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I have had USB 3.0 devices cause noise which gets picked up by silicon strip detectors in particle physics experiments. These days its common to have a computer

I have had USB 3.0 devices cause noise which gets picked up by silicon strip detectors in particle physics experiments. These days its common to have a computer in the target room next to the digitizers to avoid long analog cable runs. Now you have to be careful which USB port you plug into with what device.

harha 6y ago
Have you tried putting a Raspberry Pi 3 (without the USB 3.0) in between and sending the signals over Ethernet?
- yummypaint 6y ago
  We have historically avoided using PIs for critical things because of innevitable memory card corruption after a few years. Now that there are means to boot from other storage media that might change. What i would really like is a BIOS option to kill 3.0 capability.
  - harha 6y ago
    Only model 4 has USB3 (and that one comes with two ports that only have USB2), in case you don't need the higher performance.
Lucasoato 6y ago
Have you tried wrapping everything with lead?
- ben509 6y ago
  It's going to be a PITA when USB 832.1 comes out and we need a light-year of lead to deal with neutrino interference.
- yummypaint 6y ago
  We do make liberal use of lead in general, but in this case the noise is electrical in nature. The detectors we use tend to behave like radio antennas and so they are well shielded electrically. I suspect the mechanism is the USB 3 making extremely sharp transients that make their way into preamplifiers via the power supplies. It's a slippery thing to track down, though.
- Johnythree 6y ago
  Lead makes for fairly poor EMC shielding. It has relatively high resistance and quickly builds an oxide layer. Copper tape is better, thick copper even better, and thick copper with welded seams better still.
hilbert42 6y ago
One of the problems is the many shitty USB cables about in the wild. The screening on many of them is pathetically inadequate. Not only do these cables emit noise from the USB electronics but also the USB equipment to which they are connected becomes susceptible to noise from external sources. On more than one occasion I've had external USB drives lose their MFT (Master File Table) data as a write update was corrupted by noise. Essentially, the external noise killed the data on the disk. Often, when one pulls these USB cables apart one can see the shielding coverage is 30% or less.
- tinus_hn 6y ago
  Would be interesting to see if this can be used for eavesdropping as a keylogger.
- Johnythree 6y ago
  While good shielding is important, the important thing is to use twisted/balanced pairs, eliminate longitudinal currents by means of common mode chokes, and to eliminate ground loops via differential transformers.
  - hilbert42 6y ago
    I agree with you completely—and I'm not saying that as just an obsequious response but because I know the issues you've raised are so important. Yet nowadays they are so often overlooked or paid scant attention thereto—which I'd suggest is even more so than in the past because training now has to cover a much more diverse range of subject matter than in the past. Leaving specialist courses aside, today, general courses on electrical engineering and electronics pay less emphasis on low noise/low-level analogue techniques and more on digital technology. For instance, I recall a good but inexperienced engineer coming to me with a board he'd constructed that was full of digital ICs but which he couldn't get working. A quick glance and I saw that he had left off all the bypass capacitors across the ICs' power rails—not by accident but by not realising their importance. There's not the time or space to address your points in sufficient detail except to say that years ago, I used to work for a well-known electronics company that made radio and television broadcasting equipment and I was employed in its prototype laboratory. My work covered a diverse range of technologies including audio, VHF and microwave. All those points you've mentioned were day-to-day bread and butter and we had to address them in detail as the equipment had to pass/comply with broadcast standards. For example, we had to design audio equipment so that the 600Ω balanced lines joining them had to reach a specified common mode rejection ratio, this involved multiple techniques, shielding, good earthing, using 'technical' earths and testing EMR leakage to and from interconnecting cables (for instance, Belden Beldfoil cables)—all of which were especially important in very low distortion designs that didn't rely on transformers to achieve balanced inputs and outputs. Similar issues were relevant in RF and microwave equipment, minimizing stray capacitance and inductance in chassis/component layouts, etc. Rather than give you an example I refer you to one of my treasured books on the subject, Microwave Receivers edited by S.N. Van Voorhis, 1948, specifically pages 261-266, Section 10.6 (although other nearby sections are also relevant). This book is ancient but the theory and rules still apply. It's part (vol 23) of the 28 volume Rad Lab† series produced after WWII and this set is still one of the greatest tomes ever written on any subject in engineering. It can be downloaded from the Internet Archive from here: https://archive.org/details/MITRadiationLaboratorySeries23MicrowaveReceivers https://archive.org/details/MITRadiationLaboratorySeries23Mi.... (Incidentally, I still have my softcover Dover edition from when I was a teenager, it's not the kind of book you throw out.) † List of Rad Lab series: http://web.mit.edu/klund/www/books/radlab.html http://web.mit.edu/klund/www/books/radlab.html

harha 6y ago

Have you tried putting a Raspberry Pi 3 (without the USB 3.0) in between and sending the signals over Ethernet?

yummypaint 6y ago
We have historically avoided using PIs for critical things because of innevitable memory card corruption after a few years. Now that there are means to boot from other storage media that might change. What i would really like is a BIOS option to kill 3.0 capability.
- harha 6y ago
  Only model 4 has USB3 (and that one comes with two ports that only have USB2), in case you don't need the higher performance.

