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On Fri, 4 Oct 2019 at 19:17, amdiog via Groups.Io <amdiog=
[email protected]> wrote:

Hi, windows does not recognize the port, how should I do?





--

Yes, calibrated fine. S11 works fine. With a direct cable between the
ports, I get the noise centered around 0dB. Removing the cable, the display
is exactly the same. Inserting an attenuator, there is no change.

Thanks for the clarification Erik,
With everything Rune has on his plate I'd hate for him to waste his programming efforts on something the firmware does not implement. Usually all save commands come with a reciprocal load command. In this case I guess the firmware developer(s) were being cautious about corrupting the device with erroneous data.

Herb

Hi, windows does not recognize the port, how should I do?

My unit has developed a problem I can't solve.? It is intermittent.? Sometimes it works well but then it gives me a gratuitous reboot or shuts down and then isn't working.? I recalibrate a few times and it seems to recover for a while.
I don't know what to do, other than scrap the unit and get another.? At the price, it's not all that painful.? I haven't tried it today but it's a crap shoot.
Bob

Have you calibrated it? If you connect a fly-lead between port 0 &1, what do you measure ? And a 3dB pad?

I found the progam DfuSe_Demo_V3.0.6_Setup.exe, but it's a demo. Are there any limitations?

Is there a document that explains the update procedure for those who have never done this?

Thanks

Hi all. I am new to this group. I recently bought a nanovna off Ebay. It's a black one, set up for 900MHz and 2 traces. It will not measure S21. All I get is noise at +/-10dB peak levels. S11 works just fine. Should all nanovna units be able to measure S21 regardless of being a "antenna analyzer" or "vector network analyzer". BTW, what is the difference? Of what value is the 4-trace version? I read that in order to flash a 4-trace firmware onto a 2-trace unit, the pgm needs to be unloaded? I tried upgrading the firmware, installing the boot-loader and I found 3 versions of firmware. The boot-loader seems to work fine, sees the device but when I try to load a firmware file, I get a message "not correct format" or something like that. Both softwares used for operating the unit work OK. Should I send this one back and buy a new one or have I not done something I should have? I am not a programmer. I would like to turn the switch on and use it. Thanks.
Ken

I agree, return loss should be a positive number, and I can remember endless debates in our engineering-team about it, but when you tune filters on a Network analyzer, it is nice to have the insertion loss (S12) and return loss (S11) going the other way on a single screen. My memory is not too good after having a brain tumor and a couple of strokes, but I seem to recall the HP network analyzers (HP8712???) also showing S11 as a negative number, whilst S21 as a positive number. My memory is a bit fuzzy, bit I can remember the one graph, S12 going up (less negative), and S11 going more negative on the same screen, making it easy to tune. Whether it was the default mode for the HP8712 or whether it was a custom-mode, I can’t remember.

Hi,
For filters the steepness of the skirts is important apart from the 3dB bandwidth.
-6DB and -80 dB are a real measure for the skirts!
However ,many filters ( or measuring conditions ) are not attaining the -80dB , so -60dB will have to do.
This is OK as long as you realise or/and that this is CLEARLY mentioned/stated.
I have seen many tables with comparisons of filters and their steepness.
Steepness was then 80/3 or 60/3 dB value.
Older engineers told me that this was better than using the ratio of the frequency of the -3 and -60 dB points because the difference between the types of filters( number of poles/crystal,L-C;etc/etc.) could be better evaluated.
I know of discussions because of mixing between -60 and -80 dB values( don't compare two sorts of beasts)

Jan ON4MMW

The current firmware allows dumping the internal calibration table with the data command
data [0-6]
where
0: S11
1: S21
and
2 /* error term directivity */
3 /* error term source match */
4 /* error term refrection tracking */
5 /* error term transmission tracking */
6 /* error term isolation */
but it is currently NOT possible to upload calibration tables into the nanoVNA

a link about measuring filters

In my own experience coming from a R&D environment, we would specify filters with the -3dB and -60dB (theoretical) points, but for production and customer tests, AND specifications, we would only test the -3dB point and the -45 dB points, as those points were achievable by most equipment. The -60dB point was considered to be theoretical as very few customers could measure it.

Hello Run,

I like to use your program and I am very happy with it.
You try to realize feasible expansion requests during the program development.
And all for free and for the three main operating systems. That's a great achievement.
Thanks a lot for this.
The criticism of someone sitting on a high horse should not impress you.

73, Rudi DL5FA

On Fri, 4 Oct 2019 at 13:38, Martin via Groups.Io <martin_ehrenfried=
[email protected]> wrote:

i All,

Owen Duffy has recently posted a note about the Nano VNA on his blog.



He makes a few points about the accuracy of calculated values with both
the Nano VNA and Saver in particular.

Whilst agreeing on his return loss statement, the blog is written in a
childish condescending way. If anyone wants to forward him the post I made
about how the HP LCR meter can display things, they are welcome to, but I
can't be bothered to communicate with people like that.

