开云体育

bryburns,

I think its always a good idea to keep in mind that the NanoVNA is a mass produced product intended for the hobbyist market. If your requirements need a certain level of confidence then your check seems good for that day, under those test conditions, and for your unit. I used a commercially made HP 50 ohm load as my standard until David Taylor pointed out that even though it was manufactured by HP its specs were lukewarm at best. My S11 measurements on known devices were slightly off, but that was because my NanoVNA OSL calibration was made with a load that was slightly off. Changing to a Mini-Circuits 50 ohm load solved the problem. To my point, what you observe may be confidence in repeatability and not in accuracy unless your calibration standard is well characterized. For my own measurement confidence, I keep several "gold" standards in my kit whose performance has been verified outside of the NanoVNA. I fortunate to have friends in my ham club who can check my "gold" standards on their calibrated workplace VNA's periodically.

Herb

Excellent idea!

Roy
WA0YMH

On Sat, Oct 5, 2019, 7:41 AM Torbj?rn Toreson <torbjorn.toreson@...>
wrote:

Just a little screen stylus tip (in double sense).

Torbjorn

On Sat, Oct 5, 2019 at 06:10 PM, Oristo wrote:

Including Android versions with success and failure reports
should help sort support.

On my tablet Galaxy Tab A runs the Android version 8.1.0

--
Hans-Peter Prast, DL2KHP

It might be helpful to newcomers
if these links could be put into the footer of each message.

Let me know what is missing (bottom Wiki entry):

I found an old Sakura "Nocksos NS100c" disposable drafting pencil laying around here that has a hard all plastic tip when the lead is retracted. It works absolutely perfectly for a stylus on this display. I don't know if they still make them...

M

The easiest way to imagine it is to place a 3dB attenuator on the CH0 port and measure the Return Loss with nothing connected to the other side of the attenuator so that is open circuit.

The power will flow one way and be subject to 3dB attenuation (approx) and then reflected back from the open circuit and experience another 3dB of attenuation, making it 6dB in total.

The same happens if the other side of the attenuator is short circuit.

With higher values of attenuation, the actual value, when incorrectly terminated at one port gets closer to the theoretical value, so there is a closer relationship between the measured RL as being twice the value of attenuation.

Regards,

Martin - G8JNJ

Return loss is a measure of the loss of incident power that is not being returned because it is being "lost" to the load resistance.

Folks,

I am interested in learning how much I can trust the results from my nanoVNA. I understand that a T-Check is a good approach to evaluate VNA performance. Here are the results of a brief investigation which I think turned out fairly well using my nanoVNA.

Here is the software used:
Firmware loaded from file NanoVNA-H__900_ch_20190924.dfu
Running nanoVNA-Saver version 0.1.0

Procedure:
I attached SMA to female BNC adapters to the SMA inputs of the nanoVNA. I performed open, short, load, through, and isolation calibration using a commercially available BNC 50-ohm load and short within the nanoVNA and saved the results in memory 0. I repeated this calibration using nanoVNA-Saver 0.1.0. The open was just the female BNC connector without any connection. The through was a 9-inch length of RG58C/U cable. No special termination conditions were used in the nanoVNASaver software.

I connected 50 ohms across a coaxial transmission line for the T-Check using a Tektronix "through" 50-ohm load typically used for a scope input termination. This device is intended for use up to about 3 GHz. A high quality ohmmeter showed the resistance of this termination to be 50.0 ohms at DC. Measuring S11 of this device with the nanoVNA device after calibration showed logmag of channel 0 <-50 dB below 300 MHz. Similar results were achieved with a miniVNA Tiny which I also use. I think it is a pretty good termination at these frequencies. I put the Tektronix 50-ohm load in the through connection mentioned above which I assumed satisfied the testing requirements for a T-Check. Comments on this approach are welcome.

Within nanoVNASaver I averaged 3 measurements and used 5 scans which produced 1010 samples across the bandwidth from 50 kHz to 300 MHz. I saved the resulting data in an S2P file from nanoVNASaver 0.1.0. I then copied S11 to S22 and S21 to S12. I understand that this is not completely valid because I did not reverse the test device and remeasure. I could reverse the connections and make another measurement but did not in order to save a little time. How bad is this? Is it worth the extra effort?

I then used the T-Check equation found on page 12 of the file "Reeve_S-ParamTestSet.pdf" found at



to compute the T-test result as a function of frequency which is plotted in the attached ".jpg" file.

My understanding from page 12 of the Reeve_S-Parameter TestSet file referenced here is that variations of less than +/- 10% are "Minor" and +/- 10% to +/-15% are in the "Acceptable" range.

Considering the attached plot, the results are +/- 2% up to 150 MHz. This seems excellent! Using the guidance mentioned, it appears that the errors in the nanoVNA are "Minor" below 200 MHz and "Acceptable" up to 300 MHz. The only range which exceeds the +/-10% criterion is from about 220 to 280 MHz with a worst-case deviation of < 13%.

How valid are my results given my procedure and equipment?

