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 This communication and its attachments contain information from PCTEST Engineering Laboratory, Inc., and is intended for the exclusive use of the recipient (s) named above. It may contain information that is confidential and/or legally privileged. Any unauthorized use that may compromise that confidentiality via distribution or disclosure is prohibited. Please notify the sender immediately if you receive this communication in error, and delete it from your computer system. Usage of PCTEST email addresses for non-business related activities is strictly prohibited. No warranty is made that the e-mail or attachment(s) are free from computer virus or other defect. Thank you. From: Michael Derby [mailto:micha...@acbcert.com] Sent: Friday, January 31, 2014 1:28 AM To: EMC-PSTC@LISTSERV.IEEE.ORG 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:mcnam...@umn.edu] Sent: 30 January 2014 23:48 To: EMC-PSTC@LISTSERV.IEEE.ORG 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 <https://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=352&tn=40250 1> &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 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
