CN207218667U - A satellite navigation time correction device - Google Patents

Abstract

The utility model relates to the technical field of atomic clocks, in particular to a satellite navigation time correction device, which comprises a temperature control module connected to a VCXO, and the VCXO is respectively connected to a DDS frequency division module, a voltage control correction module, a gain control module and a traditional electronic circuit, and the traditional electronic circuit is connected to In the quantum system, the voltage control correction module is connected to the servo circuit, the DDS frequency division module is connected to the phase accumulation module, and the phase accumulation module is connected to the GPS signal receiver; the gain control module is connected to the voltage control correction module, and the quantum system is connected to the servo circuit and the phase accumulation module in turn. The frequency of the frequency-divided signal by the correction device is consistent with the frequency of the synchronous reference signal, so as to realize the detection of the same frequency and different phases, so as to improve the detection accuracy.

Description

A satellite navigation time correction device

technical field

The utility model belongs to the technical field of atomic clocks, in particular to a satellite navigation time correction device.

Background technique

In passive rubidium timing equipment, the quantum system is the core component of the entire timing equipment, which provides an atomic resonance absorption line with stable frequency and narrow linewidth. After comprehensive modulation, the modulated microwave interrogation signal from the voltage-controlled quartz crystal oscillator (VCXO) generated by the electronic circuit acts on the quantum system. After quantum frequency discrimination, the quantum frequency discrimination information is processed by the servo circuit, and finally The output frequency of the local oscillator is locked on the center frequency of the hyperfine 0-0 transition of the rubidium atom. Most of the existing servo circuits perform synchronous phase identification on the quantum frequency identification signal according to the synchronous phase identification signal provided comprehensively, and use an independent D/A voltage-controlled local oscillator to realize the closed-loop locking of the whole machine according to the phase identification result information. Finally, a frequency signal with high stability is output through the local oscillator. With the promotion of GPS synchronous calibration, it can be said that a new stage is provided for the existing atomic clocks. The long-term running indicators of the atomic clocks are synchronized with the GPS, while the short-term indicators retain the existing technology, so that the overall system caused by internal reasons can be avoided. The output signal frequency changes caused by machine drift.

Utility model content

The purpose of the utility model is to provide a correction device that makes the frequency of the frequency-divided signal consistent with the frequency of the synchronous reference signal, so as to realize the detection of the same frequency and different phases, so as to improve the detection accuracy.

In order to achieve the above object, the technical solution adopted by the utility model is: a satellite navigation time correction device, including a temperature control module connected to a VCXO, and the VCXO is respectively connected to a DDS frequency division module, a voltage control correction module, a gain control module and a traditional electronic circuit, The traditional electronic circuit is connected to the quantum system, the voltage control correction module is connected to the servo circuit, the DDS frequency division module is connected to the phase accumulation module, and the phase accumulation module is connected to the GPS signal receiver; the gain control module is connected to the voltage control correction module, and the quantum system is sequentially connected to the servo circuit, Phase accumulation module.

In the above-mentioned satellite navigation time correction device, the DDS frequency division module includes an isolation amplifier, a travel time counter, a latch, a DDS processing module, a low-pass filter module and a single-chip microcomputer; the isolation amplifier is respectively connected to the travel time counter, the DDS processing module, and the travel time counter is connected to the The latch is connected to the single-chip microcomputer; the DDS processing module is respectively connected to the single-chip microcomputer and the low-pass filter module.

In the above-mentioned satellite navigation time correction device, the DDS processing module adopts AD9852.

In the above-mentioned satellite navigation time correction device, the temperature control module includes a voltage source, a temperature acquisition module, a differential amplifier A, a negative feedback resistor Rw and a heating coil loop; the temperature acquisition module is connected to the voltage source and the differential amplifier A respectively, and the differential amplifier A Connect negative feedback resistor Rw, heating coil loop and voltage source respectively.

In the above-mentioned satellite navigation time correction device, the temperature acquisition module includes a bridge formed by two resistors R, resistor R1 and resistor Rk; Rk is equivalent; resistor Rk is a thermistor, and is attached to the surface of the temperature control module.

