开云体育

I just released NanoVNA-Saver 0.1.5:



Release notes:
This release, after a short break in the release schedule, offers a few new
features and improvements:

Configurable Markers
There are a number of new configuration options for markers:

The size of the markers can be changed under Display Setup,
Marker numbers can be displayed in the charts,
Marker data box headings can be coloured or not, depending on user
preference,
The data displayed for markers is now configurable
Impedance Analysis
The Time Domain Reflectometry window now has a display of an impedance
transform, showing the calculated impedance of the transmission line the
NanoVNA is looking at from the calibration plane onwards.

New analyses - and automatic running
The Analysis window has two new analysis options, peak search and VSWR
analysis. It also adds the option to run the analysis automatically
whenever new data is acquired, for example for adjusting filters.

Frequency display changed
DG5DBH kindly sent me updated functions to display frequencies on GitHub.
You can still enter frequencies in the manner you are used to, as Hz, kHz
or MHz, but now calculated or read frequencies should more consistently be
displayed in a nicely formatted way.


As ever, dear mailing list users, I very much look forward to your
comments, feedback, suggestion and bug reports. I already have a number of
things I want to try to get done for next week - so it shouldn't be a
2-week gap this time around! :-)

Thank you to all the testers who helped me fix the bugs in the first two
alpha releases of this!

--
Rune / 5Q5R

Hi Rune,

Thanks for the latest update, especially the ability to change the marker size and the relabeling of the Series L & C values

One small bug I've noticed is that the Marker number on the S11 R+Jx graph is incorrect, as it always shows as zero.

Regards,

Martin - G8JNJ

Hi Martin,
thanks for the bug report. I'll have a look at it (and probably a fix!) for
the next version :-)

--
Rune / 5Q5R

On Tue, 5 Nov 2019 at 12:56, Martin via Groups.Io <martin_ehrenfried=
[email protected]> wrote:

Hi Rune,

Thanks for the latest update, especially the ability to change the marker
size and the relabeling of the Series L & C values

One small bug I've noticed is that the Marker number on the S11 R+Jx graph
is incorrect, as it always shows as zero.

Regards,

Martin - G8JNJ

Hi Rune,

The new TDR impedance measurement is good too.

However it really could use the ability to manually scale the impedance in addition to the length, as the low impedance end of the scale is too compressed to read when used with typical coax in auto-scaling mode.

Regards,

Martin - G8JNJ

A quick note, for those running from the Python source: "scipy" is required
for the TDR impedance measurement display, and you therefore need to
install this, for example by re-running the "pip install ." command to
fetch it from pip. :-)

--
Rune / 5Q5R

Hope someone can give me some insight on the TDR impedance measurement display. I have attached TDR impedance displays for two cable assemblies.

The first cable assembly was made up of a 0.3m length of RG-174, connected to a 1m length of RG-223 that was terminated in a 50 ohm load. The TDR impedance measurement display showed a 50 ohm impedance step for the RG-174 cable and then another slight impedance step for the terminated RG-223 cable. Pretty much what I was expecting.

The second cable assembly was made up of a 0.3m length of RG-174, connected to a 200 ohm coaxial feed-thru, connected to a 1m length of RG-223 that was terminated in a 50 ohm load. The TDR impedance measurement display showed a impedance step for the 200 ohm feed-thru but never stepped back down for the 50 ohm terminated RG-223 cable.

Am I misunderstanding how the second cable assembly should be shown on the TDR impedance measurement display?

BTW, really appreciate the capabilities Rune continues to add to NanoVNA-Saver. Just trying to wrap my head around the new TDR impedance measurement display.

- Herb

Rune,

Thanks for the new version. Has anyone given any thought to using
interpolation to display the data between the measurement points when in
line mode? Sometimes more often than not there isn't a data point where you
would like to have an idea what the value is at the measurement marker when
it is place between points (which can not be done at present). I have used
DSO's that have this ability. Of course one must be aware of the possible
pitfalls.

Sam

Sam Reaves
ARS W3OHM
Owner and Moderator of:
LeCroy Owners Group on Groups.io (Current and Future Group)
LeCroy_Owners_Group on Yahoo! Groups (NOW DEAD Legacy Group)

Hi Sam,
you're welcome :-) I have considered interpolation; but my original idea
for the software was to allow more data points to avoid interpolation, and
instead provide better data resolution. For this reason, the default
behaviour of the application is to draw points, not lines - only showing
the actual data available.

