Electronics > RF, Microwave, Ham Radio

NanoVNA Custom Software

<< < (284/317) > >>

ON7CH:

Can someone help me with the definitions/coefficients for this SMA Wiltron calibration sets.
See attachment.
[attach=1]

It concerns the standards type 22S50 and 22SF50.
I searched the internet with no results. I can't find a detailed data sheet.

Thanks in advance.
Guido

joeqsmith:

--- Quote from: ON7CH on December 02, 2021, 03:39:57 pm ---
Can someone help me with the definitions/coefficients for this SMA Wiltron calibration sets.
See attachment.
[attach=1]

It concerns the standards type 22S50 and 22SF50.
I searched the internet with no results. I can't find a detailed data sheet.

Thanks in advance.
Guido

--- End quote ---

Guessing you have a similar story as this person:
https://www.eevblog.com/forum/testgear/a-general-question-about-vna-calibration-kit-definitionsconstants/

Maybe you will find some useful advice there.

joeqsmith:
State of the software.....

I corrected the autoscale for the antenna scanning feature, added averaging and fixed a few other minor problems.  I decided against releasing this version as I started to give some thought to more complex calibrations.   


--- Quote from: joeqsmith on November 24, 2021, 07:13:01 pm ---While looking over OWOs projected specs for the V3,

https://nanorfe.com/nanovna-v3.html

I noticed they are planning to support unknown thru.   I doubt they are planning on producing a four receiver VNA. 

From:
https://www.picotech.com/vector-network-analyzer/picovna/picovna-features


--- Quote ---In a VNA a swept sine-wave signal source is used to sequentially stimulate the ports of the interconnect or device under test. The amplitude and phase of the resultant transmitted and reflected signals appearing at both VNA ports are then received and measured. To wholly characterize a 2-port device under test (DUT), six pairs of measurements need to be made: the amplitude and phase of the signal that was emitted from both ports, and the amplitude and phase of the signal that was received at both ports for each source. In practice this can be achieved with a reasonable degree of accuracy with a single source, a transfer switch and two receivers; the latter inputs being switched through a further pair of transfer switches. Alternatively three receivers can be used with an additional input transfer switch or, as in the PicoVNA, four receivers can be used.

Using four receivers eliminates the receiver input transfer switch errors (chiefly leakage and crosstalk) that cannot be corrected. These residual errors are always present in two- and three-receiver architectures and lead to lower accuracy than that of the Quad RX design.
--- End quote ---

I've never tried it with these low cost VNAs.

--- End quote ---


--- Quote from: joeqsmith on November 25, 2021, 08:34:56 pm ---Using my homemade standards to calibrate the V2Plus4.  Next I measured an SMA to SMA adapter, short section of semi-rigid and a longer section of RG400/U to simulate an unknown thru.  Then wrote a simple program to determine the Unknown and feed the data back through with corrections. Plots show the raw data in green and violet after correction.

--- End quote ---


OWO was recently posting about the V3 and they were requesting feedback on features.   

https://www.eevblog.com/forum/testgear/nanovna-v3-(6ghz)/msg3847832/#msg3847832

With the squarewave drive, I don't see a lot of value in a full 2-port system.   We may be stuck with using a external transfer relay.  Which gets back the the topic of calibration.  For the couple of you actually trying to use my software, I am sure you realized that the calibration is pretty limited.    The main reason for this is because of pure laziness and the lack of performance on these low cost VNAs.   Because the original NanoVNA worked much like my old
HP8754A, I stayed with the same software structure.   The calibration for the NanoVNA is actually a bit more advanced than what I wrote for the HP8754A which isn't saying much.  Consider the 8754A at best could normalize the data where my software allowed me to run a SOL on it. 

My software normally applies the error correction as soon as it sees a valid sweep.  This works fine for the 1-port VNAs but as we add the transfer relay,   the software has to make multiple requests to read all 4 four S-parameters.   This means a change to how the software was structured.   All doable but I doubt the gains are worth it.

As I continue to ponder my software for the low cost VNAs, the first problem I see is we need to ditch the current calibration file format.  This means the new software will not be compatible with the old files.    If the transfer relay was selected when a calibration was performed, the software prompts the user to run an SOL on both ports.   The new software would work the same way, however when selecting the 2PSwp (2 port sweep) it will test the state of the transfer relay and that the unit was calibrated.   It will then enable the full SOLT or SOLR (unknown thru) model.   This would only be useful when using the Advanced, 2-Port Plot tab.    When only S11/21 are required, the software will continue to normalize the thru but will use the 12-term model if SOLT is selected with the transfer relay.   

If I get something that I think may be useful to users, I will release it.   Going forward, I don't intend to put any more effort into supporting the original NanoVNA outside of correcting problems.  We have the LiteVNAs on order and are expecting them soon.  Looking forward to seeing how their performance compares with the V2Plus4.

Attached screen shots of version 3.0.


 

joeqsmith:
I'm looking for a reference book that covers the unknown thru in detail (along with other techniques).   

joeqsmith:
We received the LiteVNAs and ran a few tests on them.  Within a few minutes of testing we ran into a small snag with the firmware but the hardware appears like it was worth the wait.  I should have mine in the next few days.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version