RU2085958C1 - Crystal oscillator parameter measuring device - Google Patents

Abstract

FIELD: measurement technology; measurement of transient functions in setting wave frequency and amplitude of crystal oscillators and their coefficient of nonisochronism. SUBSTANCE: device has power supply 2 for oscillator 1 under analysis, first and second frequency dividers 7 and 8, respectively first and second storage units 13 and 14, respectively, time interval meter 11, recorder 16, Newly introduced in device are detector 3, storage-retrieval unit 6, analog-to-digital converter 9, delay element 10, calculator 12, and unit 15 for comparing difference of codes during moment of time when transient function slope is set at maximum frequency; oscillator frequency drift Δf_m and wave amplitude U_у are measured, and coefficient of nonisochronism β_n=Δf_m/U $\genfrac{}{}{0ex}{}{\text{2}}{\text{у}}$ is calculated. EFFECT: enlarged functional capabilities of device. 5 dwg

Description

 The invention relates to a measurement technique and is intended for measuring the function of transients of establishing the frequency and amplitude of oscillations of crystal oscillators, as well as their non-isochronism coefficient.

 The purpose of the invention is the expansion of functionality.

 In FIG. 1 shows a functional diagram of a device for measuring the parameters of crystal oscillators; in FIG. 2 functional diagram of the calculator; in FIG. 3 is a functional diagram of a code difference comparison unit; in FIG. 4 functional diagram of the registrar; in FIG. 5 time functions of the change of the measured parameters in the transient process.

 A device for measuring the parameters of crystal oscillators contains the crystal oscillator 1 under investigation, a power supply 2, a detector 3, an amplifier 4, a reference frequency generator 5, a sample-storage unit 6, a first frequency divider 7, a second frequency divider 8, an analog-to-digital converter 9, an element delays 10, a time interval meter 11, a calculator 12, a first memory block 13, a second memory block 14, a code difference comparison unit 15, and a recorder 16.

 The elements of the device are connected as follows.

 The input and output of the investigated crystal oscillator 1 are connected respectively to the output of the power source 2 and to the inputs of the detector 3, amplifier 4. The output of the detector 3 is connected to the information input of the sampling-storage unit 6. The output of amplifier 4 is connected to the counting input of the first frequency divider 7, the output connected to the control input of the sampling-storage unit 6, with the installation input of the second frequency divider 8, the counting input of which is connected to the output of the reference frequency generator 5, the outputs of the sampling-storage unit 6 and the first the frequency divider 7 is connected to the inputs of an analog-to-digital converter 9 and the delay element 10, respectively, the outputs of the first 7 and second 8 frequency divider are connected respectively to the first and second inputs of the meter 11 time intervals. The output of the analog-to-digital converter 9 is connected to the first input of the calculator 12, the outputs of the delay element 10 and the meter 11 time intervals are connected respectively to the input of the first memory block 13, the output connected to the second input of the calculator 12 and the information input of the second memory block 14, the recording input and output the second memory unit 14 are connected respectively to the output of the first frequency divider 7 and the second input of the code difference comparison unit 15, the first input, the control input and the output of the code difference comparison unit 15 are connected respectively Actually, with the output of the first memory unit 13, the output of the first frequency divider 7, and the recording input of the calculator 12. The first, second, third inputs and the synchronization input of the recorder 16 are connected to the outputs of the time meter 11, the calculator 12, the analog-to-digital converter 9, and the power source 2.

 The computer 12 (Fig. 2) contains a memory unit 17, a single vibrator 18, an element 2I 19 and a read-only memory 20 (programmable logic matrix).

 The node 15 comparing the difference code (Fig. 3) contains a subtractor 21, a memory unit 22, a node 23 code comparison, a resistor 24 and a capacitor 25.

 The registrar 16 (Fig. 4) contains digital-to-analog converters 26, a pulse generator 27, an analog switch 28, a ring shift register 29 and an oscilloscope 30.

 A device for measuring the parameters of crystal oscillators works as follows.

где V_y амплитуда колебаний в установившемся режиме;
q= 2π f_xo•(μ₁-1)/Q;
здесь f_x0 начальное значение исследуемой частоты;
μ₁ фактор генерации кварцевого генератора;
Q добротность кварцевого резонатора, входящего в состав исследуемого кварцевого генератора 1;
n=V_y/U_ш,
где U_ш напряжение шумов в начальной момент запуска кварцевого генератора;
Δf_x(t) изменение частоты исследуемого кварцевого генератора 1 на участке переходного процесса;
β_н коэффициент неизохронности, характеризующий связь между изменениями амплитуды и частоты колебаний кварцевого генератора, который может быть рассчитан по формуле
β_н= Δf_x(t)/[U(t)]² (3)
Выходной сигнал исследуемого кварцевого генератора 1 через усилитель 4, который для уменьшения влияния амплитудных измерений на результаты измерения частоты должен иметь стабильные фазовые характеристики, поступает на счетный вход первого делителя частоты 7. На его выходе формируется последовательность импульсов усреднения, следующих с периодом
τ_x= n_x/f_x(t)=n_xT_x(t) (4)
где n_x коэффициент деления первого делителя частоты 7.The power source 2 periodically supplies a supply voltage to the investigated crystal oscillator 1, after which transient processes of establishing the amplitude U (t) and frequency f _x (t) of the oscillations occur, which are described respectively by the relations:

