Hello David,
following a request to add better calibration to my app for the NanoVNA, I
have implemented it in the software, but using "ideal" calibration
standards as the reference, as I have nothing better to go on.
I understand from your post that relevant data would be C0-3 of opens, and
offset delays on opens and shorts. Would there be any correction data for a
load? Could you perhaps give an example of values, so I can use appropriate
units for the input fields?
I hope you can find the time to help.
Thanks,
--
Rune / 5Q5R
On Mon, 2 Sep 2019 at 14:09, Dr. David Kirkby from Kirkby Microwave Ltd <
drkirkby@...> wrote:
On Sun, 1 Sep 2019 at 02:18, Larry Rothman <ac293@...> wrote:
Great!
Thank you.
Of note:
If you go over to edy555's ttrftech repo, he has entered a few 'bug'
reports in the last few days. One that caught my eye was a comment about
not having enough space left in flash to implement a TDR function on the
nano itself. For the AA version there is little room left but hugen's CH
version only occupies about 95k out of 130k.
I wonder if that's enough room for that function....
If space is short, I would think better support for calibration kits is
more important than TDR. The idealised opens and shorts assumed by the
instrument are fine for female SMA connectors, but problems are going to
exist for both N and male SMA test ports. One really needs to be able to
enter:
1) Offset delay of opens and shorts,
2) C0, C1, C2 and C3 of the open standards.
where C(f) = C0 10^-15 + C1 10^-27 f + C2 10^-36 f^2 + C3 10^-45 f^3
where f is in Hz, C in farads.
Certainly, two or three user-defined calibration kits would be desirable,
but the most common ones should be stored I feel be in the firmware. Two of
the cal kits defined in the HP 8753 series are readily available on the
used market.
* Agilent 85032B for N
* Agilent 85033D/E for SMA/3.5 mm.
Personally, they are not the kits I use, (I use 85050B, 85052B and 85054B)
but none of those kits are going to be as useful to most people.
*TDR would be useful in firmware, but there are plenty of more important
things. *
When I get a chance to play with mine more, I will list what I think are
the most important omissions, but calibration kits is the most obvious to
me.
Dave
--
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
