Thread: How do I get an arbitrary phase shift using two (2) E8257Ds?


Permlink Replies: 3 - Pages: 1 - Last Post: May 18, 2012 9:32 AM Last Post By: tabbott
CMYKuser

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Registered: 05/08/12
How do I get an arbitrary phase shift using two (2) E8257Ds?
Posted: May 8, 2012 1:55 AM
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Problem: I want to get two separate output signals (pure sine, no modulation), at the same frequency, with an arbitrary phase shift between them. How do I accomplish this with the instrument setup described below? The output frequency is about 1 GHz.

Setup: I have access to two (2) Agilent E8257Ds, with pulse option, and one (1) external 50 MHz function generator (configured to output a square wave). All three instruments use the same 10 MHz reference. The function generator output is connected to the pulse input ports on the E8257Ds, with approximately the same length of cable.

Related question: If I configure the E8257Ds to output a non-modulated signal, will the E8257D output signal from each instrument be phase-locked to the 10 MHz reference? (And so, by extension, to each other?)

My initial idea: To set the pulse modulator to "Triggered with delay" on both instruments, then adjust the delay.

Am I on the right track?

CMYKuser

Posts: 3
Registered: 05/08/12
Re: How do I get an arbitrary phase shift using two (2) E8257Ds?
Posted: May 14, 2012 5:14 AM   in response to: CMYKuser in response to: CMYKuser
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A self-reply:

The datasheet (http://cp.literature.agilent.com/litweb/pdf/5989-0698EN.pdf) states:
"Triggered with delay and doublet modes 75 ns to 42 s with ±10 ns jitter
Resolution 10 ns (width, delay, and PRI)"

I.e., not nearly enough for my application. Seems I have to resort to splitters and variable delay lines instead.
CMYKuser

Posts: 3
Registered: 05/08/12
Re: How do I get an arbitrary phase shift using two (2) E8257Ds?
Posted: May 14, 2012 5:16 AM   in response to: CMYKuser in response to: CMYKuser
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Edited by: CMYKuser on May 14, 2012 5:18 AM
tabbott


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Registered: 07/24/09
Re: How do I get an arbitrary phase shift using two (2) E8257Ds?
Posted: May 18, 2012 9:32 AM   in response to: CMYKuser in response to: CMYKuser
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Hi -

When shared/tied the 10Mhz reference together, the frequency of the two E8257D’s are synchronized. The phase output of the 2 E8257D’s will not be coherence to 10 MHz reference because there are several phase locked loops within the E8257D and their phase angle vary over temperature. So just lock the 10 MHz together you should have the same frequency and arbitrary phase shift.

Hope this helps -

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