NanoVNA Custom Software

[joeqsmith]

Ran a quick check to try out the stage with the added math.   showing 0.1" increments and a total travel of 2.0".   It may be basic but it sure is impressive. 

[jluu]

Another article on TRL calibration: https://coppermountaintech.com/design-calibration-of-a-trl-calibration-kit/

[jluu]

Another article on TRL calibration: https://coppermountaintech.com/design-calibration-of-a-trl-calibration-kit/

One more, same source: https://coppermountaintech.com/trl-calibration/

[rhb]

Ran a quick check to try out the stage with the added math.   showing 0.1" increments and a total travel of 2.0".   It may be basic but it sure is impressive.

Very nice.  That's the way to do it.  I'm planning on making  a picosecond level stage once I get all my machine tools set up for such work.  Rather fiddly if you want a clean response.

[joeqsmith]

I'm not too concerned with the absolute numbers.  40 steps, 0.050" per step.  The top is showing the histogram.   It moves around a bit too much but certainly proves the concept.   

[radiolistener]

joeqsmith, it's better to use nanoseconds. It doesn't depends on cable type

[joeqsmith]

joeqsmith, it's better to use nanoseconds. It doesn't depends on cable type

No doubt people have their opinions.       

Currently my software supports metric, English, time and samples for the graphing units.  Most likely it will include phase as well.  Much like the filter settings,  the units are hard coded and changed depending on the test I am running.  In this case, I am working with a stage where I am dealing with distance.  Being from the USA where we can't seem to make the leap to metric, I normally work in English.     

If I had a desire to make the software public, it would include a way to change the units and also store the default settings.  At the present time, I'm more interested in experimenting with the Nano than making polished bit of software for public use.   The software evolves as my requirements change.

That said, the time/distance will have the same profiles.  No matter what units you like, the error is still the same.

[jMachina]

I know this thread is for complaining about not getting free software when there is free software and complaining about not having your questions answered even though they are answered  , I thought I'd add this interesting write-up that takes pains to explain some of the math that I found to be a useful refresher.

https://mightydevices.com/index.php/2019/08/complex-impedance-matching-using-scalar-measurements-math-and-resistors/

I have ordered both the least expensive and most expensive nanoVNA clones on Amazon and will post some photos of the PCBs, etc. at a later date.

Thank you Joe for your videos, I am watching my way through all of them and learning a lot!

- Joshua

[joeqsmith]

I know this thread is for complaining about not getting free software when there is free software and complaining about not having your questions answered even though they are answered  ,
....

It does seem like this from time to time.   

I thought I'd add this interesting write-up that takes pains to explain some of the math that I found to be a useful refresher.

https://mightydevices.com/index.php/2019/08/complex-impedance-matching-using-scalar-measurements-math-and-resistors/

I have ordered both the least expensive and most expensive nanoVNA clones on Amazon and will post some photos of the PCBs, etc. at a later date.

Thank you Joe for your videos, I am watching my way through all of them and learning a lot!

- Joshua

You are very welcome.  I'm glad to hear a few people have found them helpful.

I still only have the one Nano.  If they produce the gen 2 unit that's been mentioned, I may pick one up to help quench my thirst. 

Looking at the error, I discovered a major problem (race condition) with my software design that I have now corrected.  This could cause the data to be corrupt.  Sadly, it didn't help with the error.  What's interesting is plotting the change in distance during the test, we get this sort of U shape.  This is reproducible. 

[joeqsmith]

Using the same setup but not moving the stage, the signal is very stable.   I suspect the home made phase trimmer is the cause of the majority of my problems.   

[joeqsmith]

Replacing the home made trimmer with a commercial one made by Sage and manually adjusting it. 

[joeqsmith]

Going back to the home made phase trimmer with the Beatty cable I show with the Sage, and using roughly the same step size.   

