David,
I have used Pontis EMC USB converters and they worked meaning they had good
radiated immunity and radiated emissions were below CISPR25 levels even in the
150kHz - 30MHz band.
hvtechnologies is the US distributor.
My first EMC certification test at low frequencies was a humbling experience
due to the noise from the switching power supply. At $7.50 per minute we went
with stacks of AA batteries in parallel.
regards,Jay Cordaro
On Friday, December 6, 2019, 03:48:18 PM PST, David Van Horn via time-nuts
<[email protected]> wrote:
It's not shielded, and ferrites are pretty useless down here.
I did try, but the ferrites I have did nothing.
My backup plan arrives supposedly in the next 2 hours....
--
David VanHorn
Lead Hardware Engineer
Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO 80301 USA
phone: 303-417-1345 x110
email: [email protected]
-----Original Message-----
From: time-nuts <[email protected]> On Behalf Of Dana Whitlow
Sent: Friday, December 6, 2019 10:10 AM
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] USB over optical fiber
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 <
[email protected]> 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: [email protected]
>
> -----Original Message-----
> From: Scott McGrath <[email protected]>
> Sent: Friday, December 6, 2019 6:29 AM
> To: David Van Horn <[email protected]>
> Cc: Discussion of precise time and frequency measurement <
> [email protected]>
> 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 <
> [email protected]> 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: [email protected]
>
> -----Original Message-----
> From: time-nuts <[email protected]> On Behalf Of David
> Van Horn via time-nuts
> Sent: Thursday, December 5, 2019 6:15 AM
> To: Scott McGrath <[email protected]>; Discussion of precise time
> and frequency measurement <[email protected]>
> Cc: David Van Horn <[email protected]>
> 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: [email protected]
>
> -----Original Message-----
> From: Scott McGrath <[email protected]>
> Sent: Wednesday, December 4, 2019 9:16 PM
> To: Discussion of precise time and frequency measurement <
> [email protected]>
> Cc: David Van Horn <[email protected]>
> 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 <
> [email protected]> wrote:
> >
>
> I'm not too worried up there, my receivers are working at 457 kHz.
>
> -----Original Message-----
> From: Scott McGrath <[email protected]>
> Sent: Wednesday, December 4, 2019 12:14 AM
> To: Discussion of precise time and frequency measurement <
> [email protected]>
> Cc: David Van Horn <[email protected]>
> 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 <
> [email protected]> 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: [email protected]<mailto:
> [email protected]>
>
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