JP2002094580A - Carrier reproducing means of long wave standard radio wave and synchronous oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous oscillator for suppressing the amplitude ringing in an output signal due to feedback control and for generating a frequency reference signal stable for a long-term and a short-term. SOLUTION: A carrier reproducing means which receives and amplifies a long wave standard radio wave, outputs a high frequency amplified signal and also reproduces a long wave standard radio wave carrier from the high frequency amplified signal, is provided with a long wave receiver 12 and a variable gain amplifier 6, supplies the long wave standard radio wave received and amplified by the receiver 12 as the high frequency amplified signal to the amplifier 6, and also makes the amplitude of the high frequency amplified signal amplified by the amplifier 6 fixed to reproduce the carrier by controlling the gain of the amplifier 6 in accordance with the waveform timing of a time signal demodulated by the receiver 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier regenerating means for regenerating a carrier from a long-wave standard radio wave and an oscillator using the carrier regenerating means.

[0002]

2. Description of the Related Art Standard radio waves are based on time and frequency standards and Japan Standard Time (JST) based on Coordinated Universal Time (UTC).
Is a radio wave operated by the Ministry of Posts and Telecommunications Research Institute to notify nationwide. In recent years, the transmission station of the standard radio wave using the 40 kHz long wave band (hereinafter, referred to as the long wave standard radio wave) has shifted from the experimental station to full-scale operation, and various applied devices using the long wave standard radio wave have been researched and developed. , Has come to be sold. For example, a clock is available that can receive and demodulate a time signal from a long-wave standard radio wave to enable time correction. However, the advantage is that the long-wave standard radio wave is not easily affected by the ionosphere and can stably receive radio waves. It can be said that it was used for.

On the other hand, it is also possible to use a stable radio wave propagation characteristic of a long-wave standard radio wave and a high-precision frequency of the radio wave as a frequency standard. That is, an oscillator that is phase-synchronized with the carrier frequency of the received long-wave standard radio wave is an example, and such an oscillator can be used as a clock oscillator or a local oscillator for an electronic device.

FIG. 4 is a block diagram of a conventional example of a synchronous oscillator which performs phase synchronization with a carrier frequency of a long-wave standard radio wave. The synchronous oscillator shown in FIG. 4 includes a long-wave receiver 1 that receives and amplifies a long-wave standard radio wave and outputs a high-frequency amplified signal, and a carrier-wave reproducing unit 2 that outputs a carrier signal from the high-frequency amplified signal supplied from the long-wave receiver 1. And the carrier recovery unit 2
And a synchronous oscillator 3 that outputs, as a frequency reference signal, an oscillation signal that is phase-locked to the carrier signal supplied from the oscilloscope.

The long-wave receiver 1 has an antenna 4 for receiving a long-wave standard radio wave, and a receiving section 5 for amplifying a high-frequency signal supplied from the antenna 4 and outputting a high-frequency amplified signal. The carrier reproducing unit 2 amplifies the high-frequency amplified signal supplied from the receiving unit 5 while controlling the gain thereof and outputs a carrier signal. The variable gain amplifier 6 detects the output of the variable gain amplifier 6 and sends the signal to the variable gain amplifier 6. An automatic gain control section 7 for supplying a gain control voltage.

Further, the synchronous oscillator 3 inputs the carrier signal supplied from the variable gain amplifier 6 to a first input terminal and sets the phase difference between the carrier signal and a frequency-divided signal input to a second input terminal described later to 0 °. A phase comparator 8 for outputting a phase control signal, a loop filter 9 for filtering a phase control signal from the phase comparator 8 in accordance with a predetermined cutoff frequency to generate a phase control voltage, A voltage-controlled crystal oscillator 10 whose oscillation frequency changes in accordance with the phase control voltage supplied from the phase control circuit; a frequency-divided oscillation signal output from the voltage-controlled crystal oscillator 10 by a predetermined number; And a frequency divider 11 for supplying the frequency to the two input terminals. The oscillation signal of the voltage controlled crystal oscillator 10 is output as a frequency reference signal.

