| Frequency response analyzers consist
of a sweep oscillator, voltmeter, and phase meter. Digital
Fourier transform calculations*
allow voltage and phase to be obtained simultaneously and
with high accuracy, with the oscillator as the
reference(Note). When measurement at a frequency ends, the
frequency is switched to the next frequency. Thus, an
identical measurement is automatically repeated. This is
similar to the operations which are performed by using an
independent oscillator and phase meter. In this way, setting
on the frequency response analyzer is easy. Furthermore,
since the range of the voltmeter can be changed for each
measuring point, a high dynamic range measurement far beyond
the limit of bits of the A/D converter can be done.
|
 |
*Fourier transform calculations
The products of measured values and a reference (sine wave
signal) are integrated. This is similar to operations for
obtaining the basic waves of a Fourier series. An
asynchronous element such as an external disturbance
attenuates in proportion to the square root of integration
time.
|
