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More time domain samples will not provide better resolution because of the upper frequency limit. However, if the UI allowed picking a peak on the time domain display, one could window that in time, Fourier transform and do a linear fit to the phase to get the delay time and display that.

For peaks which are close together, the Rayleigh criterion set by the maximum frequency is the best you can do. However, the phase fit is most easily done with just a single peak. For an isolated peak the phase resolution and wavelength of the highest frequency measured determines the spatial resolution. I doubt that the velocity factor sufficiently consistent to do better than a few cm.

A basis pursuit will resolve closely spaced reflections, but that's not something that an STM32F series MCU can do.

Off the top of my head, I don't see a way to solve d = a0*exp(j*2*pi*f*t0) + a1*exp(j*2*pi*f*t1) by least squares. Though you might get close enough by estimating a0 & a1 in the time domain and only solving for for t0 and t1.

I wish I had time to work on this more, but other tasks must be attended to.

Have Fun!
Reg

Just the question of the beginner.
Would it be possible to implement some of the features of this project into NanoVNA?



Palo.

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: NanoVNA User Guide - cho45 - reformat-a.pdf

Uploaded By: Larry Rothman

Description:
This is a slightly reformatted and edited version of cho45's excellent (github-based) NanoVNA User Guide. I have made the URL links live as well as added some additional verbiage in order to clarify some content.

You can access this file at the URL:
/g/nanovna-users/files/NanoVNA%20User%20Guide%20-%20cho45%20-%20reformat-a.pdf

Cheers,
The Groups.io Team

Update as promised:
Today, Thursday 26th September 2019 the status of my order from TomTop updated by '17 Track' to "arrived at local Post Office".

I have collected, paid a nominal customs charge (shipping details reflected lower value than purchase + 'Trade sample') and unit was adequately packed (small box with single layer of bubble wrap inside small poly courier packet) with no sign of damage.

Unpacking and initial inspection the legend on front is missing 'Ch 0'as noted by Garry but otherwise all looks correct.

No battery fitted (description on web site makes mention of this) and main board has a 2 pin polarized connector for a battery.

Fitted an old but 'new and unused' Blackberry JM1 battery via direct wiring to rear of connector. Battery is attached to rear panel using double sided tape and although protrudes a couple of mm from bottom, is acceptable.

Powering up the first observation is that both LED's are green (colour is of no consequence) and display, touch input and toggle rocker switch is working.

I have removed the original protective film from the display with intention to cover using suitable size cut from a tablet screen protector.

Charging battery via USB C connector resulted in flashing LED for about 4 min's and then steady as fully charged state achieved.

Accessories included 2 cables and the calibration items (4 in total).

Now to start a new learning curve <smile>.

Any suggestions as to where should start and perhaps a series of 'exercises' (including calibration) so as to have a logical plan to become proficient at using the NanoVNA? Sure would appreciate any guidance from those who have already journeyed down this path - MANY thanks in advance if you can point me in the correct direction.

I am happy that air mail postal delivery (at no extra cost) to South Africa has worked and that I have a seemingly working unit. As to specifics, that is something to report on at a later date.

Wishing all everything of the best learning / using the NanoVNA.

73 Nigel de ZS6RN ex G8DEV

Here's a ham radio application of where a zeroing function would simplify a process:

Let's say you are building a vertical array for 40 meters - two vertical antennas, separated by some distance and with each vertical fed out phase with respect to the other one. You could zero the VNA on one vertical (and call it your 'reference" element) and then, when measuring the phase of the other element, you would be reading the delta between the two, which is what you care about, rather than absolute values.

For only two elements, it's easy enough to subtract one from the other so not a big deal. The software is great as it is!

John AE5X

You flash in the new firmware.
Look in the FILES & WIKI sections for instructions, utilities and files.

As hugen mentioned yesterday, he is thinking of re-integrating (merging?) the larger fonts with his current source code.
The larger fonts were created in order to display Chinese characters.
Hopefully, that will offer more options to all us old, er, more mature folk.

As for the number of traces, install the 4 trace firmware and just turn off 2 of them, if you want.

Regards,
Larry

How do you change to a different version of the firmware?

There are at least two versions of the firmware: one with 2 traces and larger font for an easier to use display or the one with four traces.? You load whichever one you like for your current project.
Mike WY6K


"... somewhere in the distance, there's a tower and a light, broadcastin' the resistance, through the rain and through the night..."

I purchased a NanoVNA from Amazon. I chose the white face version, just for looks. Reading through messages and manuals here, I see descriptions of unit with 4 traces. The one I received only has two traces. Unlike the latest posted manual, there does not appear to be anyway to determine the firmware version. I suspect I may have received a very old unit. I believe the page said "BY HKCNMA".
Anyone provide some guidance?
Thanks
Fred

Rune, I cannot overstate how important your software is.? It is the difference between poor results + frustration vs joy joy joy!
Thank you so much,Mike WY6K


"... somewhere in the distance, there's a tower and a light, broadcastin' the resistance, through the rain and through the night..."

