Hello DiSlord,
Should the interpolation not be based on radial interpolation: so average
of modulus and average of angle? All things here are complex numbers, so I
think that we should also do a complex interpolation.
Or do I misunderstand?
All the best,
Victor
Op di 5 okt. 2021 om 19:18 schreef DiSlord <dislordlive@...>:
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Better do one calibration or on NanoVNA or on CPU side
Calibration data contain noise, this noise added to calibrated value
(increase noise), after send to CPU and use as basic calibration in CPU
side, and additional increase noise after.
About interpolation, NanoVNA use linear interpolation, and if
phase/amplitude rotate fast between points - can give big error (see image):
Exist 2 points, on linear interpolation used line, so result vector - red
point, but correct value - green point. On small phase between 2 points
error small, but on big ... can be wrong
Bigger point count - reduce phase/amplitude shift
V2 - have this problem in range < 30MHz, so need calibrated in 2 ranges
1MHz to 140MHz and 40MHz - max (on less 1 MHz better add additional
calibration)
H/H4 - not critical calibrate in 1 to 1500MHz range (but also have
problems in harmonic change near 300, 900MHz at this point i use
extrapolation, this reduce error, but not remove it)