In the satellite navigation time correction device mentioned above, the resistance Rw adopts a digital potentiometer.

In the above satellite navigation time correction device, the temperature control module is placed in the VCXO.

In the above-mentioned satellite navigation time correction device, the voltage control correction module includes a bridge temperature measurement module, voltage followers A1, A2, and a differential amplifier A3; the bridge temperature measurement module consists of two resistors R4, resistor _R0 and resistor Rk1 The bridge, the two resistors R4 and the resistor _R0 are resistors with the same temperature coefficient, and their resistance value is equivalent to that of the resistor Rk1.

In the above satellite navigation time correction device, the gain control module is a gain linear adjustment circuit A4; it is connected to the output terminal of the differential amplifier A3.

In the above satellite navigation time correction device, the resistor Rk1 is a thermistor, and the resistor _R0 is a thermistor sensor.

The beneficial effect of the utility model is that the frequency of the frequency-divided signal can be consistent with the frequency of the synchronous reference signal, and the detection of the same frequency and different phases can be realized to improve the detection accuracy. The frequency change of the output signal caused by the drift of the whole machine caused by the internal reasons of the system is avoided.

Description of drawings

Fig. 1 is a schematic diagram of a satellite navigation time correction device of an embodiment of the present invention;

Fig. 2 is a schematic diagram of a DDS frequency division module of an embodiment of the present invention;

Fig. 3 is a sequence diagram of the phase accumulation module of an embodiment of the present invention;

Fig. 4 is the output frequency curve of traditional atomic clock and satellite navigation time correction device of an embodiment of the present utility model;

Fig. 5 is a schematic diagram of a temperature control module of an embodiment of the present invention;

FIG. 6 is a schematic diagram of a voltage control correction module and a gain control module according to an embodiment of the present invention.

Detailed ways

Embodiments of the utility model will be described in detail below in conjunction with the accompanying drawings.

Examples of the described embodiments are shown in the drawings, wherein like or similar reference numerals designate like or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are only used to explain the present invention, and cannot be construed as limiting the present invention.

The following disclosure provides many different embodiments or examples for realizing different structures of the present invention. To simplify the disclosure of the present invention, components and arrangements of specific examples are described below. They are examples only and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in different instances. This repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or arrangements discussed. Additionally, the present disclosure provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize the applicability of other processes and/or the use of other materials. Additionally, configurations described below in which a first feature is "on" a second feature may include embodiments where the first and second features are formed in direct contact, and may include additional features formed between the first and second features. For example, such that the first and second features may not be in direct contact.

In the description of the present utility model, it should be noted that, unless otherwise stipulated and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements , may be directly connected, or may be indirectly connected through an intermediary. Those of ordinary skill in the related art can understand the specific meanings of the above terms according to specific situations.

This embodiment adopts the following technical solutions to realize, a satellite navigation time correction device, including a temperature control module connected to a VCXO, and the VCXO is respectively connected to a DDS frequency division module, a voltage control correction module, a gain control module and a traditional electronic circuit, and the traditional electronic circuit is connected to In the quantum system, the voltage control correction module is connected to the servo circuit, the DDS frequency division module is connected to the phase accumulation module, and the phase accumulation module is connected to the GPS signal receiver; the gain control module is connected to the voltage control correction module, and the quantum system is connected to the servo circuit and the phase accumulation module in turn.

Further, the DDS frequency division module includes an isolation amplifier, a travel time counter, a latch, a DDS processing module, a low-pass filter module and a microcontroller; the isolation amplifier is connected to the travel time counter and the DDS processing module respectively, and the travel time counter is connected to the latch, and the latch is connected to the The single-chip microcomputer; the DDS processing module is respectively connected with the single-chip microcomputer and the low-pass filter module.

Further, the DDS processing module adopts AD9852.

Further, the temperature control module includes a voltage source, a temperature acquisition module, a differential amplifier A, a negative feedback resistor Rw, and a heating coil loop; the temperature acquisition module is respectively connected to the voltage source and the differential amplifier A, and the differential amplifier A is respectively connected to the negative feedback resistor Rw, heating Coil loop and voltage source.

