PXI

cancel
Showing results for 
Search instead for 
Did you mean: 

PXIe-1085 10MHz Jitter

Hi

I am trying to measure the Jitter of the 10MHz Clock (output from Ext. Ref. (10MHz Ref out)). The specification states that the RMS phase jitter is approximately less than 5ps. However when I measured the rms jitter using two techniques

 

1. Using Infinium Oscilloscope (EZJIT)  - 66ps (Scope rms of 1.8ps)

2. Using Spectrum analyzer (direct measurement) - 66ps in the Integration BW of 10KHz to 1MHz

 

May I know, what does specification RMS phase jitter refer to ? (is it periodic jitter or is it total rms jitter). Why is there such a discrepency ?

 

Venu

0 Kudos
Message 1 of 5
(2,810 Views)

Hi Venu_Cube,

 

What is the sampling rate of the oscilloscope you are using? In order to detect the jitter at 5ps it would take a very high sampling rate to detect such a small jitter. I believe the spec is referring to total RMS jitter.

 

Michael B.

Applications Engineer

National Instruments 

 

Message 2 of 5
(2,768 Views)

Hi

 

I am using a 20Gsamples (sampling rate) to capture the waveforms on the oscilloscope. I suppose this is good to see as small jitter level.

 

Regards

Venu

0 Kudos
Message 3 of 5
(2,765 Views)

Hi Venu,

 

From my calculations, the 20GSamples will be at time rate of 50ps per sample. This won't be able to capture a jitter of 5ps. I imagine the sampling rate would need to be above 400GS.

 

Michael B.

Applications Engineer

National Instruments 

0 Kudos
Message 4 of 5
(2,752 Views)

 

1./(20*10^9) // EngineeringForm
50.*10^(-12)

 

Your expected jitter is ~ <5 ps which is 10 times smaller than the number you can get with 20 GS/sec digitizer.

 

NI System Configuration:
- NI PXIe-1071, 4-Slot 3U PXI Express Chassis , 1 GB/Slot throughput, Part Number: 781368-01
- NI PXIe-PCIe8381,x8 Gen2 MXI-Express for PXI Express Interface,3m, Part Number: 782522-01
- PXIe-5160 PXI Oscilloscope, 500 MHz, 10 bits, 2.5 GS/s, 2 Channels, 64 MB, Part Number: 782621-01
- Astronics PXIe-1209 2-Channel, 100 MHz PXI Pulse Generator, Part Number: 785033-01
0 Kudos
Message 5 of 5
(2,730 Views)