开云体育

Hi Larry,
that's curious. Have you tried turning it off and on again, as they say? :-)

On the face of it, that looks exactly like what would happen if the device
was connected, and thus found, when the program started, but was
disconnected/turned off/set to DFU mode before attempting to connect. So
disconnecting the NanoVNA, turning it off, turning it back on and
connecting it again would be my first suggestion.

--
Rune / 5Q5R

YES! Thank you for the Rescan function, Rune.

However - it's throwing errors looking for COM12:

2019-09-27 07:45:32,042 - NanoVNASaver - INFO - Startup...
Settings: C:/Users/lrothman/AppData/Roaming/NanoVNASaver/NanoVNASaver.ini
2019-09-27 07:45:32,437 - NanoVNASaver.SweepWorker - INFO - Initializing SweepWorker
2019-09-27 07:45:32,579 - NanoVNASaver.NanoVNASaver - INFO - Found NanoVNA (0483 5740) on port COM12
2019-09-27 07:45:32,579 - NanoVNASaver.NanoVNASaver - DEBUG - Building user interface
2019-09-27 07:45:33,086 - NanoVNASaver.NanoVNASaver - DEBUG - Finished building interface
2019-09-27 07:45:45,613 - NanoVNASaver.NanoVNASaver - INFO - Opening serial port COM12
2019-09-27 07:45:45,614 - NanoVNASaver.NanoVNASaver - ERROR - Tried to open COM12 and failed: could not open port 'COM12': FileNotFoundError(2, 'The system cannot find the file specified.',
None, 2)
2019-09-27 07:45:49,982 - NanoVNASaver.NanoVNASaver - INFO - Opening serial port COM12
2019-09-27 07:45:49,982 - NanoVNASaver.NanoVNASaver - ERROR - Tried to open COM12 and failed: could not open port 'COM12': FileNotFoundError(2, 'The system cannot find the file specified.',
None, 2)

I tried to connect twice, hence the two INFO errors.

Regards
Larry

Thank you for the massive effort you have put into this software! I have had zero problems running previous versions with Windows 10, but this latest version AVG seems to think there could be a problem so it exports the file to test it. In the mean time AVG will not let me run the program.
73 G4XGN

17 : From A Common User's Point Of View

Hello,

Allow us, please, for the sake of completeness of
an appropriate preparation of a presentation for the
Estimation of the -sine qua non- Core of the Measurement
Uncertainty that Exists in *A N Y * VNA System, regardless
of what it really is, a VNA or a NanoVNA, facupov : that is
like that very one of ours, to also include here the initial
findings by us:

=
| Subject: vna ~ nanovna : (r,x) comparative results but no comments
| Sent: Tuesday, September 17, 2019 02:31
| To: [email protected]
| From: yin.oe3zgn.sv7dmc-pez.oe3zzp.sv7bax-arg yza@...
=
| Hello,
|
| 1 one-port box + adapter - initial version:
|
|
| 2 one-port box + adapter - modified version:
|
|
| 3 one-port box + adapter - modified version:
|
| black : vna system
| red : nanovna + 31 mm adapter
| blue : nanovna - 31 mm adapter mathematically
|
| r :
|
| x :
|
| Sincerely,
|
| yin&pez@arg
=
0 : /g/nanovna-users/message/2521

Sincerely,

yin&pez@arg

17

I just released 0.0.12:



This release of NanoVNA-Saver offers a number of new features, all of which
have been widely requested.

First of all, there's now the option of scaling the plots: right click them
for a menu, where it's possible to set the maximum and minimum values for
the frequency and data axes. Sadly not yet ready for the polar plots, and
mouse control of zoom is also pushed to a future release.

Second, it's not possible to have "bands" displayed in the frequency based
plots: Select "Display setup" to find the option for this. The default data
is for amateur radio bands - or you can put in your own.

Thirdly, the calibration procedure has received a new "calibration
assistant": A series of popup messages prompting you to switch between
calibration standards, and code to automatically sweep them for you and
store the results.

Finally, there's as always a number of bugfixes and stability improvements.

With more than 800 downloads of the 0.0.11 version, I can't wait to hear
what you all think of it this time - and I can't thank this community and
mailing list enough for the support, encouragement, suggestions and testing
you have provided!

I am interested in knowing what platforms you are getting this software
running on, *particularly* if you had had to jump through hoops or do
anything unexpected to get it to run: Do email me at mihtjel@... if
you can tell me what you had to do to make it work, so that I may update
the documentation, or make things easier to install in the future.

Thank you!
--
Rune / 5Q5R

qrp.ddc,

Thanks for confirmation( #1831 ) and additional advise.

Bug was confirmed and fixed in edy555 (ttrftech) commit 0b885f2. Beware older versions have a bug in S21 calibration.

Carlos

Hi all,
did someone of the group measure the initial charging current of the battery when almost empty?
My NanoVNA draws 900mA while connected to a 5VDC power supply! The current drops down to 850mA after 10min. For a 400mA, 1.48Wh battery that is for my opinion way to much.

73, Norbert, DG1KPN

If you carefully remove the for plastic screws you will have access to the screen cover. Simply peel it off and reassemble

Or use a Standard 5v USB Power Pack!
Enough choices Up to 25Ah

I am in complete agreement. That was the point of my post. Unless the velocity factor is a lot more consistent than I would expect, that's all you'll be able to do with *any* TDR. And for practical RF tasks, all you need.

For measuring cable length to 100 m , 256 measurements from 1-256 MHz should suffice for 2 cm resolution if the phase angle is accurate to 10 degrees at 256 MHz.

