How to estimate the measurement uncertainty of an oscilloscope ?

[nordmoon]

TL;DR Summary

How to estimate the measurement uncertainty of an Textronics 500 MHz oscilloscope ?

I have an Textronics oscilloscope with 500 MHz sampling rate and using an 50 ohm cable for the measurement.

I can’t find the measurement uncertainty in the manual or the calibration sheet.

In the calibration sheet it says an ‘uncertainty’ for the used channel in divisions, for example 1m up to 10m (the scale) and with highest value being 1. It states the nominal value, upper and lower value and the measurement value. It also state an uncertainty (value between 1-2m) but not in %. I don’t understand how to determine the measurement uncertainty from this data. Anyone understand this?

The manual is even more cryptic .. no words on measurement uncertainty.

 

[Averagesupernova]

Do you have a model number?

 

[nordmoon]

Do you have a model number?

If I remember correctly it’s a DPO7054 or DPO7254.

 

[berkeman]

If I remember correctly it’s a DPO7054 or DPO7254.

The datasheet does seem to have a lot of accuracy-type specs. Are they not what you are looking for?

http://www.testequipmenthq.com/datasheets/TEKTRONIX-DPO7254-Datasheet.pdf

 

[nordmoon]

The datasheet does seem to have a lot of accuracy-type specs. Are they not what you are looking for?

http://www.testequipmenthq.com/datasheets/TEKTRONIX-DPO7254-Datasheet.pdf

Yes but I don’t understand how to determine the measurement uncertainty, for the measured pulse area, with this oscilloscope ?

 

[berkeman]

Yes but I don’t understand how to determine the measurement uncertainty, for the measured pulse area, with this oscilloscope ?

Pulse area? Are you checking Eye Diagrams for communication circuits? What is the application?

I would think that you would combine the error specs for the vertical amplitude and horizontal time base jitter, but maybe there are other considerations. What frequency and rise/fall times are involved? What range of voltage amplitudes?

 

[Tom.G]

In the manual, for vertical accuracy see Appendix A, page A-8 "Effective bits, typical." Depending on frequency, the accuracy ranges between 5.2 and 6 bits.

Therefore, at 2.5GHz the vertical accuracy would be:
1/(2^5.2) = 1/36.76 = 2.7% of Full Scale reading

User Manual .pdf is available at:
https://download.tek.com/manual/071087903.pdf

Cheers,
Tom