[joeqsmith]

Definition of insanity

1 dated : a severely disordered state of the mind usually occurring as a specific disorder
2 law : unsoundness of mind or lack of the ability to understand that prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or that releases one from criminal or civil responsibility
3a : extreme folly or unreasonableness the insanity of violence His comments were pure insanity.
b : something utterly foolish or unreasonable the insanities of modern life


Let's see, I'm looking at a $50 Chinese VNA with a $1000 phase trimmer attached to it with a $200 torque wrench.  Why?  Because a $500 stage with the $30 home made phase trimmer wouldn't let me play with some basic algorithm.   

[Efcis]

Hi

If they produce the gen 2 unit that's been mentioned, I may pick one up to help quench my thirst. 

It may be this one : https://www.aliexpress.com/wholesale?SearchText=nanovna-f

Rgds

[radiolistener]

It may be this one : https://www.aliexpress.com/wholesale?SearchText=nanovna-f

this is the same NanoVNA, but pcb redesigned for large IPS display, more powerful MCU and large 5000 mAh battery. 

[joeqsmith]

Someone was posting about a 2.4GHz version without using  harmonics and at the same cost, plus improved communications.     I've been using the Nano headless for the most part but have tried it with my 8" tablet.

I made an attempt to improve the home made delay line.  Stepping 0.01"ish  for 150 steps or  1.5"ish total travel.  Shown also is the absolute phase and distance.

[rhb]

I'd really appreciate more construction details of your phase shifter as I intend to build at least one and possibly more.  I can resolve delays to picosecond levels on the 11801 & SD-24 combination.

I actually need 8 short (~10-20 ps maximum) phase shifters to phase match the cables from an FPGA board to my Tek 11801 w/ four 2 channel SD-26 sampling heads.  That's for measuring adder-multiplier bit skew for various DSP topologies for use in a FOSS DSO based on Zynq 7010 or 7020 FPGAs.

Making stuff like that is the justification for having a lathe and mill.  I have a Chinese 7" x 14" mini-lathe completely disassembled awaiting new bearings and scraping to make a precision toolmaker's lathe out of it.  As sold they are just a set of parts assembled at the factory to make sure they don't leave any parts out of the kit.

I'm confused by the axis labels on your displays, particularly the Y axes on the display with 3 plots.   In an earlier post you showed the sidelobes of the sinc(x) changing.  It would be helpful to know more about that data.  I spent my career doing oil industry DSP.  My instincts are that your "error" is actually exactly what you should be getting, but I need to know more about the data.

The best test of your software is to construct synthetic test cases.  For example, to test solving for the length, create  several series which are exactly exp(j*2*pi*t) for various values of t.  If t is not an integer multiple of the sample interval dT, then you'll see a sinc(x) for dT = 1/(2*Fn).  If dT is a small faction of that you will always see the sinc(x).  When it is exactly at Nyquist, the time samples all fall at the zero crossings in sinc(x).

Have Fun!
Reg

[joeqsmith]

Consider the very top graph of the set of three, where I use the terms Amplitude, Distance and Length to describe the vertical axis.   This is showing the change in distance per step.  For example, looking at post 333, I an moving the stage in 0.1" increments.  The Nano is showing it from 0.101" down to 0.042".   That was using the home made phase trimmer.     

Looking at post 334, where the stage is not moving, the change is +/-0.002". 

Looking at post 335, where the home made trimmer was replaced with the Sage commercial part where I am adjusting it by hand, it shows between 0.224 and 0.271"   

Post 336 was an attempt to do an A/B compare between the home made trimmer and the commercial part by stepping roughly the same amount.   The was between 0.174
 and 0.280".

Post 340, the stage is incremented  by 0.01" (its really 0.01000976... as it is not an even divisor).  The software reports a mean of 0.0103".  The stage moves 150 steps and show move 1.501465" compared with the reported 1.5314".   I zoomed into the side lobes to show the spacing and we can see they are not uniform.   

The middle graph is just the histogram of the step sizes.  Or how many times the step size falls into a bucket.   

The trimmer is brass.  Your local hobby shop should have all sorts of shapes and sizes to choose from.  There is also McMaster Carr.   