Further, the temperature acquisition module includes a bridge composed of two resistors R, resistor R1 and resistor Rk; and the two resistors R and resistor R1 are resistors with the same temperature coefficient, and their resistance value is equivalent to that of resistor Rk; resistor Rk is thermally sensitive resistor, and stick it on the surface of the temperature control module.

Further, the resistor Rw adopts a digital potentiometer.

Further, the temperature control module is placed in the VCXO.

Further, the voltage control correction module includes a bridge temperature measurement module, voltage followers A1, A2, and a differential amplifier A3; the bridge temperature measurement module includes two resistors R4, resistor _R0 and resistor Rk1 to form a bridge, two resistors R4 and Resistor _R0 is a resistor with the same temperature coefficient, and its resistance value is equivalent to that of resistor Rk1.

Further, the gain control module is a gain linear adjustment circuit A4; it is connected to the output terminal of the differential amplifier A3.

Furthermore, the resistor Rk1 is a thermistor, and the resistor _R0 is a thermistor sensor.

During specific implementation, as shown in Figure 1, the receiver obtains the signal sent by the GPS satellite, and after conversion, the second pulse signal f0 is obtained and sent to the phase accumulation module, and the 1KHz synchronization reference signal f1 generated based on the GPS second pulse signal is also sent to the phase accumulation module; at the same time, the output signal of the VCXO is sent to the phase accumulation module by obtaining f2 after the DDS frequency division module. Here we set the frequency division ratio of DDS, and the ultimate goal is to make the frequency of the divided signal consistent with the frequency of the synchronous reference signal f1.

It is hoped that f1=f2 in theory, so that the detection of the same frequency and different phases can be realized to improve the detection accuracy. But it is impossible to make the two exactly the same, for example, f1=1.0012KHz, f2=1.0023KHz. The DDS frequency division module structure shown in Figure 2 is set in the phase accumulation module to make the values of f1 and f2 as close as possible.

The measured frequency signal f _x (f1 or f2) is sent to the travel time counter and the DDS processing module after passing through the isolation amplifier. Send it to the travel time counter for rough frequency measurement. After the single-chip microcomputer reads the value sampled by the latch to the travel time counter, record the frequency value at this time, and then the rough frequency value F of the measured signal can be obtained. The other signal under test passing through the isolation amplifier is sent to the external clock input of DDS as the reference clock when DDS works. At the same time, the external communication port of the DDS is connected to the single-chip microcomputer, and the single-chip microcomputer calculates the frequency division value used for communication with the DDS according to the existing DDS processing technology; the DDS uses AD9852, which has a 48-bit frequency control word register: Among them, F is the rough frequency value of the measured signal obtained by the counting of the travel time counter and the operation of the single-chip microcomputer, f is 1KHz, and the specific frequency division value obtained is written into the DDS buffer area through the serial communication sequence, and the frequency of 1KHz is obtained after DDS signal, and then send the obtained frequency signal to the low-pass filter module to obtain the final 1KHz frequency signal output.

Through the correction device shown in Figure 2, f1=f2=1KHz can be theoretically obtained.

As shown in FIG. 3 , the timing sequence of the specific processing method of the phase accumulation module.

GPS second pulse gate signal f0, the width is T=1 second; at high level, after t1 time, the rising edge of the first pulse of the frequency division signal f2 (1KHz) of VCXO makes the phase accumulation effective and starts to refer to the signal f1 The cumulative calculation of the phase difference with the VCXO frequency division signal. When T seconds later, when the high level of the GPS second pulse gate comes again, after t2 time, when the rising edge of the subsequent VCXO frequency signal arrives, the cumulative calculation process of the phase difference between the reference signal f1 and the VCXO frequency division signal is always Continuous; and the servo circuit shown in Figure 1 has been recording the specific value Δφ of the phase difference between the reference signal f1 and the VCXO frequency-divided signal f2, and the information of Δφ is judged by the servo circuit at this moment. Here, the time width of the enable signal (actual gate signal) is exactly equal to the number of complete cycles (N) of the VCXO frequency signal.