--
Bryan, WA5VAH

On Sat, 5 Oct 2019 at 16:39, Rune Broberg <mihtjel@...> wrote:

Tomohiro,
thank you very much for your efforts in creating this project, and for your
continued effort in developing both the firmware, and any upcoming new
revisions of the hardware! It is a great asset, and your efforts have been
the seed that created this blossoming community.

I fully support and stand by your request to not have other projects,
particularly ones of a completely different design, infringing on the name
you have chosen. I trust that any serious vendor would as well!

I look forward to seeing and hearing more from you in the future!

--
Rune / 5Q5R

Rune,
if you consider supporting other VNAs too, it might be worthwhile dropping
the “NanoVNA” from the name of your software. That would get around the
possibility of confusion, as it seems that there are several people
releasing products with a very similar name.

I used to work on the port of an open source mathematics research package
called Sage. I always thought the name was a bit dubious as there is
accounting software of the same name. The lead developer dismissed my
concerns. He said that the packages are so completely different, it was not
a problem. Some years later he did rename the software to Sagemath.

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

Ross Bell wrote: ... I am including a ST-link V2 programmer.

I ordered on of those. Where does it tell how to hook those 4 wires up to a NanoVNA? NRST->RST? TCK->SWCLK? TMS->SWIM? GND->GND? How about SWDIO on the ST-link?

I have tested it briefly on my Galaxy Tab A

Including Android versions with success and failure reports
should help sort support.

Tomohiro,
Welcome to the group! We all appreciate your pioneering work on the open source NanoVNA project. The fact that the NanoVNA works so reliably when produced by so many different clone manufacturers is a testament to the correctness of your original engineering design. Gabriel Tenma White estimates that the NanoVNA-H has reached a current sells volume of around 4000 units/month. I'm sure you lament not marketing your original design prior to Hugen getting his clone of your open source project to market. It would be interesting to hear why you decided not to manufacture the unit in 2017 or 2018 after your design was pretty much complete. Glad you plan to develope another VNA design. If its as good as the NanoVNA then there will be a ready market for you.

Regards,

Herb

On Thu, Oct 3, 2019 at 03:03 PM, Larry Rothman wrote:

More Forum member should be browsing through the WIKI
/g/nanovna-users/wiki and FILES?
/g/nanovna-users/files sections of this group.
There is a TON if info in there folks !!

And don't forget to print a copy of the Oct 2nd User Guide (29 pg) for
reference while you're at it.
/g/nanovna-users/files/NanoVNA%20User%20Guide-English-reformat-Oct-2-19.pdf

It might be helpful to newcomers if these links could be put into the footer of each message.
--buck

Thank you very much for this app. I have tested it briefly on my Galaxy Tab A and am excited.

--
Hans-Peter Prast, DL2KHP

Tomohiro,
thank you very much for your efforts in creating this project, and for your
continued effort in developing both the firmware, and any upcoming new
revisions of the hardware! It is a great asset, and your efforts have been
the seed that created this blossoming community.

I fully support and stand by your request to not have other projects,
particularly ones of a completely different design, infringing on the name
you have chosen. I trust that any serious vendor would as well!

I look forward to seeing and hearing more from you in the future!

--
Rune / 5Q5R

Hello folks,

I'm edy555, the original developer of NanoVNA.
This is the first time to post this group.
It's very exciting that such many people enjoy the gadget from my small project.

By the way, according to this thread discussion, it seems that a new and wonderful VNA project is in progress.
If my project triggered a new VNA project, it is my great pleasure.

But as far as I can see, its design is quite different from NanoVNA, so the project here needs to be named differently than NanoVNA.
And in addition, I have a plan to develop a new design of VNA my own, which has extended frequency range. I might hope to give my project that name.
Therefore I'd like to request people related to the V2 project to change its name.

I hope you have respect for the original and think about this issue seriously.
And many thanks to all people here who like NanoVNA.

Regards,

Tomohiro - TTRFTECH @edy555

my code thus far does indeed try to extrapolate

I would prefer defaulting to no extrapolation.

I only know what impact comments like his
can have on the motivation of a developer.

I learned to accept that malcontents (and spouses) will complain about style
when substantive complaints are not credible.

On Fri, Oct 4, 2019 at 03:47 PM, Larry Rothman wrote:

Mike,Look at the schematic at the end of the July user guide.?The 5v output
from the inverter powers the 612 mixers and also feeds an LDO 3v regulator
that powers everything else.

I see that now...
I will cobble up an external LDO regulator to make 5.0V from the big external SLA 6V battery.

Runs great on my Lenovo Tab4 8


Sent from Mail for Windows 10

From: Larry Rothman
Sent: Saturday, October 5, 2019 9:56 AM
To: [email protected]
Subject: Re: [nanovna-users] Is there an Android app for the NanoVNA - WebUSB

My LG G-PAD3 is running 7.0.?
I'll try it on my rooted Nexus 7 - 2013 and follow-up here.?



On Sat, 5 Oct 2019 at 10:02 AM, cho45<cho101101@...> wrote:

On my phone, 5 tablet computers did not work. Just a white screen.
cho45, What version of android do you have?

I'm using Huawei P20 (Android 9). I don't have an old Android anymore ...
So it's hard to develop for old devices.