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Pulse setup in PNA-X for pulsed s-parameter measuremnt

Question asked by tongxi on Aug 8, 2013
Latest reply on Aug 11, 2013 by xinchen
We have just got the PNA-X (N5242A, 10MHz to 26.5GHz, 4 ports) DSP upgraed from version 4 to 5, and at the same time firmware from A.09.85 to A.09.90.02.

Before this upgradeWe were able to setup correctly for the pulsed s-parameter measurement on the PNA-X which is externally triggered by Auriga 4550. Thanks to Dr. Joel for your great support.

However, with the latest upgrade, we are observing something strange, andI am wondering if it is a bug of the integrated pulse application.  

1) When I started the pulse application from Sweep menu, it comes with the default setting for 100us pulse width, with calculated IFBW of 100KHZ. The width for all the receivers are the same: 14.520 usec, and with the delay of : 80.480 usec. I chose the Standard Pulse, Pulse1 for pulse Gen of Source2  (as I want to use the port1 and port3 for pulse s-parameter measurement), Master Pulse Trigger: External, Autoselect Width & Delay is checked (please see attached file fro the screenshot). then I click " Apply".  The measurement timing for the receivers (width and delay) look all right as the measuremnt window will stay within the RF pulse.

2) however, when I change the pulse width to some other values on the previous screen (for example to 101us), and then changed it back to 100us, the pulse application will calculate automatically, but this time the width for the receivers changed to 96.800 usec with 0.000 psec delay. It seems it is very odd with 0ps delay. and the IFBW has changed to 15KHZ from 100kHz.

3) I tried to see what the pulse application will calculate the measurement timing for different RFpulse width, and I have included the results in the attached Excel file.  I don't know if there is anything wrong with the application, fror example, for some pulse widths entered, the application gives a width for receivers (all receivers has the same width) longer than the pulse width, for some pulse widths, the delay for the receivers is 0.000psce.  

I read the help menu with the firmware, it is still saying: Autoselect Width and Delay - When checked, for Wideband mode and Pulse0, the receiver is adjusted to approximately 75% of the source pulse width, with 20% delay. This leaves approximately 5% of the source pulse ON after acquisition is complete.  

But how can we explain 0.0ps delay obatined when I did check the  "autoelect Autoselect Width and Delay ".

Coudl you let me know the measurement timing calculated by the integrated pulse application is correct or not? 

Thanks.

Tongxi

Edited by: tongxi on Aug 8, 2013 1:13 PM  

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