RU2178196C1 - Oscillation frequency storage technique - Google Patents

Abstract

FIELD: metrology; frequency meters. SUBSTANCE: proposed technique is based on periodic measurement of meter frequency deviation from standard and correction of meter frequency to eliminate this deviation. Novelty is additional periodic correction of meter frequency throughout time interval between two moments of measuring meter frequency deviation from standard. Additional correction value is determined by predicted rate of meter frequency drift. EFFECT: reduced error of meter with respect to its frequency periodically compared with standard. 2 dwg

Description

 The invention relates to the field of metrology and can be used in the operation of frequency measures (sometimes we will call them simply measures).

A known method of storing oscillation frequency with a frequency measure [1], which is repeated at time intervals T _i (where i is the number of time intervals) of measuring the deviation of the measure frequency from the standard frequency Δf _i and correcting the measure frequency by Δf _i . The deviation of the measure frequency from the frequency of the spatially remote reference can be measured by radio, television or satellite signals or by the method of the transported clock, and from the frequency of the reference, located in close proximity to the measure, using frequency or phase comparators and electronically counted frequency meters.

The interval T _i through which the deviation of the measure frequency is measured depends on the error of the measure in frequency that needs to be obtained, the measurement error, on the availability of the standard in time (it may not work continuously, but turn on from time to time, for example, once every 3 months ) and other factors.

So, for example, the error in measuring the frequency of radio signals is ~ 1 • 10 ^-12 when measuring within 1 day, and to obtain the error of a measure in frequency ~ 1 • 10 ^-14, it is necessary to carry out measurements continuously for 100 days, while the correction of the measure frequency can be carried out only 1 time in 100 days.

 If measurements are carried out using a transported watch, then at large distances between the measure and the standard (hundreds and thousands of kilometers) it is difficult to carry out such measurements, therefore they are carried out no more than 1 time per month or even quarterly.

 This method of storing the oscillation frequency in the aggregate of essential features is taken as a prototype.

 The disadvantage of the prototype is the large error of the frequency measure obtained by this method, due to the presence of a systematic frequency drift, which even such highly stable measures as quantum hydrogen frequency standards have.

For example, a relatively small drift in the frequency of the hydrogen standard ~ 1 • 10 ^-15 per day leads to a deviation of the frequency of the measure (frequency error) ~ 10 ^-13 in 3 months, and modern requirements for high-precision frequency measures are much higher.

 The present invention solves the problem of reducing the error in the frequency of measures periodically compared with the standard.

, Δt много меньше Т_i) корректируют частоту меры на величину

где β_i-1 - величина дополнительной коррекции частоты меры в моменты времени kΔt на интервале времени Т_i-1, при этом β₁= 0;
Т_i-1 величина (i-1)-гo интервала времени, через который осуществляют измерение отклонения частоты меры от частоты эталона и коррекцию частоты меры на величину измеренного отклонения;
Δt интервал времени, через который дополнительно корректируют частоту меры;
Δf_i-1 отклонение частоты меры от частоты эталона, измеренное в конце интервала времени T_i-1.The essence of the invention lies in the fact that in the method of storing the frequency of electrical vibrations, containing repeated at time intervals T _i (where i = 1, 2, 3, ... the number of the time interval), starting from the initial moment of time, the operation of measuring the frequency deviation measures from the frequency of the reference and correction of the frequency of the measure by the value of the measured deviation, additionally for each time interval T _i , starting from the interval T ₂ , at time instants kΔt (k = 1,2, ...,

, Δt is much less than T _i ) adjust the frequency of the measure by

where β _i-1 is the value of the additional correction of the measure frequency at time instants kΔt on the time interval T _i-1 , while β ₁ = 0;
T _{i-1 is the} value of the (i-1) -th time interval through which the measure deviation is measured from the reference frequency and the measure frequency is corrected by the measured deviation;
Δt is the time interval after which the measure frequency is further adjusted;
Δf _{i-1 the} deviation of the measure frequency from the frequency of the standard, measured at the end of the time interval T _i-1 .

 In FIG. 1 dashed lines show the change in time of the deviation of the frequency of the measure from the frequency of the standard according to the method adopted for the prototype, and solid lines according to the proposed method.

In FIG. 2 shows a structural diagram of one of the possible variants of a device that implements the proposed method, in which the measurement of the deviation of the measure frequency from the reference frequency is carried out using a frequency comparator and an electronically counted frequency meter, where it is indicated:
1 measure of frequency;
2 reference (frequencies);
3 frequency comparator;
4 electronically counted frequency meter.

