Hello Norbert,
Thank you very much! :-)
The "span" value is the -3 dB bandwidth - assuming the -3 dB points get
placed correctly.
The setup currently analyses as follows:
1) From the marker 1 frequency, search up and down in frequency to find
initial -3 dB points.
2) Find the peak value between those two points, and set that as the
passband dB value
3) Search up and down in frequency from the peak value point to new, final
-3 dB points
I don't know if this method is any good - I'm open to other methods, and
the code is quite modular, so it's easy to implement new types. :-)
Again, thank you for all the kind words! :D
--
Rune / 5Q5R
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On Tue, 8 Oct 2019 at 15:19, <norbert.kohns@...> wrote: Hi Rune,
first impression is outstanding!
If you take a look at the BP-Filter I can't find the value of the width
for the bandpass in respect to the -3dB points. Same for the -6dB BW.
LP&HP analysis looks good.
For the narrow band SFZ450F BP-Filter we have two problems: If you go
higher than 1 segment you can't set a marker (same problem I already
reported).
If you select 1 segment, you can set a marker, but due to the fact that
the filter is not matched to 50 ohm the analysis doesn't find the correct
BW because only one peak is analyzed.
General remark: In order to find the -3dB points correctly the calibration
needs many points. Depending upon the filter type you might need more than
20 segments.
Rune, this a large step ahead! Very well done!
Thank you very much for all the work you have done!
Kind regards
Norbert, DG1KPN
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If I can say a little something about this Idea.
A tracking generator would not cost a lot more in ressources and would
be a nice addon in a NanoSa.
And the possibility to add an amplifier to the TG to bring the level
to 30 DBm (1watt) would also be cool.
And lastly with the Generator in the TG, if you can modulate the
signal with a tone at a deviation level you can set, we could do some
really nice stuff.
With that said, I have a nice pelican box that could house all of
those nice device with a large rechargeable bank of Lithium/ion
battery lots of cable and adaptors. A Raspberry Pi4, 2 hdmi touche
screen And we have a portable RF labs..
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Le mar. 8 oct. 2019 ¨¤ 09:18, Larry Rothman <nlroth@...> a ¨¦crit :
On Tue, Oct 8, 2019 at 08:51 AM, <erik@...> wrote:
Would it be wonderful if there would be, next to the nanoVNA, a nanoSA or nano
Spectrum Analyzer?
Well I decided to test what the most simple SA could look like, just good
enough to test the harmonics level of your signals till 400MHz and some other,
not too complex, measurements.
Thanks for playing with this idea, Erik.
There was a comment from a Japanese NanoVNA user on Twitter comparing the use of the Nano to an oscilloscope that is in the same price range but has poor specs.
They gave an example of JYE Tech's 200KHz bandwidth scope kit for $30 vs the Nano's capabilities - image attached.
At this time, there is not near enough memory to implement a scope function - maybe in the version 2 device?
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Dr. David Kirkby from Kirkby Microwave Ltd
On Tue, 8 Oct 2019 at 13:51, <erik@...> wrote: Would it be wonderful if there would be, next to the nanoVNA, a nanoSA or
nano Spectrum Analyzer?
Well I decided to test what the most simple SA could look like, just good
enough to test the harmonics level of your signals till 400MHz and some
other, not too complex, measurements.
According to my estimate the BOM of the nanoSA on the photo would be
around 12$ Yes, it would be very useful. But could one go further and combine the SA & VNA into one unit? For what it is worth, Keysight sell a range of portable FieldFox instruments. They are either * Spectrum analyzers * Vector Network analyzers * Combination analyzers with the latter having SA & VNA capabilities.
I hope someone gets inspired and puts everything on a PCB with a LCD as a
small standalone SA (nanoSA)
Or NanoCA - combination analyzer??????? 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
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Re: Measurement challenge
Years ago, an otherwise knowledgeable ham and I had a public argument about the phase shift and delay through a 75m mobile antenna loading coil. Those conclusions are still posted on his web page - i.e. that an RF signal can travel through a 70 uH loading coil in 3 nanoseconds based on s21 measurements. At the time, he didn't seem to realize that to obtain an accurate measure of s21, the lumped-circuit model needed to be discarded and that the coil needed to be considered to be a distributed network which should be terminated with the characteristic impedance of the coil. An estimate of the Z0 of a mobile loading coil can be had at:
Here's the web page with the conceptual measurement error:
Here's a couple of my mobile loading coil articles: and
At the time of the writing of those last two articles, I didn't have access to a VNA but Steve, G3TXQ/sk, did and confirmed that an accurate s21 measurement of a 75m mobile loading coil cannot be made with a load of 50 ohms. Steve's technique was to use a variable resistance for the load and adjust it until he got a "flat" response. Here's what he said about his homebrew 200 nH coil:
"The 3350 Ohm termination (3k3 + Port B) gave a markedly "flat" response of S21 delay with frequencies below the SRF, and I'm presuming that's where the optimum termination was. That would lead us to assume the true delay is close to 51.8nS."
