and Shibby is newly married. So going to answer own question. Not sure exactly what hardware defaults to for output power but if Toastman left it at 42 (or changed it to 42 when he forked the original Tomato code) will leave what Toastman recommend as the default setting.

    Either 42 or zero probably has negligible difference anyways.
  3. Sean B.

    Sean B. LI Guru Member

    What scale do you want? If dBm is acceptable, then simply set txpwr to 0 on the appropriate radio and then check it's value for max target power:

    wl -i eth1 txpwr 0
    wl -i eth1 txpwr_target_max
    If milliwatts is what you prefer, get the dBm value as stated above then start entering values into txpwr and check the corresponding target value until you get a match. Or, find an online conversion chart.
    Last edited: Oct 10, 2017
  4. Monk E. Boy

    Monk E. Boy Network Guru Member

    I think he's asking what the OEM firmware sets the power level to for his particular model (N66).

    Merlin might know, he has a variant that runs on an N66 and to my knowledge it's identical to OEM as far as transmit power is concerned.
  5. Sean B.

    Sean B. LI Guru Member

    Woops, read your statement wrong so let me reword. While OEM firmware may set the power to some unknown level between 0 and regulatory limit, the OP had asked about hardware defaults:

    And, correct me if I'm wrong, but from my understanding when txpwr is set to 0 then wl will use a default power level according to the chipset series. My method should be sound with either OEM firmware ( if user space access to wl was available ) or Tomato, as far as hardware default is concerned.

    As a side note: While this question may be just out of curiosity, in case it's out of concern that manipulating the txpwr setting could cause damage or premature wear to your router then worry not. The txpwr setting is really a txpwr suggestion. Wl will accept whatever number you want to provide for it and not argue or toss an error back. This is because it will only implement the setting to a level at or below the regulatory limits in the CFE for your country/region, all of which the chipset and power amps etc were designed to handle as normal. This can been seen by setting txpwr to several over-limit values that progressively get higher. You will see that txpwr_target_max doesn't change.. and corresponds to the maximum output power allowed per regulation.
    Last edited: Oct 11, 2017
    Monk E. Boy likes this.
  6. schnappi

    schnappi Networkin' Nut Member

    Adding to above here is what Merlin (Asuswrt-Merlin) had to say:

    It (hardware default transmit power) depends on the region, the channel, the number of streams, etc... The driver will dynamically adjust it based on numerous factors.
    No idea what effect that (Tomato transmit option set to zero) value will have on the wireless driver, so I can't recommend any particular value (zero versus 42 on Tomato), sorry.
  7. Sean B.

    Sean B. LI Guru Member

    The value of 0 for txpwr is not a Tomato introduced setting, it's directly stated by the broadcom driver "Set to 0 for hardware default ". Run " wl | grep txpwr " , which should catch the referenced line from the output. If not you'll have to scan through the full output an find it.
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