JPH06338795A - Highly stable resonance frequency controller for cavity resonator - Google Patents

Abstract

PURPOSE:To provide a highly stable resonance frequency controller for a cavity resonator capable of controlling the resonance frequency of the cavity resonator extending over from a short period to a long period with high accuracy. CONSTITUTION:A resonance frequency sensing signal generated from a resonance frequency sensing signal generator 2 is injected to the cavity resonator 1 via a coupling means 3 for input use including an element 3a for use of resonance frequency control. Deviation information from the resonance frequency is taken out by both a coupling means 4 for output use and a resonance frequency deviation detecting means 5, and is sent to an electronic control means 6 and a correction control signal generating part 10. Two correction control signals generated by the correction control signal generating part 10 are sent to both the electronic control means 6 of an electronic control system and a temperature control means 8 which comprises a temperature control system along with a temperature sensing element 7 and a heater 9 for heating, respectively, thereby, the control values of two control systems can be corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly stable resonance frequency control device for a cavity resonator used in a hydrogen maser atomic frequency standard, and more particularly to a resonance frequency deviation signal obtained by a resonance frequency deviation detecting means. In addition, the resonance frequency of the cavity resonator can be reduced in the short term by adding a correction control signal according to each time constant to the control signal of the electronic control system of the resonance frequency and the control signal of the temperature control system of the cavity resonator. The present invention relates to a resonance frequency control device for a cavity resonator, which performs stable control with high accuracy in the long term.

[0002]

2. Description of the Related Art A drawback of a hydrogen maser atomic frequency standard that can obtain high frequency stability is that the maser oscillation frequency (fm) is slightly affected by the resonance frequency (fc) of the cavity resonator. The relationship is as follows. fm−fo ＝ (Qc / Ql) (fc −fo) where fo: Resonant frequency peculiar to hydrogen atom Qc: Q value of cavity resonator Ql: Q value of resonance line Therefore, resonant frequency (fc) is always hydrogen atom. Natural resonance frequency
A resonance frequency control device for the cavity resonator is provided to match (fo).

Hydrogen pressure quenching method and resonance frequency sensing method are known as resonance frequency control methods for the cavity resonator in the hydrogen maser atomic frequency standard.
In both control methods, the amount of deviation of the resonance frequency (Δfc = fc-fo)
The resonance frequency (fc) is controlled by controlling the temperature of the cavity resonator or the bias voltage of the electronic control element coupled to the cavity resonator by the deviation signal proportional to the.

[0004]

In the hydrogen pressure quenching method, the amount of hydrogen beam is increased / decreased to detect the Δfc, so that it takes a long time to obtain a deviation signal with high accuracy. Moreover, the frequency stability is impaired because the hydrogen maser oscillation power changes. Further, there is a problem in that a highly stable external reference signal having equivalent performance or higher is additionally required, and control is delayed because the control system is an open loop.

In the resonance frequency sensing method, the sensing frequency (fd ± Δf) from the resonance frequency sensing signal generator is input to the cavity resonator through the input coupling means, the resonance frequency deviation detection signal is extracted from the output coupling means, and the resonance frequency is detected. The electronic control element is controlled by the control signal corresponding to the frequency deviation amount. Since this method is a closed-loop control system, real-time control is possible.

However, as in the above-mentioned hydrogen pressure quenching method, this resonance frequency sensing method also has a weak resonance frequency deviation detection signal, and noise is easily mixed in, and the control signal is apt to contain an error, and the electronic control is performed. Since the control by the system has a short time constant, it has a drawback that a control signal including an error easily causes unnecessary fluctuation. Further, as another control method, there is a control by a temperature control system, but the control by the temperature control system of the cavity resonator generally has a long time constant and delays the correction control of the required resonance frequency only by the control of this system. Especially when using a metal cavity resonator for the purpose of a robust structure, it is necessary to suppress the resonator temperature fluctuation for a short time to 1 × 10 ^-5 ℃ or less to obtain the required frequency stability. I can not cope.

