JPH1051307A - Nuclear magnetic resonance oscillator - Google Patents

Abstract

(57) Abstract: The present invention relates to a nuclear magnetic resonance type oscillator, and has an object to stabilize an output frequency from the time of startup until the frequency is locked (at the time of frequency unlocking). A frequency control circuit (DDS) which receives an output signal of a voltage controlled oscillator (VCO) and changes and outputs a VCO output frequency according to frequency setting data;
To generate the setting data of the value corresponding to the control voltage to the DDS
Switching control at start-up to control the DDS with the setting data from the frequency setting data generating circuit when the frequency is unlocked and to set the DDS setting data to a fixed value when the frequency is locked And a circuit (not shown), wherein the frequency setting data generation circuit changes the setting data in accordance with the control voltage of the VCO swept at the start-up of the device, and changes the output frequency of the DSS even when the output frequency of the VCO changes. Is set to a constant value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear magnetic resonance oscillator. The nuclear magnetic resonance oscillator of the present invention is used as a rubidium atomic oscillator or an atomic clock using an optical pumping method used for a reference frequency source for broadcasting or the like. In recent years, there has been a demand for a rubidium atomic oscillator and a system using the same to reduce the time required for startup and improve stability.

[0002]

2. Description of the Related Art FIG. 12 shows a configuration example of a conventional rubidium atomic oscillator. In the figure, 1 is a signal amplifier, 2 is a synchronous detector, 3 is a switching circuit, 4 is a sweep circuit, 5 is an integrator, 6 is a low frequency oscillator, 7 is a crystal oscillator as a voltage controlled oscillator, and 8 is a frequency synthesizer. Reference numeral 9 denotes an atomic resonance unit, and reference numeral 10 denotes a temperature control circuit. The rubidium atomic oscillator multiplies the output frequency of the crystal oscillator 7 by the frequency synthesizer 8 and supplies it to the atomic resonance unit 9. The specific output frequency of the crystal oscillator 7 causes the atomic resonance unit 9 to cause nuclear magnetic resonance and resonate. A signal is obtained and fed back as a control voltage to the crystal oscillator 7 through a feedback path passing through the signal amplifier 1, the synchronous detector 2, the switching circuit 3, and the integrator 5, so that the output frequency of the crystal oscillator 7 is changed by nuclear magnetic resonance. Is controlled to a constant value with extremely high stability based on.

In this rubidium atomic oscillator, the atomic resonance section 9 is controlled to a constant temperature by a temperature control circuit 10 in order to keep the frequency of nuclear magnetic resonance accurately constant. Since the nuclear magnetic resonance does not occur yet because the power supply is not performed, the switching circuit 3 is switched to the sweep circuit 4 side, and the sweep output output from the sweep circuit 4 as shown in FIG. It is converted into an integrated waveform as shown and supplied to the crystal oscillator 7 as a control voltage. Thus, the output frequency from the crystal oscillator 7 is continuously swept in a certain frequency range. Eventually, when the temperature of the atomic resonance section 9 is controlled to cause nuclear magnetic resonance, a resonance signal is output at a specific frequency among the output frequencies being swept.
The switching circuit 3 is switched to the synchronous detector 2 upon detection by the M circuit, and thereafter, a feedback control loop passing through the atomic resonance section 9 is formed to control the oscillation frequency of the crystal oscillator 7.

[0004] The operation of the conventional rubidium atomic oscillator from startup to frequency lock will be described below. The output signal of the sweep circuit 4 as shown in FIG. FIG. 14 shows the output voltage of the integrator 5 at this time. When the output of the integrator 5 that changes as shown in FIG. 14 is applied to the crystal oscillator 7 as a control voltage, the crystal oscillator 7 enters a “frequency sweep state” in which the output frequency changes continuously. Similarly, the output signal of the frequency synthesizer 8 input to the atomic resonance unit 9 is in the “frequency sweep state”, and the output signal of the low frequency oscillator 6 is subjected to phase modulation. 20 to 30 minutes after the start-up, the temperature of the atomic resonance unit 9 reaches the set temperature, a resonance signal is detected from the atomic resonance unit 9 and amplified by the signal amplifier 1. The output signal of the signal amplifier 1 is input to the synchronous detector 2,
Synchronous detection is performed at the oscillation frequency of the low frequency oscillator 6. When the resonance signal is detected, the input to the integrator 5 is switched to the output signal side of the synchronous detector 2 by the switching circuit 3, and the control voltage according to the resonance signal is applied to the crystal oscillator 7 thereafter. Operates in frequency locked state.