The operation of the conventional embodiment shown in the drawings will be described below. First, the modulation waveform of the long-wave standard radio wave will be briefly described. The long-wave standard radio wave is obtained by subjecting a carrier of 40 kHz to AM modulation (pulse modulation) according to a digital data sequence of 1 bit / sec. As shown in FIG.
bit / sec digital data strings "0", "1" and "M"
(Marker), the pulse width of the carrier changes to 0.8 seconds, 0.5 seconds, or 0.2 seconds, respectively. The time information is "0" arranged in 60 seconds as one frame.
Year, month, day, hour, and minute information are represented by a combination of "1" and "M". The amplitude of the modulated wave is different from normal AM modulation (pulse modulation), and the ratio between the maximum amplitude (V1) and the minimum amplitude (V2) is 10: 1. That is, the modulated wave always has a carrier (40 kHz).
It is characteristic that the frequency component of z) is included.

Therefore, when the long wave receiver 1 receives the above-mentioned long wave standard wave, the antenna 4 supplies the received long wave standard wave to the receiver 5 as a high frequency signal. The receiver 5 amplifies the high-frequency signal to a predetermined level and supplies the high-frequency signal to the variable gain amplifier 6 as a high-frequency amplified signal. The variable gain amplifier 6 amplifies the high-frequency amplified signal, outputs the amplified signal, and supplies the amplified signal to the gain controller 7. Then, the gain control unit 7
After detecting the output of the variable gain amplifier 6 and filtering it, a gain control voltage is generated and supplied to the variable gain amplifier 6.
Therefore, the output voltage of the variable gain amplifier 6 is maintained substantially constant because the gain of the variable gain amplifier 6 is feedback controlled.

Here, the high-frequency amplified signal input to the variable gain amplifier 6 has an amplitude ratio between the maximum amplitude and the minimum amplitude changed to 10: 1 according to the timing of the modulation signal as shown in FIG. When this is amplified by the variable gain amplifier 6, as a result of feedback control by the gain control unit 7,
A change in amplitude between the maximum amplitude and the minimum amplitude is suppressed, and a signal waveform having a substantially constant amplitude, that is, a carrier signal having a constant frequency of 40 kHz is obtained.

Next, the carrier signal is supplied to a first input terminal of the phase comparator 8 as a reference signal. The phase comparator 8 outputs a phase control signal such that the phase difference between the reference signal and a frequency-divided signal from a frequency divider 11 described later becomes 0 °,
The phase control signal is filtered by a loop filter and supplied to the crystal controlled crystal oscillator 10 as a phase control voltage. The oscillation frequency of the voltage controlled crystal oscillator 10 is controlled according to the phase control voltage. Then, the output signal of the voltage controlled crystal oscillator 10 is fed back and frequency-divided by the frequency divider 11 by a predetermined number, and then supplied to the second input terminal of the phase comparator 8 as a frequency-divided signal.

Therefore, the phase difference between the reference signal (carrier signal) and the divided signal input to the phase comparator 8 is 0 °.
The frequency and phase of the output signal of the voltage-controlled oscillator 10 are controlled so that a signal of a predetermined frequency having the same frequency accuracy as the carrier signal reproduced from the long-wave standard time signal is output from the output of the voltage-controlled oscillator 10. Obtained as a frequency reference signal.

[0012]

However, the conventional synchronous oscillator described above has the following problems. That is, the gain of the carrier signal output from the variable gain amplifier 6 in the carrier recovery unit 2 is feedback-controlled by the gain control unit 7, so that the change in the maximum amplitude and the minimum amplitude shown in FIG. However, undershoot and overshoot occur in the output amplitude corresponding to the portion where the amplitude changes between the maximum amplitude and the minimum amplitude in FIG. 5 in the output waveform of the variable gain amplifier 6, and the amplitude fluctuates. There will be parts.

That is, the gain control section 7 is provided with the variable gain amplifier 6
After the output signal of the variable gain amplifier 6 is detected and filtered, a gain control voltage is generated and fed back to the variable gain amplifier 6, so that the gain control voltage always has a response time corresponding to the amplitude change of the output signal of the variable gain amplifier 6. Exists. Due to the response characteristic determined by the response time, the change in the amplitude of the high-frequency amplified signal input to the variable gain amplifier 6 (the change in the amplitude between the maximum amplitude and the minimum amplitude in FIG. 3) causes A phenomenon called ringing occurs in which the output amplitude repeatedly overshoots or undershoots and converges to a constant value while following the response time with a delay.

