FAQs from Rohde & Schwarz

Delta Time Accuracy Calculation for my Oscilloscope


I do not completely understand the delta time accuracy calculation for my oscilloscope.

In the formula "Fs" is mentioned. This sound like Full Sclae to me. I do not really understand the calculation.

Can you give me an example how to perform it?


The following informations can be found in the specification sheet of the scope (here RTM3000):

Delta Time Accuracy Calculation for my Oscilloscope

With "Fs" we do not mean "Full Scale" - it is the variable value standing for the Sample Rate in Sa/s.

Let's assume a requested sample rate of 1,09E8 Sa/s and a time delta measurement value of 50 µs and perform a sample calculation @ a time base accuracy of 3.5 ppm:

1,34/1,09*10E8 Sa/s + 3,5 ppm * 50 µs

= 1,229 * 10E-8 s + 3,5E-6 * 50E-6 s

= 1,229 * 10E-8 s + 1,75E-10 s= 1,247 * 10E-8 s

= 12,47 ns