CN1189622A - Timing method and device based on GPS signals - Google Patents
Timing method and device based on GPS signals Download PDFInfo
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- CN1189622A CN1189622A CN97108825A CN97108825A CN1189622A CN 1189622 A CN1189622 A CN 1189622A CN 97108825 A CN97108825 A CN 97108825A CN 97108825 A CN97108825 A CN 97108825A CN 1189622 A CN1189622 A CN 1189622A
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- 238000012545 processing Methods 0.000 claims description 5
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Abstract
A timing method based on GPS signals and its apparatus feature use of a binary voltage control table which uses phase differente change value and rate as arguments. A three-stage transistor circuit is used to overcome the S. A. interference and frequency shift and jitter of voltate-controlled transistor by regulating voltage value of transistors.
Description
The present invention relates to provide in the communications field technology of precision clock, more particularly, relate to a kind of timing method and equipment based on GPS.
The whole world that U.S. Department of Defense sets up regularly location navigation satellite system (NAVSTARGPS is hereinafter to be referred as gps system) for people whenever in any place accurate timing and location be provided may.But U.S. government has and has added selectivity interference (SELECTIVE AVAILABILITY disturbs hereinafter to be referred as S.A.) in the signal of the satellites transmits of being intended to, and the timing bearing accuracy that domestic consumer is obtained descends greatly, timing accuracy reduces to ± and more than the 150ns.Various countries major company is corresponding to develop various GPS receiving equipments to extract a metastable output from the satellite-signal that is being mingled with the S.A. interference, wherein HP 58503 gps times of Hewlett-Packard and frequency standard receiver disturb with elimination S.A. by the smothing filtering of long-time (a hour), obtain effect preferably.But this scheme needs an expensive long-time stable crystal (more than the secondary), could come filtering S.A. to disturb with long-time smothing filtering effectively, crystal instability (for example adopt be three grades of crystal) else if, the frequency drift of crystal self is considerable in one hour, can't carry out long smothing filtering; This scheme also needs the crystal periphery circuit of corresponding complexity so that the crystal operate as normal; In addition, in order to carry out long smothing filtering, need the data of jumbo storer with storage a very long time record, and worsen suddenly in satellite signal quality, under the situation through recovering again after a while, because this scheme averages the data of non-volatile recording, the data of record also will still be continued to use as valid data in a very long time when satellite signal quality worsens, and make this equipment need the long period could recover stable output.
Purpose of the present invention overcomes above-mentioned shortcoming exactly, provides a kind of cost low, simple in structure, can catch gps signal rapidly, and can recover the timing method and the equipment based on gps signal of stable output under the situation about recovering again after satellite-signal worsens rapidly.
For realizing purpose of the present invention, the present invention is based on following design: select one fully long period, guarantee to adjust crystal in time simultaneously, to solve the frequency drift problem of three grades of crystal by the smoothly filtering S.A. interference effectively in this section period; And introduce one to differ changing value and to differ the binary voltages control table that rate of change is an independent variable, take all factors into consideration the magnitude of voltage of adjusting crystal, to solve the phase drift problem that can't recover that the crystal frequency that causes because of simple phase modulation is shaken or simple frequency modulation causes.
Each the GPS pulse that need relatively receive based on the timing method of gps signal of the present invention and the phase differential of local divided pulse, and store this phase differential, it is characterized in that: the data memory space N of requirement setting that disturbs and in time adjust crystal according to effective filtering S.A., after being filled with N described phase differential, data are carried out smoothing processing, adjust local crystal (producing behind the output frequency division of local divided pulse by local crystal).
Wherein said to data carry out smoothing processing, the process of adjusting local crystal comprises following concrete steps:
(1) calculates the mean value of N the described phase differential stored, obtain one and on average differ, and store this and on average differ;
(2) described on average differing with a predefined standard differed comparison, obtain differing changing value E;
Described on average the differing with last described on average differing of being stored that (3) will obtain specifically compares, and obtains differing rate of change EC;
(4) according to described changing value E and the described rate of change EC that differs of differing, consult deposit in advance differ changing value E and the described rate of change EC that differs is that the crystal control voltage difference Δ U that should apply is determined in the binary voltages control table of independent variable with described;
(5) described crystal control voltage difference Δ U is added on the current control voltage, adjusts local crystal.