where V _{y the} amplitude of the oscillations in the steady state;
q = 2π f _xo • (μ ₁ -1) / Q;
here f _{x0 is the} initial value of the studied frequency;
μ ₁ crystal oscillator generation factor;
Q is the quality factor of the quartz resonator, which is part of the investigated quartz generator 1;
n = V _y / U _w ,
where U _W the noise voltage at the initial moment of launch of the crystal oscillator;
Δf _x (t) the change in the frequency of the investigated crystal oscillator 1 on the transient;
β _n isochronism coefficient characterizing the relationship between changes in the amplitude and frequency of oscillations of a crystal oscillator, which can be calculated by the formula
β _n = Δf _x (t) / [U (t)] ² (3)
The output signal of the investigated crystal oscillator 1 through amplifier 4, which in order to reduce the influence of amplitude measurements on the frequency measurement results must have stable phase characteristics, is fed to the counting input of the first frequency divider 7. At its output, a sequence of averaging pulses is formed, which follow with a period
τ _x = n _x / f _x (t) = n _x T _x (t) (4)
where n _{x is} the division coefficient of the first frequency divider 7.

Each averaging pulse sets the division coefficient of the second frequency divider 8 (n _o ). As a result, the sequence of reference pulses generated at the output of the second frequency divider 8 from the pulses of the reference frequency generator 5 is delayed relative to the sequence of averaging pulses by a time interval τ _o equal to
τ _o = n _o • T _o (5)
where T is _the pulse repetition period of the reference frequency.

The meter 11 time intervals generates a code N _f proportional to the duration of the time interval between the averaging pulse and the corresponding reference pulse:
N _f = (τ _x -τ _o ) / T, (6)
where T is the pulse repetition period of the filling frequency of the time interval.

где T_xo= 1/f_xo начальное значение периода исследуемой частоты;
ΔT_x(t) изменение периода исследуемых колебаний на участке переходного процесса, аналитическое описание которого получено в результате решения очевидного уравнения
± Δf_x(t)= 1/T_xo∓ 1/[T_xo± ΔT_x(t)]
и имеет вид
± ΔT_x(t) = ∓ Δf_x(t)/ {f_xo•[f_xo± Δf_x(t)]} (8)
Соотношение (7) с учетом (8) и того, что у кварцевых генераторов f_xo≫ Δf_x(t) а коэффициенты деления первого 7 и второго 8 делителей частоты выбирают из условия
n_oT_o=n_xT_xo,
принимает вид
N_f= ± n_x•Δf_x(t)/(f $\genfrac{}{}{0ex}{}{\text{2}}{\text{xo}}$ •T),
т. е. выходной код измерителя 11 временных интервалов не зависит от начального значения периода исследуемых колебаний.Relation (6), taking into account (4), (5), takes the form

where T _xo = 1 / f _{xo is the} initial value of the period of the studied frequency;
ΔT _x (t) is the change in the period of the studied oscillations in the transient region, the analytical description of which is obtained by solving the obvious equation
± Δf _x (t) = 1 / T _xo ∓ 1 / [T _xo ± ΔT _x (t)]
and has the form
± ΔT _x (t) = ∓ Δf _x (t) / {f _xo • [f _xo ± Δf _x (t)]} (8)
Relation (7) taking into account (8) and the fact that for quartz oscillators f _xo ≫ Δf _x (t) and the division coefficients of the first 7 and second 8 frequency dividers are selected from the condition
n _o T _o = n _x T _xo ,
takes the form
N _f = ± n _x • Δf _x (t) / (f $\genfrac{}{}{0ex}{}{\text{2}}{\text{xo}}$ • T)
i.e., the output code of the meter for 11 time intervals does not depend on the initial value of the period of the studied oscillations.

At the same time, the output signal of the investigated crystal oscillator 1 through the detector 3, designed to isolate the envelope of the amplitude transient, is fed to the node 6 sample-storage. To synchronize the moments of obtaining codes of frequency N _f and amplitude N _u information in the node 6 sample-storage is entered by the averaging pulse. The stored voltage is converted by an analog-to-digital converter 9 into the code N _u , which is supplied to the recorder 16 for registration, and the output signal of the node 15 for comparing the difference of codes is entered into the calculator 12.

Each averaging pulse rewrites the previous value of the code N _f from the first memory block 13 to the second memory block 14 and then, after a time τ ₃₁ (where τ _{31 is} the delay time of the signal in the delay element 10), writes the code N _fi to the first memory block 13. Comparison node 15 the difference code generates the code [N _fi N _{f (i-1)} ] and compares it with the code [N _{f (i-2)} - N _{f (i-1)} ] until time t = t _mf = ln (n ² - 1) / g corresponding to the point of maximum steepness of the function Δf _x (t), [N _{f (i-2)} N _{f (i-1)} ]> [N _fi N _{f (i-1)} ] and the output signal of the comparison node 15 the difference of codes has, for example, a zero level.

