Once the input signal passes the Trigger level the Scope will trigger, and at the same time its state will change from Armed to Active. Note that the Scope will continue to record data for as long as it is in the Armed state, and that if no trigger is defined, the Scope will simply pass straight through the Armed state. In this state the Scope is ready to accept the trigger signal. Once sufficient data has been recorded, the Scope will transition to the Armed state. It will remain in this state until sufficient data has been recorded to fulfill the user requirement for recording data prior to the trigger point as controlled by the trigger Reference and Delay fields in the user interface. In this state the Scope will start to record the input signal. When the user then activates the Scope, it will transition into a Buffer state. When the Scope is completely inactive, it is said to be in the Idle state. The state is shown below the input signal in the figure. The Scope can be thought of as having a state, which changes over time. As can be seen from the figure, with a rate reduction by a factor of 4, every output sample is simply computed as the average of 4 consecutive samples acquired at 60 MSa/s. The effective signal bandwidth is thereby reduced and aliasing effects are largely suppressed. BW Limitation means that for a rate reduction by a factor of N, each sample produced by the Scope is computed as the average of N samples acquired at the maximum sampling rate. The default rate reduction mechanism of BW Limitation is illustrated by the lowermost signal in the figure. As a consequence, the Nyquist sampling criterion is no longer satisfied and aliasing effects may be observed. The advantage to this method is its simplicity, but the disadvantage is that the signal is undersampled because the input filter bandwidth of the MFIA instrument is fixed at 7 MHz. For decimation, a rate reduction by a factor of N is performed by only keeping every N th sample and discarding the rest. Is configured and the rate reduction method of decimation is used. The next signal shows the Scope output when a rate reduction by a factor of 4 The figure shows an example of an input signal at the top, followed by the Scope output when the highest sample rate of 60 MSa/s is used. BW Limitation is activated by default, but it can be deactivated in the Advanced sub-tab. The Scope can perform sampling rate reduction either using decimation or BW Limitation as illustrated in Figure 2. Hence, longer time intervals can be captured by reducing the sampling rate. The product of the inverse sampling rate and the number of acquired points (Length) determines the total recording time for each shot.
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