Patent ID: 7166995

Claim:
A digital electrical power meter, comprising a first input channel and a second input channel for receiving a first analog input signal and a second analog input signal, respectively; a first signal conversion unit and a second signal conversion unit connected to the output of the first input channel and a second input channel and converting the first analog input signal and the second analog input signal into corresponding digital signals; a first frequency-down filter unit and a second frequency-down filter unit connected to the first signal conversion unit and the second signal conversion unit, respectively and used to filter the corresponding digital signals; a first logic operation unit having two input ends connected to the output of first frequency-down filter and the output of the second frequency-down filter unit; a third low-pass filter connected to the output of the first logic operation unit in order to filter the output of the first logic operation unit; a first low-pass filter and a second low-pass filter connected to the output of the first frequency-down filter unit and the second frequency-down filter unit, respectively; a second logic operation unit processing the output signal from the first low-pass filter and the second low-pass filter; and a third logic operation unit performed a subtracting operation between the output from the first logic operation unit and the second logic operation unit to obtain a digital power signal proportion to the product of the first analog input signal and the second analog input signal.