In my current employment I work with ED-14/DO-160 etc. and in THAT environment every cable counts.
I don't have a product to worry about in this matter but it seems to me that an ITE port connected to (and meant to connect to) a certain kind of wireless device might well by reason of that connection, fall into the "telecommunications" category -- with possibly undesired regulatory consequences. For example, I have an EVDO card plugged into a USB port. Whether the manufacturers of the *hardware* intend them to be called telecom ports is almost irrelevant if they market it with software that allows them to be used as such. WRT to being " 'regulated' if a case of interference actually occurs,"it appears OFCOM is reluctant to do even that. Different subject. Cortland Richmond KA5S > [Original Message] > From: John Woodgate <[email protected]> > To: Chris Wells <[email protected]> > Cc: Steve O'Steen <[email protected]>; <[email protected]> > Date: 9/16/2009 4:28:19 AM > Subject: Re: EMC question > > In message <0B2083BBF5664BCCA52EF295AE71B4B5@christopher>, dated Tue, 15 > Sep 2009, Chris Wells <[email protected]> writes: > > >I can see where the emission issues have a lot of meaning in telecom > >links since we need to keep this common/public link clean. At the same > >time I appreciate that my local proprietary RS485 link should strive to > >meet the same goal but I do want to know when I will be regulated to do > >so and want to see the boundaries clearly. We all need to know where > >the line lays and try to keep on the proper side. > > I don't think you will 'see the boundaries clearly' by reading the > standards, and in Britain you will only be 'regulated' if a case of > interference actually occurs. > > The reason is that there are too many variables affecting the potential > emissions from these cables. To be 100 % (actually only 99.9.. %) sure, > one would have to test for conducted common-mode emissions every port > that could have a cable longer than about 1 metre connected (0.1 > wavelength at 30 MHz). This is clearly (I think) over-onerous, as > 99.9.. % of products would pass. > > The EMC Directive is written so that manufacturers can (and have to) use > their own judgement about what testing is necessary. So it's really up > to you what you do. For example, you could pre-compliance test some of > your daisy-chained RS-485 products, to see whether there is any need to > test them fully. > > > >Another tangent on telecom is in regards to safety. To me telecom > >brings in exposure to surge from links outside of a building. Telecom > >POTS systems represent some of the more dangerous circuits that you can > >be exposed to. > > Well, they would be, if the system operator didn't have a lot of > protection fitted. POTS wring is dangerous if there is a nearby > lightning strike, but then so is practically anything metallic that > isn't deeply embedded in the planet. > > > In contrast an RS485 system restricted to the inside of a building > >does not represent the same threat. > > This is certainly the case. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > Things can always get better. But that's not the only option. > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > - 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