[0005]

In the above-described rubidium atomic oscillator, when the system is started up, as shown in FIG. 15, the output frequency is swept by the frequency variable width of the crystal oscillator 7 until the frequency locks, as shown in FIG. In this state, a stable frequency supply that can be used as a broadcast reference frequency source or the like cannot be performed until the frequency is locked (about 20 to 30 minutes).

Accordingly, it is an object of the present invention to keep the output frequency constant from the time of startup until the frequency is locked (when the frequency is unlocked).

[0007]

FIG. 1 is an explanatory view of the principle according to the present invention. In order to solve the above-described problem, the nuclear magnetic resonance type oscillator according to the present invention has, as one form, an atomic resonance section 102 in a feedback loop of a control voltage of a voltage controlled oscillator 101 as shown in FIG. In the nuclear magnetic resonance type oscillator that stabilizes the oscillation frequency by the nuclear magnetic resonance phenomenon, an output signal of the voltage controlled oscillator 101 is input,
A frequency control circuit 103 for changing an output signal frequency of the voltage controlled oscillator 101 in accordance with frequency setting data and outputting the output signal as an oscillator output frequency;
From the frequency setting data generating circuit 104 which generates frequency setting data having a value corresponding to the control voltage to be supplied to the frequency control circuit 103 and supplies the frequency setting data to the frequency control circuit 103. And a start-up switching control circuit (not shown) for switching the frequency control circuit 103 to a fixed value when the frequency is locked after the start-up. The frequency setting data generation circuit 104 changes the frequency setting data in accordance with the control voltage of the voltage controlled oscillator 101 swept at the time of device startup, and also responds to a change in the output frequency of the voltage controlled oscillator 101. The output frequency of the frequency control circuit 103 is configured to have a constant value.

The switching of the frequency setting data by the switching control circuit at start-up is performed by changing the output data in accordance with the control voltage to be swept, a detecting circuit for detecting the presence or absence of nuclear magnetic resonance, The selector can select output data output from the conversion circuit when the frequency is unlocked in response to the detection signal of the circuit, and select fixed data output from the frequency setting circuit when the frequency is locked.

[0009] Alternatively, the switching of the frequency setting data by the switching control circuit at the time of startup is performed by detecting a presence or absence of nuclear magnetic resonance, and responding to a detection signal of the detection circuit, when the input signal is unlocked when the frequency is unlocked. The switching can be performed by a switching circuit that switches to a fixed voltage when the frequency is locked to the control voltage of the voltage controlled oscillator, and a conversion circuit that converts an output signal of the switching circuit into output data corresponding to the value.

According to another aspect of the present invention, there is provided a nuclear magnetic resonance type oscillator in which an atomic resonance section is provided in a feedback loop of a control voltage of a voltage controlled oscillator to stabilize an oscillation frequency by a nuclear magnetic resonance phenomenon. A frequency control circuit for receiving an output signal of the voltage controlled oscillator, changing an output signal frequency of the voltage controlled oscillator in accordance with frequency setting data and outputting the output signal as an oscillator output frequency; A frequency setting data generating circuit for generating frequency setting data having a value corresponding to a control voltage to the oscillator and supplying the frequency setting data to the frequency control circuit; and an output signal from the frequency control circuit when the frequency is unlocked at the time of starting the device. At startup, when the frequency is locked after startup, switching is performed so as to select an output signal from the voltage controlled oscillator that does not pass through the frequency control circuit. A control circuit, wherein the frequency setting data generating circuit changes the frequency setting data according to a control voltage of the voltage controlled oscillator that is swept when the device is started up, and responds to a change in the output frequency of the voltage controlled oscillator. Is also configured so that the output frequency of the frequency control circuit becomes a constant value.

