[OpenWrt-Devel] [OpenWrt] 2.4Ghz limited to 50mW in DFS-ETSI

Ben West ben at gowasabi.net
Wed Jul 29 11:39:34 EDT 2015 

This is what I observe running Barrier Breaker on UBNT M5 products, too.  I
believe the 17dBm limit is intentional, i.e. per regulation.  The 30dBm tx
power limit applies to channels 149 and above, I believe.

>  Also (kind of off-topic): Do you know why 5Ghz channels 36-48 are forced
>  to be 17dBm only on the WNDR3800? I found two possible explanations:
>  either because of the factory calibration


On Wed, Jul 29, 2015 at 10:25 AM, Gerald Matzka <mgerald21 at yahoo.de> wrote:

> Well, it looks like the txpower of your wdnr3800 is limited to 17dBm
> because of the hardware reg-domain settings.
>
> Kind regards,
>
> ... sent from my iPhone
>
> > Am 29.07.2015 um 10:43 schrieb Nicola von Thadden <nico at vthadden.de>:
> >
> > Hi,
> >
> > I have this strange behaviour down below, for which I also opened a
> > ticket because I think this should not be like that ;)
> >
> > Does anyone have an idea where the problem could originate from and how
> > to fix it?
> >
> > Thanks
> > Nico
> >
> >> On 07/29/2015 12:37 AM, OpenWrt wrote:
> >> #20222: 2.4Ghz limited to 50mW in DFS-ETSI
> >> ----------------------+----------------------------------
> >> Reporter:  nicoduck  |      Owner:  developers
> >>     Type:  defect    |     Status:  new
> >> Priority:  normal    |  Milestone:  Chaos Calmer (trunk)
> >> Component:  kernel    |    Version:  Trunk
> >> Keywords:  wndr3800  |
> >> ----------------------+----------------------------------
> >> I have got a Netgear WNDR 3800 running with openwrt since quite a while.
> >> I now upgraded to the latest version (trunk) and wanted to use WLAN
> within
> >> the regulations here in Germany but also wanted to max out the output
> >> power (within the regulations).
> >> Switching the country to Germany limits the maximum output power to
> 17dBm,
> >> although it does show as being limited on 20dBm:
> >> root at OpenWrt:/# iwinfo wlan0 txpower
> >>    0 dBm (   1 mW)
> >>    1 dBm (   1 mW)
> >>    2 dBm (   1 mW)
> >>    3 dBm (   1 mW)
> >>    4 dBm (   2 mW)
> >>    5 dBm (   3 mW)
> >>    6 dBm (   3 mW)
> >>    7 dBm (   5 mW)
> >>    8 dBm (   6 mW)
> >>    9 dBm (   7 mW)
> >>   10 dBm (  10 mW)
> >>   11 dBm (  12 mW)
> >>   12 dBm (  15 mW)
> >>   13 dBm (  19 mW)
> >>   14 dBm (  25 mW)
> >>   15 dBm (  31 mW)
> >>   16 dBm (  39 mW)
> >> * 17 dBm (  50 mW)
> >>   18 dBm (  63 mW)
> >>   19 dBm (  79 mW)
> >>   20 dBm ( 100 mW)
> >>
> >> What I did: reset the device, flash it with various builts from trunk
> and
> >> try to figure out what was going on.
> >> I now modified my regdb and was able to isolate the source of the
> problem:
> >> country DE: DFS-ETSI
> >>         # entries 279004 and 280006
> >>         (2400 - 2483.5 @ 40), (100 mW)
> >>         # entry 303005
> >>         (5150 - 5250 @ 80), (200 mW), NO-OUTDOOR, AUTO-BW
> >>         # entries 304002 and 305002
> >>         (5250 - 5350 @ 80), (100 mW), NO-OUTDOOR, DFS, AUTO-BW
> >>         # entries 308002, 309001 and 310003
> >>         (5470 - 5725 @ 160), (500 mW), DFS
> >>         # 60 gHz band channels 1-4, ref: Etsi En 302 567
> >>         (57000 - 66000 @ 2160), (40)
> >> Thas does not work and has the mentioned behaviour, 2.4Ghz is limited at
