Impedance measuring apparatus
First Claim
1. An impedance measuring apparatus for measuring the impedance of a measuring object, comprising:
- a phase accumulator for repeatedly adding a given value to produce, as an output, a series of digital values, repeatedly;
digital sine wave generating means which includes waveform memory means which is read at a sampling frequency using, as addresses, the digital values output from said phase accumulator to generate successive sample values of a first digital sine wave, successive sample values of a second digital sine wave, and successive sample values of a digital cosine wave;
a D-A converter, coupled to said digital sine wave generating means, for converting the successive sample values of the first digital sine wave into an analog signal at the sampling frequency for supply to the measuring object, the measuring object producing an output in response to the analog signal;
a first multiplying type D-A converter, coupled to said digital sine wave generating means and the measuring object, for multiplying the output of the measuring object and the successive sample values of the second digital sine wave to produce an output;
a second multiplying type D-A converter, coupled to said digital sine wave generating means and the measuring object, for multiplying the output of the measuring object and the successive sample values of the digital cosine wave to produce an output;
a first integrator, coupled to said first multiplying type D-A converter, for integrating the output of said first multiplying type D-A converter for a period of time which is an integral multiple of the sine wave period; and
a second integrator, coupled to said second multiplying type D-A converter, for integrating the output of said second multiplying type D-A converter for a period of time which is an integral multiple of the sine wave period.
1 Assignment
0 Petitions
Accused Products
Abstract
A digital sine-wave generator, which includes at least one sine waveform memory, is read out by the output of a phase accumulator to generate a first digital sine wave, a second digital sine wave and a digital cosine wave. The first digital sine wave is converted by a D-A converter into an analog signal and then supplied to a measuring object. The output of the measuring object and the second digital sine wave are multiplied in a first multiplying type D-A converter, and the output of the measuring object and the digital cosine wave are multiplied in a second multiplying type D-A converter. The outputs of the first and second multiplying type D-A converters are respectively integrated by first and second integrators for a period which is an integral multiple of the sine wave period.
14 Citations
13 Claims
-
1. An impedance measuring apparatus for measuring the impedance of a measuring object, comprising:
-
a phase accumulator for repeatedly adding a given value to produce, as an output, a series of digital values, repeatedly; digital sine wave generating means which includes waveform memory means which is read at a sampling frequency using, as addresses, the digital values output from said phase accumulator to generate successive sample values of a first digital sine wave, successive sample values of a second digital sine wave, and successive sample values of a digital cosine wave; a D-A converter, coupled to said digital sine wave generating means, for converting the successive sample values of the first digital sine wave into an analog signal at the sampling frequency for supply to the measuring object, the measuring object producing an output in response to the analog signal; a first multiplying type D-A converter, coupled to said digital sine wave generating means and the measuring object, for multiplying the output of the measuring object and the successive sample values of the second digital sine wave to produce an output; a second multiplying type D-A converter, coupled to said digital sine wave generating means and the measuring object, for multiplying the output of the measuring object and the successive sample values of the digital cosine wave to produce an output; a first integrator, coupled to said first multiplying type D-A converter, for integrating the output of said first multiplying type D-A converter for a period of time which is an integral multiple of the sine wave period; and a second integrator, coupled to said second multiplying type D-A converter, for integrating the output of said second multiplying type D-A converter for a period of time which is an integral multiple of the sine wave period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. An impedance measuring apparatus for measuring the impedance of a measuring object, comprising:
-
a phase accumulator for providing an accumulative output; a digital sine-wave generator, coupled to said phase accumulator, for generating a first digital sine wave, a second digital sine wave and a digital cosine wave based on the accumulative output; a D-A converter, coupled to said digital sine-wave generator, for converting the first digital sine wave into a first analog signal which is supplied to the measuring object, the measuring object producing a measured signal in response to the analog signal; a first multiplying type D-A converter, coupled to said digital sine-wave generator and the measuring object, for multiplying the measured signal by the second digital sine wave, and for producing a second analog signal; a second multiplying type D-A converter, coupled to said digital sine-wave generator and the measuring object, for multiplying the measured signal by the digital cosine wave to produce a third analog signal; a first integrator, coupled to said first multiplying type D-A converter, for integrating the second analog signal for a period of time which is an integral multiple of the sine wave period; and a second integrator, coupled to said second multiplying type D-A converter, for integrating the third analog signal for a period of time which is an integral multiple of the sine wave period and for producing a second integrated signal, the first and second integrated signals forming components of the impedance of the measuring object.
-
-
13. An impedance measuring apparatus for measuring the impedance of a measuring object, comprising:
-
a phase accumulator for producing an accumulative output; digital sine-wave generating means for generating a first digital sine wave, a second digital sine wave and a digital cosine wave based on the accumulative output; a D-A converter, coupled to said digital sine-wave generating means, for converting the first digital sine wave into a first analog signal which is supplied to the measuring object, the measuring object producing a measured output in response to the first analog signal; multiplying type D-A conversion means for multiplying the measured output by the second digital sine wave to obtain a second analog signal, and for multiplying the measured output by the digital cosine wave to obtain a third analog signal; and integrating means for integrating the second and third analog signals for a period of time which is an integral multiple of the sine wave period to produce first and second integrated outputs which are components of the impedance of the measuring object.
-
Specification