RU34765U1 - HYDROGEN FREQUENCY AND TIME STANDARD - Google Patents

Description

Hydrogen frequency and time standard

The utility model relates to passive-type quantum hydrogen standards of frequency and time and can be used to operate as a generator of highly stable, high-precision, spectrally pure signals.

The principle of operation of such devices is based on the automatic tuning of the frequency of a 5 MHz crystal oscillator according to the frequency of the emission line of hydrogen atoms, such as, for example, a passive hydrogen frequency and time standard of type 4176 (catalog of the Nizhny Novgorod PIPI “Quartz for 1999, p. 35) or type VCH1004 ( development of the Nizhny Novgorod enterprise "Time V).

As the closest analogue of the proposed technical solution, a block diagram of a passive quantum standard of frequency and time of type 41-76 is adopted (see Appendix).

A quantum device of such standards emits only under the influence of an external frequency-modulated discriminator excitation signal generated from a crystal oscillator signal, and is used for auto-tuning as a frequency discriminator. When interacting with the atomic emission line and the discriminator resonator, the frequency-modulated excitation signal acquires an amplitude-modulated component proportional to the detuning value. From the output of the discriminator, an amplitude-modulated (AM) signal is converted into a frequency converter using an auxiliary local oscillator, amplified and detected.

IPC: G04G 3/00

The disadvantage of such standards schemes is the presence of parasitic (interfering) amplitude modulation, which appears due to the non-uniformity (asymmetry with respect to the carrier frequency) of the amplitude-frequency characteristic of the frequency conversion path and its dependence on temperature.

The technical task of the utility model is to reduce the level of spurious amplitude modulation and, accordingly, increase the stability of the standard frequency.

The essence of the technical solution to the problem lies in the fact that the hydrogen frequency standard, including a quantum discriminator, a frequency converter, an amplitude detector, a crystal oscillator and a tunable frequency synthesizer, is connected in series to a second input of the frequency converter.

The second tunable frequency synthesizer is made with frequency switching symmetrically with respect to the center carrier frequency of the signal.

The figure shows a simplified block diagram of the proposed frequency standard.

The hydrogen frequency and time standard includes a quantum discriminator 1, a frequency converter 2, an amplitude detector 3, a crystal oscillator 4 and a first tunable frequency synthesizer 5, connected in series to a ring, and a second tunable frequency synthesizer 6, connected to the second input of the frequency converter 2.

0 / О УУ Device works as follows.

The principle of the standard’s operation is based on automatic tuning of the frequency of the crystal oscillator 4 to the frequency of the emission line of hydrogen atoms of discriminator 1. When interacting with the atomic line and resonator of discriminator 1, a frequency-modulated signal

the excitation of the discriminator is converted to amplitude-modulated, the amplitude and phase of the envelope of this signal carries information about the deviation of the frequency of the crystal oscillator 4 from the frequency of the emission line of hydrogen atoms. At the output of the discriminator there is a mixture of frequency-modulated and amplitude-modulated signals. The amplitude-modulated signal from the output of discriminator 1 is converted into a frequency converter 2, detected in amplitude detector 3, and controls the frequency of the crystal oscillator. In this case, the presence of a parasitic amplitude modulation signal arising due to the non-uniformity of the amplitude-frequency characteristic of the converter 2 when a frequency-modulated signal passes through it distorts the amplitude modulation of the useful signal (with information about the actual deviation of the frequency of the crystal oscillator 4 from the frequency of the emission line of hydrogen atoms), leads to a shift in the output frequency of the crystal oscillator, that is, the output frequency of the standard. To reduce the influence of parasitic amplitude modulation due to a shift in the amplitude-frequency characteristic of converter 2, a tunable frequency synthesizer 6 is used as an auxiliary local oscillator, allowing

control the heterodyne frequency symmetrically, "substituting it either to the right or to the left of the excitation signal with a frequency of 1420.405 MHz, while the intermediate frequency remains constant. At a sufficiently high switching frequency of the local oscillator (frequency synthesizer 6), compensation (averaging) of the error signal caused by spurious amplitude modulation occurs due to the different signs of the occurring spurious modulation with a mirror change in the frequency of the synthesizer 6 relative to the input signal.

The use of a utility model in passive hydrogen frequency standards makes it possible to increase the frequency stability produced by the quantum standard by eliminating the error signal caused by spurious amplitude modulation in the amplification path — the frequency conversion of the discriminator output signal.

Claims (2)

1. The hydrogen frequency and time standard, which includes a quantum discriminator in series with the ring, a frequency converter, an amplitude detector, a crystal oscillator and a tunable frequency synthesizer, characterized in that a second tunable frequency synthesizer is connected to it and connected to the second input of the frequency converter. 2. The device according to claim 1, characterized in that the second tunable frequency synthesizer is configured to switch the frequency symmetrically with respect to the center carrier frequency of the signal.