How Much Residual Noise Should There be on a Yokogawa Oscilloscope?
The residual noise may be measured by making a Peak-Peak measurement with all cables and probes disconnected, and the V/DIV set to the lowest value. On the display will be a baseline of the internal noise of the scope. This noise occurs after the front-end attenuator circuit. In terms of visually comparing noise, verify these settings on your Yokogawa scope:
- Sampling Mode: RealTime
- Interleave: OFF
- Attenuation: 1:1
- Trigger Mode: Auto
- Interpolation: OFF
- Accumulate: OFF
If the attenuation ratio is not kept at 1:1, the residual noise level is multiplied by whatever attenuation factor you have set. A 10:1 passive probe has a 10:1 attenuation ratio which means that the probe divides the signal by a factor of 10 before it is introduced to the scope. The scope will compensate for this attenuation by multiplying the input signal by a factor of 10. Therefore, if the attenuation ratio is set to 10:1 using a 10:1 probe, you can expect the residual noise level to increase by a factor of 10, i.e. 2mVpp at 1:1 attenuation will be 20mVpp at 10:1 attenuation.
Remember that probes, environment related, and the DUT itself will introduce additional noise. Please take the necessary precautions to prevent these additional noise sources. You may manage some of these noise sources through the use of Hi-Res mode, LP Filters, and /G2 User-Defined Math filters.