[OpenWrt-Devel] [OpenWrt] 2.4Ghz limited to 50mW in DFS-ETSI
David Lang
david at lang.hm
Thu Jul 30 15:14:50 EDT 2015
What's more, The regulation is on the signal strength of the radiated
signal, not the transmitter power. so if you go to max transmitter power and add
a better antenna, you actually exceed the limits.
There is apparently an exception to this for point-to-point use. But you still
can't use full power + high gain antenna
David Lang
On Thu, 30 Jul 2015, Ben West wrote:
> You can look up your respective country's spectrum regulations. It is
> possible prior versions OpenWRT didn't fully conform to each regulatory
> domain and were fixed in more recent versions (just as the converse is
> possible).
>
> For example, for the USA, here is a table of power limits for the 2.4GHz
> and 5GHz bands. Channels 36-48 are limited to 16dBm transmitter power.
> http://www.air802.com/fcc-rules-and-regulations.html
>
> On Thu, Jul 30, 2015 at 3:32 AM, Nicola von Thadden <nico at vthadden.de>
> wrote:
>
>> Hi,
>>
>> I also thought to have used 20dBm or 23dBm in earlier releases (AA).
>> Is there a way to find out to which txpower levels the 5Ghz transceiver
>> is limited? I think the driver reads them out, maybe there is a way to
>> print them on the cmd?
>>
>> But my main problem is the 17dBm on 2.4Ghz when setting DFS-ETSI
>> countries. I don't think that it is a problem of the hardware but of the
>> software parsing the regdom. Maybe there is a fixed limit of 17dBm on
>> non-DFS channels, even when DFS is not required, which is not very
>> useful. Does anyone have an idea where that could be set? My search in
>> the source code had no results until now, where it could be.
>>
>> Thanks
>> Nico
>>
>> On 07/29/2015 06:21 PM, Atanas Vladimirov wrote:
>>> https://dev.openwrt.org/ticket/20201
>>>
>>> On BB I used 20dBm for both 2.4 and 5GHz on the same router.
>>>
>>> Sent with AquaMail for Android
>>> http://www.aqua-mail.com
>>>
>>> On 29 юли 2015 г. 18:40:10 Ben West <ben at gowasabi.net> wrote:
>>>
>>>> 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
>>>> <mailto: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 <mailto: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
>>>> <mailto: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 <mailto:ben at gowasabi.net>
>>>> 314-246-9434
>>>> _______________________________________________
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>>>>
>>>
>>>
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>>
>
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