John,
On my NanoVNA if I have my cables attached as your photo shows; and set the frequency range to 50k-900MHz, performing a reset gives me a display with the reference level at -10 dB. When I perform a "THRU-DONE-BACK-BACK" sequence, my new reference level is 0 dB. If I narrow my range to 50k-5MHz as shown in your photo, my reference level stays at 0 dB and does not drop 10 dB as your photo shows.

This measurement clearly shows why doing an isolation test hides the limited dynamic range of the nanoVNA and you are better of not doing isolation calibration.
When not doing isolation calibration you measurement of S21 without any connection between CH0 and CH1 will give you a clear indication of the dynamic range.
And when measuring a filter you will also see the limitations of the nanoVNA

Erik, PD0EK

I srr the same problem.? I will try recalling the cal.? Yhanks for the tip.
Mike WY6K


"... somewhere in the distance, there's a tower and a light, broadcastin' the resistance, through the rain and through the night..."

Hi John,
I guess I *could* make a "zero" offset function; at least for S21. But I
don't think it would be particularly accurate, considering what you're
trying to do?

The premise of the app - which is poorly explained, I'll admit - is to have
a fairly well calibrated signal from the NanoVNA, as good as it will make
it, which (for me at least) has been achievable with a calibration set for
50k-1500M @ 101 points, saved as cal 0. Any sweeps made will then make
semi-reasonable data, the accuracy of which can be further enhanced using
the in-app calibration, using many more data points.

In what might come as a surprise to some, my experience using the NanoVNA
is actually very limited. I spend a substantial amount of time writing
emails about it - ;-) - and I spend even more time writing code, which I
thoroughly enjoy. But the time spent playing with various firmwares or
functions of the device is *very* limited. I don't do all the exciting
things the rest of you do, and most of my antenna work is HF, or at a push,
2m/144MHz. So there might be a lot of small errors in the device that I
just haven't come across yet!

Anyway, this became a bit rambly: Thank you very much for the suggestion!
Maybe there is a good point to setting a reference level in the app. I'll
put it on the backlog as a possible feature!

--
Rune / 5Q5R

Hi Maurizio that's probably what is happening here although the new sweep freq was within the range that the cal covered.

Ideally (hint to Rune!) the software would contain a "Zero the sweep" button that would set the active trace (S21 in my case) to zero regardless of the cal data, freq range, etc.

Hi all,
please find attached a dynamic range test of the NanoVNA with several DC-18GHz precision SMA attenuator.
Prior to the test I performed a fresh calibration.
I think the result leaves some room for discussions!

73, Norbert, DG1KPN

On Thu, Sep 26, 2019 at 08:37 AM, John AE5X wrote:

Hi John , the VNA Agilent ( like hp8753D hp8720 hp8510C ) that I used at work , when you change parameter of frequency sweep
used during the CALIBRATE procedure , turn off the ACTIVE CALIBRATION. For some parameters like IF Filter , Output level , Average counts , the VNA put a warning " the CALIBRATION mybe incorrect ".
73 de IZ1MDJ Maurizio

Thanks guys - I got it corrected and have posted the new result to the link
listed above. The fix was that I have to recall the saved cal data each time I
change the sweep. I calibrated the nanoVNA on the device itself, not via the
software - I will re-cal within Rune's program and see if that makes any
difference in whether or not the cal data is applied even after changing sweep
frequencies.

Here is a shot of where I see 10 dB loss (where there should be none with both
ports connected together) even though I did perform a RESET prior to the cal:



73,

John

On Thu, 26 Sep 2019 at 16:30, <qrp.ddc@...> wrote:

My shipment is delivered with air mail. So, it seems like your seller
provided you with false information. He just sell devices with no battery.
:)

It is tricky to *legally* ship batteries - in particular lithium ion
batteries, especially as an individual or small company.

When my company ships VNA calibration kits, we always put “Contains no
batteries. No radiation” on the export documents, in an attempt to avoid
problems.

When I buy very small lithium batteries from Farnell, it will come in a box
with hazardous labels on the outside, and say it should not be shipped if
damaged. I can buy much more dangerous items, like 5 litres of acetone from
eBay, and there will be nothing on the packaging to indicate the contents
are dangerous.

Dave.
--
Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

@ qrp
Thank for the info.

I got NanoVNA with 3.7V 450mAh >battery It has code 602040 and no other
identification. But NanoVNA works 2 >hours from it.

Seller did mention right information (without battery) & i opted for it
because of restrictions from customs dept. for clearance of items with
battery.

On Thu, Sep 26, 2019, 9:00 PM <qrp.ddc@...> wrote:

On Thu, Sep 26, 2019 at 08:44 AM, Praveena NG wrote:

my first nano vna and does not contain internal
battery due to shipment restrictions.

I got NanoVNA with 3.7V 450mAh battery It has code 602040 and no other
identification. But NanoVNA works 2 hours from it.

My shipment is delivered with air mail. So, it seems like your seller
provided you with false information. He just sell devices with no battery.
:)