JPS6335944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring a phase difference between a signal whose phase has changed in a reference phase signal output and a reference phase signal output.

When measuring the phase difference between a reference phase signal with a phase change and a reference phase signal, a phase-locked loop has been used as a means for extracting a signal synchronized with a reference phase signal with a phase change. The device for controlling the local phase of this phase-locked loop has conventionally been a device using a voltage-controlled oscillator as shown in FIG.
The device for performing digital phase control shown in FIG. 2 was used.

The device shown in Fig. 1 is composed of a phase comparator 1, a loop filter 2, a voltage controlled oscillator 3, a reference phase signal generator 4, and a phase measuring device 5. When the loop band is narrow, the voltage controlled oscillator The disadvantage was that the phase measurement error increased due to the short-term stability of . Further, in order to perform high-resolution phase measurement, a large amount of measurement time is required in the phase measuring device 5, so a time delay in the phase difference measurement output has been a problem.

The device shown in FIG. 2 also includes a phase comparator 1, a loop
Filter 2, reference phase signal generator 4, voltage frequency converter 6, clock generation circuit 7 and counter 1
4 and a digital phase control circuit 8 consisting of a data register 15.

The counter 14 of the digital phase control circuit 8 divides the output of the clock generation circuit 7 by 1/N.
The frequency-divided output is sent to the phase comparator 1.
The voltage frequency converter 6 outputs a pulse signal according to the phase difference between the input signal and the frequency-divided output. For example, when the phase difference becomes large, the pulse signal is output more frequently.

The phase of the counter 14 is changed by causing the counter 14 to lose count by the pulse signal, or by adding a pulse.

The data register 15 registers the counter 14 at the timing of the coherent signal from the reference phase signal generator 4.
Since the contents of the input signal are captured and held, it is possible to directly read the phase difference between the reference phase signal and the input signal. In order to perform high-resolution phase measurement, it is necessary to make the clock frequency extremely high, but the digital phase control circuit 8 counts the clocks 7 while being controlled by the output of the voltage frequency converter 6.
There is an upper limit to the clock frequency at which it can operate.
With current technology, the resolution of phase difference measurement is limited to about 6 ns.

It is an object of the present invention to set the clock frequency in a digital phase control circuit to a relatively low frequency at which the digital circuit can operate satisfactorily. An object of the present invention is to provide a phase measuring device that enables high-resolution, high-precision measurement by converting signals to relatively high frequencies.

In order to achieve the above object, the high-resolution phase measuring device according to the present invention includes a reference phase signal generation section that outputs a reference phase signal and a signal coherent thereto;
Input the phase-changed signal of the reference phase signal and the output of the voltage controlled oscillator of the frequency conversion circuit, and digitally calculate the phase of the divided output obtained by dividing the clock by a pulse wave signal with a frequency proportional to the phase difference between them. and a phase difference between the phase-changed signal of the reference phase signal and the reference phase signal by taking out a divided output whose phase is controlled by the pulse wave signal at the timing of the coherent signal of the reference phase signal generator. a coherent signal of the reference phase signal generator and the divided output of the digitally controlling the phase are input, and the output signal of the voltage controlled oscillator and the coherent signal are mixed. , and a frequency conversion circuit that converts the frequency-divided output into a relatively high frequency by controlling the voltage-controlled oscillator so that the mixed output signal and the frequency-divided output signal are synchronized.

Hereinafter, the present invention will be explained in more detail with reference to the drawings and the like.

FIG. 3 is a circuit block diagram showing an embodiment of the phase measuring device according to the present invention. In the figure, circuit sections common to those in FIGS. 1 and 2 are given the same reference numerals, and 9, 10, 11, and 12 are phase comparators, loop filters, voltage-controlled oscillators, respectively.
A mixer is shown. These 9, 10, 11, 1
The frequency conversion circuit 13 is configured by the circuit No. 2.

The phase comparator 1 receives the phase-changed input signal of the reference phase signal output and the output signal of the voltage controlled oscillator 11, and outputs a voltage signal proportional to the phase difference between the two signals. This signal is input through a loop filter 2 to a voltage frequency converter 6.

The voltage frequency converter 6 generates a pulse signal with a frequency proportional to the loop filter output.

This pulse signal is input to the counter 14 of the digital phase control circuit 8, and its output phase is digitally controlled by omitting or adding count pulses from the counter 14.

The means for digitally controlling the phase includes a phase comparator 1, a loop filter 2, a voltage frequency converter 6,
This corresponds to the clock generator 7 and the counter 14 of the digital phase control circuit 8.

Further, the data register 15 corresponds to the measurement output means.

The output of the counter 14 has a frequency that is 1/N of the clock frequency of the clock generator 7, and since the phase is controlled by the pulse signal of the voltage frequency converter 6 as described above, the phase control pulse of the output of the voltage frequency converter 6 is When there is no signal, it changes linearly and represents the momentary phase. Further, while outputting the reference phase signal, the reference phase signal generator 4 also generates two signals coherent with the reference phase signal output and supplies them to the mixer 12 and the data register 15 of the digital phase control circuit 8. ing. The data register 15 reads and holds the divided output of the counter 14 at the timing of the reference phase signal and the coherent signal, and outputs a phase difference measurement output. The output signal of the voltage controlled oscillator 11 and the signal coherent with the output of the reference phase signal generator 4 are input to the mixer 12, and the difference frequency between these signals is output as an output. This mixer 12
A loop of a phase comparator 9, a loop filter 10, and a voltage controlled oscillator 11 is arranged so that the output signal of the digital phase control circuit 8 has the same phase as the output signal of the digital phase control circuit 8.

Now, if the input signal i(t) is a sine wave with a frequency ω ₀ and a phase difference φ ₀ from the reference phase signal output, then i(t)=sin(ω ₀ t+φ ₀ ) …(1) .

coherent to the reference phase signal output (i.e.
When the reference phase signal generator 4 generates a cosine wave r(t)=cosω ₁ t (2) with a phase difference of 0) and a frequency _ω 1 from the reference phase signal output, the output of the voltage controlled oscillator 11 Since a signal i'(t) = Ki(t) (K is a positive constant) is generated that is precisely synchronized with the input signal i(t), the signal i'(t) and the reference phase signal are When the output is multiplied by a coherent signal r(t) in the mixer 12, from equations (1) and (2), i'(t)・r(t)=Ksin(ω ₀ t+φ ₀ )・cosω ₁ t = K/2 {sin [(ω ₀ +ω ₁ )t+φ ₀ ]+sin [(ω ₀
−ω ₁ )t+φ ₀ ]}…(3).

If we extract only the low-frequency sine wave from equation (3) and set it as the output m(t) of the mixer 12, then m(t)=K/2sin [(ω ₀ −ω ₁ )t+φ ₀ ]... (4) However, in the phase comparator 9, since the output m(t) of the mixer 12 and the output d(t) of the digital phase control circuit 8 are synchronized, K' can be corrected from equation (4). As a constant, d(t) becomes:

d(t)=K′sin [(ω ₀ −ω ₁ )t+φ ₀ ]…(5) Here, if ω ₁ is set to a slightly lower frequency than ω ₀ , in equation (5), (ω ₀ −ω ₁ ) can be made relatively small, and the clock frequency in the digital phase control circuit 8 can be made low.

Furthermore, since the phase of d(t) is equal to the phase difference φ ₀ between the input signal i(t) and the reference phase signal output,
In the digital phase control circuit 8, it is possible to directly obtain the phase difference φ ₀ between the input signal and the reference phase signal output.

As explained in detail above, this device can configure a digital phase control circuit using a clock with a relatively low frequency, and also uses a frequency conversion circuit to increase the frequency and perform phase comparison, so it can achieve high resolution and high precision phase control. Measurement is possible.

Currently, the distance to an artificial satellite is measured by sending a reference phase signal from the ground to the satellite, measuring the phase difference with the signal returned from the satellite, and calculating the distance from the radio wave propagation speed. By performing phase difference measurement using this device, it becomes possible to measure the distance to the satellite with high resolution and precision.

[Brief explanation of the drawing]

1 and 2 are block diagrams of a conventional phase measurement method, and FIG. 3 is a block diagram showing an embodiment of the apparatus of the present invention. 1... Phase comparator, 2... Loop filter,
3... Voltage controlled oscillator, 4... Reference phase signal generator, 5... Phase measuring device, 6... Voltage frequency converter, 7... Clock generator, 8... Digital phase control circuit, 9... Phase Comparator, 10...Loop filter, 11...Voltage controlled oscillator, 12...
...Mixer, 13...Frequency conversion circuit.

Claims (1)

[Claims] 1. A reference phase signal generation section that outputs a reference phase signal and a coherent signal thereto, and inputs a phase-changed signal of the reference phase signal and the voltage controlled oscillator output of a frequency conversion circuit, and generates a signal that is proportional to the phase difference between them. means for digitally controlling the phase of a frequency-divided output obtained by dividing a clock by a pulse wave signal of a certain frequency; and a frequency division whose phase is controlled by the pulse wave signal at the timing of a coherent signal of the reference phase signal generator. measurement output means for obtaining a phase difference between the phase-changed signal of the reference phase signal and the reference phase signal by taking out an output; and a coherent signal of the reference phase signal generator and the means for digitally controlling the phase. inputting a frequency output, mixing the output signal of the voltage controlled oscillator with the coherent signal, and controlling the voltage controlled oscillator so that the mixed output signal and the frequency divided output signal are synchronized. A high-resolution phase measuring device comprising a frequency conversion circuit that converts an output to a relatively high frequency.