CN203587689U - A long-term and short-term frequency stability measurement apparatus - Google Patents

Abstract

The utility model discloses a long-term and short-term frequency stability measurement apparatus, and belongs to the technical field of electronics. The apparatus comprises a first frequency conversion module used for generating first frequency signals, a second frequency conversion module used for generating second frequency signals, a first measurement module used for measuring the first frequency signals, a second measurement module used for measuring frequencies of second frequency signals and a processing module. The first frequency conversion module is electrically connected with the first measurement module. The second frequency conversion module is electrically connected with the second measurement module. The processing module is separately in electric connection with the first frequency conversion module, the second frequency conversion module, the first measurement module and the second module. The frequency stability and accuracy degree of an apparatus measurement signal source provided by the utility model are high.

Description

A kind of long-term and short-term frequency stability measurement mechanism

Technical field

The utility model relates to electronic technology field, particularly a kind of long-term and short-term frequency stability measurement mechanism.

Background technology

Along with the high speed development of modern society, the requirement of the precision of people to clock source output signal and degree of stability is more and more higher, and wherein, the general proportion degree of stability of the stability of clock source output signal is weighed.

Existing a kind of frequency stability measuring device, this device comprises: frequency division module, counting module, frequency computation part module and degree of stability determination module.Wherein, frequency division module is for carrying out frequency division processing to the measured signal of signal source output; Counting module is in setting-up time, and the pulse number of the measured signal after pulse number and frequency division to reference signal is counted; Frequency computation part module is calculated the frequency of measured signal for the pulse number obtaining according to counting module; Degree of stability computing module, for according to the frequency of measured signal and the standard variance formula of frequency stability of signal source output, calculates the frequency stability in measured signal source.

Realizing in process of the present utility model, inventor finds that prior art at least exists following problem:

In prior art, conventionally adopt standard variance formula to calculate the frequency stability of signal source; but; find after deliberation; a signal source has two Stability indexes conventionally; these two Stability indexes are respectively short-term frequency stability and long-term frequency stability; wherein; what short-term frequency stability characterized is the jitter level of signal; what long-term frequency stability characterized is signal frequency drift degree in time; therefore the performance that the frequency stability that, available technology adopting is single is weighed a signal source is not accurate enough.

Utility model content

In order to solve prior art, adopt single frequency stability to weigh the not accurate enough problem of performance of a signal source, the utility model embodiment provides a kind of long-term and short-term frequency stability measurement mechanism.Described technical scheme is as follows:

The embodiment of the present invention provides a kind of long-term and short-term frequency stability measurement mechanism, and described device comprises:

For take described the first reference signal as time-base signal, the output signal in measured signal source is carried out to frequency inverted, obtain the first frequency modular converter of first frequency signal;

For take described the second reference signal as time-base signal, the output signal in described measured signal source is carried out to frequency inverted, obtain the second frequency modular converter of second frequency signal;

For measuring first measurement module of frequency of the described first frequency signal that described first frequency modular converter obtains;

For measuring second measurement module of frequency of the described second frequency signal that described second frequency modular converter obtains; And

For adopting the frequency of the described first frequency signal that described the first measurement module records, according to Allan variance formula, determine the short-term frequency stability in described measured signal source, and adopt the frequency of the described second frequency signal that described the second measurement module records, according to Hadamard Variance formula, determine the processing module of the long-term frequency stability in described measured signal source;

Described first frequency modular converter is electrically connected with described the first measurement module, described second frequency modular converter is electrically connected with described the second measurement module, and described processing module is electrically connected with described first frequency modular converter, described second frequency modular converter, described the first measurement module, described the second measurement module respectively;

Wherein, described processing module comprises central processing unit, single-chip microcomputer, microcontroller or microprocessor.

Alternatively, described first frequency modular converter comprises:

For take described the first reference signal as time-base signal, the output signal in described measured signal source is carried out to count measurement, counting unit during the walking of frequency that record the output signal in described measured signal source;

For under the control of described processing module, produce the Direct Digital Synthesizer of the 3rd frequency signal, the frequency of described the 3rd frequency signal be with described walk time the described measured signal source that records of counting unit the immediate integer of frequency of output signal; And

For described the 3rd frequency signal that described Direct Digital Synthesizer is produced, carry out frequency multiplication, produce the phaselocked loop of described first frequency signal;

Described walk time counting unit by described processing module, be electrically connected with described Direct Digital Synthesizer, described phaselocked loop is electrically connected with described Direct Digital Synthesizer, described processing module respectively.