[rhb]

My question about the phase trimmer was about dimensional and construction details.  The photos I looked at looked like copper pipe with SMA-F to N-F connectors at the end.  I'd expect tube on tube and tube on wire for the line.  I was wondering what the dimensions you chose were and what the measured and calculated impedances were.  What's the reflection at the SMA-F/N-F adapter to adjustable air line look like?

The vertical axes in the first PNG of #340 are "Length" ,"Score" and "Impedance".  The horizontal axes are "Samples", "Length" and "Length".  I know from inspection that the bottom figure is reflection coefficient vs time.  If you take magnitude and phase, convert to a complex series and Fourier transform you get the band limited reflection coefficient on the Y axis and the travel time on the X axis.

In the 2nd PNG of #340, "angle" only has meaning at a single frequency.  If you are comparing change in  line length and the time domain relationship that is time change, "dT".  As a consequence, I have no idea what it describes.

Your work is very interesting, but you've omitted so many details that I am unable to evaluate it.

[joeqsmith]

The vertical axes in the first PNG of #340 are "Length" ,"Score" and "Impedance".  The horizontal axes are "Samples", "Length" and "Length".  I know from inspection that the bottom figure is reflection coefficient vs time.  If you take magnitude and phase, convert to a complex series and Fourier transform you get the band limited reflection coefficient on the Y axis and the travel time on the X axis.

Length is inches, not time.  Peak is at roughly 20 inches. 

In the 2nd PNG of #340, "angle" only has meaning at a single frequency.  If you are comparing change in  line length and the time domain relationship that is time change, "dT".  As a consequence, I have no idea what it describes.

Angle data was collected at 900MHz for each step.   Samples refers to the number of steps, which was 150 for both PNG1&2.  Trimmer moved from 19.8" to 21.3" in 150 steps.

My question about the phase trimmer was about dimensional and construction details.  The photos I looked at looked like copper pipe with SMA-F to N-F connectors at the end.  I'd expect tube on tube and tube on wire for the line.  I was wondering what the dimensions you chose were and what the measured and calculated impedances were.  What's the reflection at the SMA-F/N-F adapter to adjustable air line look like?

There is no wire as you expect.  55.7 ohms, 18.2pf / 56.7nH per meter.   

[rhb]

My question about the phase trimmer was about dimensional and construction details.  The photos I looked at looked like copper pipe with SMA-F to N-F connectors at the end.  I'd expect tube on tube and tube on wire for the line.  I was wondering what the dimensions you chose were and what the measured and calculated impedances were.  What's the reflection at the SMA-F/N-F adapter to adjustable air line look like?

There is no wire as you expect.  55.7 ohms, 18.2pf / 56.7nH per meter.

Calculated or measured?  You are either a *very*  poor communicator or  being deliberately obtuse.  I asked for physical dimensions and construction details.  You furnished *nothing* useful.

I asked a simple question about the construction of your delay line.  A linear adjustable length air dielectric delay line must of necessity have inner and outer conductors which telescope.  One *might* get acceptable results by sliding an inner conductor through an end termination, but I'm doubtful.  I'd expect significant issues with stray capacitance and inductance if you did that. You are being willfully mysterious.

Sadly, I'm forced to conclude this thread is a waste of time.  It's just joeqsmith pimping his ego.

[joeqsmith]

My question about the phase trimmer was about dimensional and construction details.  The photos I looked at looked like copper pipe with SMA-F to N-F connectors at the end.  I'd expect tube on tube and tube on wire for the line.  I was wondering what the dimensions you chose were and what the measured and calculated impedances were.  What's the reflection at the SMA-F/N-F adapter to adjustable air line look like?

There is no wire as you expect.  55.7 ohms, 18.2pf / 56.7nH per meter.

Calculated or measured?  You are either a *very*  poor communicator or  being deliberately obtuse.  I asked for physical dimensions and construction details.  You furnished *nothing* useful.

