Dear Michael,
Thanks for your useful example of WiFi devices! The permissible limit is 20 dBm or 100 mW. Where can we find it for different type of products? Can you shed light why <20 dBm is considered useless. That is the design to allow for this type of products. Each designer can fully utilise the allowable power for optimising the performance of the product. I agree on rated power for each product to be quoted. Did you mean the tolerance +/- 1 dB is subject to the upper limit and lower limit of mass production. Each product may vary depending on the complexity of the product. What are about Bluetooth devices? I have learnt the permissible limit is 13 dBm or 20 mW but did not find the reference. However I read a test report of EN 62479 on a Bluetooth speaker. It was measured max E.I.R.P. = -7.9 dBm or 0.16 mW in 2.4 GHz. The manual and the RED compliance cert are stated <20 dBm. It seems not right, isn’t it? If the limit is used in mass production, the devices may be faulty and still fall into the limit. For frequency range, did the compliance test verify it? If so, where I can find the test result so I can put appropriate statement on manual accordingly. Thanks and regards, Scott From: Michael Derby <micha...@acbcert.com> Date: Tuesday, 18 April 2017 at 6:22 PM To: 'Scott Xe' <scott...@gmail.com>, <EMC-PSTC@LISTSERV.IEEE.ORG> Subject: RE: [PSES] Frequency range & transitted power for RED Hi Scott, The most common, and most recent, guidance is that the user manual should list the rated power of the product. For example, let’s say you have a WiFi device in the 2.4 GHz band, and the power (e.i.r.p.) is rated at 14 dBm +/- 1 dB.. Let’s say that you measure 13.8 dBm e.i.r.p. in the test lab. We know the limit in the standard is 20 dBm. It would not be necessary to state 13.8 dBm exactly. That value only applies to the one unit you tested, and of course it means you cannot plan your user manual until you tested! Similarly, it would be rather useless to state “<20 dBm” in the user manual; because of course we all know that. The user manual should therefore state: 14 dBm, +/- 1 dB. (the rated power) You can use common terms, like GSM 900, or LTE Band 1. But be careful with some things, like “5 GHz WLAN” because that would not be specific enough…. Because there are so many 5 GHz WLAN bands (some of which are permitted in the EU and some are not) I am not sure I understand the second part of your question: “With a compliance report, where do we check if they fall into the permissible limits?” Are you testing to the standards? Or are you checking the accuracy of the user manual statements? Michael. Michael Derby Senior Regulatory Engineer Director ACB Europe Certification Resource for the Wireless Industry Web: www.acbcert.com e-mail: micha...@acbcert.com Mobile phone: (+44) 7939 880829 (UK area code) Corporate office phone: USA: (+1) 703 847 4700 From: Scott Xe [mailto:scott...@gmail.com] Sent: 17 April 2017 10:27 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Frequency range & transitted power for RED In user manual, it is required to give the info on frequency range & transmitted power. What is the right info to give there? With a compliance report, where do we check if they fall into the permissible limits? The products are Bluetooth speakers and keyboard/mouse with a RF dongle. Thanks and regards, Scott - ---------------------------------------------------------------- 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) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