If you need more data points, you can increase the "segments" settings to
tell the application to split the swept area into multiple segments of 101
data points each. I think this is in most cases the preferable way to go,
but I could of course be convinced by arguments for the opposite :-)

--
Rune / 5Q5R

Rune,
I'm still hoping someone can help me understand the new TDR impedance measurement display ( see message /g/nanovna-users/message/6520 ). One other thing in regards to the TDR display which I hope eventually makes your "to do" list is related to the attachment.

The cable assembly in the attachment was made up of a 0.3m length of RG-174, a BNC bullet and a 1m length of RG-223 terminated in a 50 ohm load. The TDR measurement display showed a peak at around 0.3m for the RG-174 cable and then another peak at around 1.3m for the RG-223 cable. Very happy with the numbers, but currently NanoVNA-Saver only displays a marker for the highest peak, which as shown in the attachment, is not always the only peak of interest. It would be great if an additional user selected marker could be enabled to more accurately mark additional peaks.

Best Regards,

-Herb

On Tue, Nov 5, 2019 at 02:12 AM, Rune Broberg wrote:

The Time Domain Reflectometry window now has a display of an impedance
transform, showing the calculated impedance of the transmission line the
NanoVNA is looking at from the calibration plane onwards.

Rune,

Thanks for the new release and your continued work on this project. I took a quick look at your new TDR output.

Not sure what is happening with the new TDR plot you are displaying. The impulse TDR seems correct; however, the impedance TDR may not be correct. But, I cannot be sure.

The purpose of the impedance TDR plot is to show the impedance as a function of time by transforming frequency domain data into the time domain. Version 0.3.0m firmware (and several others) seem to show what I would expect on the nanoVNA for the Low-Pass Step Transform of the frequency domain data. I give 2 simple examples below.

When a length of open ended 50 ohm line is connected to CH0, the impedance should show ~50 ohms for a time that corresponds to the length of the transmission line and then the impedance should go to a very large value. This can be seen in the screen capture of such a cable in the file "RG316_50ohmCable_0.5m_TDR.png which is attached. This is a piece of RG316 that is ~0.5 m long with the end away from the VNA open. You can see the marker at 3.47ns which is equivalent to 359 mm along the transmission line reading 50.3 ohms. I have set the display to read the "resistance" on the nanoVNA and set the scale to 25 ohms per division. Of course, once the end of the cable is reached, the resistance goes off scale toward the top because the cable is open at that distance (time.) Measurements beyond the end of the cable are not often useful but do represent multiple traverses along the cable which are caused by mismatches at both ends of the cable. For the purpose of evaluating the impedance of the transmission line we can ignore information at times (distances) beyond the end of the cable. We can verify that the transmission line is ~50 ohms along its length by moving the cursor in time (or distance.)

To make the point further, I have included a second example (75OhmCable_1meter.png) which is a piece of 75 ohm coax that is approximately 1-meter in length. The setup on the nanoVNA was the same. Here we see that the impedance is showing 74.4 ohms at 5.2ns (538mm) along the transmission line. And, again, measurements beyond the end of the transmission line are not important to verifying that the transmission line impedance is good along its length. Again, we can verify that the impedance is good for the entire length.

With the TDR plotting in nanoVNA-Saver 0.1.5 I can't see the part that is of interest. I have shown the two plots from the two cables here from nanoVNA-Saver 0.1.5. These attachments are "R316_50ohmCable_0.5m_TDR_nanoVNASaver0_1_5.png" and "75OhmCable_1meter_nanoVNASaver0_1_5.png". A major part of the problem is that the impedance scale does not make observations in the range of interest (50-75 ohms) easily observed. It is not at all important to represent the entire range of impedance measurement but, it is important to enable the user to see what is happening in the early part of the time domain. To facilitate the user observing what is of interest, you need to enable y-axis scaling as you have on other charts.

Perhaps setting the minimum and maximum impedance values to display will be enough. The user will know what they are measuring where you cannot know. I hope these examples illustrate why.

Thanks for considering this issue in your next release.