For t ≥ t _{mf, the} code [N _fi N _{f (i-1)} ] is equal to or greater than [N _{f (i-2)} N _{f (i-1)} ] and a zero level is formed at the output of the node 15 for comparing the difference of moves, which indicates at the point in time at which the steepness of the transition function of the frequency establishment is maximum.

(где Δf_m измерение частоты исследуемых колебаний на участке переходного процесса) в соответствии с (3) рассчитывается код коэффициента неизохронности по соотношению

Из анализа соотношения (9) следует, что в момент времени t=t_mf величина коэффициента неизохронности определяется только изменением частоты на участке переходного процесса и амплитудой колебаний в установившемся режиме.In the calculator 12 according to the codes N _f and N _u recorded at the time t = t _mf , which at this moment in time are respectively equal to N _f = Δf _m / 2 and

(where Δf _{m is the} measurement of the frequency of the studied oscillations in the transient region) in accordance with (3), the code of the nonisochronism coefficient is calculated by

From the analysis of relation (9), it follows that at the time t = t _{mf the} value of the nonisochronism coefficient is determined only by a change in the frequency in the transient region and the amplitude of the oscillations in the steady state.

для их визуализации подаются на регистратор 16 (фиг.5), работа которого синхронизируется выходным сигналом источника 2 питания.The obtained values of the codes N _f , N _u and

for their visualization served on the recorder 16 (figure 5), the operation of which is synchronized by the output signal of the power supply 2.

 The operation of the calculator 12 is as follows.

The pulse received at the recording input of the calculator 12, fixes the codes N _f and N _u in the memory blocks 17 and starts the one-shot 18. Elements 2I 19 are closed by the zero level of the output signal of the latter. As a result, the zero code values.

 In the read-only memory 20 (programmable logic matrix), a truth table described by relation (8) is pre-recorded.

 The node 15 comparing the difference of the codes as follows.

Subtractor 21 generates the difference of the codes received at its inputs. According to the next averaging pulse, the output code of the subtractor 21 is entered into the memory block 22, after which the codes at the inputs of the node 15 for comparing the code difference are changed (codes N _fi and N _{f (i-1)} are entered into the first 13 and second 14 memory blocks, respectively.

 At the output of the subtractor 21, a new code difference is formed, which in the code comparison node 23 is compared with the output code of the memory unit 22.

 An integrating chain (resistor 24 and capacitor 25) prevents false triggering of the nodes of the proposed device from short pulses that may appear during the change of codes at the inputs of the subtractor 21.

 The registrar 16 operates as follows.

 Digital-to-analog converters 26 convert the received codes into voltages, which are alternately switched by an analog switch 28 to an oscilloscope 30. The operation of an analog switch 28 is controlled by a ring shift register 29. The frequency of voltage switching is determined by the frequency of the output signal of the pulse generator 27.

 Compared with the prototype, a device for measuring the parameters of crystal oscillators has the advantage of expanding the functionality.

This is due to the possibility of measuring the following parameters of crystal oscillators:
functions of the transition process of establishing the oscillation amplitude of the crystal oscillator;
non-isochronism coefficient;
time t _mf corresponding to the point of maximum steepness of the transition function of the frequency establishment.

 A device for measuring the parameters of crystal oscillators can be used independently, as well as in automated systems and complexes for testing controlled crystal oscillators.

Claims (1)

 A device for measuring parameters of crystal oscillators, comprising a power source, amplifier, reference frequency generator, first and second frequency dividers, first and second memory blocks, a time interval meter and a recorder, the output of the power source being connected to the input of the crystal oscillator under study, the first input of the time meter intervals with the installation input of the second frequency divider, and the output of the reference frequency generator is connected to the counting input of the second frequency divider, characterized in that, in order to expand I have functionality, a detector, a sampling-storage unit, an analog-to-digital converter, a delay element, a calculator, and a code difference comparison unit are introduced into it, while the output of the crystal oscillator under investigation is connected through an amplifier to the counting input of the first frequency divider, the output connected to the first input a time interval meter, with control inputs of a sample-storage node and a code difference comparison node, through a delay element with a recording input of the first memory block, the information input of which is connected It is connected to the first input of the recorder and to the output of the time interval meter, the second input of the latter is connected to the output of the second frequency divider, the output of the crystal oscillator under investigation is connected through the detector to the information input of the sample-storage node, the control input of which is connected to the recording input of the second memory block, node output sample-storage through an analog-to-digital converter is connected to the first input of the calculator and the third input of the recorder, the output of the first memory block is connected to the information input of the second flash memory to the second input of the calculator and to the first input node comparing the difference codes, a second input and whose output is connected respectively to the output of the second storage unit and calculating an input record, the outputs of the calculator and a power source are connected respectively to the second input and the input of recorder synchronization.

Images