CN102315895B - Design method of L1 carrier frequency GPS (Global Processing System) signal jammer and jammer - Google Patents
Design method of L1 carrier frequency GPS (Global Processing System) signal jammer and jammer Download PDFInfo
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- CN102315895B CN102315895B CN201110196119.7A CN201110196119A CN102315895B CN 102315895 B CN102315895 B CN 102315895B CN 201110196119 A CN201110196119 A CN 201110196119A CN 102315895 B CN102315895 B CN 102315895B
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Abstract
The invention relates to the field of wireless communication, and discloses a design method of an L1 carrier frequency GPS (Global Processing System) signal jammer and the jammer. The design method comprises the following steps that: a C/A (Coarse/Acquisition) code is generated at a baseband, and a data code is modulated by the C/A coarse acquisition code with pseudo-random noise code characters to form spread spectrum modulation signals; at the same time, a random sequence with code element rate of 10.23MHz is used to simulate a precision code ( P code), and the data code is spread-spectrum modulated; and two paths of spread spectrum modulation signals are respectively modulated to the L1 carrier frequency of the GPS by using orthogonal carrier at two phases. Accordingly, a GPS receiver can be effectively jammed by transmitting the formed modulated waves out, so that the receiver can not receive useful signals so as to achieve the jamming purpose. In the invention, the energy can be completely covered on an L1 carrier frequency GPS signal frequency spectrum to carry out blocking jamming so as to achieve very good results.
Description
Technical field
The present invention relates to wireless communication field, particularly the GPS navigation countermeasure techniques in Military Electronics countermeasure techniques.
Background technology
In modern war, global position system GPS is accurately commanded control, precision strike and the accurate key of force projection by becoming enemy state and ally thereof.They take containment and the policy that weakens China always for a long time, therefore, improve to greatest extent the homing capability of own army, contain to greatest extent enemy's homing capability, are vital to the process of war.Can be divided into the interference to ground control station to the interference of gps system, the data feedback channel of GPS ground station is disturbed, the down channel of GPS receiver is disturbed.And the most possible exactly down channel of GPS receiver being disturbed of realizing.
The down channel of GPS receiver is disturbed and can be divided into pressing type interference and deception formula interference two large classes.Pressing type disturbs and refers to by transmitting interference signal and be compressed on the gps satellite signal of GPS receiver end, makes it not receive gps satellite signal and cannot locate, thereby reaching the object of interference.Interference involved in the present invention just belongs to pressing type and disturbs.Pressing type disturbs can be divided into again 3 kinds: spot jamming, barrage jamming and relevant interference.Barrage jamming claims again same frequency band broad-band interference, and it is the pseudo noise modulation signal that a kind of and spread frequency spectrum gps signal have same band.Barrage jamming is to disturb GPS receiver the most effective mode, does not also have up to now technology can effectively suppress and the interference signal of spread-spectrum signal equiband.For above feature, interference used in the present invention is exactly barrage jamming.
Very easy to not carrying out that the C/A code GPS receiver of anti-interference process disturbs.According to test, the FM noise GPS jammer of 1W power can make the commercial receiver in 22 kilometers lose efficacy.This can use theory analysis to reach a conclusion completely.
GPS jammer should have following characteristics:
The transmitting power lower limit of 1.GPS jammer should be for making receiver cannot receive normal gps signal.But transmitting power again can not be too large, otherwise jammer is easy to be detected and destroyed by enemy's detector, thus the interference effect of losing.
2. because GPS has disclosed operating frequency, so the most direct effective method is exactly that the energy of jammer is covered on the frequency spectrum of gps signal completely. carry out the interference of block type.In order to achieve the above object, the present invention will adopt the modulation system BPSK that generates L1 signal to modulate, and base band sources is used C/A code generator and simulation P code generator to modulate numeric data code.