Seems that when measuring s21, if a coil is more than a few electrical degrees long at the operating frequency, it can no longer be considered to be a lumped-circuit inductor.
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Re: Short-Open-Load - expected reflected power
Warren,
Where can I purchase the 1-3000 MHz RF bridges?
Thanks,
Mike N2MS
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Been looking at this lab card, and I wonder what is it useful for?
I must not get it.. Is it a way to test our NanoVNA?
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Le mar. 8 oct. 2019 ¨¤ 07:26, Urban Ohlsson <sm5oxv@...> a ¨¦crit :
Hi First test with the lab card. I'm a little worried about the contacts on the lab card
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Re: Latest edy555 firmware release with dfu file
Rudi,
You could also omit the "-d 0483:df11" parameter from the dfu-util command line.
Ralph
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minimum frequency interval
While described as 101 fixed steps,
fewer are evidently used by nanoVNA firmware for small spans.
Given Si5351 setting granularity for artifact-free switching,
what are rule-of-thumb minimum frequency increments
over the full range?
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Hi Rune,
first impression is outstanding!
If you take a look at the BP-Filter I can't find the value of the width for the bandpass in respect to the -3dB points. Same for the -6dB BW.
LP&HP analysis looks good.
For the narrow band SFZ450F BP-Filter we have two problems: If you go higher than 1 segment you can't set a marker (same problem I already reported).
If you select 1 segment, you can set a marker, but due to the fact that the filter is not matched to 50 ohm the analysis doesn't find the correct BW because only one peak is analyzed.
General remark: In order to find the -3dB points correctly the calibration needs many points. Depending upon the filter type you might need more than 20 segments.
Rune, this a large step ahead! Very well done!
Thank you very much for all the work you have done!
Kind regards
Norbert, DG1KPN
|
On Tue, Oct 8, 2019 at 08:51 AM, <erik@...> wrote:
Would it be wonderful if there would be, next to the nanoVNA, a nanoSA or nano
Spectrum Analyzer?
Well I decided to test what the most simple SA could look like, just good
enough to test the harmonics level of your signals till 400MHz and some other,
not too complex, measurements.
Thanks for playing with this idea, Erik. There was a comment from a Japanese NanoVNA user on Twitter comparing the use of the Nano to an oscilloscope that is in the same price range but has poor specs. They gave an example of JYE Tech's 200KHz bandwidth scope kit for $30 vs the Nano's capabilities - image attached. At this time, there is not near enough memory to implement a scope function - maybe in the version 2 device?
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Screened NanoVNA from eBay UK
For those who live in the UK seeking a screened NanoVNA, I have just received a black NanoVNA from eBay seller: maybeshewill (2849, 99.6% Positive Feedback). Cost ?43.50
It would appear to be correctly screened. It came with cables and a calibration pack. It appears to power-on correctly, although I haven't tested it yet. Took a while to arrive. Appreciate it is nowhere near the least expensive unit available. Also, appreciate that some feel that the screening doesn't matter.
Best regards, Andrew, G1RVD
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If calibrated for amplitude at spot frequencies using nanoVNA,
then could some SDR (e.g. SDRplay has Android API) be useful for spectrum analyses?
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Re: Measurement challenge
What amplitude (dB) and phase (degrees) resolution are credible for nanoVNA?
I read e.g. 0.1dB and 1 degree for other VNAs for amateurs..
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Would it be wonderful if there would be, next to the nanoVNA, a nanoSA or nano Spectrum Analyzer?
Well I decided to test what the most simple SA could look like, just good enough to test the harmonics level of your signals till 400MHz and some other, not too complex, measurements.
According to my estimate the BOM of the nanoSA on the photo would be around 12$
Main components are two SI4432 modules, one in RX mode at 443MHz using the RSSI as log detector, one as +20dBm LO for the mixer (443MHz - 886MHz), a 443mHz SAW filter as first IF filter, a Double balanced diode mixer and an arduino zero (3.3 volt) or compatible (arduino micro with 3.3v serial to USB module will also work), adding a LCD will still keep the cost below 25$ or 50$ retail.
