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vrf The RF "slot" on Agilent E4438C is slipping in time.

Question asked by VRFuser on Jun 16, 2004
Hi Henrik

I think I have been able to reproduce what you are seeing. With the 10M references locked, and using the square wave output from a 33120A (which is pretty similar to the 33220A), there is a quite distinct 'jitter' of the event1 output against the trigger input. This varies a little depending on the frequency selected. At most frequencies it looks like jitter, but if I select the frequency carrefully, I found 216.49Hz eg, there appears to be a slip.
As I understand it, this is due to the different methods of locking to the 10MHz reference.
To obtain a jitter free trigger, you need to have the trigger source and signal generator locked by the data clock and/or symbol sync. As you correctly noted the symbol sync is permanently high in gsm mode, as for 1 bit per symbol it is the same as the data clock. If I recall the clock is on the next pin to the symbol sync.
I can't see a way of controlling the 33220A from this however. Do you have an alternate trigger source.
Hope this helps - if you need further assistance please contact me directly.

Malcolm Kirby
Agilent Technologies
South Queensferry


-----Original Message-----
From: Henrik.Hald@nokia.com [mailto:Henrik.Hald@nokia.com]
Sent: 16 June 2004 13:59
To: PDL-LISTS,VRF (A-Lists,unix1)
Cc: PDL-LISTS,VRF (A-Lists,unix1); simonparfitt@hotmail.com
Subject: [vrf] RE: The RF "slot" on Agilent E4438C is slipping in time.


Hi again

So what you are saying is that my external trig generator (Agilent 33220A) should be sync with the frame sync from the ESG.

I have found the Sym sync out on pin5 in the  AUX I/O plug, but the level is constant high (with GSM modulation on)

I can't see how you can use the data clock, this is a clock not a sync .... Right ??

Venlig hilsen, Kind regards
Henrik Damborg Hald (C4)


-----Original Message-----
From:      ext  [mailto:malcolm_kirby@agilent.com]
Sent:     Monday, June 07, 2004 10:32 AM
To:     Hald Henrik (Nokia-TP/Copenhagen); vrf@agilent.com
Subject:     RE: [vrf] The RF "slot" on Agilent E4438C is slipping in time.

Hi Henrik

there is no problem with the E4438 - I use one all the time in various triggered modes. I suspect your problem lies with the trigger source. The trigger will need to be locked to the gsm baseband generator - using data clock or symbol sync is the easiest way. I am currently using one siggen to trigger another, and with the data clock and symbol sync connected, triggering is completely stable. The effect you describe occurs when you use an ordinary pulse generator for example as the external trigger. Hope this helps.

Malcolm Kirby
Agilent Technologies
South Queensferry


-----Original Message-----
From: Henrik.Hald@nokia.com [mailto:Henrik.Hald@nokia.com]
Sent: 07 June 2004 09:10
To: PDL-LISTS,VRF (A-Lists,unix1)
Subject: [vrf] The RF "slot" on Agilent E4438C is slipping in time.


Hi All

I' am doing a detector response measurement, that means time delay From RF on to Vdetector out.
Because of the application I have to run the RF in bursted mode.

For this use I run the E4438C in Slot mode, delayed from external trigger time. (ex. Slot1 ON)
The problem is that the RF "slot" is slipping in time.

It's slips 2-3us over every 2-3sec. It looks like a "slip" that reset (return to right place in time) every 2-3 seconds.
I am using the external 10Mhz reference clock from a test-setup included Spectrum Analyzer.

Is this an E4438C problem (that the internal GSM generator is inaccurate), meaning have this been seen before.

Or is there a better way to do this measurement, I have been looking in to using the arb. Generator but this seems to be the same problem.


Thanks in advance

Kind regards
Henrik Damborg Hald


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