Ads
related to: true rms meter
Search results
Results From The WOW.Com Content Network
Distortion of a waveform True RMS Multimeter For the measurement of an alternating current the signal is often converted into a direct current of equivalent value, the root mean square (RMS). Simple instrumentation and signal converters carry out this conversion by filtering the signal into an average rectified value and applying a correction ...
Meters which respond to true RMS rather than mean current are described as "true RMS". Typical hand-held Hall effect units can read currents as low as 200 mA, and units that can read down to 1 mA are available. The Columbia tong test ammeter (illustrated) is an example of the iron vane type, used for measuring large AC currents up to 1000 amperes.
A True RMS responding multimeter on the other hand will meet its specified accuracy on AC volts and current with any waveform type up to a specified crest factor; RMS performance is sometimes claimed for meters which report accurate RMS readings only at certain frequencies (usually low) and with certain waveforms (essentially always sine waves).
The Blackmer RMS detector is an electronic true RMS converter invented by David E. Blackmer in 1971. The Blackmer detector, coupled with the Blackmer gain cell , forms the core of the dbx noise reduction system and various professional audio signal processors developed by dbx, Inc.
The squaring in RMS and the absolute value in ARV mean that both the values and the form factor are independent of the wave function's sign (and thus, the electrical signal's direction) at any point. For this reason, the form factor is the same for a direction-changing wave with a regular average of 0 and its fully rectified version.
The core of the meter is based on a true RMS voltmeter, which measures the level of the noise signal. This was used for the first psophometers, in the 1930s. [ 2 ] As the human-perceived level of noise is more important for telephony than their raw voltage, a modern psophometer incorporates a weighting network to represent this perception.
Ad
related to: true rms meter