Summary of the invention
In order to solve the above-mentioned problems in the prior art, the technical program proposes a kind of gps signal jammer method for designing and jammer of L1 carrier frequency, specific as follows:
A method for designing for the gps signal jammer of L1 carrier frequency, step comprises:
Step 1) first at baseband design C/A code microwave circuit, be used for generating C/A code; Then use C/A code modulating data code, obtain the first via signal after band spectrum modulation; Described C/A code is easy catch code;
Step 2) design P code microwave circuit simultaneously, be used for generating P code, then with P code, numeric data code is carried out to band spectrum modulation, obtain the second road signal after band spectrum modulation; Described P code is accurate measurement code;
Finally design microwave circuit, the two paths of signals that above-mentioned steps is obtained uses respectively carrier modulation orthogonal in two phase places to the L1 carrier frequency of GPS, then goes out by antenna transmission.
Described step 1) C/A code microwave circuit produce 37 kinds of C/A codes, the respectively real C/A code of corresponding each satellite; Described 37 kinds of C/A codes are designed to manually to adjust.
Described step 2) P code microwave circuit be to simulate P code by the random sequence of 10.23MHz chip rate.
Described C/A code microwave circuits becomes two shift registers, and it is N=2 that these two shift registers produce respectively code length
10-1=1023, cycle are two m sequences of 1 millisecond;
Wherein, the output of second shift register selection is to carry out exporting after XOR in two memory cell of non-last memory cell; Again the m sequence of the output of itself and first shift register is carried out to XOR, can obtain the C/A code of 1023 kinds of different structures;
These C/A codes have 1 millisecond of cycle that identical symbol width 0.98 is delicate and identical; From these codes, select part code to use to navigation satellite.
The gps signal jammer of the L1 carrier frequency that the design of a kind of said method obtains comprises: the gps signal jammer of L1 carrier frequency comprises base band band spectrum modulation module, BPSK modulator block and adder; Described base band band spectrum modulation module comprises C/A code generator, P code generator and data producer;
Described C/A code generator generates a certain the C/A code that satellite uses; Described P code generator generates P code;
The navigation message data that produce from outside data producer, carry out band spectrum modulation by C/A code, obtain first via signal; Described navigation message data are carried out band spectrum modulation by P code, obtain broadband signal, and this broadband signal is as the second road signal;
First via signal and the second road signal are modulated on L1 carrier wave by BPS K modulator block respectively; On L1 carrier wave, between first via signal and the second road signal carrier, there is the phase shift of 90 degree; Signal after first and second road carrier modulation is gone out by antenna transmission after being added by adder.
The C/A code that C/A code generator uses by a certain satellite of two 10 grades of feedback shift register combination results.
Described C/A code generator produces 37 kinds of C/A codes, the real C/A code of respectively corresponding each satellite; Described 37 kinds of C/A codes can manually be adjusted; Described P code generator is to simulate P code by the random sequence of 10.23MHz chip rate.
The method that C/A code can manually be adjusted is, the numbering of required satellite C/A code only need be set in the S function module parameter of C/A code generator, just can produce the C/A code of reference numeral satellite.
A kind of improvement is (with reference to figure 1), after described BPSK modulator block, is connected with rf modulations module and adder; Two carrier waves that utilization has 90 degree phase shifts are modulated to the signal after the signal after C/A code baseband modulation and P code baseband modulation on L1 carrier frequency respectively, and then two paths of signals is added by adder, finally goes out by antenna transmission.
Another kind of improvement is (with reference to figure 2), after described BPSK modulator block, be connected with multiple rf modulations module and real part extraction module, its course of work is that complex baseband signal is modulated and then got real part by multiple rf modulations module, has so just realized bandpass signal by Equivalent Base-Band pattern.
The technical problem underlying that the each execution mode of the present invention will solve is a kind of gps signal jammer for L1 carrier frequency of design, make designed jammer out can successfully disturb the gps signal that is operated in L1 carrier frequency, thereby the GPS receiver that works in this frequency cannot normally be worked.
