Rigol DS1052E Flatness Revisited Using Peak Detector (7 June 2011)
I've made a little experiment to observe my Rigol DS1052E flatness using a simple Peak Detector. But result unsuccessful. I cannot observe any attenuation happening. The result and test setup are attached below (pictures and xls report). The result is graphed in "result.jpg", but the expected result should be like the sketching in the last graph of "expected.jpg".
Setup:
1) Hantek 3x25 Function Generator + PC to control
2) DIY Amplifier to boost 3x25 signal (lets just call it 10x25)
3) Peak Detector embedded in 10x25, 1N4148 diode + 1uF SMD capacitor
4) Cheapo ATX PSU to power 10x25
5) some BNC connectors and alligator clips
6) Rigol DS1052E Oscilloscope
7) Uni-T 71A Multimeter
Hypothesis: DS1052E reading will attenanuate at close to its BW
limit (50-100MHz)
Method: Vpeak will be assumed as the absolute/real value in
reading with theoretically 0% error. By inspecting Vpeak read by DMM, and
comparing with DSO reading, attenuation can be estimated from Vdrop (see
calculated variable below).
Independent variable:
1) test frequency from 3x25 & 10x25, Sine signal 1Hz - 100MHz
Dependent variable:
1) Vpeak: Peak detect reading on CH2 and DMM (CH2 reading only to confirm DMM
reading. DMM reading is to be trusted)
2) Vmax, Vmin: Reading from DS1052E (Vmax, Vmin) on CH1
Calculated variable:
1) Vdrop: voltage drop in peak detector compared to Vmax (Vmax - Vpeak)
2) Vpp: just another useless redundant calculation to better see the signal
reading/output
Result/Conclusion:
Vdrop calculated do not demonstrate any consistent attenuation. Hence DS1052E
reading does not attenuate up to the test signal (100MHz). Hypothesis
proven wrong!
end of report