Miscellaneous active electrical nonlinear devices – circuits – and – Specific signal discriminating without subsequent control – By phase
Patent
1996-05-17
1998-03-03
Tran, Toan
Miscellaneous active electrical nonlinear devices, circuits, and
Specific signal discriminating without subsequent control
By phase
327 2, G01R 2500, H03D 1300
Patent
active
057239894
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for determining the phase difference between two digital input signals. Phase measurement devices are known from the technical manual of U. Tietze and Ch. Schenk "Semiconductor Circuit Technology" Springer, eds., 1989, Sections 27.4.1 to 27.4.4, pages 956 to 967. With the scanning holding members and the synchronous rectifier described in Sections 27.4.1 and 27.4.2, which are each employed as phase measurement devices, the connection between a phase shift and the output signal is non-linear. The proposals for circuitry contained in Sections 27.4.3. and 27.4.4 generate a digital signal of a known amplitude from analog input signals, which is filtered by means of an analog low-pass filter. The voltage which can be picked up at the output of the low-pass filter is a measurement for the phase shift. The circuit described in Chapter 27.4.4 permits the determination of phase differences which exceed values above 360.degree.. With this circuit, too, the phase information is contained in the mean value of a digital signal and is provided by means of analog low-pass filtering.
SUMMARY OF THE INVENTION
It is the object of the invention to disclose a phase measurement device which allows a high rate of measuring.
The phase measurement device of the invention in accordance with a first embodiment makes possible the determination of the instantaneous phase difference between two input signals, which can be up to 360.degree.. The frequency of the first input signal can differ considerably from the frequency of the second input signal. The resolution of the phase measurement can be selected by means of fixing the frequency of a clock signal to a predetermined multiple of the frequency of the first input signal.
The phase measurement device of the invention in accordance with another embodiment of the invention allows the determination of the phase difference between two input signals of multiples of 360.degree., wherein the frequency of the second input signal is higher than the frequency of the first input signal. The appearance of a preselected edge of the first input signal is first stored in a memory. When y.gtoreq.2 preselected edges of the second input signal appear prior to the next preselected edge of the first input signal, y-1 switching signals are delivered to a counter, whose counter reading is considered to be the measurement of a multiple of 360.degree. of the phase difference.
The phase measurement device of the invention in accordance with a further embodiment of the invention allows the determination of the phase difference between two input signals of multiples of 360.degree., wherein the frequency of the first input signal is higher than the frequency of the second input signal. At the appearance of a further x.gtoreq.1 preselected edges of the first input signal prior to the next preselected edge of the second input signal, x switching signals are delivered to a counter. The counter reading is considered to be the measurement of a multiple of 360.degree. of the phase difference.
All embodiments of phase measurement devices in accordance with the invention have the advantage that an actual measured value is available immediately after the completion of a period of the second input signal. The embodiments have in common that a respective counter of preselected edges of the two input signals is controlled in such a way that the counter reading is a measurement for the phase difference. A determination of the mean value is no longer necessary. The various embodiments of phase measurement devices in accordance with the invention provide accurate measured values, even with quite different frequencies of the two input signals.
An advantageous further development provides the combination of the second and third embodiment of the phase measurement device in accordance with the invention, which can be realized in a particularly simple manner if a forward-backward counter is employed as the counter. Forward or backward counting pulses are generate
REFERENCES:
patent: 4484291 (1984-11-01), Schlosser
patent: 5019786 (1991-05-01), Fairley et al.
patent: 5128624 (1992-07-01), Hoshino et al.
U. Tietze et al.: "Halbleiter-Schaltungstechnik". Springer-Verlag, 1989, pp. 956-967.
Robert & Bosch GmbH
Tran Toan
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