Alternatively, described second frequency modular converter comprises:

For take described the second reference signal as time-base signal, the output signal in described measured signal source is carried out to count measurement, counting unit during the walking of frequency that record the output signal in described measured signal source;

For under the control of described processing module, produce the Direct Digital Synthesizer of the 4th frequency signal, the frequency of described the 4th frequency signal be with described walk time the described measured signal source that records of counting unit the immediate integer of frequency of output signal; And

For described the 4th frequency signal that described Direct Digital Synthesizer is produced, carry out frequency multiplication, produce the phaselocked loop of described second frequency signal;

Described walk time counting unit by described processing module, be electrically connected with described Direct Digital Synthesizer, described phaselocked loop is electrically connected with described Direct Digital Synthesizer, described processing module respectively.

Alternatively, described the first measurement module comprises:

For obtaining the counting unit of described first frequency signal pulse number in setting-up time; And

For the described pulse number obtaining according to described counting unit, calculate the computing unit of the frequency of described first frequency signal;

Described counting unit is electrically connected with described first frequency modular converter, described computing unit respectively.

Alternatively, described the second measurement module is frequency stabilization tester.

Alternatively, described device also comprises: for the first signal source of described the first reference signal is provided, described first signal source is electrically connected with described first frequency modular converter, described the first measurement module respectively.

Particularly, described first signal source is crystal oscillator.

Alternatively, described device also comprises:

For the secondary signal source of described the second reference signal is provided, described secondary signal source is electrically connected with described second frequency modular converter, described the second measurement module respectively.

Particularly, described secondary signal source is hydrogen atomic clock, rubidium atomic clock or cesium-beam atomic clock.

The beneficial effect that the technical scheme that the utility model embodiment provides is brought is:

By adopting first frequency modular converter, the first measurement module and processing module, determine the short-term frequency stability in measured signal source, adopt second frequency modular converter, the second measurement module and processing module to determine the long-term frequency stability in measured signal source, adopt two frequency stabilities to weigh the performance of a signal source, accuracy is high.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme in the utility model embodiment, below the accompanying drawing of required use during embodiment is described is briefly described, apparently, accompanying drawing in the following describes is only embodiment more of the present utility model, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.

Fig. 1 is the structural representation of a kind of long-term and short-term frequency stability measurement mechanism that provides of the utility model embodiment;

Fig. 2 is the structural representation of the first frequency modular converter that provides of the utility model embodiment.

Embodiment

For making the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with accompanying drawing, the utility model embodiment is described in further detail.

The utility model embodiment provides a kind of measurement mechanism of frequency stability, and referring to Fig. 1, this device comprises first frequency modular converter 1, second frequency modular converter 2, the first measurement module 3, the second measurement module 4 and processing module 5.First frequency modular converter 1, for take the first reference signal as time-base signal, carries out frequency inverted to the output signal in measured signal source, obtains first frequency signal.Second frequency modular converter 2, for take the second reference signal as time-base signal, carries out frequency inverted to the output signal in measured signal source, obtains second frequency signal.The first measurement module 3 is for the frequency of the first frequency signal measuring first frequency modular converter 1 and obtain.The second measurement module 4 is for the frequency of the second frequency signal measuring second frequency modular converter 2 and obtain.Processing module 5 is for the frequency of the first frequency signal that adopts the first measurement module 3 and record, according to Allan variance formula, determine the short-term frequency stability in measured signal source, and adopt the frequency of the second frequency signal that the second measurement module 4 records, according to Hadamard Variance formula, determine the long-term frequency stability in measured signal source.

Wherein, first frequency modular converter 1 is electrically connected with the first measurement module 3, second frequency modular converter 2 is electrically connected with the second measurement module 4, and processing module 5 is electrically connected with first frequency modular converter 1, second frequency modular converter 2, the first measurement module 3, the second measurement module 4 respectively.

Particularly, Allan variance formula (1) is as follows:

${\mathrm{\σ}}_y(2,\mathrm{\τ},\mathrm{\τ},f_h)=\sqrt{\frac{1}{2(N-1)}\underset{i=1}{\overset{N-1}{\mathrm{\Σ}}}{[y\left({\mathrm{\τ}}_{i+1}\right)-y\left({\mathrm{\τ}}_i\right)]}^2}---\left(1\right)$

Wherein, σ _yfor Allan variance value, τ is sampling period and sampling time, f _hfor the higher cutoff frequency of measuring, N is number of samples,

y is the relative frequency deviation of output frequency, the frequency that f0 is reference signal, f _ifor the frequency of the output signal in measured signal source.

In Allan variance formula (1), sampling time and sampling period are τ, and therefore this is sampled as gapless sampling, Allan variance convergence.

Hadamard Variance formula (2) is as follows:

${\mathrm{H\σ}}_y(3,\mathrm{\τ})=\sqrt{\frac{1}{6(m-2)}\underset{k=1}{\overset{m-2}{\mathrm{\Σ}}}{(y_{k+2}-2*y_{k+1}+y_k)}^2}---\left(2\right)$

Wherein, H σ _yfor Hadamard Variance value, τ is the sampling time, and m is number of samples, y _kfor the relative frequency deviation of output frequency.

