JP5196374B2 - Remote frequency calibration equipment using standard radio waves - Google Patents

Description

  The present invention receives a standard radio wave generated from a signal from a frequency standard device at a remote location, and compares the demodulated frequency standard signal with the oscillator signal of the device to be calibrated. For calibrating an oscillator located at a remote location from the remote, especially for a remote frequency calibration device using standard radio waves that can confirm that the calibration value obtained by the above comparison is appropriate Yes.

  GPS time / frequency synchronous receiver that can remotely calibrate the frequency using GPS satellites, and JJY time / frequency reference signal that is generated by the long-wave standard radio wave and synchronized with a high-precision atomic clock Frequency synchronous receivers and the like are already commercially available (for example, Nippon Communication Equipment Co., Ltd.).

  Since the radio waves received by these receivers are received through long-distance spatial propagation, disturbances in the propagation path may become a problem.

  For example, the frequency of radio waves from GPS satellites is about 1.5 GHz, which is excellent in linearity and difficult to be affected by multipath, and the propagation distance in the atmosphere can be made shorter than that of long wave standard radio waves. There is an advantage that the influence can be made smaller. However, it is easily disturbed by airplanes, flocks of birds, and heavy rain.

  In the case of long wave standard radio waves, the frequencies are 40 kHz and 60 kHz, and it is known that stable propagation characteristics can be obtained for surface waves. Moreover, since the penetration | invasion distance to the inside of a building is large, there exists an advantage that it can receive also with an indoor antenna. However, noise due to thunderclouds and ground potential fluctuations, disturbances due to ionospheric fluctuations, cycle slips caused by propagation path changes, and the like become problems.

  In general, when performing high-precision calibration, it is difficult to confirm that there is no calibration error due to disturbance during reception of signals for a long time.

  In the present invention, assuming that remote calibration of the frequency is performed using the long wave standard radio wave, an operation for confirming whether or not the disturbance received from the propagation path during the calibration time is correctly detected on the reception side is performed. Is. The operation is to intentionally shift the phase of the standard radio wave transmitted on the transmission side, and to confirm that the phase shift is correctly detected on the reception side. If it can be determined from the result of this confirmation that there is no problem, it can be determined that the result obtained by the above remote calibration is a calibration value to be applied to the apparatus to be calibrated.

  As a technique related to remote calibration of a conventional measuring instrument, Patent Document 1 (Japanese Patent Laid-Open No. 2004-326671) discloses that a reference amount for performing precise measurement is remotely supplied to a user of an engine to be calibrated or an industrial user. A remote calibration system for a weighing device and a remote calibration method for a weighing device are disclosed. This is because the measurement standard amount is converted into a parameter suitable for communication, or is generated as a parameter suitable for communication and sent to a remote location (2), or if it is not suitable for communication, the measurement standard amount is suitable for transportation. Thus, the data is sent to the remote place (2) and restored to the measurement standard at the point of arrival, thereby enabling calibration and authenticating the result.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-93323) discloses a remote calibration method and method that enables remote calibration and authentication by remotely supplying a reference amount for performing precision measurement in the field of metrology standards. Is disclosed. This is because the higher-level measurement standards organization can send a reference standard that is the measurement standard to a lower-level standard organization at a remote location via an intermediary and restore it to the measurement standard at the lower-level standard organization that has arrived. The result is certified by the higher-level measurement standards organization, and the measurement standard of the measurement device of the lower-level standard organization is traced to the reference standard of the higher-level measurement standard organization, and the uncertainty of the measurement device. The higher-level measurement standards organization verifies this, and if it is within an appropriate range, it is the responsibility of the higher-level measurement standards organization to certify that the measured value of the measurement device is calibrated.

  Further, in Patent Document 3 (Japanese Patent Laid-Open No. 2007-26397), by remotely supplying a reference amount for performing precision measurement, remote calibration at a site of a user to be calibrated or an industrial user, and its Disclosed is a remote calibration system and method for a weighing device that performs authentication. This is because the measurement standard amount is converted into a parameter suitable for communication, or is generated as a parameter suitable for communication and sent to a remote location (2), or if not suitable for communication, a measurement standard in a form suitable for transportation. The quantity is sent to the remote place (2) and restored to the measurement standard at the point of arrival, thereby enabling calibration and authenticating the result.

