RU109577U1 - HYDROGEN STANDARD OF FREQUENCY AND TIME - Google Patents

Abstract

 1. A hydrogen frequency and time standard, including a quantum hydrogen generator, the output of which is connected to the first input of the frequency converter, the second input of which is connected to the output of the heterodyne signal driver, the input of which is connected to the output of the crystal oscillator connected to the output driver, whose outputs are outputs hydrogen standard of frequency and time, characterized in that it additionally includes a clock driver and a chain of series-connected measurements of Tell time points, the processor and the digital to analog converter connected between the inverter output frequency and the input of the quartz oscillator, the output clock signal generator is connected to a second input measuring instants, and its input connected to the output of the crystal oscillator. ! 2. The frequency and time standard according to claim 1, characterized in that it contains n quantum hydrogen generators, and the frequency converter and the time meter in it are made n channel.

Description

The utility model relates to radio-measuring equipment and can be used in quantum hydrogen standards of the active type frequency for the formation of highly stable signals, as well as for temporary and frequency measurements.

The principle of operation of the hydrogen standard of the frequency and time of the active type is based on the phase synchronization of the 5 MHz crystal oscillator signal from the 1420.4 MHz quantum hydrogen generator signal, whose operation is based on stimulated emission of hydrogen atoms. The phase locked loop (PLL) provides the adjustment of slow (compared to the PLL time constant) fluctuations in the frequency of the crystal oscillator.

Among the hydrogen standards of frequency and time of the type in question are known, for example, standards of type Ch1-75, Ch1-90 (developed by FSUE NNIPI "Quartz"), VCH-1003A, VCH-1005 (developed by ZAO Vremya-Ch).

As the closest scheme for constructing the hydrogen standard, a standard of type 41-75 was chosen (see the appendix, Fig. 2), in which the signal generated by the quantum hydrogen generator at a frequency of 1420.4 MHz falls into the synchronization block, which provides amplification of the signal of the hydrogen generator with using a superheterodyne receiver, linking the phase of the crystal oscillator of 5 MHz to the phase of the signal of the hydrogen generator and the formation of spectrally pure highly stable sinusoidal signals of 5 and 100 MHz and pulse signals of a time scale of 1 Hz.

This is a classic analog phase locked loop of the frequency of a crystal oscillator by the frequency of hydrogen emission. The signal of this radiation is fed to the input of the frequency converter, to the second input of which a heterodyne signal is supplied. From the output of the frequency converter, the difference frequency signal is fed to a phase detector, the second input of which is supplied with a signal from a tunable frequency synthesizer. From the output of the phase detector, the signal passes through the integrator and enters the frequency control input of the crystal oscillator, synchronizing it to the frequency of the quantum hydrogen generator by linking the phase of the crystal oscillator 5 MHz to the phase of the signal of the hydrogen generator. By changing the frequency of the synthesizer, the output frequency of the standard is tuned.

The disadvantage of the analog phase-locked loop in the quantum standard is the influence of sources of random and temperature instability of the frequency, the difficulty of setting the synchronization loop, the need for a tunable frequency synthesizer.

The technical task of the utility model is to reduce the influence of sources of frequency instability, simplifying the synchronization process and the standard implementation scheme.

The essence of the technical solution of the problem lies in the fact that in the hydrogen standard of frequency and time, including a quantum hydrogen generator, the output of which is connected to the first input of the frequency converter, the second input of which is connected to the output of the heterodyne signal driver, the input of which is connected to the output of the crystal oscillator connected to an output signal shaper whose outputs are outputs of a hydrogen standard of frequency and time, an additional clock shaper and a chain of pos of a time meter, processor, and a digital-to-analog converter connected between the output of the frequency converter and the input of the crystal oscillator, the output of the clock generator is connected to the second input of the time meter, and its input is connected to the output of the crystal oscillator.

In an embodiment of the group frequency standard, it contains n quantum hydrogen generators, and the frequency converter and time meter are n-channel.

Figure 1 presents a simplified structural diagram of the proposed frequency standard, figure 2 is a variant of the group frequency standard.

