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Rigol HDO1000 and HDO4000 12bit oscilloscopes launched in China

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Martin72:
Strange things gentlemen...
Playing with the FFT, same Setup as before.
Setting Memory to 100 Mpoints, hanning window.
Playing with the timebase..
From say 500ms to 50ms the memory remains the same.
Then switching to 20ms - the memory drops down to 10Mpoints.
Switching back to 50ms, the memory remains 10 and the FFT is freaking out....
You can go in the menu and set the memory to 100 again, FFT becomes normal again.
Will upload a video in a few minutes.

Martin72:
Upload:

https://youtu.be/ovQ6EENpXz8

switchabl:
Looks like the FFT input is being truncated (without proper windowing). Hard to tell what exactly is going on. Some buffer size mismatch maybe?

rf-loop:
Here is small example (dynamic). (SDS2504X HD)

And note, For this particular purpose these FFT etc settings are not at all best optimal ones.

Signals: (note that these said levels are not accurate, just entered set values using SDG1032X (but I know these levels do not have high error)

If everything is ideal and accurate these are levels.

(marker 1) 5000Hz, +22dBm
(marker 2) 5100Hz -48dBm (carrier level, AM modulation with 20Hz, and modulation depth 20%). 70dB below marker 1
(marker 3) 5120Hz -68dBm (AM USB -20dBc because 20% mod depth) 90dB below marker 1

FFT mode is just Normal and acquisition just normal, no any averaging or other things. Just normal acquisition.
FFT window Flattop.

As can see displayed levels are not bad when also think what is signal source and what are all specifications. 

Martin72:
Hi,

the flattop thing from yesterday...
Here a video, look at the FFT on various timebases, especially how the form of the fundamental wave looks like.

https://youtu.be/83K0Y8Bov2k

Weird: With the flattop window memorypoints won´t change...

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