In each of the above nuclear magnetic resonance oscillators, a multiplying circuit may be inserted between the output of the voltage controlled oscillator and the input of the frequency control circuit. Alternatively, instead of inputting the output signal of the voltage controlled oscillator to the frequency control circuit, a multiplying circuit in a frequency synthesizer inserted between the output side of the voltage controlled oscillator and the input side of the atomic resonance section is used. An output signal can be extracted and used as an input signal to the frequency control circuit.

In the above-described nuclear magnetic resonance type oscillator, a frequency divider is inserted between the output side of the voltage-controlled oscillator and the input side of the switching control circuit at start-up. Can be.

[0013]

In FIG. 1, the control voltage of the voltage controlled oscillator 101 is swept in the frequency unlock state. At this time, the frequency control circuit 10 outputs the output data of the frequency setting data generation unit 104 according to the control voltage change which is swept.
3 is continuously varied so that the output frequency is constant even if the input frequency changes. Therefore, the atomic resonance unit 102
Only the input to the frequency control circuit is in a frequency sweep state, and the output frequency of the nuclear magnetic resonance oscillator is
From 3, a fixed frequency is extracted.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the drawings. In the following description, circuits denoted by the same reference numerals have the same functions throughout the drawings.

FIG. 2 shows a rubidium atomic oscillator according to a first embodiment of the present invention. In FIG. 1, a signal amplifier 1, a synchronous detector 2, a switching circuit 3, a sweep circuit 4, an integrator 5, a low frequency oscillator 6, a crystal oscillator 7, a frequency synthesizer 8, an atomic resonance unit 9, and a temperature control circuit 10 are conventional. This is the same as that described for the circuit.

The difference is that a DDS (Direct Digital Synthesizer) 16 for variably controlling the output signal of the crystal oscillator 7, a low-pass filter 17 for smoothing the output signal waveform of the DDS 16, and an output signal of the integrator 5 are predetermined. A / D converter 1 that performs A / D conversion of an output signal of the voltage conversion circuit 12 and supplies the output signal to the DDS 16 as frequency setting data.
3. The frequency setting unit 14 for supplying fixed frequency setting data to the DDS 16, the selector 15 for selecting the output of the A / D converter 13 or the frequency setting unit 14, and the output of the signal amplifier 1 are monitored, and no resonance signal is detected. Time is selector 1
5 is provided on the A / D converter 13 side, and an ALM circuit 11 for outputting a signal for switching to the frequency setting unit 14 when detected.

[0017] Here, DDS16 the frequency of the input signal is a digital device for outputting be changed according to the frequency setting data, the relationship between the input signal frequency f _in the output signal frequency f _out is the sampling theorem Based on f
the relationship of _out ≦ 1 / 2f _in.

Hereinafter, the operation of the circuit of this embodiment will be described. The ALM circuit 11 responds to the output signal of the signal amplifier 1
It outputs "H" level when a resonance signal is detected, and outputs "L" level when no resonance signal is detected. Therefore, at the time of start-up, no resonance signal is detected, and the ALM circuit 11 outputs an “L” level.

The output signal of the ALM circuit 11 is input to the switching circuit 3 and the selector 15. When the output signal of the ALM circuit 11 is at “L” level, the switching circuit 3 inputs the input signal of the sweep circuit 4 to the integrator 5. When the output signal of the ALM circuit 11 is at “L” level, the selector 15
Applies the output signal of the A / D converter 13 to the frequency setting unit of the DDS 16 as frequency setting data.

When the output signal of the sweep circuit 4 is supplied, the output signal of the integrator 5 is swept, and the output frequency of the crystal oscillator 7 is continuously swept. The output signal of the integrator 5 is also input to the voltage conversion circuit 12.

The conversion voltage of the voltage conversion circuit 12 is A /
A / D conversion is performed by the D converter 13 to become frequency setting data. The frequency setting data is based on the output frequency of the crystal oscillator 7 input as a clock of the DDS 16 according to the output voltage (control voltage) of the integrator 5. Even if it changes, a value is set so that the output frequency of the DDS 16 becomes constant in accordance with the change. For this reason, the voltage conversion circuit 12 converts the sweep output voltage of the integrator 5 to an appropriate value such that the output frequency of the DDS 16 becomes constant with respect to the change of the output frequency of the crystal oscillator 7, and the A / D converter 13 input. Since the output signal of the integrator 5 changes continuously, the frequency setting data output from the A / D converter 13 also changes continuously.