Timing device based on gps signal of the present invention comprises GPS receiving antenna, GPS card, phase detector, CPU, RAM, EPROM, D/A converter, voltage-controlled crystal (oscillator), frequency multiplier and frequency divider.Described GPS cartoon is crossed described gps antenna receiving satellite signal, therefrom recover the GPS pulse and give described phase detector, the phase differential of the local divided pulse that GPS pulse that described phase detector relatively recovers from satellite-signal and local frequency divider provide, give described CPU with this phase differential, described CPU is stored in this phase differential among the described RAM, after described RAM stores a certain amount of data, described CPU handles this batch data and obtains described changing value E and the described rate of change EC that differs of differing, differ changing value E and the described rate of change EC that differs searches the described binary voltages control table of storing among the described EPROM according to described, determine to regulate the described crystal control voltage difference Δ U of described voltage-controlled crystal (oscillator), by described D/A converter described Δ U is added on the described voltage-controlled crystal (oscillator), adjusts the output frequency of described voltage-controlled crystal (oscillator).Described frequency divider and described frequency multiplier are given in the output of described voltage-controlled crystal (oscillator) simultaneously, described frequency divider produces the output of the timing device based on gps signal of the present invention, and produce local divided pulse, described frequency multiplier produces the 65MHz signal and gives described phase detector, count with the 65MHz signal, write down differing of local divided pulse and GPS pulse.
Because what the present invention adopted is three grades of crystal, therefore greatly reduce the cost of present device; Simultaneously by adopting the inventive method to solve the frequency drift and the frequency jitter problem of S.A. interference and voltage-controlled crystal (oscillator) preferably, make the output accuracy of present device can be comparable, show that after tested present device has been achieved as follows performance index: the phase drift characteristic: hundred seconds level＜50ns with the external same category of device that has adopted gem-quality crystal (more than the secondary)
Kilosecond level＜100ns
Maximum＜170ns frequency characteristic: short-term (shake)≤5 * 10
-10
For a long time≤1 * 10
-13In addition; present device need not jumbo storer and complicated crystal holding circuit; thereby make circuit structure simple; and worsen suddenly at gps signal; under the situation through recovering again after a while; can be with the very fast renewal of data of storage, therefore (about four minutes) recover stable output rapidly.
Below in conjunction with the description of drawings embodiments of the invention.In the accompanying drawing:
Fig. 1 is the structural representation of the embodiment of timing device based on gps signal of the present invention;
Fig. 2 is the process flow diagram of the timing method based on gps signal of the present invention;
The process flow diagram of Fig. 3 for catching GPS pulse per second (PPS) frequency step S202 fast shown in Fig. 2;
Fig. 4 is the process flow diagram of the precise frequency of output shown in Fig. 2 step S206;
Fig. 5 is the process flow diagram of Control of Voltage table described in structure the present invention.
Referring to Fig. 1, this illustrates the timing device based on gps signal of the present invention and comprises: GPS receiving antenna 101, GPS card 102, phase detector 103, CPU104, RAM105, EPROM106, D/A converter 107, voltage-controlled crystal (oscillator) 108, frequency multiplier 109 and frequency divider 110.Described GPS card 102 (the VP ONCORE that produces for motorola inc in the present embodiment, per second pulse per second (PPS) SP once is provided) by described gps antenna 101 receiving satellite signals, therefrom recover the GPS pulse per second (PPS) and give described phase detector 103, the phase differential of the 1Hz signal that pulse per second (PPS) SP that described phase detector 103 relatively recovers from satellite-signal and local frequency divider 110 provide, give described CPU104 with the phase differential that obtains, described CPU104 is stored in this phase differential among the described RAM105, after described RAM is filled with a certain amount of data, described CPU handles this batch data and obtains differing changing value E and differ rate of change EC, search store among the described EPROM106 one according to E and EC to differ changing value and to differ the binary voltages control table that rate of change is an independent variable (back will be described the generation of this table in conjunction with Fig. 5 in detail), determine to regulate the crystal control voltage difference Δ U of described voltage-controlled crystal (oscillator) 108, by described D/A converter 107 Δ U is added on the described voltage-controlled crystal (oscillator) 108, adjusts the output frequency of described voltage-controlled crystal (oscillator) 108; Described CPU also with described GPS cartoon letters, the state parameter of GPS card is provided with and reads information such as whether normal satellite-signal from the GPS card.Described frequency divider 110 and described frequency multiplier 109 are given in the output of described voltage-controlled crystal (oscillator) simultaneously, the signal that described frequency divider 110 produces 2MHz and 8KHz is as the output of the timing device based on gps signal of the present invention, and produce the 1Hz signal as local pulse per second (PPS), described frequency multiplier 109 produces the 65MHz signal and gives described phase detector 103, count with the 65MHz signal, write down the phase differential of local pulse per second (PPS) and GPS pulse per second (PPS).Described RAM105 also differs changing value according to the instruction storage of described CPU and differs data such as rate of change.The required program of described CPU104 exists among the described EPROM106.
