[OT] Jam/Interference Resistant Commercial Comm Equipment

[newguy]

Sorry for the off topic post.

Can anyone recommend a commercially available off the shelf short(ish) range communication standard/equipment? A bit of background will help you to understand why I ask.

My company doesn't actually sell equipment, rather we rent it due to economic, historic, and labor reasons. Our equipment is used, under our limited supervision, on various jobs by a workforce that we have no direct control over. Sometimes that workforce, for reasons I won't go into here, can be quite hostile to the robotic equipment we build.

We use off the shelf commercial Wi-Fi routers and wireless bridges (B/G for now) to allow our on-site staff to monitor everything from a (limited) distance. On one site everything worked fine until very recently. What changed, and we cannot 100% prove (but we're at 99.9%), is that our Wi-Fi is being intentionally jammed by an aforementioned hostile worker.

So with all this in mind, is there a commercially available jam-proof or highly interference immune product I should know about? I know that simply migrating to N or AC will open a 5 GHz channel which should render a "narrowband" 2.4 GHz jammer useless. I'm just afraid that a week after we do so, the party/parties responsible will just get another jammer.

Doesn't have to be an networking based solution. Could be USB or ...?

Help?

[asmboy]

the ONLY technology that is jam-resistant at its core is
spread spectrum, which is NOT wifi compatible.

jam-PROOF? with 35 years in RF communications, i know of nothing jam-PROOF but optical links - over fiber ;-))

[gpsmikey]

Fiber is only good if you don't have heavy equipment digging around !! Spread spectrum is the only one that is going to be "mostly" jam-proof. The other option is to (if possible) spend the time with receivers and locate the jamming transmitter with the employee and remove him/her.

mikey
_________________
mikey
-- you can't have too many gadgets or too much disk space !
old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3

[temtronic]

you can't be getting much sleep !
Only idea I have comes from 30 years doing 'remote energy control'.
Solid copper wire or fiber, in conduit, with video cameras covering 100% of the installation. Loss of communications(use PICs with C to monitor status) sends alerts, time stamps cameras,etc. Heck have the PIC relay the realtime video to your cellphone ?
You've already figured out that whatever you do, 'they' WILL compromise the system.The 'key' is to record 'them' doing it.Cops love video evidence!

hth
jay

[newguy]

Thanks for the recommendations and kind words. Our application is field work with mobile equipment and a mobile on-site tech. Everything is wireless for convenience and practicality. Wish that optical free space line of sight was available, but then we'd have guys spray painting everything.

We have GPS receivers on our stuff but only to allow us to group data geographically; those receivers constantly get unplugged or worse, smashed.

Regarding disciplining those caught doing this stuff, it's not that simple. I wish it was, but it's not. It's actually really difficult to prove sabotage and even when there's evidence it's still not easy to run someone off the site.

I think I should throw a kickstarter proposal out there for some 21st century smoke signals. ;)

[Ttelmah]

Some years ago, I had to design a system that would get data through, pretty much 'no matter what'. It ended up using hamming codes transmitted simultaneously on two spread spectrum transceivers, operating on different regions of the spectrum. It was a lot of work...

Best Wishes

[asmboy]

if you want to add the maximum resistance to jamming with what you are facing then consider this practical advice:


in FM/PSK/FSK systems - a desired signal +15 db above the jamming can still work ok.
Power, directionality and polarization are all weapons you can deploy against a random attack.

a ten element yagi for the wifi band- addresses all three!

"antenna gain" is cheaper and more reliable and gives
you the ability to go horizontal instead of the typical
(random/circular) polarization of the ubiquitous wifi router.

if you have fixed locations with yagis point to point -
you can take a lot more interference and still maybe be ok.

[Ttelmah]

Very true.
Directional antennae could at the least help to reduce 'off site' interference.

Switching to (or using in parallel), 5Ghz has a big advantage in terms of 'accidental' interference, since conventional microwaves commonly interfere severely with 2.4GHz WiFi. The standard 2.4GHz band is full of interference, even if your people are not deliberately blocking it. Cordless phones, baby monitors, Bluetooth, harmonics from some TV stations, etc.. Given that the WiFi runs at a few mW, while a microwave uses 1KW+, it doesn't take much leakage to destroy communications. I can't use 2.4GHz, on a couple of sites, since they have fire stations nearby, which uses one of the bands right in this section of the spectrum, at much higher power. Tends to result in the AGC's on the tuners swamping, and loss for several seconds at a time.

