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On Mon, Oct 7, 2019 at 04:02 AM, <neb40gsm@...> wrote:

In reference to Alex_M modified version, nanoVNAv1.03TDRb4 doesn't use Python
anymore to measure TDR cable length.

I will be glad to see remark in the about window that TDR code in C# was developed by alex_m :)

You can also add window type selection option. In most case Blackman window provides best result for TDR, but sometimes Rectangle and Triangle window also useful. I didn't added it just because don't have time to work on UI interface.

It's already here, just select window type depends on user selection:

public static complex[] TDR(complex[] vector, WindowType window = WindowType.Blackman)
{
var size = DSP.GetPOT(vector.Length);
size = Math.Max(size, 16384);
vector = vector.ToArray();
if (window != WindowType.Rectangular)
{
DSP.ApplyWindow(vector, window);
}
var ifft = DSP.ZeroPadded(vector, size);
ifft = DSP.IFFT(ifft);
// padding attenuation compensation
DSP.Scale(ifft, (double)size / ((double)vector.Length));
return ifft;
}

The only discrepancy - which is fatal to the software working - that I have
seen thus far, is that the developers have changed the prompt line, which I
use to detect when output from the device has finished. Being able to
detect either prompt might make it work, or there might be other
differences. I don't have a way to test this at this time.

edy555's firmware has recently received a number of updates the use of
which is limited to newer firmwares, but which are pretty much required to
have both fast and stable PC control of the NanoVNA. I'm looking at
implementing support for these in the next version, or the one after, of
NanoVNA-Saver.

I'm all in favour of trying to support the variety of devices and firmwares
that are appearing, but the software is primarily going to be tested
against the hardware I have - a NanoVNA-H running edy555's 0.2.2 firmware
at the moment.

Rune / 5Q5R
======================================

Rune,

I have both the nanoVNA and the nanoVNA-F, and I would be happy to test any updates you may bring.

On another PC I do have Python installed (2.7, but could update) so perhaps I could help with (some elements of) the source too? I don't know whether that PC has the right drivers, though.

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

Kurt,

Good points for more precise calibration. It would certainly be more precise than my suggestion. I certainly agree with you that it is a good idea to calibrate as close to the measurement plane as possible.

My basic question is fairly simple. How much change will your approach make to the measurement of a 13 micro-Henry inductor? At 1 MHz a 13 uH inductor has a reactance of 2*pi*13 ohms which is about 82 ohms. At 10 MHz the reactance is about 820 ohms. As an example, how much impact does 100 pico-seconds have at 1 MHz or even 10 MHz. It seems a 100-pico-second delay error would be a pretty small phase change at 1 MHz or even 10 MHz. Perhaps I don't understand your procedure completely.

--
Bryan, WA5VAH

Hi Bryan
You are forgetting that the female female adaptor has a delay which when removed shift the measurement plane away form the calibration plane.
I have a suggestion which work with good precision up to 100Mhz or even higher pending the expectations and what is mentioned under Note!!.
The proposal is the following:
1. Enable a phase trace with 1degree/division at reference point 5.
2. Enable a Display/Scale/Electrical Delay of 100ps.
3. Set the frequency range of interest e.g. 50KHz to 100MHz
4. Calibrate at the end of the test cable with the male calibration kit fitted to the female female adaptor and do not use the open adaptor from the kit, just leave the female female adaptor unterminated during open calibration. Save calibration to either 1 to 4.
5. Observe after the calibration that the phase trace is slanting slightly downwards with a phase of about 0.15dgree at 100MHz
6. Remove the female female adaptor and observe the phase trace raises upwards quite considerable as we removed the phaseshift for the female female adaptor.
7. mount the bulkhead/pcb edge adaptor to the test cable and now trim the Display/Scale/Electrical delay until the phase trace is horizontal with 0 degree all over the frequency range.
8. Now the measurement plane is to the rear of the bulhead/PCB edge adaptor without any parasitic component and accurate measurements possible.
9. Remember to remove the Display/Scale/electrical delay afterwards
Note !! The condition for getting the phase trace adjusted to 0 degree is the bulkhead/pcb edge adaptor must have a shorter delay than the female female adaptor. If not increase the 100 ps delay.
I recommend to use a better SMA testcable than the one supplied and if you have another Female Female aadaptor use it as the one supplied have excessive loss
Kind regards
Kurt
-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af bryburns via Groups.Io
Sendt: 6. oktober 2019 23:13
Til: [email protected]
Emne: Re: [nanovna-users] Inductor S21 measurement using nanoVNA

Hi, aa_talaat,

Here is a suggestion.

