What is the noise floor of the ZDS2022 oscilloscope like?

Overview

The so-called "noise floor" usually refers to the "baseline noise floor" of the oscilloscope, which is the vertical noise caused by the analog front end and digital conversion process of the oscilloscope. The noise floor appears on the oscilloscope screen as the noise waveform generated when the oscilloscope is set to the most sensitive vertical position (minimum vertical position). The noise floor of the oscilloscope is related to the components used in the instrument, hardware design, signal processing, and other aspects. In addition, when testing and comparing the noise floor of the instrument, there are many factors that affect the noise test results, such as: bandwidth, sampling rate, channel vertical resolution, horizontal time base position, and channel coupling mode. Generally, the noise floor value measured under DC coupling and full bandwidth is more accurate.

How to measure the noise floor

Here is how to measure the oscilloscope noise floor:

(1) Ensure that the oscilloscope is in normal operating condition;

(2) Do not connect the probe to the oscilloscope or short-circuit the BNC terminal of the oscilloscope probe with the ground terminal;

(3) Set appropriate horizontal and vertical time base gears (usually very sensitive gears, such as 2mv/div, 1us/div, etc.);

(4) Short press the [Trigger] knob to adjust the trigger level so that the background noise waveform is displayed stably;

(5) Since the oscilloscope screen displays the peak deviation of the noise, the most intuitive measurement parameter for the background noise is the peak-to-peak measurement. Press [Measure] and select "Peak-to-peak" measurement.

10.3.3 Noise Floor of ZDS2022 Oscilloscope

To more clearly illustrate the noise floor of the ZDS2022 oscilloscope, the following is a comparison with Tektronix and Agilent oscilloscopes.

As shown in Figure 10.1 and Figure 10.2, when the horizontal time base is 2us/div and the vertical time base is 2ms/div, the peak-to-peak value average measured by the MSO4054 oscilloscope (sampling rate is 500MSa/S) is 1.60mV, while the peak-to-peak value average measured by the ZDS2022 oscilloscope (sampling rate is 1GSa/S) is 351uV. Theoretically, the higher the sampling rate, the clearer the waveform details, and the greater the noise floor should be, but from the measurement results, it can be seen that the noise floor of the ZDS2022 oscilloscope is significantly better than that of the Tektronix MSO4054 oscilloscope.

Figure 10 1Tek's MSO4054 noise floor

Figure 10 2ZDS2022 oscilloscope noise floor 1

Figure 10 3Agilent MSO-X3012A noise floor

Figure 10 4ZDS2022 oscilloscope noise floor 2