The present invention solves the above-mentioned drawbacks in the resonance frequency control device for a cavity resonator by the following means, thereby making it possible to accurately control the resonance frequency of the cavity resonator from a short term to a long term. It is intended to provide a highly stable resonance frequency control device.

[0008]

In order to solve the above problems, the present invention comprises an electronic control system and a temperature control system, a correction control signal generator is provided, and a deviation signal obtained by a resonance frequency sensing method. Based on the above, it was decided to generate a correction control signal according to the time constants of the electronic control system and the temperature control system and add it to the control signal of each system. In particular, by combining the short time constant characteristic of the electronic control system of the resonance frequency and the long time characteristic of the temperature control system of the cavity resonator, the resonance frequency of the cavity resonator can be changed from a short period to a long period. Controlled with high accuracy. Further, in the correction control signal generator, the control value obtained by averaging the deviation detection values with the time constant time of the temperature control system of the cavity resonator, or generating a future estimated control value for how many time constant time periods, The correction control signal is added to the temperature control of the cavity resonator to obtain long-term accuracy and stability of the resonance frequency.

[0009]

The operation of the present invention will be described below with reference to FIG. In the hydrogen maser atomic frequency standard, two correction control signals are generated by the correction control signal generator 10 as shown in FIG. 1 based on the deviation signal obtained from the resonance frequency deviation detecting means 5 of the cavity resonator 1. . On the other hand, the deviation between the time τe corresponding to the short time constant of the electronic control means of the cavity resonator is averaged by τe, and the electronic control signal of the amplitude Ae and the time τe is generated based on this, and the cavity resonance is generated. Control the electronic control means of the vessel. On the other hand, the deviation between the time τt corresponding to the long time constant of the temperature control means of the cavity resonator is averaged by τt, and the temperature control signal having the amplitude At and the time τt is generated based on this, and the cavity resonator is generated. Control the temperature control means. The cavity resonator controlled by the above-mentioned two control means is short-term to long-term control by the electronic control means for short-term fast fluctuations of the resonance frequency, and mainly by temperature control means for long-term slow fluctuations. The resonance frequency is accurately maintained to be equal to the resonance frequency peculiar to the hydrogen atom.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS. The cavity resonator 1 for maser oscillation includes an input coupling means 3 including a resonance frequency control element 3a, an output coupling means 4, a temperature sensitive element 7, and a heating heater 9. The electronic control system of the resonance frequency of the cavity resonator 1 is
The resonance frequency sensing signal generator 2, the input coupling means 3 including the resonance frequency control element 3a, the output coupling means 4, the resonance frequency deviation detection means 5, and the electronic control means 6. The temperature control system of the cavity resonator 1 includes a temperature sensitive element 7,
It is composed of a temperature control means 8 and a heater 9 for heating.

A correction control signal generator 10 is provided for these two control systems.
Outputs are added together. The correction control signal generator
As shown in FIG. 2, reference numeral 10 denotes two systems of integrators 11 and 11 ', a plurality of recorders 12a, 12b, ..., 12a', 12b ', ..., A plurality of difference recorders 13a and 13b. , ..., 13a ', 13b', ..., Guessing controllers 14, 14 'and clock generators 15, 15' for generating clocks corresponding to respective control system time constants.

Since the cavity resonator 1 has a robust structure, it is made of metal or an insulator (eg, quartz glass) whose inner surface is made into a conductor. The heat capacity inevitably becomes large, and the control response characteristics deteriorate only with temperature control. However, having a large heat capacity suppresses temperature fluctuations in a short period of time, which makes it possible to extend the resonance frequency deviation detection time and reduce the error of the deviation signal detected by the integration effect. To do.