  However, in the above Patent Documents 1 to 3, it is clearly not different from the present invention because it is not confirmed whether the transmission, transport or restoration is appropriate as a calibration standard.

JP 2004-326671 A JP 2007-93323 A JP 2007-263777 A

  When remote calibration is performed using longwave standard radio waves, problems such as noise due to thunderclouds and ground potential fluctuations, disturbances due to ionospheric fluctuations, or cycle slips caused by propagation path changes occur. It is possible to determine whether the measured value is appropriate.

  According to the present invention, since it is possible to appropriately perform remote calibration of the frequency using the standard radio wave, it is possible to omit the work of transporting the device to be calibrated during calibration.

  The present invention is generally a remote frequency calibration device using a standard radio wave generated from a signal from a frequency standard, and receives a standard radio wave transmitted with high frequency accuracy at a remote location viewed from the standard signal generator. The phase of the demodulated frequency standard signal is compared with the signal of the oscillator of the device under test to calibrate the oscillator at a remote location from the frequency standard. It is provided with a configuration for avoiding inadequate calibration due to a cycle slip or the like caused by a disturbance due to a phase disturbance or ionospheric fluctuation.

  A remote frequency calibration apparatus using a standard radio wave of the present invention comprises a transmitter that transmits a standard radio wave that is a frequency standard and a receiver that receives the standard radio wave, and is covered by a signal generated from the received standard radio wave. It belongs to a frequency calibration device that calibrates the calibration device. More specifically, the transmitter includes a phase modulator that performs phase modulation on a standard radio wave to be transmitted with a modulation signal, the receiver includes a demodulator that detects the modulation signal from the received phase modulation wave, and A modulation signal generator for generating the modulation signal, a comparator for comparing the modulation signal detected by the receiver with the modulation signal from the modulation signal generator, and a modulation signal detected by the comparator from the receiver And a transmission path for transmitting the modulation signal from the modulation signal generator to the comparator. In particular, the comparator determines the quality of transmission / reception of the standard radio wave within the calibration time in the calibration target device by comparing the modulation signal detected by the receiver with the modulation signal from the modulation signal generator. The comparison data is output.

  The phase modulator delays the phase over a plurality of periods of the standard radio wave, and the demodulator extracts a time zone whose phase is adjusted, and the comparator Is for comparing the transmission time and the reception time of the portion whose phase has been adjusted.

  Further, the phase modulator described above performs adjustment for compensating the adjusted phase within the calibration time so that the total frequency within the configuration time does not change.

  The modulation signal generator generates a random signal, modulates according to the random signal, the demodulator demodulates the random signal from the received signal, and the comparator outputs the modulation signal. The random signal from the generator is compared with the random signal from the demodulator, and the comparison result is output.

  The modulation signal generator includes storage means for holding the generated modulation signal or the characteristics of the modulation signal until at least the calibration time period elapses, and keeps the external output secret until that time elapses.

  The modulation signal generator generates a modulation signal in accordance with a predetermined code that is disclosed, for example. Thereby, it is possible to determine whether or not the measurement value for calibration is appropriate only on the receiver side.

  The predetermined code is transmitted to the receiver side by some transmission means such as a public line. Through this transmission, the transmitted modulation data can be compared with the received modulation data. The result of this comparison can be authenticated by sending it to the receiving side using the above transmission means.

  The standard radio wave is a radio wave having a frequency of 300 kHz or less from the viewpoint of stable propagation characteristics.

  The standard radio wave may be a radio wave amplitude-modulated with time information. In this case, the standard radio wave for the current radio timepiece is used.

  The demodulator is a phase comparator that compares the phase of the signal generated from the received standard radio wave and the signal from the device to be calibrated. This is a configuration that is possible when the stability of the oscillation frequency of the device to be calibrated is sufficiently high, and has the advantage that the circuit configuration is simple.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, devices having the same function or similar functions are denoted by the same reference numerals unless there is a special reason.

  FIG. 1 shows an example of a remote frequency calibration apparatus using the standard radio wave of the present invention. First, the standard radio wave transmitter 10 generates a standard signal with a clear frequency accuracy based on the frequency standard 11 traced by the frequency specifying standard 1.