The ringing portion, when viewed in a short time, has an effect as a component in which the frequency of the carrier wave fluctuates in a short time, and deteriorates the short-term stability of the frequency of the reproduced carrier wave. That is, when the carrier wave signal output from the carrier wave reproducing unit 2 is used as a reference signal and a signal phase-locked to the carrier signal is obtained by the synchronous oscillator 3, the frequency reference signal is affected by a short-term fluctuation component of the frequency of the reference signal. Frequency fluctuations occur. Since the fluctuation of the frequency of this frequency reference signal is short, it does not matter if only long-term stability is to be guaranteed, but it is a problem if short-term stability must be guaranteed. .

In order to improve the short-term stability of the frequency of the carrier described above, the frequency (cutoff frequency) to be filtered in the gain control unit 7 is set to a high frequency to shorten the response time of the feedback control, thereby making the variable gain variable. Although it is possible to shorten the ringing time of the output amplitude of the amplifier 6, it is impossible in principle to eliminate the ringing itself, and conversely, if the response characteristic is too fast, the entire feedback control system May become unstable and cause abnormal oscillation, and there is a limit to shortening and suppressing the ringing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to solve the problem of short-term,
It is an object of the present invention to provide an oscillator provided with a carrier regenerating means for regenerating a carrier signal having stable frequency accuracy over a long period.

[0017]

In order to solve the above-mentioned object, the invention according to the first aspect of the present invention relates to a carrier recovery means for a long wave standard radio wave and a synchronous oscillator according to the present invention. A carrier regeneration unit for outputting a signal and regenerating a carrier of a long-wave standard radio wave from the high-frequency amplified signal, wherein the carrier regeneration unit includes a long-wave receiver and a variable gain amplifier; and the carrier regeneration unit includes the long-wave receiver. Supplying the variable-frequency standard radio wave received and amplified in the variable-gain amplifier as a high-frequency amplified signal, and controlling the gain of the variable-gain amplifier in accordance with the timing of the waveform of the time signal demodulated by the long-wave receiver. The carrier is reproduced by making the amplitude of the high frequency amplified signal amplified by the gain amplifier constant.

According to a second aspect of the present invention, there is provided a carrier recovery means and a synchronous oscillator for a long-wave standard radio wave, wherein the long-wave standard radio wave is received and amplified to output a high-frequency amplified signal. In a carrier recovery unit for recovering a carrier, the carrier recovery unit includes a long-wave receiver, a variable gain amplifier, and a predicted time generation unit, and the carrier recovery unit converts a long-wave standard wave received and amplified by the long-wave receiver to a high-frequency wave. The predicted time signal is supplied to the variable gain amplifier as an amplified signal, and the predicted time signal is generated by predicting a time signal a predetermined time ahead by the predicted time generation unit based on the time signal demodulated by the long wave receiver. Controlling the gain of the variable gain amplifier in accordance with the timing of the variable gain amplifier to increase the amplitude of the high-frequency amplified signal amplified by the variable gain amplifier. Joka and is obtained by reproducing the carrier.

In order to solve the above-mentioned object, according to the present invention, there is provided a carrier recovery means for a long-wave standard radio wave and a synchronous oscillator according to the present invention. An oscillator, wherein the synchronous oscillator outputs an oscillation signal phase-locked to the carrier reproduced by the carrier reproducing means.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 1 is a block diagram showing a first embodiment of a synchronous oscillator according to the present invention. The synchronous oscillator shown in FIG. 1 receives and amplifies a long-wave standard radio wave, outputs a high-frequency amplified signal, and demodulates a time signal. The synchronous oscillator converts a carrier signal from the high-frequency amplified signal supplied from the long-wave receiver 12. A carrier reproducing unit 13 for outputting the signal and a synchronous oscillator 3 for outputting, as a frequency reference signal, an oscillation signal phase-synchronized with the carrier signal supplied from the carrier reproducing unit 13 are provided.

