FV Converter Frequently Asked Questions

When the input and output signals of the FV-1400 are connected to an AD conversion board built into a PC, noise from the AD conversion board's sample clock may be superimposed. The figure below shows an example of noise waveforms superimposed on both the input and output signals.

■ Example 1

Noise waveform superimposed on the analog output signal of the FV-1400

■ Example 2

Even when only the output signal of the FV-1400 is connected to the AD conversion board as shown in the diagram above, noise caused by the sampling clock can be superimposed on the output voltage and even leak into the input signal. If the FV-1400's input is used in "AC coupling" mode, malfunctions due to noise superimposed on the input signal may occur, resulting in incorrect measurements.

■ Countermeasures

In such cases, try the following solutions. In the example above, the problem could be solved by using (1) and (2) together.

• (1) The sensor signal should be routed through an amplifier whenever possible, and a "square wave signal" output such as that of the MP-981 type rotation detector should be used. The input coupling of the FV-1400 should be set to "DC coupling".

• (2) Adjust the trigger level of the FV-1400 to a level where it does not pick up noise.

• (3) Check with the AD conversion board manufacturer about noise reduction measures.

• (4) Add a filter circuit (such as an isolation amplifier) to the output voltage or input signal of the FV-1400 to prevent the sampling clock of the AD conversion board from interfering with the input signal. The filter circuit must be provided by the customer.