  The phase of the standard signal is advanced (or delayed) by a plurality of cycles of the standard signal according to the signal from the adjustment signal generator 22 using the phase adjuster 12. After maintaining the state where the phase has advanced (or delayed) for a while, phase adjustment opposite to the above is performed to compensate for the advance (or delay). Here, the reason why the phase is advanced in a plurality of cycles is to keep the bandwidth of the standard signal narrow. The phase adjuster 12 can be realized by a well-known phase modulator. Further, this phase adjustment may be performed when the frequency standard 11 is traced by the frequency standard 11. The phase-adjusted signal is transmitted from the transmitter 13. Before this transmission, amplitude modulation may be performed with time information.

  The transmitted radio wave is received by the receiver 33 of the calibration terminal 30. The receiver 33 demodulates time information and extracts a carrier wave. However, the time information is not demodulated if it is not necessary. The phase comparator 32 compares the carrier wave from the receiver 33 and the phase of the signal from the device under test 2.

  The results of this comparison are accumulated by the data acquisition device 31 and recorded as time series data. This time series data is transmitted to the comparator 21 via the communication line 23.

  In general, the characteristics of the device to be calibrated deviate uniformly from the frequency of the standard radio wave in time, and do not deviate randomly. Therefore, when the time-series data is correctly received, as shown in FIG. 2, the time-series data is translated by the amount corresponding to the phase adjustment amount only while the accumulated phase difference corresponds to the phase adjustment period. However, as described above, the phase adjustment period described above is affected by noise caused by thunderclouds or ground potential fluctuations, disturbances caused by ionospheric fluctuations, or cycle slips caused by propagation path changes. And the phase adjustment amount do not match the transmission data.

  The comparator 21 compares the signal from the adjustment signal generator 22 as transmission data and the signal from the data acquisition device 31 as reception data. The result of the comparator 21 is output as a calibration result.

  Also, the adjustment signal generator 22 outputs the adjustment signal or adjustment signal data having the characteristics of the adjustment signal. This output is kept secret during the calibration period and is output together with the output of the calibration result. Alternatively, it is made public prior to transmission. When concealing in this way, a calibration report can be issued on the transmission side. That is, by analyzing the amount and time of the phase change from the received data, it can be confirmed that the standard radio wave has been correctly received, so that proof can be safely performed. In the case of disclosure, by using this, self-calibration can be easily performed only on the reception side of whether the phase comparator is operating correctly.

  The configuration shown in FIG. 1 can be made simpler by digitizing the circuit as shown in FIG.

  In the standard radio wave transmitter 40, first, in order to generate a standard signal traced to the frequency specifying standard 1 and having a clear frequency accuracy, the signal from the frequency specifying standard 1 is converted into a digital signal by an analog-to-digital (AD) converter 41. Convert to The phase of this digital signal is adjusted by the phase adjuster 42. This adjustment amount is controlled by a signal from the adjustment signal generator 52. The digital signal whose phase has been adjusted is converted into an analog signal by a digital-analog (DA) converter 43. This analog signal is transmitted by the transmitter 44. When transmitting time information at the same time, an operation corresponding to amplitude modulation is performed on the digital signal before the DA converter 43. Alternatively, amplitude modulation is performed on the analog signal after the DA converter 43.

  Here, it is desirable that there are a plurality of phase adjustments by the phase adjuster 42 during the calibration period. Further, it is desirable that the phase adjustment amount or the length of the transmission phase adjustment period is different. Furthermore, it is desirable that the phase adjustment amount and the length of the transmission phase adjustment period be determined by a random signal from a random generator. This can be realized by providing a random signal generator in the adjustment signal generator 52.

  The transmitted radio wave is received by the receiver 65 of the calibration terminal 60. The receiver 65 demodulates time information and extracts a carrier wave. However, the time information is not demodulated if it is not necessary. The phase accumulator 63 performs time accumulation of the phase of the carrier wave from the receiver 65. Similarly, the phase accumulator 64 accumulates the phase of the signal from the device under calibration 2 over time. The phase difference calculator 62 calculates the difference between the phase accumulator 63 and the phase accumulator 64.

  The output of the phase difference calculator 62 is recorded as time series data by the time series recorder 61. This time series data is transmitted to the comparator 51 via the communication line 23.

  The comparator 51 compares the signal from the adjustment signal generator 52 with the signal from the time series recorder 61. The result of the comparator 21 is output as a calibration result.