As shown in Figure 3, the frequency of the GPS second pulse f0 is 1 Hz, that is, T=1 second. From the above principle, it can be seen that the difference Δφ between f1 and f2 is performed once every T=1 second interval. When Δφ=0 after M times of sampling for T=1 second, then the servo module obtains the corresponding f1 and f2 signals from the phase difference data obtained within M*T time according to the traditional "phase difference-frequency difference" conversion theory The frequency difference value Δf, the servo module will convert Δf into ΔV (DC correction voltage value) according to the VCXO "voltage control slope" relationship shown in Figure 1 to enable the voltage control correction module to work on the VCXO.

As shown in Figure 1, select the corresponding voltage control slope value of the VCXO, such as selecting 1E-7/V, and select a VCXO with a small aging drift rate, for example: -1E-6/year, and convert according to 365 days a year: -2.7E-9/day.

As shown in Fig. 4, the curve part (atomic clock output) expresses the frequency sampling curve of a formed atomic clock obtained by traditional atomic clock technology. It can be seen from the curve in Figure 4 that during the entire sampling process, the output of the atomic clock has large fluctuation points: the upper limit of frequency fluctuation and the lower limit of frequency fluctuation. This is extremely unfavorable for some occasions that have strict requirements on the absolute value of the frequency, such as precise guidance of missiles and precise navigation of GPS. The new atomic clock obtained by using the device of this embodiment suppresses the output frequency of the atomic clock within the range of the expected value box shown in FIG. 4 . Concrete implementation scheme is as follows:

As shown in Figure 1, the voltage control slope data of VCXO is recorded internally, and the relationship of "voltage-frequency" is established to realize the range of expected values f _H and f _L shown in Figure 4, and the corresponding voltage values V1 and V2 are recorded by the servo . Assuming that the voltage value Vo delivered to the voltage control correction module by the servo circuit at a certain moment, according to the existing atomic clock technology, the quantum correction voltage ΔV is obtained at the quantum system. At this time, the servo judges whether the corresponding V=V ₀ ±ΔV value is It is within the range of V1 and V2, (1), if it is not within this range (V>V1 or V<V2), then the servo maintains the voltage value Vo to the voltage control correction module at this time; (2) if there is (V2<V< V1), then the servo sends the voltage V value to the voltage control correction module at this time. Thus, the output frequency of the atomic clock is controlled within the expected value box shown in FIG. 4 .

Combined with the selected VCXO aging drift data: -2.7E-9/day, and the voltage control slope value of VCXO: 1E-7/V, the servo circuit will make corresponding main adjustments to the correction voltage V every day, that is, make the correction voltage V every day , plus a fixed correction value, such as: 27mV, the corresponding VCXO output frequency will increase by 1E-7/V×27mV=+-2.7E-9, which can compensate the influence of the frequency change caused by the aging drift of the branch VCXO.

The temperature control module contains a temperature control chip (for temperature control) and a thermistor (for temperature measurement). The temperature value T can be set under the control of the central processor. Since the entire temperature control module is placed in the VCXO (temperature control module), the central processor can set the corresponding working environment temperature and obtain the actual working environment temperature information. Its principle is shown in Figure 5. Among them, two R and R1 are resistors with the same temperature coefficient, and their resistance value should be selected to be equivalent to Rk. The value of R1 here reflects the actual working environment temperature T. Rk is a thermistor attached to the surface of the temperature control module to sense the actual working environment temperature T. Therefore, when the working environment temperature T does not change, the bridge in the above figure is in balance, and the temperature compensation voltage value sent to the heating coil loop is 0. Once the temperature T of the working environment changes, the resistance value of the thermistor Rk will become smaller (temperature rise) or larger (temperature drop), then there is a voltage difference between the two ends of the bridge, which is differentially amplified by the operational amplifier A and becomes The temperature compensated voltage is fed to a voltage source and output to a conventional heating wire coil loop. The amplification gain of the whole circuit is adjusted by the negative feedback resistor Rw of the operational amplifier, and Rw is a digital potentiometer. By adjusting the resistance value of Rw, the compensation factor change function of the above-mentioned circuit can be achieved.