As I have the great pleasure of a Tek 11801 and SD-24 along with a new coil of high quality coax, I'll do some tests once I get connectors. That setup has better than 5 ps TDR resolution. I'm going to make up a set of jumper cables. When I do, I'll be testing them and posting them to a thread on the testing RF connectors and cables I started on the EEVblog forum. I'll make a point of cutting each length under uniform tension so they are the same physical length. I've also got an HP 8753B. So I'll be solving the problem in both domains with 1st rate gear. Albeit rather old.

The nanoVNA has derailed a bunch of my projects because it's a $50 device and can do so much that was out of reach of post hams because of cost in the past.

Have Fun!
Reg

It's a tricksy little thing...the screen protector film is frequently UNDER
the front bezel. You need to take the front bezel OFF before you can easily
peel the film off using the handy green tab.

73,
Gwen, NG3P

On Thu, Sep 26, 2019 at 9:05 PM mike watts via Groups.Io <wy6k=
[email protected]> wrote:

So you removed the plastic film that is on the screen?
Mike WY6K


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

On Thursday, September 26, 2019, 7:50:15 PM CDT, w6nmw <W6NMW@...>
wrote:

My screen tab is on the protective screen.
-------- Original message --------From: "Ron Spencer via Groups.Io"
<ron.spencer@...> Date: 9/26/19 14:03 (GMT-08:00) To:
nanovna-users <[email protected]> Subject: Re: [nanovna-users] That
green plastic tab That green tab might be to disable the battery during
shipping? Sent using On Thu, 26 Sep 2019
17:00:15 -0400 mike watts via Groups.Io <wy6k@...> wrote
----My unit arrived with a small green plastic tab sticking out the top
near the left side. What is that all about? Do I remove it? Mike WY6K
"... somewhere in the distance, there's a tower and a light, broadcastin'
the resistance, through the rain and through the night..."

--

-+-+-+-+-
Jenny Everywhere's Infinite: Quark Time

So you removed the plastic film that is on the screen?
Mike WY6K


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

My screen tab is on the protective screen.

I don't understand all the theoretical limitations associated with different FFT sizes; but from a practical use point of view if my $50 device, as a additional throw-in, can measure a 65 meter length cable accurate to 0.1 meter then I'm impressed.

The 900 MHz upper limit implies a sinc(t) width of 2.2 ns. A 256 point complex to 512 point real FFT will provide a long enough trace to reach the end of a ~50 m cable. The screen pixel count is not large enough to display all of that in time in a single screen.

The 1500 MHz upper frequency implies a 1.33 ns sinc(t). In that case the distance will be limited to ~30 m by only having 256 complex points. While more points would interpolate the sinc(t) and make it easier to pick the correct time looking at the TDR response, calculating the shift in the frequency domain will be *much* more accurate.

The screen resolution makes more than 256 samples not especially useful. Better to display the time to the cursor with picosecond resolution calculated in the frequency domain by a linear fit to the phase.

To reiterate. The sampling in time determines the maximum frequency. The sampling in frequency determines the maximum time. The maximum frequency and the numerical precision govern the achievable resolution picking a TDR trace.

The initial spike is a bug. It is a real constant added at all frequencies to the correct magnitude, but with no change in the phase angle. One can determine what that is by zeroing out everything after that initial spike and transforming back to frequency. I suspect that it is the result of a naive attempt to set the DC value in the frequency domain. If the frequency sampling were were infinitesimally fine (and the series length infinitely long), then setting that would be easy, but because it is discrete, that DC value is smeared out across the low frequency components. I did the smearing in frequency as a result of limited series length in grad school. I'll leave the problem one faces going the other way to the reader, at least for now. If you've taken a course in integral transforms or at least the Fourier transform, it's a very valuable exercise. The transform is symmetric, so once you've done one you know the other.

I haven't looked at the code, but I do know the mathematics well enough to be very sure of the preceding statement. "The Fourier Transform and Its Applications" by Ronald Bracewell will fill in all the details anyone might desire. At least until you want all the important theorems about the Fourier transform. For that, "A Handbook of Fourier Theorems" by D.C. Champeney is what you want. However, the latter is only really of use if you're concerned about whether doing the transform is valid.

Have Fun!
Reg

Erik
Congrats with your Call

73's
Erik ON8DC

Additional tidbits of information.

1. The V2 PCB is 4 layers.
2. The schematics will be posted soon, at the same time as the launch on taobao,
3. Design objectives include keeping BOM cost below $100 and compatibility with current software base.

Rather than larger, I was hoping for wireless (Bluetooth), perhaps by ESP32,
using a smartphone or tablet for display and complex calculations
without USB and ground loop concerns.

Hello,

Allow us, please, to inform you that, after:

[15] : /g/nanovna-users/message/3147

we just uploaded our well-formed mathematical expressions
of full-one port vna measurements [*] :



which--due to their apparent symmetries, as well as to their
arrangement--we consider them as the most economical and
appropriate ones for programming them in any computer
language - either having the complex data type internally or not.

Sincerely,

yin@pez@arg

[*]

16

On Mon, Sep 23, 2019 at 08:04 PM, <erik@...> wrote:

Can you show the measurement? preferably the smith chart of another VNA doing
the CH0 measurement.

I'm talking about OUTPUT impedance of CH0 (don't confuse with INPUT impedance). I didn't hear that it is possible to measure output impendance with another VNA :)

You're needs to measure amplitude on different loads and then calculate source impedance:

Z = (R1 - R1*(U1/U2)) / (U1/U2 - R1/R2)

My measurements for CH0 in attachment. R1 = 1 MOhm, R2 = 50 Ohm. Of course this is just a draft measurement for overage amplitude. I'm too lazy to perform measurement for specific frequencies. :)