  Further, although similar to the first embodiment, the adjustment signal generator 52 outputs the adjustment signal or adjustment signal data having the characteristics of the adjustment signal. This output is kept secret during the calibration period and is output together with the output of the calibration result. Alternatively, it is made public prior to transmission.

  The blocks in FIG. 3 are controlled by the transmission-side controller 71 and the reception-side controller 72 for the transmission side and the reception side, respectively.

  In the above description, the remote calibration using the long wave charging wave has been described. However, the remote calibration can be performed in the same manner as described above even using the radio wave from the medium wave band to the ultra-short wave band.

It is a block diagram which shows the example of the remote frequency calibration apparatus using the standard radio wave of this invention. FIG. 6 is a diagram illustrating a parallel movement corresponding to a phase adjustment amount only while an accumulated phase difference corresponds to a phase adjustment period. It is a block diagram which shows the example of the remote frequency calibration apparatus using the standard radio wave which carried out the digital circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Frequency specific standard device 2 Device to be calibrated 10 Standard radio wave transmitter 11 Frequency standard device 12 Phase adjuster 13 Transmitter 21 Comparator 22 Adjustment signal generator 23 Communication line 30 Calibration terminal 31 Data acquisition device 32 Phase comparator 33 Receiver 40 Standard radio wave transmitter 41 Analog to digital (AD) converter 42 Phase adjuster 43 Digital to analog (DA) converter 51 Comparator 52 Adjustment signal generator 60 Calibration terminal 61 Time series recorder 62 Phase difference calculator 63, 64 Phase Accumulator 65 Receiver 71 Transmitter controller 72 Receiver controller

Claims (10)

A transmitter that transmits a standard radio wave that is a frequency standard;
A receiver for receiving the standard radio wave,
In the frequency calibration device that calibrates the device under calibration with the signal generated from the received standard radio wave,
The transmitter includes a phase modulator that performs phase modulation on a standard radio wave to be transmitted with a modulation signal,
The receiver includes a demodulator that detects the modulated signal from the received phase-modulated wave,
A modulation signal generator for generating the modulation signal;
A comparator for comparing the modulated signal detected by the receiver with the modulated signal from the modulated signal generator;
A transmission path for transmitting the detected modulated signal from the receiver to the comparator;
A transmission path for transmitting the modulated signal from the modulated signal generator to the comparator;
With
The comparator is for determining whether the standard radio wave is transmitted or received within the calibration time in the calibration target device by comparing the modulation signal detected by the receiver with the modulation signal from the modulation signal generator. Remote frequency calibration device using standard radio waves, characterized by outputting comparison data. The phase modulator is for delaying the phase over a plurality of periods of the standard radio wave,
further,
The demodulator extracts a time zone whose phase is adjusted,
2. The remote frequency calibration apparatus using a standard radio wave according to claim 1, wherein the comparator compares a transmission time and a reception time of a portion whose phase is adjusted.   3. The remote frequency calibration apparatus using a standard radio wave according to claim 2, wherein the phase modulator performs adjustment for compensating the adjusted phase within a calibration time. The modulation signal generator is for generating a random code signal,
The demodulator demodulates the received random code signal,
2. The comparator according to claim 1, wherein the comparator compares a random code signal from the modulation signal generator with a random code signal from the demodulator and outputs a comparison result. Remote frequency calibration device using standard radio waves.   5. The remote control using a standard radio wave according to claim 4, wherein the modulation signal generator comprises storage means for holding the generated modulation signal or the characteristics of the modulation signal at least until the calibration time zone elapses. Frequency calibration device.   2. The remote frequency calibration apparatus using a standard radio wave according to claim 1, wherein the modulation signal generator generates a modulation signal in accordance with a predetermined code.   7. The remote frequency calibration apparatus using a standard radio wave according to claim 6, wherein the predetermined code is transmitted to the receiver side by some transmission means.   The remote frequency calibration apparatus using the standard radio wave according to any one of claims 1 to 7, wherein the standard radio wave is a radio wave having a frequency of 300 kHz or less.   The remote frequency calibration apparatus using the standard radio wave according to any one of claims 1 to 8, wherein the standard radio wave is a radio wave amplitude-modulated by time information.   10. The phase demodulator according to claim 1, wherein the demodulator is a phase comparator that compares the phase of the signal generated from the received standard radio wave and the signal from the device to be calibrated. Remote frequency calibration equipment using the standard radio wave described.

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