Filter action
1. Separate the useful signal from the noise.
2. Suppress the frequency components that are not of interest and improve the analysis accuracy of the signal.
Filter classification
According to the frequency band of the signal passed, the filter can be divided into low pass, high pass, band pass and band stop filters.
1. Low-pass filter: Allows the low-frequency and DC components in the signal to pass, suppressing high-frequency components.
2. High-pass filter: Allows high-frequency components of the signal to pass, suppressing low-frequency and DC components.
3. Bandpass filter: Allows signals in certain frequency bands to pass, suppressing signals below or above this band.
4. Band-rejection filter: suppresses signals in a certain frequency band and allows signals outside the band to pass.
What is the difference between a line filter and a frequency filter?
The line filter is an analog filter implemented by a hardware circuit that operates before ADC sampling. The 300KHz, 1MHz or closed low-pass filter can be selected according to the interference signal frequency range. Since the high frequency components are filtered out, the RMS value will be reduced from the measurement results.
The digital filter is a bandpass filter implemented by software. When the digital filter is turned on, the corresponding analog filter is also turned on to eliminate the aliasing frequency component.
The frequency filter does not affect the ADC sampling results, only for the frequency measurement and the PLL source required for the synchronization source and harmonic analysis required for the calculation.
u What are the filters supported by Zhou Ligong Zhiyuan Electronics' PA5000 power analyzer and their applications?
1. 300KHz, 1MHz analog line filter, digital filter from 100Hz to 100KHz.
In conventional measurements, if you only want to get the analysis result of the fundamental wave, you can choose to turn on the line filter.
When analyzing all frequency components in FFT and harmonic mode, turn off the line filter.
2. Frequency filter of 100Hz, 500Hz, 1KHz, 45~65Hz (used in IEC harmonic mode).
The frequency filter is used to obtain the fundamental signal frequency in the signal with large interference and distortion, and generate a more accurate synchronization source and PLL source, so that the calculation interval is correctly intercepted and the measurement accuracy is improved.
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