Rotary Joint

I would... cross wire an Ethernet cable and connect two PCs together. Copy large files from one to the other, go both ways, then do 32 bit CRC checks on them. If the results are the same, the copies are good. If you get different CRC values, then the files are damaged.

That's what I had planned to do, but in these days of fantastic hand-held

test gear, I was hoping somebody knew of one that might give be a bit-error-rate, in

the process.

thanks gentlemen

you can set one up as a server and have the other repeatedly ping it, using a 100 base T cable to connect your test system to the DWW. All this while turning under real world conditions. You can probably use a simple hand held computer capable of operating with a rudimentary linux server to actually turn around on the rotating part, if you are a Linux guru(which I am not). There might be a way to use a Blackberry in this role as it is capable of this operation if you can improvise an application

DWW = Desk Wide Web

Well if you are looking for a bit error rate, my approach will kind of give you one. A known file of a known size moved over a given time period will give you a pretty good approximation of a bit error rate.

I do, however, have to agree with Andy's comments, why move the data packets across a rotary link? Is there a requirement of some sort to do it this way? There are other ways beside RF wireless to do this is you have a problem with a wireless approach. There are some pretty good infrared units made for just this type of situation.

To test what you already have (I personally would not build it like this!), use a a WiFi Router on the moving part to send the test data onto a PC, check the data validity there....

Putting Ethernet signals over such aconnection could be quite difficult I feel. Using a WiFi system in the first place strikes me as far better, then only power needs to be made over the rotary contact(s).....

If this rotary joint is a gold on gold gas excluding joint it may be capable of good data integrity. It will not be dealing with low level noisy signals, it will be dealing with digital data, which should pass through with little loss.

Is the signal a high level signal or a low level noisy, almost analog signal?

There is a freeware program called Wireshark (used to be called Etherreal) that will monitor packets, this can definitely show you which packets are corrupted and it's capable of displaying statistics charts too.