The hydrogen frequency and time standard includes (Fig. 1) a series-connected quantum hydrogen generator 1, a frequency converter 2, a time meter 3, a processor 4, a digital-to-analog converter (DAC) 5, a crystal oscillator 6, and an output signal generator 7 of a hydrogen frequency standard and time. The heterodyne signal generator 8 is connected to the second input of the frequency converter 2 by an output, and connected to the output of a crystal oscillator connected to a clock signal generator 9, the output of which is connected to the second input of the time meter 3.

Blocks 1, 2, 6 - 8 can be performed similarly to the prototype. Block 3 can be made on the basis of IVI type Ch3-38 or Ch3-64 with a measurement resolution of 10 ns. The processor 4 can be performed on the basis of a signal processor of the TMS320VC5402 type, and a frequency multiplier of a signal of a crystal oscillator can be used as a clock shaper.

In an embodiment of the group frequency standard (FIG. 2), including n quantum hydrogen generators 1, the frequency converter 2 and the time meter 3 are made n channels, that is, the frequency converter has respectively n inputs of a high-frequency signal and n outputs of an intermediate frequency signal, and a meter moments of time has n inputs of the intermediate frequency signal.

The device operates as follows.

A feature of the proposed scheme of the hydrogen frequency standard is the implementation of a digital loop for automatically adjusting the signal of the crystal oscillator based on the signal of the quantum hydrogen generator. For this, the intermediate frequency signal f _IF = f _in -f _get is not supplied to the analog phase detector, but to the time meter 3 - a cyclic counter, the state of which changes sequentially with a clock frequency of 100 MHz, formed from the standard output signal by the clock generator 9. The digitized moments of arrival of the fronts X _{i of} the _IF signal f (the current state of the cyclic counter at the time of the arrival of the next pulse edge of the signal f _pc ) are transmitted to processor 4, where their successive differences (current e the phase difference of the signal f _IF and the reference clock signal), the error signal is processed, filtered and integrated. A digital error signal from the processor is fed to the DAC 5, which generates the control voltage of the crystal oscillator 6.

The current phase error is calculated by comparing the current values of the measured (X _i ) and calculated phase (X _ip ).

X _ip = X _{(i-1) p} + 1 / f _IF (1 + Δ × f _VH / f _IF ), where Δ is the frequency offset.

Amendments to the digital-to-analog converter code 4 are determined

Here: δ is the frequency step of the DAC, the T-nominal measurement period of time instants T _i .

The coefficients K ₁ , K ₂ , K ₃ are set programmatically and determine the proportional, integrating and differentiating parts of the correction. The optimal selection of these coefficients provides the best characteristics of the output signal of the frequency standard (the amount of phase noise and frequency instability).

The advantages of such a standard construction scheme are due to the wide possibilities of digital signal processing and consist in the simplicity of optimal tuning of the PLL loop, reducing the number of sources of random and temperature instability of the frequency, the absence of a tunable frequency synthesizer and an unlimited small frequency tuning step.

In an embodiment of the group frequency and time standard (FIG. 2), the frequency of the crystal oscillator 6 is synchronized by the group frequency of the signals of n quantum hydrogen generators 1. For this, an n - channel frequency converter 2 and n - a channel time meter 3 are used. Further, when calculating phase errors and DAC code corrections in formulas (1 and (2) instead of T samples; a weighted average of the current measurements in the channels is used. As a result, in the capture mode, the frequency of the crystal oscillator 6 is the average shennuyu frequency band quantum hydrogen generators 1 - 1 _n.

This ensures increased frequency stability (due to group averaging), increased reliability or redundancy of the output signal (it is possible to connect and disconnect quantum hydrogen generators without loss of frequency and phase), saving money, dimensions, mass, energy on the implementation of group frequency (in comparison with group standards based on a group of traditional frequency standards).

Claims (2)

1. A hydrogen frequency and time standard, including a quantum hydrogen generator, the output of which is connected to the first input of the frequency converter, the second input of which is connected to the output of the heterodyne signal driver, the input of which is connected to the output of the crystal oscillator connected to the output driver, whose outputs are outputs hydrogen standard of frequency and time, characterized in that it additionally includes a clock driver and a chain of series-connected measurements of Tell time points, the processor and the digital to analog converter connected between the inverter output frequency and the input of the quartz oscillator, the output clock signal generator is connected to a second input measuring instants, and its input connected to the output of the crystal oscillator. 2. The frequency and time standard according to claim 1, characterized in that it contains n quantum hydrogen generators, and the frequency converter and the time meter in it are made n channel.