Remember that there are routers, that will automatically switch between different ethernet connections. Use a 2.4GHz link, _and_ a 5GHz link at the same time. Apple's AirPort base station, in it's newest versions does this.

Some chipset's (particularly those advertised as 'long range'), are much better at auto-switching the bands than others.

Best Wishes

[newguy]

Never thought of a directional antenna(e) - I have to research what I can get. The application is complex because the location of the equipment that must be monitored and our tech's position relative to that is constantly changing.

The application is automatic (robotic) pipeline welding. Location can be almost anywhere, but is most often the middle of a farmer's field or the bush, far from civilization. A job is typically bid on by a consortium headed by the general contractor who lines up a pipe supplier, a welding company (us), and a labor source (typically union sourced).

This particular union is, for the most part, quite hostile. Line of reasoning is that the robotic equipment, even though it must be run by them, is far faster than say if the job "went stick rod", which would keep said welders employed for a longer period of time.

Our tech, using his Wi-Fi link to our stuff, proved a couple of weeks ago that one person in particular wasn't doing what he was supposed to be. Two days later his Wi-Fi went down. It's up when he gets to the site but when the workers arrive some time later, poof, it's gone. When the workers clear out at the end of the day, he gets Wi-Fi back.

Without a directional antenna and a battery powered spectrum analyzer to track down the source of the interference, there's not much we can do. Unfortunately the only thing that can get someone fired is to produce a series of bad welds, and even that can be hard to prove when they swear that they didn't do anything wrong (in spite of the fact that the ultrasonic testing company identified the depth of the defect and that can be tied directly to only one person).

Intentionally smashing our equipment or cutting cables, etc. is just too hard to pin on one person unless they're caught red handed by multiple witnesses. And yes, that happens too. One guy a month ago took all our stuff apart, pulled every cable he could find, then put it all back together. He actually did get fired, but only because the welds he produced when he did that were full of defects, not because he monkeyed around.

[asmboy]

ok -you've got luddites...bummer indeed

unfortunately it has often been proved that
'social' problems can be quite resistant to 'technical' solutions.

sucks 2 B U

[languer]

What does your equipment do? What is it you provide that gets destroyed? If whatever you provide can get tagged to a specific individual at a specific time, then you could implement some sort of logger mechanism to identify when it went down (i.e. black box).

What information are you obtaining through WIFI? If whatever you are relaying through WIFI also gets communicated through a serial protocol, then you should add some wireless modem which operates spread spectrum, or on different frequency from WIFI. In other words, send the information via two methods. From what you describe, I would doubt the workforce that is giving you problems has a high degree of technical savvy. They probably known how to look for WIFI Jammer in eBay, but cannot probably discern a WIFI device, from a ZIGBEE device, from any other device. So give them something they think they know to jam; and provide an alternate method which is the real way you want to monitor your info.

[oxo]

You have a people problem, not a technical one OP. There is no technical solution to guys who will disconnect and smash the equipment.

Having said that, for jam-proofing on a short range link, I would be looking at UWB.

[Ttelmah]

Separately though, WiFi, with arc welding, is not likely to be reliable even if everybody is as 'good as gold'. It may be simply that one particular set of welding kit is generating more interference, or that one particular welder tends to maintain the arc 'better' at a length that accidentally hits a resonance to the WiFi frequency....

[newguy]

TTelmah: In the past 5 years or so we've done approximately 50k joints and we've never experienced RF interference until the past couple of weeks on this one job. Weld characteristics are about the same as on every other job.

languer: Unfortunately our equipment is rather set in stone. We have an embedded SBC with 10 Mbps Ethernet and no other interface. We've begun the process of replacing these things with higher performance more modern devices that feature USB and several serial ports, but they haven't been widely distributed yet. For now we're locked into a commercial Wi-Fi interface.

oxo: You're absolutely right. If I ran things we wouldn't tolerate this but unfortunately I don't, which is probably a good thing.