averaging and i/f bandwidth selection support

ttrftech / NanoVNA

Very Tiny Palmtop Vector Network Analyzer

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averaging and i/f bandwidth selection support #46

Open edy555 opened 4 years ago

edy555 commented 4 years ago

作ってみた https://github.com/ttrftech/NanoVNA/commit/fb643ece9c7983d4f5c6ad7bf17c0900ed25235d けど、測定結果に違いは見えない(S21のノイズフロアが下がらない)。 https://github.com/ttrftech/NanoVNA/tree/bandwidth

bandwidth bandwidth30

帯域幅を狭くすると、スイープにそれなりに時間がかかる。10Hzで100倍=100ms/pt

d51r3verse commented 4 years ago

100Hz traces more linear/quieter than 1kHz( bandwidth seems to work I think 😁 ) But, unexpected readings found bandwidthed calibration&sweeps. Here is my experience( both ends terminated LOAD )

Cal:1kHz / Sweep:1kHz

Cal:100Hz / Sweep:100Hz

Pmax65 commented 4 years ago

Hi to all,

what is the sweep time for the 100Hz RBW?

I don't want to "teach the cat climbing to the roof", but remember that a 100Hz filtering have a longer dwell time, if you don't reduce the sweep time according to the filter dwell time you may get just wrong measurements.

Just to say, for example: my HP8711A set to 101pts/scan with a 250Hz BW filtering, it takes a sweep time of 731ms that is about 73ms delay time between samples,

Have a great day.

Massimo