Lucasoato 6y ago

Have you tried wrapping everything with lead?

ben509 6y ago
It's going to be a PITA when USB 832.1 comes out and we need a light-year of lead to deal with neutrino interference.
yummypaint 6y ago
We do make liberal use of lead in general, but in this case the noise is electrical in nature. The detectors we use tend to behave like radio antennas and so they are well shielded electrically. I suspect the mechanism is the USB 3 making extremely sharp transients that make their way into preamplifiers via the power supplies. It's a slippery thing to track down, though.
Johnythree 6y ago
Lead makes for fairly poor EMC shielding. It has relatively high resistance and quickly builds an oxide layer. Copper tape is better, thick copper even better, and thick copper with welded seams better still.

hilbert42 6y ago

One of the problems is the many shitty USB cables about in the wild. The screening on many of them is pathetically inadequate. Not only do these cables emit noise from the USB electronics but also the USB equipment to which they are connected becomes susceptible to noise from external sources. On more than one occasion I've had external USB drives lose their MFT (Master File Table) data as a write update was corrupted by noise. Essentially, the external noise killed the data on the disk. Often, when one pulls these USB cables apart one can see the shielding coverage is 30% or less.

tinus_hn 6y ago
Would be interesting to see if this can be used for eavesdropping as a keylogger.
Johnythree 6y ago
While good shielding is important, the important thing is to use twisted/balanced pairs, eliminate longitudinal currents by means of common mode chokes, and to eliminate ground loops via differential transformers.
- hilbert42 6y ago
  I agree with you completely—and I'm not saying that as just an obsequious response but because I know the issues you've raised are so important. Yet nowadays they are so often overlooked or paid scant attention thereto—which I'd suggest is even more so than in the past because training now has to cover a much more diverse range of subject matter than in the past. Leaving specialist courses aside, today, general courses on electrical engineering and electronics pay less emphasis on low noise/low-level analogue techniques and more on digital technology. For instance, I recall a good but inexperienced engineer coming to me with a board he'd constructed that was full of digital ICs but which he couldn't get working. A quick glance and I saw that he had left off all the bypass capacitors across the ICs' power rails—not by accident but by not realising their importance. There's not the time or space to address your points in sufficient detail except to say that years ago, I used to work for a well-known electronics company that made radio and television broadcasting equipment and I was employed in its prototype laboratory. My work covered a diverse range of technologies including audio, VHF and microwave. All those points you've mentioned were day-to-day bread and butter and we had to address them in detail as the equipment had to pass/comply with broadcast standards. For example, we had to design audio equipment so that the 600Ω balanced lines joining them had to reach a specified common mode rejection ratio, this involved multiple techniques, shielding, good earthing, using 'technical' earths and testing EMR leakage to and from interconnecting cables (for instance, Belden Beldfoil cables)—all of which were especially important in very low distortion designs that didn't rely on transformers to achieve balanced inputs and outputs. Similar issues were relevant in RF and microwave equipment, minimizing stray capacitance and inductance in chassis/component layouts, etc. Rather than give you an example I refer you to one of my treasured books on the subject, Microwave Receivers edited by S.N. Van Voorhis, 1948, specifically pages 261-266, Section 10.6 (although other nearby sections are also relevant). This book is ancient but the theory and rules still apply. It's part (vol 23) of the 28 volume Rad Lab† series produced after WWII and this set is still one of the greatest tomes ever written on any subject in engineering. It can be downloaded from the Internet Archive from here: https://archive.org/details/MITRadiationLaboratorySeries23MicrowaveReceivers https://archive.org/details/MITRadiationLaboratorySeries23Mi.... (Incidentally, I still have my softcover Dover edition from when I was a teenager, it's not the kind of book you throw out.) † List of Rad Lab series: http://web.mit.edu/klund/www/books/radlab.html http://web.mit.edu/klund/www/books/radlab.html