Even without any funny business with boost converters (or whatever). those copper wires make a nice antenna for coupling noise from both ends (PC and USB accessory) into the environment inside the chamber. Unless, of course, the cable is well-shielded, which you did not mention.
I suppose it's too late to ask, but did you perhance try adding some clamp-on ferrite chokes to the cable? Dana On Fri, Dec 6, 2019 at 10:05 AM David Van Horn via time-nuts < time-nuts@lists.febo.com> wrote: > This is my backup plan: > https://industrialcomponent.com/opticis/opm210003.html > > The docs are a bit chinglish, but I'm encouraged by the fact that the > distal end needs external power. I was hoping the corning one was > powering the distal end by CW laser of maybe 200mW with data carried on > other wavelengths, or modulation of the power laser, but NOPE, just copper > wires. That one's packed up and ready to go back right now. > > -- > David VanHorn > Lead Hardware Engineer > > Backcountry Access, Inc. > 2820 Wilderness Pl, Unit H > Boulder, CO 80301 USA > phone: 303-417-1345 x110 > email: david.vanh...@backcountryaccess.com > > -----Original Message----- > From: Scott McGrath <scmcgr...@gmail.com> > Sent: Friday, December 6, 2019 6:29 AM > To: David Van Horn <david.vanh...@backcountryaccess.com> > Cc: Discussion of precise time and frequency measurement < > time-nuts@lists.febo.com> > Subject: Re: [time-nuts] USB over optical fiber > > Wow, cost cutting at work I have the corning one but its 3 years old > Remember when FCC certification meant something for EMC > > > > > > > On Dec 6, 2019, at 3:21 PM, David Van Horn < > david.vanh...@backcountryaccess.com> wrote: > > > > Well, it arrived, and it is NOISY. ☹ > It's pushing out longitudinal noise along the cable, and it's deafening my > receiver. > > After doing some research this morning, it appears that they do the DATA > optically but power is taken on copper wires, and I'm betting a boost > switcher to compensate for the voltage drop in the 28 ga wire. > > https://www.corning.com/microsites/coc/ocbc/Documents/CNT-075-AEN.pdf > > > > I have another candidate arriving today which will require a 5V supply > inside the cage, but I can do that with batteries and a linear regulator, > much quieter. > > > -- > David VanHorn > Lead Hardware Engineer > > Backcountry Access, Inc. > 2820 Wilderness Pl, Unit H > Boulder, CO 80301 USA > phone: 303-417-1345 x110 > email: david.vanh...@backcountryaccess.com > > -----Original Message----- > From: time-nuts <time-nuts-boun...@lists.febo.com> On Behalf Of David Van > Horn via time-nuts > Sent: Thursday, December 5, 2019 6:15 AM > To: Scott McGrath <scmcgr...@gmail.com>; Discussion of precise time and > frequency measurement <time-nuts@lists.febo.com> > Cc: David Van Horn <david.vanh...@backcountryaccess.com> > Subject: Re: [time-nuts] USB over optical fiber > > Ok, thanks for the info. My unit should be arriving today or tomorrow. > > -- > David VanHorn > Lead Hardware Engineer > > Backcountry Access, Inc. > 2820 Wilderness Pl, Unit H > Boulder, CO 80301 USA > phone: 303-417-1345 x110 > email: david.vanh...@backcountryaccess.com > > -----Original Message----- > From: Scott McGrath <scmcgr...@gmail.com> > Sent: Wednesday, December 4, 2019 9:16 PM > To: Discussion of precise time and frequency measurement < > time-nuts@lists.febo.com> > Cc: David Van Horn <david.vanh...@backcountryaccess.com> > Subject: Re: [time-nuts] USB over optical fiber > > You may still have a problem, That said most of your noise power is going > to come from your USB device itself and perhaps the power supply > > That said ive never really had a problem doing similar testing using small > chambers from ETS-Lindgren and similar vendors using the Corning > interface. > > That said i’d recommend you go a step up to the Newnex and similar devices > they are 3x the price but the fiber interlink is just a standard fiber > LC-LC patch cord. > > With the low cost interface crimp its cable once accidentally you are > buying a new one. > > With the newnex you are buying a 20-30 dollar patch cord. > > All that said performance is the same in the end but the newnex and > similar have an advantage in an open lab. For permanent installation in > raceway the cost advantage is with the one piece units. > > Content by Scott > Typos by Siri > > > On Dec 4, 2019, at 10:07 PM, Davida Van Horn via time-nuts < > time-nuts@lists.febo.com> wrote: > > > > I'm not too worried up there, my receivers are working at 457 kHz. > > -----Original Message----- > From: Scott McGrath <scmcgr...@gmail.com> > Sent: Wednesday, December 4, 2019 12:14 AM > To: Discussion of precise time and frequency measurement < > time-nuts@lists.febo.com> > Cc: David Van Horn <david.vanh...@backcountryaccess.com> > Subject: Re: [time-nuts] USB over optical fiber > > Its not so much the noise from the interface its the USB device itself i’d > worry about as USB 3.0 generates RF signals up to 3 GHz. And also has > fairly strong signals in the 2.4 GHz ISM band. > > Content by Scott > Typos by Siri > > > On Dec 4, 2019, at 12:07 AM, David Van Horn via time-nuts < > time-nuts@lists.febo.com> wrote: > > > > I suppose this is vaguely time-nutty. 😊 > > I have an application where I need to take USB into an EMC faraday cage. > I see a number of optical fiber implementations available, and the prices > ($200-300) are acceptable, but I’m worried about noise that the downstream > end may cause, since it will need to be inside the cage. > > Does anyone have experience with these? Ones to stay away from? > > > > -- > David VanHorn > Lead Hardware Engineer > > Backcountry Access, Inc. > 2820 Wilderness Pl, Unit H > Boulder, CO 80301 USA > phone: 303-417-1345 x110 > email: david.vanh...@backcountryaccess.com<mailto: > david.vanh...@backcountryaccess.com> > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