A long-wave receiver 12 includes an antenna 4 for receiving a long-wave standard radio wave, and a receiving unit 5 for amplifying a high-frequency signal supplied from the antenna 4 and outputting a high-frequency amplified signal.
And a demodulation unit 14 for demodulating a time signal from the high frequency amplified signal. The carrier recovery unit 13 amplifies the high-frequency amplification signal supplied from the reception unit 5 while controlling the gain thereof and outputs a carrier signal, and a gain control voltage in accordance with the timing of the time signal from the demodulation unit 14. A gain control unit 15 that supplies the variable gain amplifier 6 with the variable gain amplifier 6.

Further, the synchronous oscillator 3 inputs the carrier signal supplied from the variable gain amplifier 6 to a first input terminal and sets the phase difference between the carrier signal and a frequency-divided signal input to a second input terminal described later to 0 °. A phase comparator 8 for outputting a phase control signal, a loop filter 9 for filtering a phase control signal from the phase comparator 8 in accordance with a predetermined cutoff frequency to generate a phase control voltage, A voltage-controlled crystal oscillator 10 whose oscillation frequency changes in accordance with the phase control voltage supplied from the phase control circuit; a frequency-divided oscillation signal output from the voltage-controlled crystal oscillator 10 by a predetermined number; And a frequency divider 11 for supplying the frequency to the two input terminals. The oscillation signal of the voltage controlled crystal oscillator 10 is output as a frequency reference signal.

The operation of the illustrated embodiment will be described in detail below. First, when the long wave receiver 12 receives the long wave standard wave, the antenna 4 supplies the received long wave standard wave to the receiver 5 as a high frequency signal. The receiving unit 5 amplifies the high-frequency signal to a predetermined level and supplies the high-frequency amplified signal to the variable gain amplifier 6 and the demodulation unit 14, respectively. The demodulator 14 demodulates the high-frequency amplified signal and outputs a time signal. Here, the time signal is obtained by envelope-detecting the AM-modulated (pulse-modulated) wave shown in FIG. 5, and a pulse waveform according to the envelope of the amplitude is output.

On the other hand, the gain control section 15 generates a gain control voltage in accordance with the rise and fall timings of the time signal (pulse waveform) supplied from the demodulation section 14 and supplies the same to the variable gain amplifier 6. Here, the gain control voltage is output by switching between a first predetermined voltage value and a second predetermined voltage value at the timing of the time signal (pulse waveform). That is, the first control voltage value is output while the pulse waveform of the time signal is rising, and the second control voltage value is output while the pulse waveform of the time signal is falling. .

Therefore, the variable gain amplifier 6 includes the gain control unit 1
The high-frequency amplification signal from the receiving unit 5 is amplified according to the gain control voltage supplied from the reception unit 5. Here, the waveform of the high-frequency amplified signal input to the variable gain amplifier 6 has its amplitude value changed 10: 1 as shown in FIG. 3, but the gain control section 15 has the same timing as the change in amplitude. , A gain control voltage is selected and output by taking the first control voltage value or the second control voltage value, and the gain of the variable gain amplifier 6 indicated by the first control voltage value and the second control voltage value has the maximum amplitude. The voltage value is optimized so as to have a ratio of 1 to 10 with respect to the minimum amplitude.

Therefore, the signal amplified and output by the variable gain amplifier 6 has a waveform with a fixed amplitude, that is, a signal reproduced as a carrier signal of a long-wave standard radio wave. Next, the carrier signal reproduced by the variable gain control section 6 is supplied to the phase comparator 8 of the synchronous oscillator 3 as a reference signal. Since the operation is the same as that of the conventional embodiment, detailed description thereof will be omitted. Although omitted, an oscillation signal having a predetermined frequency synchronized with the reference signal is output from the voltage controlled crystal oscillator 10 and is obtained as a frequency reference signal.

