Impedance Analyzer

Just about everything about Red Pitaya
Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Impedance Analyzer

Post by Bulova » Fri Feb 03, 2023 7:19 pm

Hello,
I have the simple Impedance Analyzer arrangement with a shunt of 1 Ohm and a series resonant circuit. The one with OS 1.04/07 provides a plausable result, while with OS 1.04/18 makes junk and each time, when I started it again, a different picture.

Regards

Dieter

User avatar
redpitaya
Site Admin
Posts: 882
Joined: Wed Mar 26, 2014 7:04 pm

Re: Impedance Analyzer

Post by redpitaya » Tue Feb 07, 2023 11:05 am

Try using a 50-Ohm shunt. Red Pitaya's output filter is tuned to a 50-ohm load, so you are most likely experiencing mismatched impedance problems (line ringing, etc.).
https://content.redpitaya.com/blog/usin ... e-analyser

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Impedance Analyzer

Post by Bulova » Tue Feb 07, 2023 7:39 pm

Hello,

thanks for the response. My apologies for the impatience and my angry reactions.

I try to include the whole effects I am having into one thread now.

1st:I tried it again with 1.04-18 and the Impedance Analyzer, but was not successful. It is still a corrupt result, while I can get just one stable and single peak, when I run 1.04-7 together with the shunt circuitry and a parallel resonance circuit as my DUT.

2nd: When I tried it with 1.04-18, I had to use my WiFi dongle Edimax. The wired LAN connection alone did not work, I got no connection.

3rd: When I worled with 1.04-7, the Impedance Analyzer worked -- as mentioned before -- and the LAN and WiFi connection worked both (alternatively). Although the wpa_supplicant.conf file is the same in both SD cards. -> very weird.

4th: After 1...3 issue, I thought, maybe the whole OS 1.04-18 on the one SD card is not okay. So I will try to install the OS again on this SD card, but this time the Beta version 1.04-28. I will report that too.

Best regards

Dieter

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Impedance Analyzer

Post by Bulova » Wed Feb 08, 2023 9:59 am

Hello,

I tested OS 1.04-28, and now it works even with LAN (wired) connection. I changed the entry in Network Manager from static to DHCP. But I am not sure if this was the root cause of not functioning with LAN connection before.

The Impedance Analyzer is still a problem, even with the load of 50 Ohms at the IN1/OUT1 line.
I attached pictures of the results of 1.04-7 (ok) and 1.04-28 (two tries, different and not ok).

By the way: I cannot reach Market Place, only error messages there.

Best regards

Dieter

P.S. Attachment didn't work: board attachment quota has been reached

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Impedance Analyzer

Post by Bulova » Wed Feb 08, 2023 2:05 pm

Hello,

is it possible just to exchange the parts of the "new" Impedance Analyzer in 1.04-28 against the "old" one in 1.04-7? If I knew which parts are specific for this App, I could change this.

Best regards

Dieter

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Impedance Analyzer

Post by Bulova » Thu Feb 09, 2023 9:31 am

Hello,

now it is proved, that the new Impedance Analyzer (from 1.04-18/28) does not function at all. I measured the output from OUT1 (neither OUT2) and there is nothing except a DC offset during the measuring period. Exactly the same setup with the older Impedance Analyzer there is a sweep sinusoidal signal on OUT1 during the measuring period, and the result is plausible.

I found two additional threads from other people, who experienced the exact same effect with the Impedance Analyzer of the newer OS.

So I would say, this App needs to be revised.

Best regards

Dieter

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

Re: Impedance Analyzer

Post by pavel » Thu Feb 09, 2023 10:07 am

Hello Dieter,

Seeing your recent posts about issues with Wi-Fi adapters and the impedance analyzer application, I would dare to suggest trying my SD card image that works with a wider range of Wi-Fi adapters and the VNA application that comes with this SD card image.

The SD card image does not have a GUI for network configuration, so some familiarity with the SSH command line and Linux is required.

For the VNA application, a very simple series fixture can be assembled from a couple of resistors and SMA or BNC connectors. A picture of my solderless series fixture can be found at this link.

Best regards,

Pavel

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Impedance Analyzer

Post by Bulova » Thu Feb 09, 2023 2:42 pm

Hello Pavel,

thank you very much for this information. I am afraid, that I have to admit, I did not really understand what to do with this. I downloaded the zipfile, unzipped it and copied the content onto an empty SD card. I am sure that this is not the right strategy. You are writing about an image file, but what I have unzipped, is not an image file. So, when I started with this card in the RP, nothing happens, except a message, that there is no connection estabilished. Or shall these files be copied to a SD card, where an RP OS is already installed? Or do I have to install something about Alpine? I really don't know. I am not familiar with Linux and Linux distributions at all. I just can passable operate with Windows, nothing else.

Sorry,

best regards

Dieter

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

Re: Impedance Analyzer

Post by pavel » Thu Feb 09, 2023 3:46 pm

Thank you for giving it a try.

I agree that the word "image" can be confusing, but I do not know what else to call this zip file.
Bulova wrote:
Thu Feb 09, 2023 2:42 pm
I downloaded the zipfile, unzipped it and copied the content onto an empty SD card. I am sure that this is not the right strategy.
This is the right strategy. I think that your Red Pitaya board should already be able to boot from this SD card. If not, the Troubleshooting section may be able to provide some guidance.

The next steps depend on the network configuration around your Red Pitaya board. Here is a list of steps that I normally use:
  • use the IP address or the local hostname (rp-f0xxxx.local) to connect to the web interface
  • start the Vector Network Analyzer application by clicking on the corresponding link in the web interface
  • start the client program for the Vector Network Analyzer application
  • do calibration, measurements, etc
If the network connection cannot be established, then I check the boot process using the USB/serial console as explained at this link.

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Impedance Analyzer

Post by Bulova » Thu Feb 09, 2023 5:05 pm

Hello Pavel,

yes, you are right, it really works. I tested it with wired connection now, and this seems to work. The VNA also opened. Now I have to play with this. By the way, the pulsed NMR is very interesting too, as I wanted to start a NMR project anyway.

Now I have to read some descriptions and so on.

Thank you for the good tip.

Best regards

Dieter

Post Reply
jadalnie klasyczne ekskluzywne meble wypoczynkowe do salonu ekskluzywne meble tapicerowane ekskluzywne meble do sypialni ekskluzywne meble włoskie

Who is online

Users browsing this forum: No registered users and 22 guests