Hi Nick,
by same I mean the *same*. The NanoVNA-Saver calibration is *not*
independent of the device calibration - on the contrary, it is in fact
dependent on that calibration staying the same.
The values returned by the NanoVNA to NanoVNA-Saver are the adjusted values
from the device calibration. NanoVNA-Saver further offers a calibration
based on these values - but it does not know the original raw values from
the device. I guess that could be implemented, but it is not currently. So
for application calibration to work, you must use the same calibration on
the NanoVNA when you take your measurements as you did when you calibrated
NanoVNA-Saver.
In general, while it's useful to save the calibration if you are using a
fixed installation with the same cables etc., calibrations are by their
nature very dependant on the connectors, cables etc. used, and any changes
of these necessitate a new calibration if you want accurate results.
--
Rune / 5Q5R
toggle quoted message
Show quoted text
On Fri, 8 Nov 2019 at 12:34, Nick <g3vnc@...> wrote:
On Fri, Nov 8, 2019 at 08:26 AM, Rune Broberg wrote:
You should always use the *same* calibration on the
NanoVNA itself when using NanoVNA-Saver's application calibration.
Hi Rune
Your github page says
"Before using NanoVNA-Saver, please ensure that the device itself is in a
reasonable calibration state. A calibration of both ports across the entire
frequency span, saved to save slot 0, is sufficient. If the NanoVNA is
completely uncalibrated, its readings may be outside the range accepted by
the application."
I have experienced corrupted calibration data on the device which results
in big numbers that cannot be read by nvna-s which then disconnects, so I
understand the need to ensure some kind of device calibration before using
nvna-s.
I understand that nvna-s can use the device calibration, or use one of its
own calibration data sets which are independent of those stored on the
device in C0 through C4.
But I must admit that I am unclear as to what is meant by "reasonable" and
the "same" calibration.
Do you mean the same calibration kit, the same calibration regime i.e. SOL
or SOILT, the same frequency span, the same reference plane etc?
Please could you elaborate.
73
Nick
G3VNC
