I work in a USB test area and I am hoping to figure out in short order how long it takes to get a signal from point a to point b. I believe the calculation is speed of light times a factor. I was wondering what the formula is exactly. I know that the Dialectric constant is 2 for the circuit.

Tony

 

Hi,

There's probably some trove of data somewhere, but knowinf things like the insulation and conductor to shielding spacing plus per meter capacitance might help.

For RF purposes, signals in coax were considered to propagate at 96% light speed (in vacuum) for calculating resonant lengths.

If you don't turn up a calculator formula, there's always time-domain reflectometry. You might even be able to rent a TDR setup. Airliner mfr's use 'em to locate the non-conformity in a wire running from A to B - it's cheaper than pulling the whole thing and replacing it. If they can calculate distance, then they have to know the time of transit very accurately.