Rigol DHO924S bandwidth measurement

[juhand]

Hi, I made a Rigol HDO924S bandwidth measurement.

I used R&S SMB100A signal generator for source, and I calibrated with a R&S URV35.

I used 0 dBm @ 50ohm, that is
sqrt(50*10^0/1000)=224mVrms
sqrt(50*10^0/1000)*sqrt(2)*2=632mVpp
and I set the oscilloscope to 200mV/div.

[TimFox]

And the answer was?

[egonotto]

And the answer was?

303 +-5 MHz

[Fungus]

My DHO804 measures at about 280Mhz when I tell it to be a DHO924.

nb. I did it via a rise time calculation, I don't have a 300MHz signal generator.

[J-R]

My DHO804 measures at about 280Mhz when I tell it to be a DHO924.

nb. I did it via a rise time calculation, I don't have a 300MHz signal generator.

Maybe pick up a tinySA Ultra?

[Martin72]

It depends on how linear the thing itself is.

[TimFox]

The usual (BW) x (T_r) = 0.35 formula for rise time vs. -3 dB bandwidth is not valid in general:  it depends on the shape of the low-pass filter function.
For the typical amplifiers used in analog oscilloscopes, it is reasonably accurate.

[Martin72]

For most new scopes, you have to use 0.4....0.45 in the formula.
This was the case with the DHO800 when I first measured the risetime and then the bandwidth with an R&S SML01.

[Fungus]

I used 0.45 in my calculation. I'm not going to argue 100% correctness but it gives a much better answer than 0.35 when applied to these devices. Definitely in the right ballpark.

FWIW: Other people have measured the bandwidth of these 'scopes using signal generators and all got numbers in the 280-300Mhz range when they're configured as a DHO924.

My measured bandwidths using rise time calculation on a hacked DHO804:
DHO804 125Mhz      (70MHz sticker)
DHO814 200Mhz     (100MHz sticker)
DHO914 225Mhz     (125MHz sticker)
DHO924 280Mhz     (250MHz sticker)