The measurement performance is surprisingly useful.
Attached a scan of the harmonics and spurs of a SI5351 at 25MHz
And a scan of the AD9851 ast 25MHz, both connected through a 30dB attenuator
Specs:
Range 0-400MHz (0-200MHz with unmodified modules)
RBW selectable between 3kHz and 600kHz
With RWB=300kHz noise floor below -90dBm
Max signal around -5dBm
Did not yet do the IIP3 measurement but the used ADE-25MH is supposed to be +13dBm
Good enough for many measurements.
Things to further improve:
- 400MHz low pass filter at input
- remove output filter of TX module to get full 400MHz bandwidth
- Put everything in a box.
I hope someone gets inspired and puts everything on a PCB with a LCD as a small standalone SA (nanoSA)
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Locked
Re: Inflation of this forum
I agree. This is a mess and hard to follow. It should have been a forum from the beginning. Suggest that since this project and others like it will continue into the future, that a forum should be started and all messages (if possible) be moved there. Do this ASAP.
This is my opinion.
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Hi First test with the lab card. I'm a little worried about the contacts on the lab card
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Re: Inductor S21 measurement using nanoVNA
Something that I have never fully understood is that S21 is supposed to be
measured using a "matched load". Many VNA receiver ports do NOT precisely match 50 Ohms; inserting a precision attenuator before CH1 improves matching. Isn't the "matched load" of a VNA equal to 50 ohms? nanoVNA bridge and ICs are nominally designed for 50 Ohms; I don't find a nanoVNA specification for CH1 return. Are we to assume that 50 ohms is the only possible "matched load"?
Or can a VNA be calibrated for any value of "matched load"? Software can "calibrate" for other loads, but e.g. S11 sensitivity is not improved. For two-port measurements without precision attenuator at CH1, nanoVNA firmware does NOT compensate S11 for CH1 mismatch (see attached). Consequently, S11 measurement for 2-port DUT is ideally terminated by precision load or equivalent, rather than CH1, and use only S21 measurements for DUT terminated by CH1 while appreciating that S21 are somewhat impacted by CH1 mismatch. Warren Allgyer's 1-3000 MHz RF bridge method compensates CH1 return.. /g/nanovna-users/message/2484
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Re: Are there any firmware releases supporting calibration kits?
On Mon, Oct 7, 2019 at 05:36 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:
Are there any *firmware* releases that have support for *proper*
calibration kits? By that I minimum of
* offset delay of the open
* offset delay of the short.
* C0 of the open
Did you mean that user will be able to enter offset delay for open, short and load and specify C0 for the open? I can try to add it at least for C0. Regarding to the delay offset, I'm not sure on how to apply it to the calibration terms. Is it correct to apply electronic delay before error term calculations?
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Locked
Re: Inflation of this forum
Hi Dave
Re hashtags:
You can use whichever you prefer, i.e. email client program or web interface.
A post can have more than one hashtag.
Subscribers can mute a a certain hashtag if they prefer, e.g. because it is irrelevant.
Bo
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Locked
Re: Inflation of this forum
Dr. David Kirkby from Kirkby Microwave Ltd
On Tue, 8 Oct 2019 at 10:08, Bo, OZ2M <groups.io@...> wrote: Hi
I all for using hashtags. A group on groups.io can be set to require
hashtags and also that only the owner and moderators can create hashtags.
The latter might be a good idea too. Does that mean that users would need to use the groups.io website, and be unable to post from an email client? If so, I would stop posting anything. I fully agree that the traffic is too high. I wrote last month that this group had more posts than any other I would have to start muting topics. The Keysight VNA forums are nowhere near as active as this one, but they have five subgroups * General Use * Applications * Programming and remote control * Calibration and Error Correction. * Handheld Instruments Obviously such subgroups would not be appropriate here - in particular ¡°Handheld Instruments¡±. *I have no experience of groups.io <> subgroups*, but if subgroups were a suitable way forward, I would suggest the following, based on my experience of the Keysight VNA group and here. *1) Beginners* I suggest this because I believe any new owners, especially if they have never used a VNA before, who are going to get overwhelmed by discussion of firmware changes, NanoVNA-Saver, the mathematics of measurement uncertainties etc. *2) Firmware development* *3 Programming and remote control* - for software like NanoVNA-Sharp, *4) Advanced applications* *& technical discussion * *5) Calibration and error correction* *6) General Use*. 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
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Oristo
Bo, OZ2M