I would recommend that you connect the inductor from the center conductor of port 0 to the ground of port 0 with the shortest possible wires. If you could, I would recommend soldering it across an SMA female connector that directly connects to the location where you did the Open, Short, and Load calibration for S11. In your most recent pictures, with short cables, that would mean you use an SMA femaile connector and solder the part to the back of the SMA connector where you would normally mount it to the circuit board. As long as you connect to the same point as you did the open, short, and load calibration, the measurements should be pretty good. You can then measure the inductor directly by observing the S11 information.

Several of the programs (nanoVNASaver or nanoVNA_mod_v2 for example) will show you the equivalent parallel impedance of the device connected to port 0. What you should see on the Smith chart is a short at very low frequencies, say 50 kHz, (a dot near the left side of the Smith Chart) with an increasing impedance (primarily inductive reactance) of the device you have connected. On the Smith chart the plot should start near the left edge of the horizontal axis and proceed clockwise around the outer circle on the Smith chart as the frequency is increased. Based on what you have said, I wouldn't go much beyond 30-100 MHz as the stop frequency; however, experimenting with the stop frequency would be instructive regarding the device you are measuring. At some frequency, the inductor will appear as a very high impedance (this will be reflected by the plot going to the right side of the chart) because it will have a parallel resonance which is an indication of the amount of capacitance in your coil.

I hope this helps.

--
Bryan, WA5VAH

Hi,

In reference to Alex_M modified version, nanoVNAv1.03TDRb4 doesn't use Python anymore to measure TDR cable length.

neb

On Sun, Oct 6, 2019 at 03:47 PM, <bryburns@...> wrote:

However, I don't think it will not run everything directly.

Should read: "However, I don't think it will run everything directly."

--
Bryan, WA5VAH

Hi Stan -

That would make it just a little bit narrower also.

Sadly, that little horizontal twig just right of "Press control" block
is hard-wired for all vertical branches
and would be pretty hard to remove for only one; I tried...
I may try again, after help is updated for new firmware functions,
but that involves much CSS whittling, not my strong suit.
I could move that block closer to the left edge, though.

I am hoping that iOS 13 (which adds mouse support) will allow
tool tips to appear for mouse hovers. Even without nanoVNA attach support,
being able to better use iProducts for help would be worthwhile..

associated help file content is revised,
but not yet for firmware updates (the next step):

Maybe also put
"Press control or touch screen for menu"
into a horizontal box, and on 1 line instead of 3, similar to the "Display" box, and have the left side of it even with, and above, the "Display" box.
That would make it just a little bit narrower also.

Thank you for the nanoVNA menu diagram! It's helped me more than once.

Hi Sean,

Your VNA will be used to measure your antenna or other elements in shunt form or it could be used to measure in series through form, that would be a S21 measurement. However, for sake of simplicity let's confine ourselves to SERIES form. That case provides you with S11. And S11 when properly handled will result in the SERIES impedance. You can than convert that series Z to its equivalent parallel form. The method for doing this is quite well documented. Just look for "converting series impedance to its parallel form". Currently, the nano save PC program does that conversion. However, its worthwhile understanding the arithmetic behind the scenes. Its not hard.

Once you have the series form of the Z for the antenna which may be complex, you will have to conjugate match that to your other device. There are a number of utilities that preform that task. Again, the math behind this process is not hard. A portion of the Z, the real part contains both the radiation R as well as the portion that is LOSS. That ratio between radiation R and loss R is sometimes referenced as the antenna efficiency factor.

If you have issues with any of this I highly recommend you get a copy of the TEXT Solid State Radio Engineering by Krauss, Bostain, Raab and READ CHAPTER THREE. The discussion there is EXCELLENT. Hell... Read the whole BOOK!.

Regards, Alan

I had the .dfu file generated and uploaded.
The edy555 firmware didn't convince me ... then I discovered that I have a problem with all types of firmware (NanoVNA-edy555, NanoVNA-H):
If you execute and save more than two calibrations, the others saved make me show always SWR 1:1, even with the SMA connector open (CH0)!

Usually memories (calibrated) that I saved are this:
0) 1Mhz-900Mhz; track 1: SWR CH0; track 2: Smith CH0
1) 1Mhz-30Mhz; track 1: SWR CH0; track 2: Smith CH0
2) 30Mhz-100Mhz; track 1: SWR CH0; track 2: Smith CH0
3) 80Mhz-500Mhz; track 1: SWR CH0; track 2: Smith CH0
4) 1Mhz-900Mhz; track 1: LOG CH0; track 2: LOG CH1 (for filter)

Note: before any upgrade I used the file for cleaning "DMR-CLEAR_MEMORY_DFU.dfu " (131 kB; Sep 30).

