5644 Synchronization

[Zarrar456]

I want to generate two RF out using TWO VST 5644R. One should be 72ns delayed by another but these should be synchronized. I also do not know is LO sharing required or not. Please provide solution

[mbb25]

The 5644R supports IQ rates up to 250 MS/s, or 4 ns per sample.  You can synchronize the two devices, and shift one of the device's waveforms, moving n samples from the end of the waveform to the front.  For a 72 ns shift, n = 72e-9 * IQ rate.

This happens to be an integer number of samples.  If you needed a subsample shift, that is possible as well.  The interpolation delay attribute allows you to shift one of the devices by up to 1/2 of an IQ sample.  Note: if your IQ rate is low enough (<= 6.944 MHz), then you could get a 72 ns delay this way.  I believe the relative delay attribute has even finer resolution (smaller shifts).

I'm attaching an example I found that synchronizes two 5644R devices.  The 72 ns shift is left to you.  Based on the diagram, it seems this was intended to be a shipping example, but I don't see it installed anywhere on my system.

Hopefully this helps.

[mbb25]

Oh, and this page may help as well:

http://zone.ni.com/reference/en-XX/help/373680C-01/vstdevices/5646_rfsa_gsynchronization/

[Zarrar456]

Thank you soo much for reply it is helpful. 

Please also tell me that is LO sharing required in TWO VSTs 5644R. Which trigger should i use ? and which clock i should use for syncronization.  I want to interface DIO also , using DIO I have to generate different frequencies and powers on RFout which will be sychronized and 72ns second delay.

I am new to VSTS thats why I need support. Kindly elobarate.It will me much helpful to me and I will share the LabVIEW codes when this application will be done so that It will help someone else also.

[Zarrar456]

Respected Member,

 Can you please sare you email I need to verfify some points 

Zarrar456@gmail.com is my email. I ave to give to customer and I need urgent help

[James_Battleaxe]

Hi Zarrar456,

I looked at the example mbb25 provided and there's lots of good information in the comments on the code. Specifically, comments on steps 5 and 6 talk about LO sharing and triggering. After looking through those notes, if you have other specific questions to follow up on, feel free to post here!

[Zarrar456]

Dear Sir, 

               I want to generate CWs with 72ns delay.On run time I have to change frequencies also. I want to generate frequencies starting from 1GHz to 6 Ghz. How would I change IQ rate. Woul it work on one I/Q rate?. 

[mbb25]

Hum...if you are generating CW, then 72 ns of delay is just a phase shift.  You can use the phase offset attribute to get this.  A 1 GHz CW signal has a period of 1 ns, so a 72 ns "delay" is a 0 degree phase shift (integer number of CW periods).

[James_Battleaxe]

Hi Zarrar456,

As for changing frequencies on run time, we have some examples for that. You can find those examples in LabVIEW. On the menu bar, click Help >> Find Examples. Within the example finder you can look in the folder Hardware Input and Output >> Modular Instruments >> NI-RFSG >> Sweeps. Within that folder, I think the "RFSG Configuration List Frequency and Power Sweep.vi" is a good one to start with.