Fluke 95 Oscilloscope Sampling

[Tony R]

So i was browsing the pages of ebay and i found an add that got me a little confused and hope some of you guys can help clear it up for me

I found a Fluke 95 50 Mhz hand held scopemeter. in the add it stated "*** 50 Mhz Dual Channel *** 25 Megasamples/second ***"

Now when taking signals and systems i was always told that your sampling frequency must be at least twice the frequency of the signal you want to sample so fs>= 2*f.

So if this is sampling 25 million times a second, how can it be rated for 50 MHz waves?

[Zero999]

It'd possible to have a higher analogue bandwidth than double the sample rate for repetitive waveforms.

[Alex]

Ahh, used to have that one!

Sure, look up equivalent time sampling. Here is a dcent app note:

http://www2.tek.com/cmswpt/tidetails.lotr?ct=TI&cs=Application+Note&ci=14295&lc=EN

[saturation]

2x is minimum, realistically its 10x.  So that scope is effectively 2.5 MHz worse case, in single shot applications.