开云体育

Great idea John!
I guess with some effort (netcat?) raspi could pass nanovna's serial port over wifi to the host PC.

p.s. seems there are free USART1 pins 30,31 on STM for some BT solution, but as you said, it needs too much efforts comparing to rpi zero w.
Zilvis LY2SS

Jeff,

Perhaps mention at the start what you assume the reader already knows,
and perhaps give pointers of where to learn about it.
I'd say this would be Ohm's law, complex number arithmetic, and complex impedance.
I find Python very handy for playing with complex numbers.

I had said:

I'd say it's more useful because it is bounded to a magnitude of 1.0 for passive devices, with points of primary interest at high resolution near the center of the chart.
And that the rather wild curves you get from plotting raw impedance become well behaved circles when plotting the reflection coefficient.

As you know, constant resistance and constant reactance are horizontal and vertical lines, respectively, in the raw impedance plot.
However, the Smith Chart's constant SWR circles would be harder to deal with in the impedance plot.
And since SWR remains constant regardless of the length of series transmission line added, the Smith Chart repeats itself
for every half wavelength of transmission line added by going around that constant SWR circle.

Somebody who makes it through your tutorial might want a pointer to instructions on how to use it.
Here's a possibility:

The companion piece on transmission line theory:

is reasonably good, except it tries to be (somewhat) complete by including a bunch of
higher math (equations with e to the power j times something) on pages 2, 3, and 4
to derive the equations we actually use. Those new to this material should skim that math,
waking up when he gives equations for "voltage reflection coefficient" and "VSWR" on page 3
and the equation for Zin(L) on page 4. Everything after the Zin(L) equation is
well worth thorough study, and uses only secondary school algebra.

Jerry, KE7ER

is this one for real ?

i like the case, first I have seen like it and comes with a USB C to C cable

Nigel/Oristopo,
Thanks for the tips. 'Diginow Serial Terminal' works as Oristopo described for sending shell commands. That means the cabling between the Chromebook and the NanoVNA is correct. The developer doesn't have access to a Chromebook so probably cannot expect any assistance from him in getting the NanoVNA-Web-Client to recognize the NanoVNA.

The Linux Chromium OS distribution looks interesting. I noticed the last Chromebook update offered a new feature to enable Linux, but I wanted to learn more about it before doing so. Using the Chromebook with the NanoVNA seems like a good reason to try it out.

Herb

Hugen has been developing further both the hardware and firmware of the edy555 design.
There are now many clones of what Hugen laid out.

I ordered a nanoVNA from Hugen's friend:

It arrived very quickly via DHL, included battery, cables, and calibration set, I am very pleased.

Here's the post where Hugen mentioned his friend:
/g/nanovna-users/message/658

And a few old threads about where to buy:
/g/nanovna-users/topic/32843998
/g/nanovna-users/topic/32309232

Warranty?
Some might say that they all fail due to a flaky thumbswitch.
But you really don't need to use the thumbswitch much, the touchscreen is fine.
Do you really care about a 6 mo warranty on a $50 device?
I'm fine without, being able to immediately return a defective unit is
about all I could hope for on something like this.

Authorized distributor?
I'd say Hugen's friend, though perhaps there is a way to buy something from edy555 also.
The clones mostly work fine, but there have been some reports of bad workmanship,
no battery (understandable, some shipping services won't take a lithium battery),
no shielding (not clear that it really helps much), some may not work quite as well
at frequencies of 300 mhz and beyond, have older firmware installed,
no callibration kit, no cables, etc ...

Jerry, KE7ER

Probably the easiest solution would be to use a Pi Zero W attached to the VNA and then connect to it remotely with your method of choice (VNC, etc.) With the Zero W you could even use an ad-hoc wifi connection on your phone or tablet while in the field. I look forward to other solutions (like the one mentioned), but if you want to get up and running with the least development time and a moderate cost then this is probably it.

Cheers,
John VA7JBE

Hi Doug

I did it a couple of year ago with a different VNA. I used a wireless USB server. I think the NanoVNA would work this way round as well.

to Operate VNWA2 and VNWA3 Remotely Wired or Wireless.pdf <> copy paste the link into a browser if I does not work

May to day some smart method using the small wonderful Wifi devices with ESP8266 can be developed to do I bidirectional USB link but that is far beyond my skill. I am a hardway hobbyist ?