In Hadamard Variance formula (2), y _k+2-2*y _k+1+ y _k=(y _k+2-y _k+1)-(y _k+1-y _k), due to previous bracket (y _k+2-y _k+1) in include the impact of frequency drift on frequency stability, a rear bracket (y _k+1-y _k) in also include the impact of frequency drift, therefore previous bracket and a rear bracket subtract each other, and can eliminate the impact of frequency drift on frequency stability.

Particularly, referring to Fig. 2, counting unit 11, DDS(Direct Digital Synthesizer when first frequency modular converter 13 can comprise walking, Direct Digital Synthesizer) 12 and PLL(Phase Locked Loop, phaselocked loop) 13.While walking, counting unit 11, for take the first reference signal as time-base signal, is carried out count measurement to the output signal in measured signal source, records the frequency of the output signal in measured signal source.DDS12 under the control of processing module 5, produces the 3rd frequency signal, and the frequency of the 3rd frequency signal is the immediate integer of frequency of the output signal in the measured signal source that counting unit 11 records when walking.PLL13 carries out frequency multiplication for the 3rd frequency signal that DDS12 is produced, and produces first frequency signal.While walking, counting unit 11 is electrically connected with DDS12 by processing module 5.PLL13 is electrically connected with DDS12, processing module 5 respectively.

It should be noted that, the immediate integer of frequency of the output signal in the measured signal source that counting unit 11 records when walking, generally take MHz(megahertz) be unit, the frequency of the output signal in the measured signal source that counting unit 11 records when walking rounds.

The frequency of frequency signal and the frequency multiplication ratio of PLL13 that DDS12 obtains are controlled by processing module 5.Processing module 5 can be by sending command control word to DDS12, rewrite the internal frequency register of DDS12, making DDS12 output frequency is the frequency signal of the immediate integer of measured signal frequency that counting unit 11 obtains when walking, and the measured signal frequency that command control word is processing module 5 counting unit 11 obtains when walking obtains.

For instance, while walking, to obtain the frequency of measured signal be 5.3125MHz to counting unit 11, it is 5MHz that processing module 5 obtains with the immediate integer of frequency according to this frequency, processing module 5 sends the command control word corresponding with 5MHz to DDS12, rewritten the internal frequency register of DDS12, making DDS12 output frequency is the frequency signal of 5MHz.PLL13, according to the frequency multiplication ratio of processing module 5, carries out frequency multiplication to the frequency signal of 11MHz, obtains the frequency signal of required frequency, as the frequency signal of 1KHz.

Counting unit, DDS and PLL when particularly, second frequency modular converter 2 can comprise walking.While walking, counting unit, for take the second reference signal as time-base signal, is carried out count measurement to the output signal in measured signal source, records the frequency of the output signal in measured signal source.DDS under the control of processing module, produces the 4th frequency signal, and the frequency of the 4th frequency signal is the immediate integer of frequency of the output signal in the measured signal source that counting unit records when walking.PLL carries out frequency multiplication for the 4th frequency signal that DDS is produced, and produces second frequency signal.While walking, counting unit is electrically connected with DDS by processing module.PLL is electrically connected with DDS, processing module respectively.

Alternatively, the first measurement module 3 can comprise counting unit and computing unit.Counting unit is used for obtaining first frequency signal pulse number in setting-up time.The pulse number of computing unit for obtaining according to counting unit, calculates the frequency of described first frequency signal.Counting unit is respectively at first frequency modular converter, computing unit electrical connection.

Alternatively, the second measurement module 3 can be frequency stabilization tester.

Alternatively, this device also comprises the first signal source for the first reference signal is provided, and first signal source is electrically connected with first frequency modular converter 1, the first measurement module 3 respectively.

Particularly, first signal source can be crystal oscillator, as 8607 crystal oscillators.

Alternatively, this device also comprises the secondary signal source for the second reference signal is provided, and secondary signal source is electrically connected with second frequency modular converter 2, the second measurement module 4 respectively.

Particularly, secondary signal source 2 can be hydrogen atomic clock, rubidium atomic clock or cesium-beam atomic clock.

Alternatively, processing module 7 can comprise central processing unit, single-chip microcomputer, microcontroller or microprocessor.

Simply introduce the principle of work of the long-term and short-term frequency stability measurement mechanism that the present embodiment provides below:

While measuring short-term frequency stability, first frequency modular converter 1 is take the first reference signal as time-base signal, output signal (as 10KHz) to measured signal source is carried out frequency inverted, obtain first frequency signal (as 1KHz), the first measurement module 3 is measured the frequency of first frequency signal, processing module 5 adopts the frequency of first frequency signal, determines the short-term frequency stability in number measured signal source according to Allan variance formula.