As described above, since the time signal is used as a timing signal for controlling the amplitude without directly feeding back the output signal of the variable amplifier 6, there is no amplitude ringing which has conventionally occurred due to the response characteristic of the feedback control. The carrier signal can be reproduced, and since it has no feedback portion, it can be supplied as a stable carrier signal that does not cause abnormal oscillation.

In the embodiment described above, at the time of switching the gain control voltage for controlling the gain of the variable gain amplifier 6, the time signal demodulated from the long wave standard wave is directly referred to, and the gain control is performed in accordance with the amplitude change. Although the voltage is switched, the present invention is not limited to this, and a time signal ahead of a predetermined time is predicted based on a time signal at a certain predetermined time, and this is used as a switching timing signal of the gain control voltage. May be.

FIG. 2 is a block diagram showing a synchronous oscillator according to a second embodiment of the present invention. Less than,
The illustrated second embodiment will be described in detail.
The synchronous oscillator shown in FIG. 2 is obtained by adding a predicted time generation unit 16 and a clock generator 17 to the first embodiment shown in FIG. A time signal at a predetermined time ahead of a predetermined time is predicted based on the time signal supplied from the clock signal of the predetermined frequency supplied from the clock oscillator 17 and is output as a predicted time signal.

The operation of the second embodiment shown in FIG. 2 will be described below. In FIG. 2, the operations of the long wave receiver 12, the carrier recovery unit 13, and the synchronous oscillator 3 are the same as those of the first embodiment shown in FIG. Clock oscillator 1
7 will be described with reference to FIG. FIG.
4 outputs a time signal (FIG. 3A) and a time generation unit 1
6 shows a time chart from when the time signal is read (FIG. 3 (2)), predicted time information is generated (FIG. 3 (3)) and output as the predicted time signal.

First, as shown in FIG. 3A, the demodulation unit 14 outputs a time signal at 1 bit / second every frame / minute. Here, the 60-bit time information included in each frame represents the head time of each frame.
That is, frame 1, frame 2, frame 3, frame 4
Indicates time at points A, B, C, and D, respectively. (Hereinafter, points A, B, C, and D are referred to as times A, B, C, and D, respectively).
, The time information of the frame 3 is predicted and generated based on the all time information of the frame 1. (FIG. 3
(3) ')

Here, since the generation of the time information of the frame 3 is obtained by advancing the time information of the frame 1 by 2 minutes, the 7-bit information (BCD code ) Can be easily obtained by adding 1 to the second lowest bit. Thus, the obtained predicted time information of the frame 3 is converted into a pulse waveform, and is output as a predicted time signal at a time C ′ substantially close to the time C. (“4” in FIG. 3 (4)) Note that the time C ′ is obtained by elapse of a predetermined time from the time B based on the clock signal supplied from the clock oscillator 17, and the time C ′ is It is advanced by a predetermined time Δt.

The variable gain controller 6 corrects the delay time generated in the demodulator 14 and the gain controller 15 and the like.
This is for accurately adjusting the timing of the gain control with respect to the change in the amplitude of the high-frequency amplified signal supplied to the amplifier. Similarly,
The predicted time generation unit 16 sequentially reads the time information of frame 2, frame 3,...
(2)...), And predicts time information (FIG. 3).
(3), ',', '...), a predicted time signal which is a series of pulse waveforms is output and supplied to the gain control unit 15. (“,”... In FIG. 3 (4))

The gain control unit 15 generates a gain control voltage according to the timing of the change in the amplitude of the predicted time signal and supplies the generated voltage to the variable gain amplifying unit 6. The variable gain amplifier 6 makes the amplitude of the high-frequency amplified signal supplied from the receiving unit 5 constant according to the gain control voltage, and supplies the carrier signal to the synchronous oscillator 3.
The synchronous oscillator 3 outputs an oscillation signal of a predetermined frequency synchronized with the carrier signal as a frequency reference signal.

As described above, a time signal at a predetermined time is predicted from the time signal demodulated by the demodulation unit 14 and the output timing of the predicted time signal is advanced by a predetermined time, whereby the demodulation unit 14
And the delay time generated in the gain control unit 15 and the like can be corrected, so that the timing of the amplitude change between the maximum amplitude and the minimum amplitude of the high-frequency amplified signal input to the variable gain amplifier 6 can be accurately adjusted. As compared with the first embodiment, the amplitude of the reproduced carrier can be accurately stabilized, and a carrier signal with higher stability can be reproduced.