Timing method based on gps signal of the present invention needs each the GPS pulse per second (PPS) that per second once relatively receives and the phase differential of local pulse per second (PPS), and store this phase differential, carry out following concrete steps as shown in Figure 2 simultaneously: at first finish initial work at step S201, comprise the RAM zero clearing, set crystal initialization voltage, and the phase differential number M and the N that set the requirement storage, described phase differential number has reflected the time interval that crystal control voltage is adjusted, and M＜N, the value of M is less, to satisfy the requirement of catching GPS pulse per second (PPS) frequency fast, its optimum range is 2～7, the value of N need satisfy effectively, and filtering S.A. disturbs, can in time adjust the requirement of voltage-controlled crystal (oscillator) again, its optimum range is 30～180, enters step S202 afterwards: the frequency of catching the GPS pulse per second (PPS) fast; Enter step S203 then: judge whether satellite-signal is normal, as be judged as ' denying ', then repeated execution of steps S201 after step S204 resets; Be judged as ' being ' as step S203, then execution in step S205: the more up-to-date GPS pulse per second (PPS) of receiving and the phase differential of local pulse per second (PPS) are set at standard with this phase differential and differ and store; Enter step S206 then: enter lock-in state, further adjust local pulse per second (PPS), the output precise frequency; Judge at step S207 whether satellite-signal is normal then, as be judged as ' being ', then return execution in step S206; Be judged as ' denying ' as step S207, then enter step S208: remain on the output that obtains among the step S206, and the data of storage before utilizing are when needed adjusted to crystal; Judge in step S209 then whether satellite-signal is normal, as be judged as ' denying ', then return execution in step S208; Be judged as ' being ' as step S209, then execution in step S206.Need illustrate, several circle queue data structure data such as phase differential, crystal current pressure-controlled difference of the stored record GPS pulse per second (PPS) of getting off and local pulse per second (PPS) have respectively been set up among the present invention, when formation was expired, the data of storage were erased automatically earlier; The present invention stores differing of about 8000 GPS pulse per second (PPS)s and local pulse per second (PPS), can be not normal at for example satellite-signal, S.A. disturbs and strong etc. in particular cases utilize these data that crystal is done special adjustment.
Fig. 3 illustrates the included step of the S202 of step shown in Fig. 2: at first judge whether to be filled with M phase difference value (M sets) at step S301 in step S201, as be judged as ' denying ', execution in step S301 after then delaying time 1 second in step S302; Be judged as ' being ' as step S301, then direct execution in step S303: M phase difference value of storage is average, obtain one and on average differ, and store this and on average differ; Execution in step S304 then: judge whether to be filled with M phase difference value, as be judged as ' denying ', then time-delay execution in step S304 after 1 second in step S305; Be judged as ' being ' as step S304, then direct execution in step S306: M phase difference of storage is average, obtain one and on average differ, and store this and on average differ; Enter step S307 then: this on average differing with on average differing of last stored of trying to achieve is relatively obtained differing changing value E; Then enter step S308: set and differ rate of change EC=0; In step S309, differ changing value E and differ rate of change EC inquiry Control of Voltage table (building process of Control of Voltage table will be described) in the explanation in conjunction with Fig. 5 then, obtain crystal current pressure-controlled difference DELTA U and store this difference according to described; Follow execution in step S310: Δ U is added on the current control voltage, adjusts the output frequency of crystal; Execution in step S311 then: judge whether catch process soon finishes, as be judged as ' denying ', then return execution in step S304; Be judged as ' being ' as step S311, then enter step S203 shown in Figure 2.