-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af DougVL
Sendt: 20. oktober 2019 01:11
Til: [email protected]
Emne: [nanovna-users] Wireless USB?



I would really like to connect my new NanoVNA to my laptop using a wireless connection. It doesn't seem likely that a bluetooth adapter would work at the VNA end, though. I keep wondering about the wireless mini keyboards that use a USB "dongle" that looks like a bluetooth dongle, but isn't. This would have to be two little devices with USB connectors that talk to each other "automatically" and not need any manual intervention like a mouse click to make the connection. Sort of a non-discriminatory bluetooth that would always accept the first connection attempt.



Does anyone on here know of such a device or system? I've been trying with google but I can't seem to come up with the right search terms. And maybe there is some reason why the NanoVNA wouldn't support such a connection anyway. Maybe one of the firmware developers could find a way to add a wireless connection feature to the system. Giving it a fixed, non-routable IP address to use a USB wifi adapter might be a good way.



Thanks for any help or suggestions!



Doug, K8RFT

Colin, which version of macOS and how did you set up the USB ports?
Tried it here with Catalina but some problem finding the device on the USB…

Dana VE3DS

Jerry,

Thank you very much for your recommendations. They are excellent, and I greatly appreciate your taking the time to make them. (Invariably, when I write a blog post I discover I have left something out. So suggestions such as yours are always welcome.)

I should be able to make revisions in a few days, when I’m back in town.

Thanks again, and best regards,

- Jeff, k6jca

On Sat, 19 Oct 2019 at 15:40, Jeff Anderson <jca1955@...> wrote:

On Sat, Oct 19, 2019 at 06:48 AM, Dick wrote:

ps: still trying to figure out a Smith Chart

Dick, some years ago I wrote up some notes on the Smith Chart (basically
describing where those funny curves come from). It might not be what you
are looking for, but if interested, go here:



- Jeff, k6jca

A bit too technical for the beginner I feel. But that’s just the nature of
a Smith Chart.

It is a very long article, which I didn’t look at too carefully, but you
don’t actually state what are the x & y axes of the Smith Chart, nor the
reason it is more practical to plot an *impedance* on a Smite Chart than on
a normal xy graph.

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

Did you ever figure out how to get the NanoVNA-Web-Client to connect to your Chromebook?

I have not yet tried with the store app; got distracted..

My Samsung Chromebook with either sideloaded apk or web client
also will not connect.

Did you try connecting with Chromebook 'Diginow Serial Terminal' ?
That worked on mine for nanoVNA shell commands..

You might need to run Crouton and install a full copy of Linux.
Full details here:

On 19 October 2019 at 20:23 hwalker <herbwalker2476@...> wrote:


Oristo,
Did you ever figure out how to get the NanoVNA-Web-Client to connect to your Chromebook? My Samsung Chromebook with either sideloaded apk or web client also will not connect.

- Herb

Nigel A. Gunn, 1865 El Camino Drive, Xenia, OH 45385-1115, USA. tel +1 937 825 5032
Amateur Radio G8IFF W8IFF and GMRS WRBV701, e-mail nigel@... www

I keep wondering about the wireless mini keyboards that use a USB "dongle"
that looks like a bluetooth dongle, but isn't.

Bluetooth has profiles, as does USB, so a bluetooth keyboard advertises as HID, instead of SPP,
so would not be recognized as a virtual COM port in Windows.

I researched this a little; of the few systems-on-chip with bluetooth,
I found none with USB host support, so a small e.g. PARTICLE Xenon
or ESP32 board wired to a "Mini USB Host Shield" by spi
would be the cheapest DIY "solution"



There are BC04-B demo boards, which behave like modems (AT commands and all) but USB is not host.

I also bought the AURSINC model from Amazon. It has been great. It is
shielded.
I bought a 3D printed case from ebay. I have no complaints about
anything.

Marco

I bought the one from AURSINC. The price was $73, but it had the input shields, and works fine.