With the above operation, when no resonance signal is detected, such as at the time of startup, only the output frequency of the crystal oscillator 7 and the input frequency to the atomic resonance section 9 are swept, and the DDS1
The output frequency of the rubidium atomic oscillator output via 6 is a fixed value (constant value).

After the elapse of 20 to 30 minutes from the start-up, when the temperature of the atomic resonance section 9 is stabilized and a resonance signal is detected, the switching circuit 3 is switched to the synchronous detector 2 by the switching of the output signal of the ALM circuit 11. Thus, the output signal of the synchronous detector 2 is input to the integrator 5. The output signal of the synchronous detector 2 is converted into a DC signal by the integrator 5 and applied as a control voltage of the crystal oscillator 7, whereby a control loop of a normal rubidium atomic oscillator is formed, and a frequency lock state is established. .

At this time, the selector 15 selects the ALM circuit 1
1 is switched to the frequency setting unit 14 according to the output signal of the DDS 16 and the frequency setting data of the DDS 16 is
Switch to the fixed value set in 4. Therefore,
In the frequency locked state, the frequency setting data of the DDS 16 is fixed to the value of the frequency setting unit 14, so that the DDS 16
Is fixed, and the output frequency from the DDS 16 is stabilized to a value corresponding to the output signal frequency of the crystal oscillator 7.

FIG. 3 shows a second embodiment of the present invention. The difference from the embodiment of FIG. 1 described above is that the A / D converter 13 does not have the frequency setting unit 14 and the selector 15, and instead the conversion voltage from the voltage conversion circuit 12 is supplied to the A / D converter 13 via the switching circuit 20. The frequency setting data that is input and output from the A / D converter 13 is directly input to the DDS 16, and the fixed voltage V ₀ is input to the other input of the switching circuit 20, and the switching circuit 20 is an ALM circuit. 1
When the output signal indicates the detection of the resonance signal, the output signal is switched to the fixed voltage V ₀ side, and when the output signal indicates the non-detection, the voltage is switched to the voltage conversion circuit 12 side.

The operation of the second embodiment will be described below. As in the first embodiment, the output voltage of the integrator 5 is swept by the ALM circuit 11 and the switching circuit 3 when no resonance signal is detected. At this time, the A / D converter 1
The output voltage of the voltage conversion circuit 12 is input from the switching circuit 20 to 3. When the frequency setting data of the DDS 16 changes according to the sweep output voltage of the integrator 5, only the output frequency of the crystal oscillator 7 and the input frequency to the atomic resonance unit 9 are swept, and the change of the output frequency of the crystal oscillator 7 also occurs. Regardless, the output frequency of the rubidium atomic oscillator via the DDS 16 is fixed.

After the detection of the resonance signal, the output signal of the synchronous detector 2 is input from the switching circuit 3 to the integrator 5, and the frequency is locked. At this time, by the switching instead of the output signal of the ALM circuit 11, the output signal of the switching circuit 20 becomes the input signal to the A / D converter 13 is fixed voltage V _0. Therefore, thereafter, in the frequency locked state, the setting data of the DDS 16 is fixed to a value determined by the fixed voltage V ₀ .

FIG. 4 shows a circuit according to a third embodiment of the present invention. The difference from the circuit of the first embodiment is that the multiplication circuit 18 is provided between the output side of the crystal oscillator 7 and the input side of the DDS 16.
That is, In general, the frequency that the DDS 16 can output is equal to or less than half the input frequency. Therefore, in the configuration of the first and second embodiments, it is necessary to make the oscillation frequency of the crystal oscillator 7 twice or more the desired output frequency.

On the other hand, in the circuit configuration of the third embodiment, the frequency of the output of the crystal oscillator 7 is multiplied by the multiplication circuit 18 and then input as the clock of the DDS 16 so that the output frequency of the crystal oscillator 7 is It is possible to output a frequency that is the same as or higher than.

