# EEVblog Electronics Community Forum

## Products => Test Equipment => Topic started by: Dosupi on February 01, 2018, 04:20:34 am

Title: Rigol DS1104 Oscilloscope and DG1022U Function Waveform Generator
Post by: Dosupi on February 01, 2018, 04:20:34 am
Hello Everybody,

I use Rigol DG1022U Function Waveform Generator to generate a sin waveform , V_pp = 1V, f = 1KHz.
Then, I use Rigol DS1104 Oscilloscope to watch the sin waveform , and do FFT on DS1104.
In picture 1, FFT: 20dBV   5KHz/Div   100K Sa/S
Amplitude at 1KHz is -8.8dBV, 3KHz is -50dBV, the difference between them is -41.6dBV.
(http://i1.bvimg.com/630722/c0d1a131e324ef30.png)
In picture 2, FFT: 20dBV   1KHz/Div   20K Sa/S
Amplitude at 1KHz is -8.8dBV, 3KHz is -46.4dBV, the difference between them is -37.6dBV.
In picture 3, FFT: 20dBV   500Hz/Div   10K Sa/S
Amplitude at 1KHz is -9.6dBV, 3KHz is -36.0dBV, the difference between them is -26.4dBV.
(http://i1.bvimg.com/630722/f7f07a83d136aec6.png)
In picture 3, FFT: 20dBV   500Hz/Div   10K Sa/S
Amplitude at 1KHz is -9.6dBV, 2KHz is -36.0dBV, the difference between them is -31.2dBV.
(http://i1.bvimg.com/630722/00df336d6360a9ee.png)

I don't know What's wrong with my test? and which data is correct  :'(
Title: Re: Rigol DS1104 Oscilloscope and DG1022U Function Waveform Generator
Post by: Neganur on February 01, 2018, 06:00:02 pm
What is it that you’re trying to measure?

-8.8dBV is around 1Vpp so the first picture looks correct.

The yellow sine wave in picture 2 and beyond looks distorted, try to increase the time/div without decreasing the sample rate (10ms/div is down to 50MSa/s ? Does the scope have more than 7.5Mpts of memory?)

EDIT: I saw the spec sheet mention that the sample rate is shared by all channels. Disable all except for the one you’re using to maximize the sample rate (1GSa/s * 12 div * 1ms = 12Mpts memory)