While measuring long-term frequency stability, second frequency modular converter 2 is take the second reference signal as time-base signal, output signal (as 10KHz) to measured signal source is carried out frequency inverted, obtain second frequency signal (as 1KHz), the second measurement module 4 is measured the frequency of second frequency signal, processing module 5 adopts the frequency of second frequency signal, determines the long-term frequency stability in measured signal source according to Hadamard Variance formula.

The utility model embodiment is by adopting first frequency modular converter, the first measurement module and processing module to determine the short-term frequency stability in measured signal source, adopt second frequency modular converter, the second measurement module and processing module to determine the long-term frequency stability in measured signal source, adopt two frequency stabilities to weigh the performance of a signal source, accuracy is high.

The foregoing is only preferred embodiment of the present utility model, not in order to limit the utility model, all within spirit of the present utility model and principle, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection domain of the present utility model.

Claims (9)

1. a long-term and short-term frequency stability measurement mechanism, is characterized in that, described device comprises:

For take the first reference signal as time-base signal, the output signal in measured signal source is carried out to frequency inverted, obtain the first frequency modular converter of first frequency signal;

For take the second reference signal as time-base signal, the output signal in described measured signal source is carried out to frequency inverted, obtain the second frequency modular converter of second frequency signal;

For measuring first measurement module of frequency of the described first frequency signal that described first frequency modular converter obtains;

For measuring second measurement module of frequency of the described second frequency signal that described second frequency modular converter obtains; And

For adopting the frequency of the described first frequency signal that described the first measurement module records, according to Allan variance formula, determine the short-term frequency stability in described measured signal source, and adopt the frequency of the described second frequency signal that described the second measurement module records, according to Hadamard Variance formula, determine the processing module of the long-term frequency stability in described measured signal source;

Described first frequency modular converter is electrically connected with described the first measurement module, described second frequency modular converter is electrically connected with described the second measurement module, and described processing module is electrically connected with described first frequency modular converter, described second frequency modular converter, described the first measurement module, described the second measurement module respectively;

Wherein, described processing module comprises central processing unit, single-chip microcomputer, microcontroller or microprocessor.

2. device according to claim 1, is characterized in that, described first frequency modular converter comprises:

For take described the first reference signal as time-base signal, the output signal in described measured signal source is carried out to count measurement, counting unit during the walking of frequency that record the output signal in described measured signal source;

For under the control of described processing module, produce the Direct Digital Synthesizer of the 3rd frequency signal, the frequency of described the 3rd frequency signal be with described walk time the described measured signal source that records of counting unit the immediate integer of frequency of output signal; And

For described the 3rd frequency signal that described Direct Digital Synthesizer is produced, carry out frequency multiplication, produce the phaselocked loop of described first frequency signal;

Described walk time counting unit by described processing module, be electrically connected with described Direct Digital Synthesizer, described phaselocked loop is electrically connected with described Direct Digital Synthesizer, described processing module respectively.

3. device according to claim 1, is characterized in that, described second frequency modular converter comprises:

For take described the second reference signal as time-base signal, the output signal in described measured signal source is carried out to count measurement, counting unit during the walking of frequency that record the output signal in described measured signal source;

For under the control of described processing module, produce the Direct Digital Synthesizer of the 4th frequency signal, the frequency of described the 4th frequency signal be with described walk time the described measured signal source that records of counting unit the immediate integer of frequency of output signal; And

For described the 4th frequency signal that described Direct Digital Synthesizer is produced, carry out frequency multiplication, produce the phaselocked loop of described second frequency signal;

Described walk time counting unit by described processing module, be electrically connected with described Direct Digital Synthesizer, described phaselocked loop is electrically connected with described Direct Digital Synthesizer, described processing module respectively.

4. according to the device described in claim 1-3 any one, it is characterized in that, described the first measurement module comprises:

For obtaining the counting unit of described first frequency signal pulse number in setting-up time; And

For the described pulse number obtaining according to described counting unit, calculate the computing unit of the frequency of described first frequency signal;

Described counting unit is electrically connected with described first frequency modular converter, described computing unit respectively.

5. according to the device described in claim 1-3 any one, it is characterized in that, described the second measurement module is frequency stabilization tester.

6. according to the device described in claim 1-3 any one, it is characterized in that, described device also comprises:

For the first signal source of described the first reference signal is provided, described first signal source is electrically connected with described first frequency modular converter, described the first measurement module respectively.

7. device according to claim 6, is characterized in that, described first signal source is crystal oscillator.

8. according to the device described in claim 1-3 any one, it is characterized in that, described device also comprises:

For the secondary signal source of described the second reference signal is provided, described secondary signal source is electrically connected with described second frequency modular converter, described the second measurement module respectively.

9. device according to claim 8, is characterized in that, described secondary signal source is hydrogen atomic clock, rubidium atomic clock or cesium-beam atomic clock.

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