RF causing issues with USB...

[wavetar]

Anybody else here notice that USB ports, for some makes of laptops at least, are very susceptible to RF causing issues when connected to the unshielded MotoTRBO programming/interface cables?

We've recently been in-house testing with several different dispatch/GPS packages for MotoTRBO, and have experienced a lot of instances where the USB ports 'lock up' and become inactive...sometimes power cycling the radio connected to that particular port will restore functionality, but most times ALL USB ports get shut down (won't even respond to a USB stick plugging in) & only a computer reboot restores things back to normal. This occurs with several different laptop makes/models. At least one of the software providers has acknowledged it as an issue to me. Setting everything to low power and using dummy loads where possible minimizes the occurrences.

Granted, it's only really an issue when dealing with radios in close quarters. If you have a base radio in a building with your antennas on the roof and field radios miles away, you probably won't experience it. But in situations where customers are say doing GPS tracking in a command post vehicle where the antennas may be in close proximity to the radios, it becomes important. And indeed, it's proven to happen with some beta systems we have out there.

I custom made some shielded USB cables, since Motorola doesn't provide them, and they seem to help, at least some. Next step is to add a ferrite choke to see if that helps as well.

I'm wondering if a laptop such as a toughbook might be less prone to this?

[Bill_G]

Have you tried a wrapping the usb cable into a few tight coils (pencil wrap) close to the pc connector?

[Tom in D.C.]

Todd,

I had a recent experience with my Dell desktop where the USB port ignored the thumb drive when I stuck the
drive into the port. Resetting fixed things with no problems but I have no idea what might have caused what was
obviously an OS glitch. The port I was using is an "add-on" four-port board that sits in place on the front of the
box where a second CD drive would go and is connected to one of the rear USB ports that is on the main board.

I do from time to time "test kerchunk" an HT on UHF or VHF in front of the computer so
that might have done it. OTOH I use a Motorola USB cable to program my TRBO 6500 all the time and have never
had any USB problems when doing so. My Dell is definitely subject to glitching and shutdown even in the presence
of strong RF, and IIRC it happens on VHF, but the box is full of RF components so it's probably to be expected.

I'll follow the thread to see if anyone else comes up with anything interesting and useful.

Regards,

[Jim202]

Todd,

I had a recent experience with my Dell desktop where the USB port ignored the thumb drive when I stuck the
drive into the port. Resetting fixed things with no problems but I have no idea what might have caused what was
obviously an OS glitch. The port I was using is an "add-on" four-port board that sits in place on the front of the
box where a second CD drive would go and is connected to one of the rear USB ports that is on the main board.

I do from time to time "test kerchunk" an HT on UHF or VHF in front of the computer so
that might have done it. OTOH I use a Motorola USB cable to program my TRBO 6500 all the time and have never
had any USB problems when doing so. My Dell is definitely subject to glitching and shutdown even in the presence
of strong RF, and IIRC it happens on VHF, but the box is full of RF components so it's probably to be expected.

I'll follow the thread to see if anyone else comes up with anything interesting and useful.

Regards,

We have been playing here with a 5 watt VHF portable, some USB cables and a couple of laptop computers used for our radio interop gateways. Before we started, it would take a short keying of the radio in a near by location to bomb the computer interface. In playing around we found some retangular snap on ferite cores that seemed to do the job. I can now touch the portable antenna on the USB cable and nothing. So think we have solved our problem.

Jim