Referring to Fig. 4, this illustrates the included concrete steps of step S206 shown in Figure 2: at first judge whether to be filled with N phase difference value (N sets) at step S401 in step S201, as be judged as ' denying ', repeated execution of steps S401. after in step S402, delaying time 1 second; Be judged as ' being ' as step S401, then direct execution in step S403: N phase difference value of storage is average, obtain one and on average differ, and store this and on average differ; Execution in step S404 then: the standard of setting among this on average differing of trying to achieve and the step S205 differed relatively obtain differing changing value E; Then enter step S405: on average the differing of the more current last time that on average differs Yu stored, obtain differing rate of change EC (because in step S201 with the RAM zero clearing, for the first time during execution in step S405, described ' on average differing of the last time of being stored ' is set to 0); Enter step S406 then: according to differing changing value E and differ rate of change EC, and what deposit in advance is that the crystal control voltage difference Δ U that should apply is found in the binary voltages control table of independent variable with E and EC; Execution in step S407 then: Δ U is added on the current control voltage, adjusts local pulse per second (PPS).Need illustrate, step S403 ask on average differ before, can be earlier carry out filtering to the phase difference of storage, remove and differ the bigger data of shake.
Fig. 5 illustrates structure and differs changing value and describedly differ the process flow diagram that rate of change is the described binary voltages control table of independent variable with described: at first limit the quantizing range that differs changing value E (90ns～90ns) at step S501, and be X interval (X gets 13 in this example) with this scope division, enter step S502 then: limit the quantizing range differ rate of change EC (90ns～90ns), and be Y interval (Y gets 13 in this example) with this scope division, follow execution in step S503: the quantizing range of qualification crystal control voltage difference Δ U (0.002V～0.002V), and be Z interval (Z gets 13 in this example) with this scope division, then at step S504 according to formula Δ U=λ
1E+ λ
2EC (λ herein
1, λ
2Expression is to the weighted value of E and EC) determine corresponding to each described changing value E and the described crystal control voltage difference Δ U that differs rate of change EC of differing promptly obtained a binary voltages control table, this binary voltages control table of storage in step S505 at last.
More than though the present invention has been described in conjunction with the embodiments; but obviously protection scope of the present invention is not limited thereto; those skilled in the art also may make all conspicuous changes; for example: in step S309, can not adopt the mode of inquiry binary voltages control table, and directly according to formula Δ U=λ
1E+ λ
2EC tries to achieve described crystal current pressure-controlled difference DELTA U; Adopt the GPS card of other companies, other models; Storer with other form replaces employed RAM and/or EPROM in the embodiment of the invention; Can adopt other forms of data structure during the storage data; Can also change data quantity stored among the present invention, the protection domain of described M and N, and differ changing value, differ rate of change, the span of crystal control voltage difference and the interval of division, or the like.Therefore, protection scope of the present invention is only determined by claims.
Claims (12)
1. timing method based on gps signal, comprise each the GPS pulse of relatively receiving and the phase differential of local divided pulse, and store this phase differential, it is characterized in that: the data memory space N of requirement setting that disturbs and in time adjust crystal according to effective filtering S.A., after being filled with N described differing, data are carried out smoothing processing, adjust described crystal.
2. the timing method based on gps signal as claimed in claim 1, it is characterized in that described to data carry out smoothing processing, the process of adjusting described crystal comprises following key step:
(1) calculates the mean value of N the described phase differential stored, obtain one and on average differ, and store this and on average differ;
(2) described on average differing with a predefined standard differed comparison, obtain differing changing value E;
(3) described on average the differing with last described on average differing of being stored that this is obtained compares, and obtains differing rate of change EC;
(4) differ changing value and the described rate of change that differs according to described, and deposit in advance differ changing value and the described rate of change that differs is that the crystal control voltage difference Δ U that should apply is determined in the binary voltages control table of independent variable with described;
(5) described crystal control voltage difference Δ U is added on the current control voltage, adjusts local pulse per second (PPS).
3. the timing method based on gps signal as claimed in claim 2 is characterized in that the step that makes up described binary voltages control table may further comprise the steps again:
-determine the described quantizing range that differs changing value E, and be several class with this scope division;
-determine the described quantizing range that differs rate of change EC, and be several class with this scope division;
-determine the quantizing range of described crystal control voltage difference Δ U, and be several class with this scope division;
-according to formula Δ U=λ
1E+ λ
2EC determines corresponding to each described changing value and the described described crystal control voltage difference Δ U that differs rate of change of differing promptly obtained the binary voltages control table as the Control of Voltage table;
This binary voltages control table of-storage.