, Δt<<T_i) на величину β, определяемую согласно выражению (1).Implementation of the proposed method for storing the frequency of electrical oscillations includes the following operations:
- measuring the deviation of the frequency of measure 1 from the frequency of the standard 2 Δf _i using a frequency comparator 3 and an electronically counting frequency counter 4, repeated at time intervals T _i (where i = 1, 2, ... the interval number), starting from the initial moment of time ;
- correction of the frequency of measure 1 by Δf _i repeated at time intervals T _i , starting from the initial moment of time;
- correction of the frequency of measure 1 during the interval T _i (starting from T ₂ ) at time instants kΔt (k = 1, 2, ...,

, Δt << T _i ) by the value of β, determined according to the expression (1).

 The frequency storage process and the calculations are carried out in the following order.

At the initial moment of time, using the frequency comparator 3 and the electronically counting frequency counter 4, the deviation of the measure 1 frequency from the frequency of reference 2 Δf _{0 is} measured and the frequency of measure 1 is adjusted by Δf ₀ until it matches the frequency of reference 2.

The operation of measuring the frequency deviation of the measure 1 is repeated at time T ₁ and the frequency of the measure is adjusted by the value Δf ₁ obtained from the measurement.

есть фактическая скорость систематического дрейфа частоты меры 1 на интервале времени T₁. Такую же величину скорости прогнозируют на интервал Т₂.Value

there is the actual rate of systematic frequency drift of measure 1 in the time interval T ₁ . The same speed is predicted for the interval T ₂ .

, Δt<<T₂, ) проводят коррекцию частоты меры 1 на величину β₂, где

.On the time interval T ₂ at times kΔt (k = 1, 2...,

, Δt << T ₂ ,) carry out the correction of the frequency of measure 1 by the value of β ₂ , where

.

Due to the measurement error and the discrepancy between the actual frequency change predicted at the end of the T ₂ interval, the frequency of measure 1 will have a deviation from the frequency of reference 2 equal to Δf ₂ , which is measured using a frequency comparator 3 and an electronically counting frequency counter 4 and the frequency of measure 1 is adjusted to Δf ₂ value.

.Thus, the actual rate of systematic frequency drift of measure 1 in the interval T ₂ is

.

.The same magnitude of the drift velocity is predicted for the interval T ₃ , in which at times kΔt the frequency of measure 1 is corrected by β ₃ , where

.

 The process is then repeated.

On the i-th time interval T _{i, the} correction of the frequency of measure 1 at time instants kΔt is carried out by β _i , where β _i is determined according to expression (1).

Similar operations are carried out when measuring the deviation of the frequency of measure 1 from the frequency of reference 2 is carried out not using a frequency comparator and an electronically counted frequency meter, but using radio or television receivers. In this case, the measurements are carried out not at the moment T _i , but continuously throughout the entire interval T _i , and the calculation and correction of the frequency of the measure by Δf _{i is} carried out at the end of the interval T _i .

As a rule, the rate of systematic frequency drift of measures decreases with time, therefore, frequency correction at time instants kΔt can also be performed by an amount less than β _{i /} . The specific amount of correction is determined based on the data on the rate of such a decrease, so that the value Δf _{i of the} deviation of the measure frequency from the frequency of the reference is minimal.

 From the above description and FIG. 1 shows that with the proposed method of storing the frequency, the error in the frequency of the measure is reduced in comparison with the prototype. In this case, it is possible to reduce the error by (5-10) times.

LITERATURE
1. A. I. Pikhtelev et al. Frequency and time standards based on quantum generators and discriminators. M., Sov. Radio 1978, pp. 252-262.

Claims (1)

A method for storing the frequency of electrical vibrations as a measure of frequency, containing repeating at time intervals T _i (i = 1, 2,... The number of time intervals), starting from the initial moment of time, the operation of measuring the deviation of the frequency of the measure from the frequency of the standard and correcting the frequency by the value of the measured deviations, characterized in that, in addition, for each time interval T _i , starting with T ₂ at time instants kΔt (k = l, 2, ..., -

, Δt is much less than T _i ) adjust the frequency of the measure by

where β _i-1 is the value of the additional correction of the measure frequency at time instants kΔt on the time interval T _i-1 , while β ₁ = 0;
T _i-1 - the value of the (i-1) th time interval through which the measure deviates from the reference frequency and the measure frequency is corrected by the measured deviation;
Δt is the time interval after which the measure frequency is additionally adjusted;
Δf _i-1 - the deviation of the frequency of the measure from the frequency of the standard, measured at the end (or throughout) of the interval T _i-1 .

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