Lake Shore Model 475 Gaussmeter User’s Manual
2-4
Background
In wide-band AC measurement, the instrument uses a 100 mA, DC excitation current. This type of excitation provides
the greatest frequency range for RMS measurements, up to 50 kHz. The voltage that is generated by the Hall device is
read by the A/D at 40 kHz. The readings can then be passed through a selectable band-pass filter before the RMS
calculation is made. The band-pass filter can also be bypassed, sending the raw readings directly to the RMS calculation
allowing high frequencies to be read. Refer to Paragraph 4.7.2 for information on how to set the AC filter. Analog
Output 1 can be used to output a real time, AC representation of the field being measured. Analog Output 2 can also be
used to output a digitally derived, AC representation of the field, for measured fields up to 10 kHz. Measured fields up to
20 kHz may be represented with the addition of external filters to the analog output.
Figure 2-4. RMS Wide Band AC Block Diagram
2.1.7
Peak Measurement
The Model 475 is capable of measuring the peak amplitudes of signals, either peak pulses or periodic pulses. In peak
mode, the instrument uses a 100 mA, DC excitation current. The voltage that is generated by the Hall device is read by
the A/D at 40 kHz. The readings are then passed through a peak detector that will capture and hold a maximum peak
pulse value or calculate the value of periodic peaks. Refer to Paragraph 4.8.2 for information on how to setup the peak
mode. Analog Output 1 can be used to output a real-time representation of the field being measured. Analog Output 2
can also be used to output a digitally derived representation of periodic fields being measured for signals up to 10 kHz.
Measured fields up to 20 kHz may be represented with the addition of external filters to the analog output. Analog
Output 2 should not be used in pulse mode since it is not fast enough to accurately re-create quick pulses.
Figure 2-5. Peak Measurement Block Diagram
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Страница 16: ...Lake Shore Model 475 Gaussmeter User s Manual 1 6 Introduction 1 4 SAFETY SYMBOLS ...
Страница 25: ...Lake Shore Model 475 Gaussmeter User s Manual Background 2 9 Figure 2 8 Examples of PI Control ...
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Страница 82: ...Lake Shore Model 475 Gaussmeter User s Manual 6 6 Remote Operation Figure 6 2 Model 475 Status System ...