The operation at the time of frequency unlocking and the operation after frequency locking are the same as those of the circuit of the first embodiment.
This is performed by switching the frequency setting data of the DDS 16 by the selector 15.

FIG. 5 shows a circuit according to a fourth embodiment of the present invention. In the circuit of the fourth embodiment, a multiplying circuit 18 is inserted between the crystal oscillator 7 and the DDS 16 in the circuit of the second embodiment in order to raise the upper limit of the output frequency. Similar effects are obtained.

The operation principle of the circuit of the fourth embodiment when the frequency is unlocked and the operation principle after the frequency lock is described in the second embodiment.
This is performed by switching the input to the A / D converter 13 in the same manner as in the circuit of the embodiment.

FIG. 6 shows a circuit according to a fifth embodiment of the present invention. The configuration of the circuit of the fifth embodiment is for obtaining the same effects as those of the circuits of the third and fourth embodiments.
In order to raise the upper limit of the output frequency, an input clock to the DDS 16 is extracted from the frequency synthesizer 8.

FIG. 7 shows a general configuration of the frequency synthesizer 8. The frequency synthesizer 8 includes a frequency multiplier 81 for multiplying the frequency of the output signal of the crystal oscillator 7, a phase modulation circuit 82 for performing phase modulation based on the output signal of the low frequency oscillator 6, and the crystal oscillator 7.
And a frequency multiplier 83 for multiplying the frequency of the output signal of the phase modulation circuit 82.

In the circuit of the fifth embodiment, the frequency synthesizing unit 8
By inputting the output signal of the crystal oscillator 7 multiplied by the multiplication circuit 81 in the DDS 16 into the DDS 16,
The same effect as in the circuit of the fourth embodiment is obtained.

The operation of the fifth embodiment when the frequency is unlocked and the operation after the frequency is locked are the same as those of the first embodiment, and the switching of the selector 15 connected to the frequency setting section of the DDS 16 is performed. Performed by

FIG. 8 shows a sixth embodiment of the present invention. In the configuration of the sixth embodiment, as in the case of the circuit of the fifth embodiment described above, in order to raise the upper limit of the output frequency, in the circuit of the second embodiment, the input clock to the DDS 16 is changed by the frequency synthesizer. Take out from 8.

The operation at the time of frequency unlocking and the operation principle after frequency locking in the circuit of the sixth embodiment are the same as those of the circuit of the second embodiment, and are performed by switching the input of the A / D converter 13.

FIG. 9 shows a circuit according to a seventh embodiment of the present invention. The configuration of the circuit of the seventh embodiment is to make the output frequency of the rubidium atomic oscillator the same at the time of frequency unlocking at system startup and at the time of frequency locking after a resonance signal is obtained.

As a configuration for this, a frequency divider 19 is provided in parallel with the DDS 16 to input the output signal of the crystal oscillator 7, and the output signal of the frequency divider 19 is input to a switching circuit 21. The output signal of the low-pass filter 17 is input to the other input of the
When the output signal of the LM circuit 11 indicates that the resonance signal has not been detected, it is switched to the low-pass filter 17 side, and when it indicates the detection, it is switched to the frequency divider 19 side. Also, the output voltage from the voltage conversion circuit 12 is directly input to the A / D converter 13, and the frequency setting data from the A / D converter 13 is directly input to the DDS 16. I try not to do it.

According to the configuration of the circuit of the seventh embodiment, before the frequency is locked, that is, when the frequency of the crystal oscillator 7 is swept, the frequency from the DDS 16 is controlled to a constant value as in the above-described embodiment. The output signal is output from the switching circuit 21.

When the resonance signal is detected and the output signal of the ALM circuit 11 is switched, and the crystal oscillator 7 enters the frequency locked state, the output signal of the crystal oscillator 7 divided by the frequency divider 19 from the switching circuit 21 is output. Is output. Divider 19
Sets the frequency division ratio so that the output frequency of the DDS 16 and the output frequency of the frequency divider 19 become the same. This makes it possible to make the output frequency of the rubidium atomic oscillator the same at the time of unlocking the frequency at system startup and at the time of frequency locking after the resonance phenomenon is obtained.