The electronic control system functions as follows. The resonance frequency sensing signal generator 2 oscillates by alternately switching between two frequencies fd−Δf and fd + Δf, which have the same amplitude on both sides of a desired resonance frequency fd (≈f0) and are equally spaced by Δf, in a certain fixed period. Use as frequency sensing signal. The resonance frequency sensing signal is injected into the cavity resonator 1 via the input coupling means 3. The cavity resonator 1 acts as a pass-through frequency discriminator from the input coupling means 3 to the output coupling means 4, and depending on the detuning of the resonance frequency of the cavity resonator 1 from the resonance frequency of hydrogen atoms, A resonance frequency sensing signal having an amplitude difference caused by the Q curve of the cavity resonator 1 (that is, frequency-shift modulated) is extracted from the cavity resonator 1 by the output coupling means 4.

The resonance frequency sensing signal containing the resonance frequency detuning information is synchronously detected by the resonance frequency deviation detecting means 5 based on the reference signal from the resonance frequency sensing signal generator 2, and only the detuning information component is detected. Is taken out. The detected detuning information signal is output to the electronic control means 6 and the correction control signal generator 10. The electronic control means 6 adds the correction control signal from the correction control signal generator 10 to the correction control signal to correct the short-cycle fluctuation, and applies it to the resonance frequency control element 3a as a control voltage to correct the detuning of the resonance frequency.
As a result, the resonance frequency of the cavity resonator 1 is maintained at a desired frequency.

On the other hand, the temperature control system functions as follows. The temperature of the cavity resonator 1 is detected by the temperature sensitive element 7 and used as an input signal of the temperature control means 8. The temperature control means 8 compares a signal corresponding to a preset set temperature with the input signal, and adds a correction control signal for correcting a long cycle fluctuation of the correction control signal generator 10 to the error correction amount and heats it. Heater 9
Is controlled so that the temperature of the cavity resonator 1 is maintained at a set temperature.

The correction control signal generator 10 will be described below. The correction control signal generator 10 takes in the output of the resonance frequency deviation detecting means 5 and functions as follows. One system that feeds back to the electronic control system receives the clock of the clock generator 15 that generates a clock corresponding to the short time constant τe (several seconds or less) of the electronic control system, and corresponds to the resonance frequency variation between the clocks. The voltage change is integrated by the integrator 11, and the integrated value is transferred to the next recorder 12a in response to the next clock. The previously recorded contents of the recorder 12a are transferred to the recorder 12b by receiving the same clock. The integrator that has finished outputting resets the integrated value to 0 once and repeats the operation of integrating the input value again until the next clock. Thus integrator 11
And a plurality of recorders 12a, 12b, ...
It operates as a shift register driven by τ e). At this point, the noise component of a cycle faster than the clock contained in the detuning information signal is removed, and the control accuracy is further increased.

A plurality of difference recorders 13a, 13b, ...
Also receives the same clock and operates, and the output value of integrator 11 and 1
The difference between the value of the first-stage recording device 12a, the value of the first-stage recording device 12a and the value of the second-stage recording device 12b, and so on, is similarly recorded for each same clock. That is, the fluctuation amount (moving average value) for each clock is recorded. Then, the estimation controller 14 detects the difference between the values of the plurality of difference recorders, and changes the correction control signal output amplitude Ae in accordance with the degree of variation (eg, proportional to the differential coefficient). In this way, a correction control signal is output so that the deviation values obtained from a plurality of difference recorders adjacent to each other within a short period of time shifts to zero for at least several clocks, and is added to the electronic control means 6. The resonance frequency controlling element 3a is controlled.

On the other hand, another system that feeds back to the temperature control system receives the clock of the clock generator 15 'which generates a clock corresponding to the long time constant τt (several hundreds of seconds or more) of the temperature control system, The voltage change corresponding to the resonance frequency fluctuation is accumulated in the integrator 11 ', and the next clock is received and the integrator output value is transferred to the next recorder 12a'. The previously recorded contents of the recorder 12a 'are transferred to the recorder 12b' in response to the same clock. The integrator that has finished outputting resets the integrated value to 0 once and repeats the operation of integrating the input value again until the next clock. In this way the integrator 11 'and multiple recorders 12
a ', 12b', ... Operate as a shift register driven by a long cycle clock (.apprxeq..tau.t).