Here, the predicted time generator 16 includes the demodulator 1
Although the time signal after two minutes is predicted based on the time signal demodulated in step 4, the present invention is not limited to this. For example, an arbitrary time signal may be calculated based on the time signal read at times A and B. It is possible to predict. Although the time signal is predicted every minute, it is also possible to predict the time signal every few minutes. However, since the time is measured using the clock generator 16 in order to accurately match the timing at which the predicted time signal is output with the timing of the amplitude change of the high-frequency amplified signal input to the variable gain amplifier 6, one frame is used. It is not preferable to predict the time signals of a number of frames over a long period of time on the basis of the above, since minute deviations in timing are accumulated. Therefore, as described above, it is more preferable to predict the time signal every minute every time the time signal is read.

[0037]

As described above, the present invention relates to a synchronous oscillator provided with a carrier recovery means having a long-wave receiver and a variable gain amplifier, wherein the carrier recovery means comprises a high-frequency amplified signal received and amplified by the long-wave receiver. Is supplied to the variable gain control unit, the carrier signal is controlled by controlling the gain of the variable gain control unit at the timing of the time signal demodulated by the long wave receiver or at the timing of the predicted time signal generated from the time signal. At the same time as the reproduction, the synchronous oscillator obtains an oscillation signal phase-locked to the carrier signal,
This is effective in providing a stable frequency reference signal in the long term and the short term.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment according to the present invention.

FIG. 2 is a block diagram of a second embodiment according to the present invention.

FIG. 3 is a timing chart showing a process of generating a predicted time signal according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional embodiment.

FIG. 5 is a view for explaining a modulation waveform of a long-wave standard radio wave.

[Explanation of symbols]

 1, 12 ... Long wave receiver 2, 13 ... Carrier recovery unit 3 ... Synchronous oscillator 4 ... Antenna 5 ... Reception unit 6 ... Variable gain amplifier 7, 15 ... Gain control Unit 8: Phase comparator 9: Loop filter 10: Voltage controlled crystal oscillator 14: Demodulation unit 16: Predicted time generation unit 17: Clock oscillator

Claims (3)

[Claims] 1. A carrier reproducing means for receiving and amplifying a long-wave standard radio wave to output a high-frequency amplified signal and reproducing a carrier of the long-wave standard radio wave from the high-frequency amplified signal, comprising: a carrier having a long-wave receiver and a variable gain amplifier. Regenerating means, wherein the carrier reproducing means supplies the variable gain amplifier with a long-wave standard wave received and amplified by the long-wave receiver as a high-frequency amplified signal, and adjusts the timing of the waveform of the time signal demodulated by the long-wave receiver. Carrier recovery means for controlling the gain of the variable gain amplifier to stabilize the amplitude of the high-frequency amplified signal amplified by the variable gain amplifier and reproduce the carrier. 2. A carrier reproducing means for receiving and amplifying a long-wave standard radio wave to output a high-frequency amplified signal and reproducing a carrier of the long-wave standard radio wave from the high-frequency amplified signal, comprising: a long-wave receiver, a variable gain amplifier, and a predicted time generating section. And a carrier recovery unit that supplies the variable-gain amplifier with a long-wave standard wave received and amplified by the long-wave receiver as a high-frequency amplified signal, and a time signal demodulated by the long-wave receiver. Based on the above, a predicted time signal is generated by predicting a time signal ahead of a predetermined time by the predicted time generation unit, and the variable gain amplifier is controlled by controlling the gain of the variable gain amplifier in accordance with the timing of the predicted time signal. A carrier reproducing means characterized in that a carrier is reproduced with the amplitude of the amplified high-frequency amplified signal being fixed. 3. A synchronous oscillator comprising the carrier recovery means according to claim 1 or 2, wherein the synchronous oscillator outputs an oscillation signal phase-locked to the carrier reproduced by the carrier recovery means. A synchronous oscillator characterized by the above-mentioned.