FIG. 10 shows a circuit according to an eighth embodiment of the present invention. In the circuit of the eighth embodiment, the upper limit of the output frequency of the rubidium atomic oscillator is raised. If necessary, as in the case of the circuit of the seventh embodiment described above, when the frequency is unlocked at system startup. The output frequency of the rubidium atomic oscillator at the time of frequency lock after the resonance phenomenon is obtained can be made the same.

In order to raise the upper limit of the output frequency of the rubidium atomic oscillator, the frequency dividing circuit 19 in the circuit of the seventh embodiment is deleted, and the output signal of the crystal oscillator 7 is directly input to the switching circuit 21. After the multiplication circuit 18 is inserted between the crystal oscillator 7 and the DDS 16, the output signal of the crystal oscillator 7 is multiplied by the
It is input as the clock of S16.

In the circuit of the eighth embodiment, similarly to the circuit of the seventh embodiment, when the frequency of the crystal oscillator 7 is swept, the output signal from the DDS 16 whose frequency is controlled to a constant value is output from the switching circuit 21. Is output. After detecting the resonance signal,
That is, after the frequency is locked, the output signal of the crystal oscillator 7 is output from the switching circuit 21 as it is.

Here, the multiplier 18 adjusts the output frequency of the DDS 16 and the output frequency of the crystal oscillator 7 to be the same.
If the multiplication ratio is set, the output frequency of the rubidium atomic oscillator can be the same at the time of unlocking the frequency when the system is started and at the time of locking the frequency after the resonance phenomenon is obtained.

FIG. 11 shows a ninth embodiment of the present invention. The circuit of the ninth embodiment is designed to obtain the same effect as that of the circuit of the eighth embodiment. The structure of the ninth embodiment is to increase the upper limit of the output frequency.
A signal obtained by multiplying the output frequency of the crystal oscillator 7 is taken out from the multiplying circuit 81, and is input as a clock of the DDS 15.

In the circuit of the ninth embodiment, similarly to the circuit of the eighth embodiment, when the frequency of the crystal oscillator 7 is swept, the output signal from the DDS 16 whose frequency is controlled to a constant value is output from the switching circuit 21. Is output. After detecting the resonance signal,
That is, after the frequency is locked, the output of the crystal oscillator 7 is output from the switching circuit 21.

The case where the present invention is applied to a rubidium atomic oscillator has been described above. However, the present invention is not limited to this case, and may be applied to an oscillator using a nuclear magnetic resonance phenomenon of another atom such as a cesium atomic oscillator. Is also applicable.

[0050]

As described above, according to the present invention, in the nuclear magnetic resonance type oscillator, the output frequency from the start of the system until the frequency is locked can be fixed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram showing a circuit according to a first embodiment of the present invention.

FIG. 3 is a diagram showing a circuit according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a circuit according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a circuit according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a circuit according to a fifth embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration example of a frequency synthesis unit.

FIG. 8 is a diagram showing a circuit according to a sixth embodiment of the present invention.

FIG. 9 is a diagram showing a circuit according to a seventh embodiment of the present invention.

FIG. 10 is a diagram showing a circuit according to an eighth embodiment of the present invention.

FIG. 11 is a diagram showing a circuit according to a ninth embodiment of the present invention.

FIG. 12 is a diagram showing a configuration example of a conventional rubidium atomic oscillator.

FIG. 13 is a diagram illustrating an example of an output waveform of a sweep circuit in a conventional rubidium atomic oscillator.

FIG. 14 is a diagram showing an example of an output waveform of an integrator in a conventional rubidium atomic oscillator.

FIG. 15 is a diagram showing a frequency change when a conventional rubidium atomic oscillator starts up.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Signal amplifier 2 Synchronous detector 3, 20, 21 Switching circuit 4 Sweep circuit 5 Integrator 6 Low frequency oscillator 7 Crystal oscillator 8 Frequency synthesizer 9 Atomic resonance unit 10 Temperature control circuit 11 ALM circuit 12 Voltage conversion circuit 13 A / D Converter 14 Frequency setting unit 15 Selector 16 DDS (Direct Digital Synthesizer) 17 Low-pass filter 18 Multiplier circuit 19 Frequency divider

