Huge thanks to Larry, Michael and Dennis! We had similar counsel from our
local and excellent lab. After getting your summaries we were able to get
this resolved so we can move ahead.
Thanks again!
Curt
On Fri, Jan 31, 2014 at 11:56 AM, Dward <[email protected]> wrote:
> Michael gives a good over view of the situation. The bottom line is that
> a device CANNOT transmit on any frequency that it has not been shown to
> comply. So, even if the device passive scans, it still cannot transmit on
> channels 12 and 13 unless those channels have been shown to comply in the
> application for certification. If channels 12 and 13 were part of the
> initial filing, and they passive scan, then they can transmit. Even if
> they do not passive scan, but have been shown to comply with the rules they
> can transmit. If they have not been shown to comly then they cannot
> transmit - period passive scan or not.
>
>
>
> But here is the real issue. If a device has been shown to comply and has
> channels 12 and 13 on the grant, then there would be no need to passive
> scan any more than on any of the other channels 1-11. The question then is
> why passive scan on these channels in the first place. The answer, other
> countries use these channels and at the same or similar power as the other
> channels; so using the incorrect concept that "the US does not have these
> channels, so it should be OK to passive scan because it won't transmit in
> the US" is simply NOT true. The US does have and allows these channels,
> when properly tested and shown to comply and the channel frequency is
> included on the grant. Since the beginning of the WLAN craze, it has
> always been this way.
>
>
>
> While the FCC, also in the beginning of the TCB program, tried to
> 'mandate' that only channels 1-11 could be used, that ended very quickly
> when a certain manufacturer basically said, uh NO, nothing in the rules
> stops me from using channels 12 and 13 as long as I comply to the rules.
> Needless to say, that manufacturer was and is correct and these channels
> have been certifiable all along. It is difficult, but it is doable. I can
> remember as far back as very early in the TCB program when I certified my
> first channel 12 and 13 WLAN device. So, they are out there and the
> concept that ' I should be able to simply passive scan channel 12 and 13
> for when the device is in a country that uses these channels, and not worry
> about them in the US because the US does not have these channels" simply
> does not fly and never has.
>
>
>
> In essence, the FCC has always allowed properly tested and properly
> powered channels 12 and 13 passive scanning when the device has been shown
> to comply to the rules in the channels it scans. It is only when no
> evidence of compliance for those channels exists that the FCC, rightfully
> so, says NO.
>
>
>
> Thanks
>
> Dennis Ward
>
> Senior Certification Engineer
>
> PCTEST
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>
> *From:* Michael Derby [mailto:[email protected]]
> *Sent:* Friday, January 31, 2014 1:28 AM
> *To:* [email protected]
> *Subject:* Re: [PSES] FCC draft comments on WiFi operation in channels 12
> and 13
>
>
>
> Hello Curt,
>
>
>
> It has always been possible to use channels 12 and 13 in the USA because
> they are perfectly "in band" channels. However, it is very difficult for
> a WLAN device to pass the FCC tests on those channels, so most
> manufacturers simply choose to disable them. Some manufacturers choose to
> reduce the power on those channels. Of course, if the whole device has
> sufficiently low power, then it might pass channels 12 and 13 (or just 12)
> without additional power reduction.
>
>
>
> This means that most WLAN devices use only channels 1 to 11 but some do
> use 1 to 12 or 1 to 13. (12 is easier to get passing than 13, since the
> tricky test is a band edge issue)
>
>
>
> It has always been the case that if you only test and certify your device
> up to channel 11, then you cannot sell a device which could transmit on
> channels 12 or 13.
>
>
>
> In the past, manufacturers have asked the FCC if their devices can passive
> scan on 12 and 13, even if their device is only certified up to channel 11.
>
> Of course the answer was "yes, you can passive scan" because passive
> scanning does not include transmission.
>
> Of course, the assumption then should be that if the client device sees a
> working access point on channel 12 or 13, it must not actually form a link
> and transmit!
>
>
>
> You can imagine that as a TCB, if we see an application which states that
> a device transmits on channels 1 to 11 and can also passive scan on
> channels 12 and 13; it looks perfectly reasonable. Many did not realise
> the need to ask: "Please confirm that it cannot transmit on channels 12 or
> 13 if instructed to do so by the access point".
>
>
>
> It seems that some manufacturers did not make that final step. I am not
> going to say if this was a misunderstanding or avoidance of the rules by
> the manufacturer or lack of explanation by the FCC; this is not my comment
> to make and I'm sure there is a variety of answers.
>
>
>
> So, last summer 2013, the FCC clarified the point that you can passive
> scan on those channels but you cannot transmit on those channels if you are
> not certified to use them, even if instructed to do so by an access point.
>
> (Remember that the access point could be using channels 12 and 13 by
> implementing power reduction, or could simply be breaking the rules!)
>
>
>
> This 'clarification' came as a surprise to some manufacturers (but not
> all).
>
>
>
> Due to this 'surprise', the FCC gave a "6 month amnesty" where they would
> not actively enforce/investigate this issue. I don't like to call it a
> transition period because nothing has actually changed. It is a
> clarification/explanation of the existing rules, it is not a change in the
> rules.
>
>
>
> I believe the "amnesty" expires next month.
>
>
>
>
>
> I hope this helps.
>
>
>
>
>
> Michael.
>
>
>
>
>
>
>
> Michael Derby
>
> Regulatory Engineer
>
> ACB Europe
>
>
>
> *From:* Curtis Mc Namara [mailto:[email protected] <[email protected]>]
> *Sent:* 30 January 2014 23:48
> *To:* [email protected]
> *Subject:* [PSES] FCC draft comments on WiFi operation in channels 12 and
> 13
>
>
>
> FCC Draft KDB 594280 Software Configuration Control DR04-41649:
> https://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=352&tn=402501
>
> This draft says that operation on channels 12 and 13 in the US cannot rely
> on passive scanning alone. However, at this point it is a draft, and the
> introductory paragraph says to follow previous guidance.
>
> Has a anyone here evaluated this? I have a customer with products in the
> field which use passive scanning, and they are curious whether there will
> be a transition time, and whether it is still permissible and practical to
> ship devices with passive scanning.
>
> Thanks!
>
> Curt
>
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