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The problem with noise...
It is often the case that what at first seems a routine measurement
turns out to be impossible with standard measuring equipment because of
other influences beyond your control. Noise and interference, from
whatever source, can make even the simplest measurement difficult.
| However because noise components and interference
often fall at different frequencies to the wanted signal, being able
to measure at the signal frequency only could provide an
enormous improvement to the accuracy and precision of the
measurement. |
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In the past technicians have added analog electronic filtering prior to
the actual measuring instrument, to try to reduce the effects of noise and
interference. This approach offers limited improvement in performance due
to the inherent instabilities and errors of the electronics involved and
may require a different configuration with each new measurement task.
DSP Technology…
The advent of modern Digital Signal Processing (DSP) technology
overcomes these inadequacies. Digital techniques give the ability to
specify and control such features as filter frequencies and bandwidth, and
thus selectivity, with high precision and accuracy. Additional benefit is
gained by the complete absence of drift.
It is now possible to achieve not only a high level of signal recovery,
that is measuring a signal of a specific frequency while rejecting all
others, but also the ability to measure the amplitude of different
frequency components in the same circuit.
The Noise Rejecting Voltmeter
The Noise Rejecting Voltmeter consists of a digital filter,
implemented using the latest digital signal processing (DSP) techniques,
followed by a true rms to DC converter and digital meter. The filter can
be configured as a bandpass stage with adjustable center frequency and
Q-factor, as a low-pass filter with adjustable cut-off frequency or
bypassed for broadband measurements. A separate analog line-frequency
rejection filter adds yet further filtering flexibility.
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is
a trademark of AMETEK, Inc.