Re: Phase Synchronize 2 USRP N200 w/ SBX cards

[Skyvalakis Konstantinos]

In addition to my last message regarding the INTEGER_N tuning​, ​I repeated the experiment multiple times. I even restarted the USRPs and the signal generator multiple times.

What I observed was, that there were only 4 different recurring phase offsets (Blue = RX2 of SBX1, Red = RX2 of SBX2).

I am attaching the 4 screenshots I captured.

Thank you so much for your help. I feel like we're getting there.

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From: Discuss-gnuradio <discuss-gnuradio-bounces+kskyvalakis=isc.tuc.gr@gnu.org> on behalf of Skyvalakis Konstantinos <kskyvalakis@isc.tuc.gr>
Sent: Thursday, June 10, 2021 7:37 PM
To: Marcus D. Leech
Cc: Discuss-gnuradio@gnu.org
Subject: Re: Phase Synchronize 2 USRP N200 w/ SBX cards

 

So, I replaced these 2 commands:

self.source.set_center_freq(uhd.tune_request(868e6,0), 0)

self.source.set_center_freq(uhd.tune_request(868e6,0), 1)

with these commands:

trequest = uhd.tune_request(868e6,args=uhd.device_addr('mode_n=integer'))

self.source.set_center_freq(trequest,0)

self.source.set_center_freq(trequest,1)

Did I do it right?

If yes, then the 2 channels are still out of phase.

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From: Marcus D. Leech <patchvonbraun@gmail.com>
Sent: Thursday, June 10, 2021 7:08 PM
To: Skyvalakis Konstantinos
Cc: Discuss-gnuradio@gnu.org
Subject: Re: Phase Synchronize 2 USRP N200 w/ SBX cards

 

On 06/10/2021 07:39 AM, Skyvalakis Konstantinos wrote:

Yes, I know that about GNURadio and the timed commands. I just described the flowchart here.

After I generated that flowchart in GNURadio I edited the timed commands in the generated python file, according to the code I included in my very first message in this thread.

So the timing is definitely done properly.

I also switched to QT GUI time sink, as you proposed, and I still observe a different phase offset at every experiment.​

I am using 3.7.12.0 version of GNURadio.

Thanks for your help.

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You might try forcing INTEGER_N tuning:

trequest=uhd.tune_request(your_center_freq,args=uhd.device_addr('mode_n=integer'))

Then use 'trequest' in your frequency setting.

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