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshifumi Nakajima 1-2-25 Ichibancho, Aoba-ku, Sendai, Miyagi Prefecture Inside Fujitsu Tohoku Digital Technology Co., Ltd. (72) Inventor Yoshito Furuyama Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu, Ltd. 4-1-1 Kamikodanaka (72) Inventor Hiroshi Nakamuta 4-1-1 Kamikodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited

Claims (7)

[Claims] 1. A nuclear magnetic resonance type oscillator in which an atomic resonance section is provided in a feedback loop of a control voltage of a voltage controlled oscillator to stabilize an oscillation frequency by a nuclear magnetic resonance phenomenon, wherein an output signal of the voltage controlled oscillator is inputted. A frequency control circuit that changes the output signal frequency of the voltage controlled oscillator in accordance with the frequency setting data and outputs the frequency as an oscillator output frequency; and generates frequency setting data having a value corresponding to the control voltage to the voltage controlled oscillator. A frequency setting data generation circuit to be supplied to the frequency control circuit, and controlling the frequency control circuit with frequency setting data from the frequency setting data generation circuit at the time of frequency unlocking at the time of device startup, A switching control circuit at start-up for switching the frequency setting data of the frequency control circuit to a fixed value at the time of locking; The data generation circuit changes the frequency setting data according to the control voltage of the voltage-controlled oscillator that is swept when the device is started up, and changes the output frequency of the frequency control circuit with respect to a change in the output frequency of the voltage-controlled oscillator. Nuclear magnetic resonance oscillator with a constant value. A switching circuit for changing output data according to the control voltage to be swept; a detection circuit for detecting the presence or absence of nuclear magnetic resonance; 2. A selector for selecting output data output from the conversion circuit when the frequency is unlocked in response to a detection signal of the detection circuit, and selecting fixed data output from the frequency setting circuit when the frequency is locked. Nuclear magnetic resonance oscillator. 3. A switching circuit for switching the frequency setting data by the switching control circuit at start-up, comprising: a detecting circuit for detecting the presence or absence of nuclear magnetic resonance; 2. The nuclear magnetic resonance type according to claim 1, wherein the switching is performed by a switching circuit that switches to a fixed voltage when the frequency is locked to a control voltage of the voltage controlled oscillator, and a conversion circuit that converts an output signal of the switching circuit into output data corresponding to the value. Oscillator. 4. A nuclear magnetic resonance oscillator in which an atomic resonance section is provided in a feedback loop of a control voltage of a voltage controlled oscillator to stabilize an oscillation frequency by a nuclear magnetic resonance phenomenon, wherein an output signal of the voltage controlled oscillator is input. A frequency control circuit that changes the output signal frequency of the voltage controlled oscillator in accordance with the frequency setting data and outputs it as an oscillator output frequency; and generates frequency setting data having a value corresponding to the control voltage to the voltage controlled oscillator. A frequency setting data generating circuit to supply the frequency control circuit with the frequency control circuit, and an output signal from the frequency control circuit when the frequency is unlocked at the time of starting up the apparatus, and not passing through the frequency control circuit at the time of frequency locking after the start up. A start-up switching control circuit that performs switching so as to select an output signal from the voltage-controlled oscillator. The frequency setting data is changed according to the control voltage of the voltage controlled oscillator that is swept at the time of raising, so that the output frequency of the frequency control circuit becomes a constant value even when the output frequency of the voltage controlled oscillator changes. Nuclear magnetic resonance oscillator. 5. A nuclear magnetic resonance type oscillator according to claim 4, wherein a frequency divider is inserted between the output side of said voltage controlled oscillator and the input side of said switching control circuit at start-up. 6. The nuclear magnetic resonance oscillator according to claim 1, wherein a multiplying circuit is inserted between an output of said voltage controlled oscillator and an input of said frequency control circuit. 7. A frequency synthesizing unit inserted between an output side of said voltage controlled oscillator and an input side of said atomic resonance unit instead of inputting an output signal of said voltage controlled oscillator to said frequency control circuit. The nuclear magnetic resonance oscillator according to any one of claims 1 to 4, wherein an output signal of the multiplier circuit is taken out and used as an input signal to the frequency control circuit.