JPS63114306A - Detecting method for signal phase difference - Google Patents

Abstract

PURPOSE:To detect a momentary phase difference by calculating a phase angle from a ratio of a sampling value at a specific point of time to a sampling value of a delay signal and detecting the phase difference of each input trigonometric function signal from the calculated phase angle. CONSTITUTION:Sample-and-hold circuits 10-13 retarding input trigonometric signals S1, S2 of the same frequency by pi/2 by delay circuits 14, 15 respectively sample a direct, signal and a delay signal simultaneously and A/D converters 16-19 convert outputs 10a-13a of sample-and-hold circuits 10-13 into digital values respectively. As the A/D converter, an A/D polarity having polarity or an offset binary A/D converter is used to keep the bipolar sign. An arithmetic processing unit 20 decides the quadrant depending on the polarity in case of the A/D converter with polarity and depending on the judgement of the sign of a code bit in case of an offset binary A/D converter. Thus, the phase difference between two signals is obtained surely and the circuit constitution is simplified.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to general measuring instruments, radars, etc., in which multiple input sine wave or cosine wave signals (referred to as trigonometric function signals in the present invention) have the same frequency. related to phase difference detection.

[Conventional technology]

When measuring phase values or phase differences, such as signal phase difference measurement in general measuring equipment, or detection of phase changes in signals received by antenna elements or phase differences between signals in direction finders or radars that use the Doppler effect, etc. Various methods are well known.

Analog methods include finding it from the product of two signals,
Alternatively, as a digital method, a square wave is converted into a square wave at a certain threshold value, and a phase difference between the square waves is detected using a phase comparator.

[Problem that the invention seeks to solve]

The above phase difference measuring method does not detect the phase difference instantaneously, but averages the phase difference over several waves of signals. Furthermore, a phase comparator that directly measures the phase difference between two signals needs to distinguish between lead and lag when the phase difference exceeds ±180'', and it is necessary to add a circuit for this discrimination.

An object of the present invention is to provide a phase difference detection method that can eliminate the above-mentioned problems and detect instantaneous phase differences. Since trigonometric function signals, which are the subject of the present invention, have mathematically defined characteristics, it is an object of the present invention to utilize these characteristics to obtain a simple phase difference detection method.

[Means for solving problems]

The method of the present invention includes means for delaying each of a plurality of input trigonometric function signals having the same frequency by π/2.

means for simultaneously sampling the human trigonometric function signal and its delayed signal at at least one specific point in time; means for A/D converting the sampled value; and a sampling value at the specific point in time for each input trigonometric function signal; It has means for calculating a phase angle from the ratio of the delayed signal to a sampling value, and means for detecting a phase difference between each input trigonometric function signal from the calculated phase angle.

[Effect]

The trigonometric function signal is mutually converted into a sine wave signal and a cosine wave signal due to a phase difference of ±π/2. Therefore, as shown in FIG. 2, the input is a sine wave signal S (t)=Esin(wt
+α), this signal and this signal are connected to the π/2 delay circuit 3.
When the sample-and-hold circuit 1.2 samples the delayed signal with the sampling pulse 100 at a specific time point t8, from the former, S (ts)=Es in (
wtN+α).

The latter gives the value C(ts)=-Ecos (wt, +α). Therefore, the phase angle θ(t, )(-wt, l+α) of the input sine wave signal at time tN is obtained by the following equation.

- θ(L, l) = tan-'S(L, 4)/C(
jN)=tan-'s in(wtH+α)
/ −cos(w tN+cx) Then −θ(j
N) is in the range of -90° to +90''. Therefore, it is necessary to check the signs of S(t, 4) and C(tN) to determine the quadrant.

Since the instantaneous phase angle of one sine wave signal is determined in this way, the two sine wave signals 5t(t)=E1s in(w t +α,).

The phase difference (α1-α2) of 5z(t)=E2s in(w t +α2) is the instantaneous phase angle θ+(ts) and θz(L
It can be obtained by finding N) and taking the difference.

In this method, from the signal measurement value at time tN (α1-α2)
However, (α1-α2) itself is the phase difference of the waveforms regardless of the time point.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit block diagram of a phase difference detection device between two signals as an embodiment. 2 signals, E, sin
A signal 5t(t) 102 represented by (wt+αl) is directly input to the sample-and-hold circuit 10, and
A signal 102' that has passed through the π/2 delay circuit 14 is input to the sample and hold circuit 11. Similarly, of the two signals, Ez
Signal 52(t)1 expressed as sin(wt+α2)
03 is directly input to the sample-and-hold circuit 12, and a signal 103' that has passed through the π/2 delay circuit 15 is input to the sample-and-hold circuit 13. The above signals 102', 103
' are respectively −Elcos(wum+αIL−E2c o
s (w tnα2).