--
Bryan, WA5VAH

Hi Herb,
I hope someone will be able to help you with the understanding - And I will
be following along the thread closely, as I too am not entirely certain
what it's telling me ;-)

I have put the wish for one or more extra markers for the TDR part on the
TODO list! :-)

--
Rune / 5Q5R

Hi Bryan,
thank you for looking into this! I have user selectable scaling on the list
for probably the next release, but I hadn't yet realized, that there might
be cases where a cable would show a negative impedance, as your second
screenshot suggests.

Do you know what values it is supposed to show?

Have you set the NanoVNA to normal (non-TDR) mode before making the
readings?

If you would be willing to send me a Touchstone file of the data, that
would be helpful for testing! :-)
--
Rune / 5Q5R

On Wed, 6 Nov 2019 at 06:28, bryburns via Groups.Io <bryburns=
[email protected]> wrote:

On Tue, Nov 5, 2019 at 02:12 AM, Rune Broberg wrote:

The Time Domain Reflectometry window now has a display of an impedance
transform, showing the calculated impedance of the transmission line the
NanoVNA is looking at from the calibration plane onwards.

Rune,

Thanks for the new release and your continued work on this project. I
took a quick look at your new TDR output.

Not sure what is happening with the new TDR plot you are displaying. The
impulse TDR seems correct; however, the impedance TDR may not be correct.
But, I cannot be sure.

The purpose of the impedance TDR plot is to show the impedance as a
function of time by transforming frequency domain data into the time
domain. Version 0.3.0m firmware (and several others) seem to show what I
would expect on the nanoVNA for the Low-Pass Step Transform of the
frequency domain data. I give 2 simple examples below.

When a length of open ended 50 ohm line is connected to CH0, the impedance
should show ~50 ohms for a time that corresponds to the length of the
transmission line and then the impedance should go to a very large value.
This can be seen in the screen capture of such a cable in the file
"RG316_50ohmCable_0.5m_TDR.png which is attached. This is a piece of RG316
that is ~0.5 m long with the end away from the VNA open. You can see the
marker at 3.47ns which is equivalent to 359 mm along the transmission line
reading 50.3 ohms. I have set the display to read the "resistance" on the
nanoVNA and set the scale to 25 ohms per division. Of course, once the end
of the cable is reached, the resistance goes off scale toward the top
because the cable is open at that distance (time.) Measurements beyond the
end of the cable are not often useful but do represent multiple traverses
along the cable which are caused by mismatches at both ends of the cable.
For the purpose of evaluating the impedance of the transmission line we can
ignore information at times (distances) beyond the end of the cable. We
can verify that the transmission line is ~50 ohms along its length by
moving the cursor in time (or distance.)

To make the point further, I have included a second example
(75OhmCable_1meter.png) which is a piece of 75 ohm coax that is
approximately 1-meter in length. The setup on the nanoVNA was the same.
Here we see that the impedance is showing 74.4 ohms at 5.2ns (538mm) along
the transmission line. And, again, measurements beyond the end of the
transmission line are not important to verifying that the transmission line
impedance is good along its length. Again, we can verify that the
impedance is good for the entire length.

With the TDR plotting in nanoVNA-Saver 0.1.5 I can't see the part that is
of interest. I have shown the two plots from the two cables here from
nanoVNA-Saver 0.1.5. These attachments are
"R316_50ohmCable_0.5m_TDR_nanoVNASaver0_1_5.png" and
"75OhmCable_1meter_nanoVNASaver0_1_5.png". A major part of the problem is
that the impedance scale does not make observations in the range of
interest (50-75 ohms) easily observed. It is not at all important to
represent the entire range of impedance measurement but, it is important to
enable the user to see what is happening in the early part of the time
domain. To facilitate the user observing what is of interest, you need to
enable y-axis scaling as you have on other charts.

Perhaps setting the minimum and maximum impedance values to display will
be enough. The user will know what they are measuring where you cannot
know. I hope these examples illustrate why.

Thanks for considering this issue in your next release.

--
Bryan, WA5VAH

On Wed, Nov 6, 2019 at 01:16 AM, Rune Broberg wrote:

Have you set the NanoVNA to normal (non-TDR) mode before making the
readings?
If you would be willing to send me a Touchstone file of the data, that would be helpful for testing! :-)

Rune,

Yes, I did set the nanoVNA to non-TDR mode before making the readings. This is essential to getting good data in nanoVNA-Saver from the nanoVNA. I recalled cal0 which was created with my best SMA calibrators (from another VNA) on short male-female connector savers attached directly to the nanoVNA.