Oristo,
Did you ever figure out how to get the NanoVNA-Web-Client to connect to your Chromebook? My Samsung Chromebook with either sideloaded apk or web client also will not connect.

- Herb

today i returned the non shielded one from Amazon
and see that NooElec was mentioned
they dont show any for sale now

I've just done the MacOS install, went smoothly, all I had to do was adjust
the font size up a bit ;)

Jeff,

The Smith Chart is tricky to explain, your tutorial does a much better job than most that I have seen.

Here's a few adjustments that might be considered, especially if the intended audience changes:


Maybe hammer home the impedance side of the chart before introducing admittance.

As your tutorial notes, there is a one-to-one relationship between a point in the plot of the load impedance and a plot point in the plot of the reflection coefficient. It might help to compare a plot of load impedance with a plot of reflection coefficient for the same data set, and explain how the latter is the more useful representation. I'd say it's more useful because it is bounded to a magnitude of 1.0 for passive devices, with points of primary interest at high resolution near the center of the chart. And that the rather wild curves you get from plotting raw impedance become well behaved circles when plotting the reflection coefficient.

Point out that at a given frequency, the Smith Chart plot is generally just a single point. Since the impedance of inductors and capacitors changes with frequency, a plot for a range of frequencies becomes an oddly shaped track across the Smith Chart, approaching the center of the chart when the impedance of the load approaches the characteristic impedance of 50 ohms.

Probably wise to keep the characteristic impedance at 50 ohms. But could include a brief mention that most Smith Charts will have the characteristic impedance normalized to 1.0 ohms.



Here's a couple interesting addendums to statements made in the tutorial:

Here are plots of Γ in the complex-plane with R held constant (circles) and with X held constant (not circles):

Plots of constant X are arcs of circles. If the magnitude of the reflection coefficient Γ is allowed to exceed 1.0
(as might happen in the case of an amplifier), these arcs can become complete circles.

Note: some authors use ρ in lieu of Γ to represent the Reflection Coefficient.
I believe this is a mistake.
I prefer to represent the Reflection Coefficient with Γ and its magnitude with ρ).

Page 3-1 of Walter Maxwell's book "Reflections III" has the following passages, first published in 1973:

" In combination, the magnitude ratio ρ and phase θ comprise the complex reflection coefficient ρ" (where that final ρ is shown with an overbar to indicate it is complex)

"Prior to the 1950s, ρ (rho), σ (sigma), and sometimes S were used to represent standing-wave ratio. The symbol of choice to represent reflection coefficient during that era was Γ (upper case gamma). However, in 1953 the American Standards Association (now the NTIA) announced in its publication ASA Y10.9- 1953 that ρ was to replace Γ as the standard symbol for reflection coefficient, with SWR to represent standing-wave ratio (for either voltage or current), and VSWR specifically for voltage standingwave ratio. Most of academia responded to the change, but some individuals did not. Consequently, Γ is occasionally seen representing reflection coefficient, but rarely."

From this, we can infer that the preferred manner of representing the reflection coefficient has changed back and forth over the years. It seems Γ is now back in fashion for the complex value, and ρ is now used only for the magnitude of the reflection coefficient.

Reflections III consists in part of a series of QST articles written in the 1970's, it's not organized as a cohesive book, and is not an easy read for the neophyte. Some points remain a bit controversial, but my impression is that Walt had it right. He knew his stuff. Once you get the mechanics of impedance matching and using a Smith Chart down, this book is well worth browsing if you wish to figure out exactly what goes on in a conjugate match.


All that said, you have created an excellent tutorial.
Wish I had access to something like that when first figuring out the Smith Chart.

Jerry


On Sat, Oct 19, 2019 at 07:40 AM, Jeff Anderson wrote:

Dick, some years ago I wrote up some notes on the Smith Chart (basically
describing where those funny curves come from). It might not be what you are
looking for, but if interested, go here:



- Jeff, k6jca

That sure does help, Rune. I was using it on my mobile system and my wifi doesn't reach that far. It would have never occurred to me that Saver needed the internet. Thanks very much. Do you have any idea how fast one has to be to get that screen-capture while Saver is shutting down? Displaying that screen for longer than one millisecond would help. :)