Hal Murray wrote: >> Actually, you can see this as a Shannon information channel, analog or >> digital. >> > > What sort of bandwidth do I need to run a PLL over a long link? > > I assume it takes enough to cover all the sources of error: > drift in the master > drift in the local oscillator > drift in the communication link > > Does it depend on my target accuracy? Do I need more or less bandwidth for a > better answer? Am I even asking a sensible question? > > > What sort of changes in delays to I get on 10 km of fiber or coax or twisted > pair? Is temperature the only interesting variable? > > The delay tempco of a transmission line depends primarily on the thermal characteristics of its dielectric. The thermal expansion of the conductors can also be important. Conventional coax has a delay tempco in the 50-100ppm/C range unless exotic dielectrics such a fused silica powder are used. With a plastic dielectric water diffuses lowly into and out of the dielectric with a long time constant unless the cable is hermetically sealed. > Can I measure tides with a 10 km link? Or is that swamped by temperature? > > How about microwaves? Does the speed of light in air change with temperature > or humidity or whatever? > > Yes the speed of light (and microwaves) depends on temperature, humidity as well as pressure and Carbon dioxide content.
Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.