Now I am forced to save only 2 memories:
0) 1Mhz-900Mhz; track 1: SWR CH0; track 2: Smith CH0
1) "empty"
2) "empty"
3) "empty"
4) 1Mhz-900Mhz; track 1: LOG CH0; track 2: LOG CH1 (for filter)

Why?

Thanks

Hi Herb,
I would actually suggest holding back for just a few days; NanoVNA-Saver
0.1.0 doesn't work that well with 0.2.2. The problems should be fixed in my
next release.

:-)

--
Rune / 5Q5R

I have been a long-time user of Matlab; however, the license (number 12652) I use professionally cannot be used by me in a private setting.

I recently learned of GNU Octave at . This is free software which will run many Matlab scripts. However, I don't think it will not run everything directly. They have many "packages" which are similar to Matlab toolboxes, I think. All of it is free to download and use. It might be worth checking out the capabilities of this software. I do know that they have some serial interface capability which enables communicating with devices like the nanoVNA.

73,
--
Bryan, WA5VAH

Rune,
Thanks for the heads up. I've been hesitant to upgrade to the 0.2.2 firmware because I haven't had a compelling reason to do so. I think you just gave me one :)

Herb

The only discrepancy - which is fatal to the software working - that I have
seen thus far, is that the developers have changed the prompt line, which I
use to detect when output from the device has finished. Being able to
detect either prompt might make it work, or there might be other
differences. I don't have a way to test this at this time.

edy555's firmware has recently received a number of updates the use of
which is limited to newer firmwares, but which are pretty much required to
have both fast and stable PC control of the NanoVNA. I'm looking at
implementing support for these in the next version, or the one after, of
NanoVNA-Saver.

I'm all in favour of trying to support the variety of devices and firmwares
that are appearing, but the software is primarily going to be tested
against the hardware I have - a NanoVNA-H running edy555's 0.2.2 firmware
at the moment.

--
Rune / 5Q5R

Paul,
Feedback from users so far is that the command set for the NanoVNA-F is not fully compatible with the NanoVNA and, therefore neither NanoVNA-saver or NanoVNASharp work with it.

If the only problem was adding the NanoVNA-F's VID and PID to the getPort() function of NanoVNA-saver, Rune would have made those accommodations happily. My opinion is the NanoVNA-F's developers are going to modify the firmware so that it's command set overlaps the NanoVNA. The second option is that the NanoVNA-F's developer's will branch a version of NanoVNA-saver specifically for the NanoVNA-F. Doing so would mean any improvements Rune made to NanoVNA-saver would not be immediately available to NanoVNA-F users.


Herb

IMO, you are probably better off measuring the series impedance and converting it to a parallel impedance because of the inaccuracy of the NanoVNA when measuring very high impedances.

Hi, aa_talaat,

Here is a suggestion.

I would recommend that you connect the inductor from the center conductor of port 0 to the ground of port 0 with the shortest possible wires. If you could, I would recommend soldering it across an SMA female connector that directly connects to the location where you did the Open, Short, and Load calibration for S11. In your most recent pictures, with short cables, that would mean you use an SMA femaile connector and solder the part to the back of the SMA connector where you would normally mount it to the circuit board. As long as you connect to the same point as you did the open, short, and load calibration, the measurements should be pretty good. You can then measure the inductor directly by observing the S11 information.

Several of the programs (nanoVNASaver or nanoVNA_mod_v2 for example) will show you the equivalent parallel impedance of the device connected to port 0. What you should see on the Smith chart is a short at very low frequencies, say 50 kHz, (a dot near the left side of the Smith Chart) with an increasing impedance (primarily inductive reactance) of the device you have connected. On the Smith chart the plot should start near the left edge of the horizontal axis and proceed clockwise around the outer circle on the Smith chart as the frequency is increased. Based on what you have said, I wouldn't go much beyond 30-100 MHz as the stop frequency; however, experimenting with the stop frequency would be instructive regarding the device you are measuring. At some frequency, the inductor will appear as a very high impedance (this will be reflected by the plot going to the right side of the chart) because it will have a parallel resonance which is an indication of the amount of capacitance in your coil.

I hope this helps.

--
Bryan, WA5VAH

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