The sample and hold circuits 10 to 13 sample simultaneously at 19 points in time using the sampling pulse 101. The A/D converters 16 to 19 are connected to the outputs 10a, lla, 12a, 13 of each sample and hold circuit 10 to 13.
a is converted into a digital value by A/D converters 16 to 19, respectively.

The A/D converter uses a polarized A/D converter or an offset binary A/D converter, and maintains positive and negative signs (the arithmetic processor 20 described later uses the polarized A/D converter described above).
/D converter, depending on the polarity, offset binary A
In the case of a /D converter, the quadrant is determined by determining the sign of the sign bit.

The outputs of the A/D converters 16 to 19 are respectively S + (t
N), C+(t N), Sz(t)IL cz(
tN). The arithmetic processor 20 inputs the above signal and calculates S+(tN).

The phase angle θ1 (LH) and S z (L H) of the horn signal 5l (t) input from C+ (tH) at the LN time point and S z (L H), C
The phase angle θz(tn) at the LN time point of the input signal 5t(t) is calculated from z(ts), and further [θ, (beggar,)
−02(LH)] and calculate the signals 5z(t), s+(t)
It is possible to detect the phase difference (α1-α2).

The above explanation is for finding the phase difference between two signals, but
Even in the case of two or more signals, the phase relationship of all the signals can be determined by determining the phase difference between each signal using one signal as a reference.

Modified Embodiment (1) In the embodiment shown in FIG. 1, four A/D converters are provided to measure the phase difference between two signals.

Sampling is performed only once in one cycle,
In practice, it is often the case that the phase difference is measured every cycle. In this case, unless the frequency is very high, the conversion rate of A/D converters has recently become high, so time-division operation can be performed using only one A/D converter.

(2) Next, in the embodiment, measurement of the phase difference between signals was explained, but in special cases, s+
The phase angle at time 1N can be found from (tN) and c+(ts). In this case, the sampling time 1N serves as a reference and the phase can be determined.

Note that, as is well known, the π/2 delay circuit can be realized by an operational amplifier in the case of a low frequency, and by a lattice type phase shift circuit in the case of a high frequency.

〔Effect of the invention〕

As explained in detail above, in the present invention, the phase angles of a plurality of trigonometric functions at the same specific point in time are calculated, and the phase difference as a waveform is determined by calculating the difference in phase angle of each trigonometric function. It is.

Since the phase angle of a trigonometric function can be determined at any point during the period of 2π, the phase difference between two signals can also be obtained definitively. There is no uncertainty of ±π when calculating. Therefore, the circuit configuration is correspondingly simpler.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of an embodiment of the present invention, and FIG. 2 is a diagram illustrating the principle of phase angle measurement. 10-13--Sample/hold circuit, 14, 1
5 - π/2 delay circuit, 16 to 19 - A/D converter, 20 - arithmetic processor, 101 - sampling pulse, 102.103 - human input signal. Figure 2 Procedural author's letter (spontaneous) 1985 λ month ≠ Japan Patent Office Commissioner Kuro 11) 1 Akio Yu 1, Display of the incident 1986 Patent Application No. 258125 2, Name of the invention Signal phase difference detection Method 3: Relationship with the case of the person making the amendment Patent applicant address: 45, Kamiosaki 2-chome, Tokyo Parts Block
Name Name (117) Koden Seisakusho Co., Ltd. Representative Yoshiaki Igei 4, Agent Address ■107 Line Building 806, 1-1-17 Akasaka, Minato-ku, Tokyo (
582-0797) 6. Contents of the amendment in the "Detailed Description of the Invention" column of the specification to be amended +11 In the 4th line of page 2 of the specification, "Using the Doppler effect" was changed to "Detecting a phase difference" Amendment (2) Page 4, line 9 to line 13 of the specification shall be amended as follows. θ(tN)=tan-'S(ts)/C(tM)
=Lan-'s in (wt, +cr)/cos
(wtN+α) At this time, θ(tN) is found in the range θ″ to +90″, and all quadrants can be determined by checking the signs of 5(tN) and −C(Ls). 11th edition with formalities (voluntary) November 20, 1988

Claims (1)

[Claims] Each of multiple input trigonometric function signals with the same frequency is
means for simultaneously sampling the input trigonometric function signal and its delayed signal at at least one specific point in time; means for A/D converting the sampled value; It is characterized by comprising means for calculating a phase angle from the ratio of a sampled value at a time and a sampled value of a delayed signal thereof, and means for detecting a phase difference between each input trigonometric function signal from the calculated phase angle. A method for detecting the phase difference of trigonometric function signals.