As shown in Figure 6, the bridge temperature measurement in the voltage control correction module is composed of two R4 with the same resistance value, a preset temperature value thermistor sensor Ro and a temperature measurement thermistor Rk. Ro determines the working environment temperature of the VCXO. When the working environment temperature of the VCXO is constant, that is, the measured value of the thermistor Rk1 is equal to the preset value Ro. At this time, the output voltage difference between the A and B terminals of the resistance bridge circuit will be 0, and the entire voltage control The module output Uout output is 0. When the temperature of the VCXO working environment changes, a certain voltage difference is formed at the A and B terminals of the bridge circuit, which is transmitted to A3 through the voltage follower A1 and A2 for differential amplification. Considering that the amplified voltage difference can be effectively collected , so a gain linear adjustment circuit A4 is added at the output end of the differential amplifier A3 as a gain control module. The obtained voltage control correction module voltage difference Uout is summed with the voltage control voltage generated by the microprocessor and then sent to the VCXO.

It should be understood that the parts not described in detail in this specification belong to the prior art.

Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, those of ordinary skill in the art should understand that these are only examples, and various variations or modifications can be made to these embodiments without departing from the principles of the present invention. principle and essence. The scope of the invention is limited only by the appended claims.

With reference to the following description and drawings, some specific implementation modes in the embodiments of the present invention are specifically disclosed to represent some ways of implementing the principles of the embodiments of the present invention, but it should be understood that the scope of the embodiments of the present invention Not subject to this restriction. On the contrary, the embodiments of the present invention include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.

Claims (9)

1. a kind of satellite navigation time complexity curve device, it is characterized in that, including temperature control module connection VCXO, VCXO connect DDS respectively Frequency division module, voltage-controlled correcting module, gain control module and conventional electronics, conventional electronics connection quantized system, pressure Correcting module connection servo circuit, DDS frequency division modules connection accumulation of phase module are controlled, accumulation of phase module connection gps signal connects Receipts machine；Gain control module is connected with voltage-controlled correcting module, and quantized system is sequentially connected servo circuit, accumulation of phase module；DDS Frequency division module includes isolated amplifier, walks hour counter, latch, DDS processing modules, low-pass filtering module and single-chip microcomputer；Every Connect away hour counter, DDS processing modules respectively from amplifier, walk hour counter connection latch, latch connection single-chip microcomputer； DDS processing modules connect single-chip microcomputer and low-pass filtering module respectively.

2. satellite navigation time complexity curve device as claimed in claim 1, it is characterized in that, DDS processing modules use AD9852.

3. satellite navigation time complexity curve device as claimed in claim 1, it is characterized in that, temperature control module includes voltage source, temperature Acquisition module, difference amplifier A, negative feedback resistor Rw and heating coil loop；Temperature collect module connect respectively voltage source and Difference amplifier A, difference amplifier A connect negative feedback resistor Rw, heating coil loop and voltage source respectively.

4. satellite navigation time complexity curve device as claimed in claim 3, it is characterized in that, temperature collect module includes two resistance R, the electric bridge of resistance R1 and resistance Rk compositions；And two resistance R and resistance R1 are the resistance with identical temperature coefficient, it hinders Value is suitable with resistance Rk；Resistance Rk is thermistor, and is affixed on the surface of temperature control modules.

5. satellite navigation time complexity curve device as claimed in claim 3, it is characterized in that, resistance Rw uses digital potentiometer.

6. satellite navigation time complexity curve device as claimed in claim 1, it is characterized in that, temperature control module is placed in VCXO.

7. satellite navigation time complexity curve device as claimed in claim 1, it is characterized in that, voltage-controlled correcting module includes electronic bridge measurement Module, voltage follower A1, A2, difference amplifier A3；Electronic bridge measurement module includes two resistance R4, resistance R₀With resistance Rk1 Form electric bridge, two resistance R4 and resistance R₀It is suitable with resistance Rk1 for the resistance with identical temperature coefficient, its resistance.

8. satellite navigation time complexity curve device as claimed in claim 7, it is characterized in that, gain control module is adjusted for gain linearity Economize on electricity road A4；It is connected with difference amplifier A3 output end.

9. satellite navigation time complexity curve device as claimed in claim 7, it is characterized in that, resistance Rk1 is thermistor, resistance R₀ For thermistor (temperature) sensor.