I asked a simple question about the construction of your delay line.  A linear adjustable length air dielectric delay line must of necessity have inner and outer conductors which telescope.  One *might* get acceptable results by sliding an inner conductor through an end termination, but I'm doubtful.  I'd expect significant issues with stray capacitance and inductance if you did that. You are being willfully mysterious.

Sadly, I'm forced to conclude this thread is a waste of time.  It's just joeqsmith pimping his ego.

These values were calculated based on the telescoping brass tubes that were used.

https://www.eevblog.com/forum/rf-microwave/sma-phase-adjuster-construction/msg2315619/#msg2315619
Your original post on the trimmers was from back in April and it seems you have not made any headway. 

https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/msg2640531/#msg2640531
You had mentioned having ADD and I wonder if your last comment is from your frustrations with your own personal lack of progress. 

You may find the following article helpful.
https://hackaday.io/project/162998-the-rise-and-fall-of-pulses

Personally, I would have just ordered up some tubing and started trying some things out rather than lashing out at others.   

[OA4LDR]

Dear friend, I congratulate you for the work you did with that software. It makes it easier for us radio amateurs that we like to experience every day with all kinds of antennas!  In particular I like to manufacture HF and VHF antennas for me qth!  I wanted to ask you a question?  Do you have the software you made?  Or do you share it experimentally for radio amateurs?  why I wish I could have it installed on my PC!  I have the new version of NanoVNA-F 4: 3 inch screen!  Best regards from Lima Peru I leave my email to see if you can send me the software there!  oa4ldr@gmail.com a hug and greetings to all!  73s atte OA4LDR

[OA4LDR]

Dear friend, I congratulate you for the work you did with that software. It makes it easier for us radio amateurs that we like to experience every day with all kinds of antennas!  In particular I like to manufacture HF and VHF antennas for me qth!  I wanted to ask you a question?  Do you have the software you made?  Or do you share it experimentally for radio amateurs?  why I wish I could have it installed on my PC!  I have the new version of NanoVNA-F 4: 3 inch screen!  Best regards from Lima Peru I leave my email to see if you can send me the software there!  oa4ldr@gmail.com a hug and greetings to all!  73s atte OA4LDR

[rhb]

These values were calculated based on the telescoping brass tubes that were used.

For which you provided *no* information.  There is not much burden in stating what size tubing you used and other basic construction details.  Not handing out software I fully understand.  Not providing the dimensions of the airline I don't.

https://www.eevblog.com/forum/rf-microwave/sma-phase-adjuster-construction/msg2315619/#msg2315619
Your original post on the trimmers was from back in April and it seems you have not made any headway.

Well, if you don't work on a project, nothing happens.  Tuesday I replaced a A/C condensor fan motor.  Friday I had to deal with replacing a 5 ton compressor and condensor and evaporator coil.  Today I investigated the linearity of the timebase interpolation of my 11801 for which the factory cal constants were lost.  If they actually existed.  In light of the results, I question whether they might not be mythical.

https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/msg2640531/#msg2640531
You had mentioned having ADD and I wonder if your last comment is from your frustrations with your own personal lack of progress. 

I have more projects than I have time left on this earth.  In most cases I also have no reason to prefer one over the other.  Things like HVAC repairs for tenants do take priority.

I had planned to write new FW for the nanoVNA today until a post on the 11801 showed up on TekScopes.  The 11801 was the smaller project, so I did that.

You may find the following article helpful.
https://hackaday.io/project/162998-the-rise-and-fall-of-pulses

I did almost as well 25+ years ago without having a sampling scope and just using a generic prototype board.  Leo Bodnar does <40 ps with a BNC and less with better connectors.

Personally, I would have just ordered up some tubing and started trying some things out rather than lashing out at others.   

Actually, I'd have started by calculating the impedances for airlines made from stock components rather than engaging in random activity.  I'd been hoping to be spared that tedium.

As you are unwilling to state the relevant dimensions, I stand by my comment.  You're a waste of time.  But..

Have Fun!
Reg

I'm out of here.