[time-nuts] Noise Floor

[Bob kb8tq]

Hi

Sorry about dumping the text from the previous post !!! Obviously the mailer on that
machine needs a bit of attention.

So here’s what it *should* have said:

When we are doing typical measurements on our time / frequency standards, much of it involves measuring noise. In many ways it is closer to a noise figure measurement than to a lot of other lab work. The “noise floor” of the measurement setup is an important partameter. Resolution might be 10,00X better than the noise floor. If so, resolution not a key parameter (at least not to me). 
 
When setting up a lab, one of the first things to do is to get a working measurement setup and to characterize that setup.  This often involves a lot of yelling, screaming, and kicking the dog. More often than not things like bum connectors, faulty cables, and bad grounding are what takes the most time to sort out. Weeks / months of work to get a setup going properly are *not* at all unusual.

One of the nice things about devices that work like a DMTD is that measuring the floor is a matter of driving the two inputs through a power splitter. With a single mixer setup (which *is* much easier to build) the floor is not as simple to estimate. The same is true of some (but not all)  counter based setups. 
 
Bob