Sampling of the signal with the pulsed nmr application

Applications, development tools, FPGA, C, WEB
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tt10977
Posts: 8
Joined: Sat Mar 12, 2022 9:07 am

Sampling of the signal with the pulsed nmr application

Post by tt10977 » Tue May 24, 2022 6:13 pm

Hi guys,
I have recently been working with Pavel Demins pulsed NMR application. After setting up some hardware I started performing measurements in the laboratory. Using an Oscilloscope, I was able to observe FIDs of several samples. Unfortunately, the NMR application seems to do something else than simply plotting the voltage on the input. (I couldn’t find much information about that.)

Is there a possibility to adapt the application to receive a plot of the voltage signal?
I would be very grateful, if someone could help me with that.
Thanks!

pavel
Posts: 790
Joined: Sat May 23, 2015 5:22 pm

Re: Sampling of the signal with the pulsed nmr application

Post by pavel » Tue May 24, 2022 7:36 pm

The last time I worked on this project, I mainly focused on the FPGA and server code. They are now functional and well tested.

The currently recommended way to use this project is to control the FPGA code and read the data using the following .NET library:
https://github.com/pavel-demin/red-pita ... lsedNMR.cs

The GUI part of this project is still very basic and I currently do not have the necessary hardware to work on it.

I think that to see the voltage signal it should be enough to set the RX frequency to 0 by replacing the following line in pulsed_nmr.py:

Code: Select all

self.socket.write(struct.pack('<Q', 0<<60 | int(1.0e6 * value)))
with

Code: Select all

self.socket.write(struct.pack('<Q', 0<<60 | int(1.0e6 * 0)))

tt10977
Posts: 8
Joined: Sat Mar 12, 2022 9:07 am

Re: Sampling of the signal with the pulsed nmr application

Post by tt10977 » Wed May 25, 2022 7:53 am

Dear Pawel,
thank you very much for your quick reply. I changed the line in the .py-file and everything seems to work perfectly fine. Right now I only checked it with a DC-Voltage on the input, but at least for this DC-Voltage it worked perefectly fine. I'm goning to check it with the whole hardware and the FID signal later that day. I think it should also work for a generall voltage-signal.

Thank you very much for your help!

fbalakirev
Posts: 73
Joined: Thu Sep 03, 2015 6:56 pm

Re: Sampling of the signal with the pulsed nmr application

Post by fbalakirev » Thu Jun 30, 2022 6:35 pm

pavel wrote:
Tue May 24, 2022 7:36 pm
I currently do not have the necessary hardware to work on it.
Dear Pavel,

Do you have any suggestions for the external hardware components and overall configuration for your NMR project?

pavel
Posts: 790
Joined: Sat May 23, 2015 5:22 pm

Re: Sampling of the signal with the pulsed nmr application

Post by pavel » Thu Jun 30, 2022 7:07 pm

As far as I know, the following components are required:
  • TX power amplifier
  • TX/RX switch
  • probe
  • strong uniform magnetic field
  • RX amplifier
The amplifiers connect to the RF inputs and outputs of the Red Pitaya board and the TX/RX switch is controlled by a GPIO pin.

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