The importance of being in Sync - Centralized vs Distributed

As if often happens, this post comes from a discussion I had with a customer.

One common trend that I see with test systems, is the need for them to be distributed. Having a distributed system has several benefits

- You can get your instrumentation closer to the signals, thus reducing noise. I had a customer that had to read lots of signals from sensors all around a facility and having very long cables didn't work very well with small signals, particulary when the cables had to run paralell for a long trek

- Since there will be some sort of data bus, less cabling is needed. In the case above, some of our systems act as concentrators, drastically reducing the needed lengh of cable

- You can have your instrumentation with the unit under test while having the control of your instrumentation on a safe location.

I think a graph will help explain it

So why don't we have more of this distributed architectures? Well, as you might guess from the post title, we might want to have the data that is collected synchronize. But what does it mean to be "synchronized", it basically means that signals use clocks that are correlated. The tighter the synchronization the closer the clocks need to be in synch.

Is this always neccesary? As usual, it depends on the application and the signals being developed. If you are building a control system based on temperature readings on different parts of the building (to activate the boiler, for example) signals do not need to be closely synchronized, as it is typically a slow control systems and temperature doesn't change rapidly.

On the oposite side of the spectrum, you might be building a iron-bird. In this case you need the information to share a timebase, among other things.

How is this accomplish? You'll have to read my next blog post :D

You want to see a system tightly sincronized? Behold the "Gears of Death" Demo!

Have fun!