Dave

If we first deal with the issue of Return Loss, which is probably the most
problematic par, and has certainly caught me out on several occasions.

Just about every instrument I can remember using, has RL shown as a
negative curve, even if the units themselves are positive. This is handy if
for example you are tuning a filter, as you can see the insertion gain on
the uppermost trace and the RL loss on the lower one without them
overlapping. It also matches the convention of SWR plots and when
measuring the RL of cables it matches the convention of more attenuation
being negative.

However Owen makes the point that negative loss is actually gain (double
negative) and vice versa, and the existing conventions do indeed lead to
confusion and mistakes being made. Maybe return loss should really be
called return gain, and then everyone would be happy (well maybe - but this
is not a serious suggestion).

However if we put this to one side, there is still the issue of how the
values are being calculated, and if they are in fact correct. If not then I
think this should be investigated in more detail and fixed, as there would
seem to be an opportunity to do this before it propagates further.

Regards,

Martin - G8JNJ

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100

Rune,
My school days are far behind me, but I recall that different filter designs fall off in certain dB/decades (i.e. 20 dB/decade) so if you were trying to extrapolate it would definitely help to know what type of filter is being measure and the number of poles. Otherwise you will have to do something empirical and look at trend in the dataset and do an extrapolation based on the trend from say -3 dB or - 6 dB to -40 dB which should well out of the NanoVNA's noise floor.

I'm sure members with more experience in this area will weigh in.

Herb

30 : our final report 1

29 : ann : our nanovna will be evaluated tonight :
/g/nanovna-users/message/3867

hello all,

this is our final report on the comparison of our
[nanovna] and [vna] in terms of frequency

1 : for nominal values without uncertainty :

red : nanovna - blue : vna

r :
x :

after all that said, accept, please, our humble - but sincere - congratulations

sincerely yours,

gin&pez@arg

30

Hi Herb,
my code thus far does indeed try to extrapolate what the -60 dB point would
be. Only I'm nowhere near good enough at making calculations like this, so
I'm stumbling a little. I know what the -6 dB point is, and I know
(roughly) how many dB per octave or decade the filter drops by. I think I
then need to do something magic involving logarithms, probably something
really simple - but I haven't sat down and figured it out yet.

Suggestions welcome if it's obvious to you, the reader. :-)

--
Rune / 5Q5R

On Fri, 4 Oct 2019 at 16:32, Oristo <ormpoa@...> wrote:

its become the consensus that return loss is a negative number

IMO, "return loss" is a poor term.

But one used very extensively. Personally, I don't have a problem with it.

Arguably, >>any<< return is loss, when sending power is the goal. In which

case,
"return loss" might be power sent (since lost from return)..

Not always. There are one-port amplifiers, such devices as Gunn diodes and
IMPATT diodes, but they are quite rare. For them, the signal returned is
greater than that sent to them. They work on the principle of negative
dynamic resistance. That means increasing the voltage, decreases the
current. They still have a positive resistance though. A device might draw
100 mA at 7 V, but 90 mA at 8 V. The voltage has increased, but the current
goes down.

I know what my opinion on the subject is (return loss is positive for any
passive device), but I am not going to try to force it on anyone else.

I'm an atheist, but I would never try to convince anyone of any religion
that their belief is silly. It is a waste of my time.

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100

Hi Martin,
thank you very much for your appreciation! :-)

I don't know Owen, so I couldn't possibly comment on his experiences; nor
will I speculate on where his heart is. I only know what impact comments
like his can have on the motivation of a developer.

David suggested a number of different readings in a separate post that I
think one of his pieces of hardware shows. All those could be interesting
to add, perhaps to a pop-out display in order to fit them all ;-)

The user definable SWR markers have been a request, and I think I'll put
them in for both Smith, SWR - and of course, "return loss" ;-)

--
Rune / 5Q5R

On Fri, 4 Oct 2019 at 15:11, Martin via Groups.Io <martin_ehrenfried=
[email protected]> wrote:

Hi Rune,

Understood. I really like Saver and very much appreciate what you have
achieved so far, especially in such a short space of time, and I'm very
grateful for your effort and dedication.

A lot of Owen's frustration is due to problems with other VNA's and
antenna analysers that have some serious issues with calculated values that
never seem to get fixed, and the negative response he has had from the
manufacturers when these have been flagged up, hence his reluctance to
engage directly.

I agree that amateur conventions often differ from those used in the
professional world, and that perhaps some of Owen's comments are merely a
reflection (no pun intended) of that conflict. However is heart is in the
right place when trying to point out these issues, even if perhaps his
methodology is not to your liking.

The AIM VNA shows both parallel and series values, so maybe it would be
useful to include those in addition to conductance & admittance and then
it's not necessary to resort to external calculators and spreadsheets ?

Finally - would it be possible to add some user definable SWR marker lines
to the Smith and SWR plots ?

Regards,

Martin - G8JNJ