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Two TX in one USRP with complicate transmission scenario

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Hi Amir2, 

I took a look at the channel list and it is behaving as expected on my end. In other words, when I specify channel 0, it transmits on channel 0 and the same for channel 1. To clarify, the waveform graph indicator on the example is simply showing what the created waveforms look like. If you change the channel list, that won't change the waveform graph indicator. 

This ties back to my original question of what are you using to test the results? Do you have a 2nd USRP RIO using the 2 RX channels to see when something is being transmitted on each channel and then determining that the channel list is not working? 

Shalini M.
Partner Development Engineer
Alliance Partner Network
National Instruments
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Yes! Waveform graph indicator won't change the waveform when we change the channel list. The waveform graph indicator has nothing to do with the channel list that we change inside the while loop. I totally understand it.

 

 

Yes, I use 2nd USRP RIO and by using Spectral Monitoring vi, I monitor the spectrum. I attached the result to this message below. In the transmitter part (first USRP RIO), two TX1 in channel 0 (f0 = 2.45G) and channel 1 (f1 = 2.454G) are enabled. But, the channel list is changing based on the MathScript code included inside the while loop (The VI has been posted in Message #5). As I understand based on what I see in the power spectrum graph indicator of Spectral Monitoring vi, both channels in the first USRP RIO are transmitting because I see two peaks in the graph. I would expect to see that sometimes both channels are transmitting and sometimes just one of them is transmitting. However, I always see that both channels are transmitting.

 

Just a question in this regard, how would you be able to see what you expected?

 

 

Monitoring.jpg 

 

 

 

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Message 12 of 17
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Hi all,

 

I couldn't get the solution for the problem I am encountering while prototyping a specific transmission scenario that I described in the first message.

 

Does anybody have any ideas?

 

Thank you.

 

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Solution
Accepted by topic author Amir2

Hi Amir,

 

I came up with an idea. You can use a case structure to pass an array of 0+0i elements to the USRP based on your selector. This will cause the USRP to output no signal instead of a signal. You can implement it as I have done in the image below, with your MathScript replacing the TX Channel Input.

Select Channel.png

The ch1 case looks like this:Select Ch1.png

I included the VI I made below.

 

You may also be able to use the Enabled Channels property along with the Initiate and Abort VIs. 

 

On the Discussion Forums it is okay to ask for and discuss ideas, but ultimately you may just find ideas and not solutions. It may be up to you as the engineer to develop the end solution on your own with the ideas you gained here. If you do find a solution, it is always great to contribute back to the community that helped by providing that solution. Educating the community as a whole helps everyone.

 

Cheers
Michael

Michael Bilyk
Former NI Software Engineer (IT)
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Here is the code.

Michael Bilyk
Former NI Software Engineer (IT)
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Message 15 of 17
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Hi Michael,

 

Thank you very much for your explanation and sharing your idea! I highly appreciate it.

 

I used the case structure that you used in your code. I added the MarhScript to the case structure and It totally works. 

 

I totally agree with your opinion on the Discussion Forums' purposes. I was also looking for right guidance so that I can develop the end solution. I received very helpful guides and ideas from member's of this forum and I am so grateful for all of them. 

 

Best regards,

Amir

 

 

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anyone share with me a VI with Implementing 2x1 MISO system with LabVIEW and NI USRP 2921?? I need problem with the estimation channel in the receptor, i used the alamouti code with 2 antennas trnasmitter and one antenna receiver.

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