Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Phase comparison
Patent
1988-05-24
1989-09-05
Tokar, Michael J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Phase comparison
324 78F, G01R 2500
Patent
active
048642215
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a filter, a phase-measuring device and a method to apply the said filter.
To make measurements on a radioelectric signal, it is advantageous to put the said signal through a filter adapted to increase its amplitude. However, if the quantity to be measured varies with time, there is a risk that the measurement will take two successive values of the said quantity into account. Thus, it is essential to make the measurement at the instant when the signal at the output of the adapted filter is affected only by a single value of the quantity to be measured.
The device according to the present invention can be used, in particular, to make phase measurements of a continuous signal.
SUMMARY OF THE INVENTION
The main object of the present invention is a signal-processing filter characterized in that it has an odd value transfer function, the transfer function of the said filter being symmetrical in amplitude and anti-symmetrical in phase, with respect to the center frequency of the said filter.
Another object of the present invention is a method for measuring the phase of a signal comprising several samples, characterized in that the phase measuring and/or signal sampling instant is determined by detecting the passage through 0 of the signal that has crossed a filter, the transfer function of which is anti-symmetrical in phase and symmetrical in amplitude with respect to the center frequency of the said filter.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be better understood from the following description and the appended drawings, given as non-restrictive examples, of which:
FIG. 1 is a diagram showing the envelope of a signal;
FIG. 2 is a diagram illustrating the envelope of the signal of FIG. 1 after it has gone through an adapted filter;
FIG. 3 is a diagram illustrating the envelope of a signal;
FIG. 4 is a diagram illustrating the limits of variation of the signal of FIG. 3 after it has gone through the adapted filter;
FIG. 5 is an example of the envelope of the signal of FIG. 3 after it has gone through an adapted filter;
FIG. 6 is a diagram showing the phase of a signal after it has gone through an odd value filter;
FIG. 7 is a diagram of a first alternative embodiment of the device according to the invention;
FIG. 8 is a diagram of a second alternative embodiment of the device according to the invention;
FIG. 9 is a diagram of a third alternative embodiment of the device according to the invention;
FIG. 10 is a diagram of a fourth alternative embodiment of the device according to the invention.
In FIGS. 1 to 10, the same references are used to designate the same elements.
For clarity's sake, the carriers are not shown in FIGS. 1 to 6.
DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows the envelope of a square signal 194. In the example shown, the signal 194 is a coherent signal with constant amplitude and phase.
FIG. 2 shows the envelope 195 of the signal 194 of FIG. 1 after it has gone through an adapted filter. The phase of the signal at the output of the adapted filter is the same as that of the signal 194. Thus, if it is desired to measure this phase, the measurement can be done at any moment. Advantageously the phase is measured when the amplitude of the signal at the output of the adapted filter is at its maximum.
FIG. 3 shows a timing diagram comprising three successive signals 194. The signal is, for example, a coherent signal of constant amplitude. Each sample 194 of the signal has its own phase taking, for example, data transmissions in phase modulation.
FIG. 4 shows the value that can be assumed by the value of the signal of FIG. 3 that has gone through a filter adapted to a sample 194 of the signal. The three diamonds 195 correspond to the signal that could be obtained by making each sample 194 of the signal go individually through the adapted filter. The total envelope of the signal begins with half of the first diamond 195, then includes a lined triangle 196, passes through the point 197, the value of which corres
REFERENCES:
patent: 4243935 (1981-01-01), McCool et al.
patent: 4695843 (1987-09-01), Lamiraux
G. Uohlbacher et al.; "Bauelement e mit . . . ", Nachrichteu Elektronik, vol. 32, #6, Jun. 1978, pp. 181-187, see p. 186, para 4.1.
List (2 pages) of U.S. Applications/Patents of Applicants--(Applicants Attorney does not have copies in the file).
Drabowitch Serge
Elleaume Philippe
Fouche Yvon
"Thomson-CSF"
Plottel Roland
Tokar Michael J.
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