Further, a plurality of difference recorders 13a ', 13b', ...
· Also operates by receiving the same clock, the output value of the integrator 11 ′, the value of the first-stage recorder 12a ′, the value of the first-stage recorder 12a ′ and the value of the second-stage recorder 12b ′, and so on Then, the difference between the values of the recorders adjacent to each other is recorded for each same clock. That is, the fluctuation amount (moving average value) for each clock is recorded. Then, the estimation controller 14 'detects the difference between the values of the plurality of difference recorders, and changes the correction control signal output amplitude At according to the degree of the change (for example, so as to be proportional to the differential coefficient). Also, a correction control signal (moving average value or estimated deviation value) for linearly approximating deviation values obtained from a plurality of difference recorders to obtain an estimated deviation value one clock ahead and performing estimation control so as to shift to zero within a short time ) Is generated and fed back to the output stage of the temperature control means 8 to be added to the original output of the temperature control system, and the temperature of the cavity resonator 1 is controlled to be maintained at a desired set temperature.

[0020]

According to the present invention, an electronic control system and a temperature control system are provided, a correction control signal generator is provided, and the electronic control system and the temperature control are performed on the basis of the deviation signal indicating the deviation degree of the resonance frequency. Generates and outputs a correction control signal for each system, and the electronic control system controls the short-term fluctuations in the resonance frequency, and the temperature control system controls the long-term fluctuations. Since the control is performed so as to be appropriate, the resonance frequency of the cavity resonator can be stably maintained over a short period to a long period. Further, the correction control signal generator, from the course of the change up to that point, inferring the change after that,
Since the correction control signal is generated, even if the resonance frequency fluctuates, it is quickly stabilized to a predetermined value.

[Brief description of drawings]

FIG. 1 is a block diagram showing a highly stable resonance frequency control device for a cavity resonator according to the present invention.

FIG. 2 is a block diagram showing details of a control signal distributor 10 which is a part of a highly stable resonance frequency control device for a cavity resonator according to the present invention.

[Explanation of symbols]

 1 cavity resonator 2 resonance frequency sensing signal generator 3 input coupling means 3a resonance frequency control element 4 output coupling means 5 resonance frequency deviation detection means 6 electronic control means 7 temperature sensing element 8 temperature control means 9 heating heater 10 Correction Control Signal Generator 11 Accumulator 12a Recorder 13a Difference Recorder 14 Guessing Controller

Claims (1)

[Claims] 1. A cavity resonator (1) made of a material that contracts or expands by heat, a heater (9) provided in the cavity resonator, and a temperature change of the cavity resonator. Temperature sensing element (7), an output coupling means (4) for extracting a resonance frequency deviation detection signal from the cavity resonator, a resonance frequency deviation detection signal extracted by the output coupling means, and the cavity. The resonance frequency deviation detecting means (5) for obtaining the deviation value of the resonance frequency from the set reference value of the resonance frequency of the body resonator and outputting the deviation signal, and the deviation degree of the resonance frequency output by the resonance frequency deviation detecting means A correction control signal generator (10) for outputting first and second correction control signals based on the deviation signal shown, and a resonance frequency of the cavity resonator for receiving the deviation signal and the first correction control signal. Electronic control means (6) for controlling, and A resonance frequency sensing signal generator (2) for generating a resonance frequency sensing signal for sensing the resonance frequency of the cavity resonator, and the resonance frequency sensing signal and the electronic control signal output from the electronic control means are combined. Input coupling means (3) for inputting to the cavity resonator, and temperature control means (8) for controlling the power of the heating heater by receiving the second control signal and the signal from the temperature sensitive element. ) A highly stable resonance frequency control device for a cavity resonator, comprising: