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Wideband Spectrum Monitoring

Visit http://zone.ni.com/devzone/cda/tut/p/id/13878http://zone.ni.com/devzone/cda/tut/p/id/13882 for a description of this example and background information.

Software Requirements

  • NI LabVIEW 2011 (Full, Pro, Student, or Eval edition)
  • NI USRP 1.1

Hardware Requirements

  • NI USRP 292x RF Transceiver

Release Notes

  • 9/6/2012: With the 9/6 release of this example, I've fixed a serious problem with the code,  which was causing the peak locations to shift as a function of sampling rate. The lastest  post (9-6-2012) fixes this problem, but there is still a problem where  the amplitude of the edges of the segments don't match up. I'm working on a possible solution for that now.
Sam Shearman
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I get the following error message:

Property Nodes (arg 5) in subsetupRxHWParameters.vi->subSetParameters(HL).vi->Simplified WB Spectrum Sense (Averaged).vi <ERR>

The specified attribute ID is not recognized.

There is no content in link for the description.

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The example requires the ni-usrp driver Ver 1.1 or higher. Ver 1.1 includes some new properties that werent part of Ver 1.0. The new driver will be released in less than a month and is avail now as a prerelease.

--Sam

Sam Shearman

Senior Product Mgr, National Instruments

Cell: (512) 576-6170

Sent from my iPhone.

Sam Shearman
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Hi,

there is a little mistake in the program:

if you try to average with: RMS average, Linear, Number of averages = 2,

the mistake will be visible in the spectrum,

for example in the wideband spectrum with only one strong narow carrier, instead of one line you can see two lines.

The second line, moved to upper frequencies exactly by the half of "df" is the mistake.

The "ghost" carrier, which should not be there is made by averaging moved by one iteration.

In the smallest loop in the main VI, there is shift register, but the iteration number "i" should be shifted by shift register too.

Problem solved.

lvproblem.jpg

Thanks for nice example.

Regards.

Neo

VSB Technical University Ostrava.

Czech republic

NI Employee
on

Hello Neo -

These suggestions are very helpful.  Please post your updated code to this

page in the community.  We would very much like to learn how you are using

the USRP and LabVIEW in your research.

Best Regards,

Erik

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I'm getting a change in the gain as the program steps through the frequencies. Below shows the IQ waveform samples at their original scale:

spectrumSmall.JPG

After stepping through the first few frequency ranges, there is a jump in the gain. Notice the jump in the amplitude. The underlying signal is just noise.

spectrumBig.JPG

Upping the sampling rate so that the entire frequency range is covered in one step shows that the spectrum is clean:

spectrumNoProb.JPG

The following shows the modifications I made to monitor the input waveform:

modifications.JPG

Any help would be appreciated.

-John

University of Virginia

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I found a new problem with the spectrum monitoring software. Here is a sweep of the FM spectrum with a strong signal at 97.5 MHz with a sampling rate of 200 kHz:

200k.jpg

Here is the same spectrum swept with a sampling rate of 1MHz:

1M.jpg

The 97.5 channel appears at a higher frequency as you increase the sampling rate.

-John

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Hi John,

I've just posted a revised version of the example (see the zip file dated 9/6/2012) that addresses theproblem of a frequency shift being a function of sampling rate. As you rightly pointed out, the sampling rate (bandwidth) should b independant of the location of the peaks and other components of the spectrum. The gain change is another issue that I'm still working on for this example.

--Sam

Sam Shearman
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Hi everybody,

When I run the example "Simplified WB Spectrum Sense (Averaged)", some errors are reported: niUSRP Open Rx Session.vi<ERR>A runtime or configuration error occurred.  Code: 1440 Details: RuntimeError:  Please update the firmware and FPGA images for your device. See the application notes for USRP2/N-Series for instructions. Expected protocol compatibility number [7 to 11], but got 12: The firmware build is not compatible with the host code build. I use the USRP N200 and Labview 2012. The installed USRP driver is niUSRP 110.  Is there anybody can tell me the reason? thanks a lot!

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I have downloaded the 952012 version of this code and am getting the same error as YYYs:

Property Node (arg 5) in subsetupRxHWParameters.vi->subSetParameters(HL).vi->Simplified WB Spectrum Sense (Averaged).vi <ERR>

The specified attribute ID is not recognized.

Any help would be appreciated 🙂

NI Employee
on

Hello -

Are you using the NI USRP 1.2 version of the driver?

http://joule.ni.com/nidu/cds/view/p/id/3696/lang/en

Erik

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Hi Sherman,

I could not find the updated version (see the zip file dated 9/6/2012). I can only see the old version. Can you please reattach it.

Thanks

NI Employee
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The code posted contains the latest updates made to the example in september of 2012.  Feel free to make improvements and post your own enhanced code!

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Hi airflyflame,

The reason for your error is that you are using the wrong FPGA bit file. Load the one, which is provided with the NI driver and you'll be fine.

I have the same issue, but I cannot use the provided FPGA bit file, because I have my own FPGA bit file, which is a self-developed extension to the Ettus FPGA source code, which has protocol compatibility number 12. As long as I worked with earlier versions of the FPGA source code, the NI driver was functional too. Could NI tell us, when you are going to update the Labview driver to be compatible with the latest Ettus FPGA bit file?

Vojtech

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Hi, I have a question.  What parameter (time in Rx Average power) ? Acq duration is averaging time????

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Hi, Thanks for the example.

I am new to USRP and Labview, I need to do exactly the same thing you are doing in this code. I need to find out the signal strengths of higher frequencies.

Being from Computer Science background I have no idea about transforms and averaging etc.

I am getting an error while running the code, Can you please help me with it.

Error :  -1074118626     niUSRP Initiate.vi<ERR>The local oscillator did not lock within the allotted time.

PLEASE HELP ME

I changed the Acq Duration to 10m otherwise the code won't start and I would get the same error in the beginning.

Capture.PNG

NI Employee
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Hi @gauraangKhurana

Did you ever get through your error?

Thanks!

Rahul

Rahul B.
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Error :  -1074118626     niUSRP Initiate.vi<ERR>The local oscillator did not lock within the allotted time.

 

I an doing wideband spectrum monitoring. USRP 2920 is sweeping across 50 MHz to 01 GHz. I get this error mostly in 1st sweep and sometimes after sweeping the whole band 02 times.

Any help would be valuable.

Member
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@gauraangKhurana 

Error :  -1074118626     niUSRP Initiate.vi<ERR>The local oscillator did not lock within the allotted time.

 

I an doing wideband spectrum monitoring. USRP 2920 is sweeping across 50 MHz to 01 GHz. I get this error mostly in 1st sweep and sometimes after sweeping the whole band 02 times.

Any help would be valuable.

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