Attached is an S1P file from the ~0.5m long RG316. I also have attached an S1P file from the ~1 m long 75 ohm cable that you can use for testing with nanoVNA-Saver 0.1.5. Using the velocity factor for RG316 as 0.695 give a length of 0.56 m for that cable. Setting the velocity factor for the 75 ohm cable to 0.66 yields a cable length of 1.086 m. The cables are showing a little longer than the measured length because of some 50 ohm adapters that are about a total of 2" long on the nanoVNA end of the cables. These are the same cables I used in the nanoVNA screen shots shown above.

Both cable measurements were made using my best nanoVNA calibration and the best tuned nanoVNA-Saver calibration.

I hope these help your efforts with the TDR software to show the impedance vs time.

--
Bryan, WA5VAH

Hi Bryan,
thanks for the Touchstone files - I'll have a look at them, and see if I
can figure out what's going on. :-)

--
Rune / 5Q5R

On Wed, 6 Nov 2019 at 20:21, bryburns via Groups.Io <bryburns=
[email protected]> wrote:

On Wed, Nov 6, 2019 at 01:16 AM, Rune Broberg wrote:

Have you set the NanoVNA to normal (non-TDR) mode before making the
readings?
If you would be willing to send me a Touchstone file of the data, that

would be helpful for testing! :-)


Rune,

Yes, I did set the nanoVNA to non-TDR mode before making the readings.
This is essential to getting good data in nanoVNA-Saver from the nanoVNA.
I recalled cal0 which was created with my best SMA calibrators (from
another VNA) on short male-female connector savers attached directly to the
nanoVNA.

Attached is an S1P file from the ~0.5m long RG316. I also have attached
an S1P file from the ~1 m long 75 ohm cable that you can use for testing
with nanoVNA-Saver 0.1.5. Using the velocity factor for RG316 as 0.695
give a length of 0.56 m for that cable. Setting the velocity factor for the
75 ohm cable to 0.66 yields a cable length of 1.086 m. The cables are
showing a little longer than the measured length because of some 50 ohm
adapters that are about a total of 2" long on the nanoVNA end of the
cables. These are the same cables I used in the nanoVNA screen shots shown
above.

Both cable measurements were made using my best nanoVNA calibration and
the best tuned nanoVNA-Saver calibration.

I hope these help your efforts with the TDR software to show the impedance
vs time.

--
Bryan, WA5VAH

Hello Rune,

First of all many thanks for this great software!
Maybe you can watch the bandwidth calculation again.
A ripple on a bandpass does not capture the filter width correctly.
In the attachment a comparative measurement.

Best regards

Hans-Peter Prast, DL2KHP

Hello Hans-Peter,
you're right: The algorithm assumes that the first -3dB point it finds is
the -3dB point of the filter. I'm not certain what's a good and generic way
to avoid this to allow filters to have that much ripple?

Suggestions?

--
Rune / 5Q5R

Hello Hans-Peter,
you're right: The algorithm assumes that the first -3dB point it finds is
the -3dB point of the filter. I'm not certain what's a good and generic way
to avoid this to allow filters to have that much ripple?

Suggestions?

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

Display a 2-line message:

Your filter has too much ripple to be useful. Please don't ask me to analyse such rubbish!

... or perhaps not!

"Filter unsuitable for bandwidth analysis"

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

Hello David,

It's just that quartz filters have a ripple. In the attachment the plott of an IF quartz filter.
One possibility might be to select rising and falling edges.


73, Hans-Peter Prast, DL2KHP

Hello Rune,

Unfortunately, quartz filters have a ripple. In the Attachment the plot of an IF quartz filter.
One possibility might be to select rising and falling edges.
Otherwise, I currently have no solution.

Viele Grü?e

Hans-Peter Prast, DL2KHP

Hello Rune,

Unfortunately, quartz filters have a ripple. In the Attachment the plot of an IF quartz filter.
One possibility might be to select rising and falling edges.
Otherwise, I currently have no solution.

Viele Gr????e

Hans-Peter Prast, DL2KHP
=========================================

Hans-Peter, yes, I appreciate the ripple issue.

Perhaps one approach might be to scan for Fmax, Smax and then approach upwards from a low frequency until Smax - 3 dB is reached, and then approach downwards from a high frequency until Smax - 3 dB is reached. I've not programmed that, though, just a suggestion.

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