> >> 17dBm. It also does not depend on which values are set in the regulatory
> >> database for the 2.4Ghz channels, anything over 17dBm will be limited to
> >> 17dBm.
> >> running "iw phy phy0 set txpower fixed 2000" gives no error but does not
> >> change it to 20dBm. Changing the value to anything below 17dBm works
> >> though.
> >>
> >> country DE: DFS-FCC
> >>         # entries 279004 and 280006
> >>         (2400 - 2483.5 @ 40), (100 mW)
> >>         # entry 303005
> >>         (5150 - 5250 @ 80), (200 mW), NO-OUTDOOR, AUTO-BW
> >>         # entries 304002 and 305002
> >>         (5250 - 5350 @ 80), (100 mW), NO-OUTDOOR, DFS, AUTO-BW
> >>         # entries 308002, 309001 and 310003
> >>         (5470 - 5725 @ 160), (500 mW), DFS
> >>         # 60 gHz band channels 1-4, ref: Etsi En 302 567
> >>         (57000 - 66000 @ 2160), (40)
> >>
> >> Thad does work. The only change to the entry above is "DFS-FCC" instead
> of
> >> "DFS-ETSI". I can now select any powerlevel between 1 and 20dBm and it
> is
> >> also reported as being used:
> >> root at OpenWrt:/# iwinfo wlan0 txpower
> >>    0 dBm (   1 mW)
> >>    1 dBm (   1 mW)
> >>    2 dBm (   1 mW)
> >>    3 dBm (   1 mW)
> >>    4 dBm (   2 mW)
> >>    5 dBm (   3 mW)
> >>    6 dBm (   3 mW)
> >>    7 dBm (   5 mW)
> >>    8 dBm (   6 mW)
> >>    9 dBm (   7 mW)
> >>   10 dBm (  10 mW)
> >>   11 dBm (  12 mW)
> >>   12 dBm (  15 mW)
> >>   13 dBm (  19 mW)
> >>   14 dBm (  25 mW)
> >>   15 dBm (  31 mW)
> >>   16 dBm (  39 mW)
> >>   17 dBm (  50 mW)
> >>   18 dBm (  63 mW)
> >>   19 dBm (  79 mW)
> >> * 20 dBm ( 100 mW)
> >>
> >>
> >> I have no idea why but there seems to be a bug in the code parsing the
> DFS
> >> regulations, limiting 2.4Ghz to lot lower values than allowed. Changing
> it
> >> to DFS-FCC works for using the applicaple output power but does not seem
> >> to be in compliance which German law.
> >>
> >> Do you have an idea where the problem could be? I'm happy to try out
> more
> >> builds and future versions.
> >>
> >> Also (kind of off-topic): Do you know why 5Ghz channels 36-48 are forced
> >> to be 17dBm only on the WNDR3800? I found two possible explanations:
> >> either because of the factory calibration (is it possible to get them
> in a
> >> human readable form somehow? The hexdump is not really readable and I
> have
> >> not been able to find the code which pases them) or because these
> channels
> >> are considered as "edge-channels" and someone thought it would be safe
> to
> >> limit the power, to not disturb any other systems running on even lower
> >> channels. The latter explanation is kind of weird because it would make
> no
> >> sense to limit these 4 channels but no other ones. I find it especially
> >> strange because that is typically the job of regulatory authorities, to
> >> define those power levels.
> >>
> >> --
> >> Ticket URL: <https://dev.openwrt.org/ticket/20222>
> >> OpenWrt <http://openwrt.org>
> >> Opensource Wireless Router Technology
> > _______________________________________________
> > openwrt-devel mailing list
> > openwrt-devel at lists.openwrt.org
> > https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
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>



-- 
Ben West
http://gowasabi.net
ben at gowasabi.net
314-246-9434
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