Why does the Output of my 5401/5411/5431 Function Generator Glitch when I Change the Output Settings on the Fly?Hardware: Signal Sources (AWG/FG/AO)>>Arbitrary Waveform and Function Generators
Problem: I am outputting a signal on my NI 5401/5411/5431 function generator. When I change the waveform values on the fly, there is a brief moment where the output goes to zero. Why does this happen? Solution: This is caused by the mechanical action of the relays on the board changing the output attenuation. When the signal leaves the DAC, it passes through a series of attenuators that are switched open or closed depending on the attenuation value selected by the user. When this is selected during generation, the Output Enable state is changed while opening and closing electromechanical relays and distorts the output signal. When you change the Output Enable setting, the bouncing of electromechanical relays in Function Generator/Frequency List mode on the NI 5401/5411/5431 distorts the output signal for approximately 200 ms. In the Arbitrary Waveform/Arbitrary Sequence Waveform mode on the NI 5401/5411/5431 the output signal is distorted for approximately 10 ms. On the other hand, the NI 5404 can change specific waveform values such as amplitude and frequency on the fly without any glitches. It can change frequency smoothly because of the direct digital synthesis (DDS) technology. Amplitude can be adjusted glitch free because the amplitude is changed through the DAC by reducing the resolution of the sine wave. Unlike the NI 5401/5411/5431 there are no relays used to adjust the amplitude. Please see the user manual for more information on the functionality of the board. Related Links: Product Manuals: NI Signal Generators Help Attachments:
Report Date: 05/02/2003 Last Updated: 09/10/2008 Document ID: 2X19HMZO |
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