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USRP N200 , GPSDO toolkit , Magnitude and "Phase" !!

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I need to run a simple experiment using two USRP N200 adjunct with labview program to receive magnitude and phase of the received signal ?  Is it possible ? and how much is that received phase value reliable since i checked the magnitude value calulating it manually which is OK !!

Also Has anyone incorpated GPSDO toolkit with USRPs ? does that help in synchronising two USRP ? It would be a great help if some one has the labview VI to check to check the GPSDO toolkit is working well with USRP or not ? 

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Hi Asimnud,

 

The N200 is an Ettus product rather than an NI product, so you may want to check the capabilities of the N200 on their website.  I found a couple of articles on their website that may be of use to you:

 

Ettus N200

Ettus- Synchronization and MIMO Capability with USRP Devices

 

Thanks,

 

David B

National Instruments

Applications Engineer

 

 

 

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Thanks David,

 

Well I have been using LABVIEW example files availabe to run ettus N200 as transmitter and receiver. It works Ok. Also video tutorial has been a great help for that matter. Now, I want to know if the received signal is synchronised with the transmitting one . I got GPSDO tool kit for that purpose since application of my project is in wider geographic area. All I wanted to know that if there is any example file (VI) on labview to be used for N200 with GPSDO .

I am not sure about some changes need to be done in labview program to change the clock signal from PPS to GPSDO clock. or is it necessary at all?

 

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Hi Asimund,

 

If you are looking for a USRP VI that uses GPS signals, I'd recommend looking at "niUSRP EX Tx with GPS"; it can be found at:

 

<LabVIEW Installation path>\examples\instr\niUSRP


Also, we have an online community for the USRP linked below.  There is a wealth of USRP examples there that may benefit you.

 

https://decibel.ni.com/content/groups/ni-usrp-example-labview-vis

 

I'd also recommend looking through the posts on the USRP forums; these are dedicated to the USRP:

 

http://forums.ni.com/t5/USRP-Software-Radio/bd-p/500

 

Thanks,

 

David B

National Instruments

Applications Engineer

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Hey David,

I was succeful in selecting GPS clock as internal clock ( well, this is ettus related thing) . Thanks for your suggestions.
BUt, During this process, I have to burn rev2.0 framework and fpga files on to usrp.

I used NI USRP configuration Utility to burn frameworks and fpga for revision 2.0 N200 USRP. Even after succesfully burning , while  clicking " Find Devices " , it still shows USRP N200 Rev3. Whereas the USRP that I have clearly says rev 2.0 on its back side .
Should this question directed to you ( since I used NI utility to burn the image ) or do you think this should be directed to Ettus?

Thanks

Nischal

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I have attached the image of NI utility

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Accepted by topic author Asimnud

Hi Asimund,

 

David is currently out of the office, so I wanted to touch base with you about your question regarding flashing your N200.

 

I would speak with Ettus about this since you are flashing their FPGA.  They may have some utilities for you to use in stead, as well as some insight about why you are seeing this information in the flash utility.

 

Regards,

Regards,
Chris Elliott
x36772
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Well, I figured out the problem related to magnitude and phase and thanks for previous suggestions. But, Now have problem synchronising two N200 USRP and the labview program is working intermittently and then shows some error. Much detailed description is scripted below.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I have been trying to synchronize two N200 USRP (Receiver and Transmitter) using GPSDO toolkit + GPS antenna. I am using niUSRP EX PSK TX and niUSRP EX PSK Rx example file (Labview 2011) at the transmitter and receiver end. I have been using following step:


1. Used the aforementioned labview example files without any modification as step no 2 of Instructions provided in ( https://www.ettus.com/content/files/gpsdo-kit_4.pdf ) clearly mentions that changing J510 jumper on motherboard from 1-2 to 2-3 switches external 10 MHz Ref Clock to GPSDO’s 10 MHz Ref Clock. I assume that the hardware change made in the Ettus’ N200 USRP box while installing the GPSDO toolkit is enough to let the Labview program to know about where its reference clock signal is coming from.

 

2. I made some modification to the labview file (both TX and Rx) by adding a property node which selects “Reference Frequency Source” and added a controller which selects it as internal as shown in the attachment_freq.

 

3. Similar to (2), I made some modification to the labview file ( both TX and RX ), this time around by adding a property node which selects “Time base clock Source” and added a controller which selects it  as internal as shown in attachment_time.

 

à Point to be noted while performing this entire step (1, 2 and 3) was:
"The labview program works perfectly fine when no GPS antenna is connected to the GPSDO output of the N200 USRP. As soon as I connect the antenna to the USRPs, it throws error as shown in attachment_error"

 

So, my questions are directed towards these are:
[A]. What does the error actually mean?
[B]. What has the error to do with connection or disconnection of the GPS antenna to GPSDO tool-kit?
[C]. My objective is just to update both devices that the Ref-clock signal is coming from the same source ( as a mode for synchronizing both devices). I am using Ettus’ GPSDO clock with GPS antenna for that purpose. Since, my modification in program in step2 and step3 doesn’t work well. I would want to know how you incorporate that with labview. Is not there any example VI in labview that uses previously mentioned product to synchronize?
[D].What does the labview program takes as a Ref-Clock source as default ?

 

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Hi Asinmud,

 

I'm sorry to hear you're having trouble with synchronization.  Since this is a different issue, it would be best to post this in a separate thread and mark a solution to your original question in this one.  By keeping discussions on topic with their subject, we can keep our online community organized and more searchable when others need help.

 

I would also advise in this situation that you contact Ettus for assistance since NI does not provide support for Ettus hardware.

 

Regards,

Regards,
Chris Elliott
x36772
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