4. the timing method based on gps signal as claimed in claim 2, it is characterized in that calculate described ask on average differ before, can carry out filtering to the described phase difference of storage earlier, remove and differ the bigger data of shake.
5. the timing method based on gps signal as claimed in claim 2 is characterized in that the step (4) of the described binary voltages control table of described inquiry can replace with following steps: by formula Δ U=λ
1E+ λ
2EC directly tries to achieve described crystal current pressure-controlled difference.
6. as claim 3,4 or 5 described timing methods based on gps signal, the span that it is characterized in that described N is 30～180.
7. the timing method based on gps signal as claimed in claim 6, it is characterized in that setting the described quantizing range that differs changing value is-90ns to 90ns, the described quantizing range that differs rate of change is-90ns to 90ns that the quantizing range of described crystal control voltage difference is-0.002V to 0.002V.
8. the timing method based on gps signal as claimed in claim 7, it is characterized in that with describedly differ changing value, the described quantizing range that differs rate of change, described crystal control voltage difference all is divided into 13 class.
9. as claim 1,2,3,4,5,7 or 8 described timing methods, it is characterized in that: store described phase differential and the described circle queue data structure that adopted when on average differing based on gps signal.
10. the timing method based on gps signal as claimed in claim 9, its feature also is: can utilize the described phase difference of being preserved to adjust crystal under special circumstances.
11. a realization comprises as the timing device based on gps signal of method as described in the claim 1-10:
The antenna of-receiving satellite signal (101);
The GPS receiving circuit (102) of-recovery GPS pulse from satellite-signal;
-voltage-controlled crystal (oscillator) (108) and the frequency divider (110) of local divided pulse be provided;
The phase detector (103) of-comparison GPS pulse and local divided pulse phase differential;
The RAM (105) of-storage data;
-data are carried out smoothing processing, provided described crystal to control the CPU (104) of voltage difference;
-described crystal control voltage difference is added in D/A converter (107) on the described voltage-controlled crystal (oscillator) (108); It is characterized in that this equipment also comprises:
-one storer (106) that is used for stored programme and described binary voltages control table.
12. the timing device based on gps signal as claimed in claim 11 is characterized in that: also comprise a frequency multiplier (109) that produces the 65MHz signal of the phase differential that writes down local divided pulse and GPS pulse.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97108825A CN1084479C (en) | 1997-01-27 | 1997-01-27 | Timing method and device based on GPS signals |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97108825A CN1084479C (en) | 1997-01-27 | 1997-01-27 | Timing method and device based on GPS signals |
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| Publication Number | Publication Date |
|---|---|
| CN1189622A true CN1189622A (en) | 1998-08-05 |
| CN1084479C CN1084479C (en) | 2002-05-08 |
Family
ID=5170672
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN97108825A Expired - Lifetime CN1084479C (en) | 1997-01-27 | 1997-01-27 | Timing method and device based on GPS signals |
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| CN (1) | CN1084479C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100397094C (en) * | 2002-03-28 | 2008-06-25 | 摩托罗拉公司(在特拉华州注册的公司) | Time determination in satellite positioning system receivers and methods therefor |
| CN1784841B (en) * | 2003-03-27 | 2010-08-11 | 高通股份有限公司 | Virtual real-time clock based on time information from multiple communication systems |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100583685C (en) * | 2006-08-11 | 2010-01-20 | 华为技术有限公司 | Method for improving satellite time synchronism pulse keeping performance |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2091962A1 (en) * | 1992-03-31 | 1993-10-01 | Mark L. Witsaman | Clock synchronization system |
| US5440313A (en) * | 1993-05-27 | 1995-08-08 | Stellar Gps Corporation | GPS synchronized frequency/time source |
| US5481258A (en) * | 1993-08-11 | 1996-01-02 | Glenayre Electronics, Inc. | Method and apparatus for coordinating clocks in a simulcast network |
-
1997
- 1997-01-27 CN CN97108825A patent/CN1084479C/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100397094C (en) * | 2002-03-28 | 2008-06-25 | 摩托罗拉公司(在特拉华州注册的公司) | Time determination in satellite positioning system receivers and methods therefor |
| CN1784841B (en) * | 2003-03-27 | 2010-08-11 | 高通股份有限公司 | Virtual real-time clock based on time information from multiple communication systems |
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| CN1084479C (en) | 2002-05-08 |
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