The design's Method And Principle is to produce the easy catch code of C/A in base band, and use the easy catch code modulating data of the C/A code with Pseudo-Random Noise Code characteristic to form the signal after band spectrum modulation; Simulate accurate measurement code P code by the random sequence of 10.23MHz chip rate simultaneously, and numeric data code is carried out to band spectrum modulation; Signal after two-way band spectrum modulation uses respectively carrier modulation orthogonal in two phase places to the L1 carrier frequency of GPS;
The modulated wave forming is like this launched just can disturb GPS receiver effectively, makes receiver cannot receive useful signal, thereby reaches the object of interference.
Beneficial effect: the jamming signal bandwidth that the designed jammer of the present invention produces covers L1 frequency gps signal bandwidth completely, has realized the barrage jamming very strong to the L1 frequency of GPS.
Accompanying drawing explanation
Fig. 1 is a kind of model of embodiment,
Fig. 2 is the model of another kind of embodiment,
Fig. 3 is the baseband frequency spectrum figure after numeric data code is modulated by C/A code,
Fig. 4 is that numeric data code simulated the baseband frequency spectrum figure after the modulation of P code,
Baseband frequency spectrum figure after Fig. 5 two paths of signals is added,
The band passband spectrogram of Fig. 6 interference signal.
Embodiment
Embodiments of the present invention disclose the example for the gps signal jammer method for designing of L1 carrier frequency, comprise the following steps:
The gps signal jammer of a.L1 carrier frequency is made up of base band band spectrum modulation module, BPSK modulator block, adder,
B. base band band spectrum modulation module comprises C/A code generator, P code generator and three submodule compositions of data producer,
The C/A code that c.C/A code generator uses by a certain satellite of two 10 grades of feedback shift register combination results,
D. the navigation message data that data producer produced are used C/A code to carry out band spectrum modulation, form first via signal after modulation,
E. the navigation message data that data producer produced are used the higher simulation P code of bit rate to carry out band spectrum modulation, form the wider broadband signal of frequency band as the second road signal after modulation,
F. first via signal and the second road signal are modulated on L1 carrier wave by phase shift keying BPSK, on L1 carrier wave, between first via signal and the second road signal carrier, have the phase shift of 90 degree,
G. the signal after two-way carrier modulation is added by adder, finally goes out by antenna transmission.
Described C/A code generator can produce 37 kinds of C/A codes, respectively corresponding the real C/A code of each satellite, and can manually adjust in jammer;
Described P code generator uses the method for simulation to produce the random sequence equating with the bit rate of P code, and this is because the information of P code holds in close confidence, cannot obtain.
With reference to figure 1, utilize two 10 grades of feedback shift register combination results easily to catch C/A code.It is N=2 that two shift registers produce respectively code length
10-1=1023, cycle are two m sequences of 1 millisecond.Wherein the output of second shift register is not a memory cell in the end, but selects wherein two memory cell to carry out exporting after XOR, then itself and first m sequence is carried out to XOR, can obtain the C/A code of 1023 kinds of different structures.These C/A codes have 1 millisecond of cycle that identical symbol width 0.98 is delicate and identical.From these codes, select part code to use to navigation satellite.The transmission rate of navigation message is 50b/s, then uses C/A code to modulate navigation message, produces first via spread-spectrum signal after modulation.
P code is the accurate measurement code of satellite, bit rate is 10.23MHz, it respectively has two 12 grades of feedback shift registers in conjunction with producing by two groups, its basic principle is similar to C/A code, but its line design details is more than C/A code complexity, and U.S. government holds in close confidence P code, so the present invention replaces the generation of P code with the random binary sequence that bit rate is 10.23MHz, then use simulation P code to modulate navigation message, after modulation, produce the second road spread-spectrum signal.
First via signal and the second road signal are modulated on L1 carrier wave by phase shift keying BP SK, on L1 carrier wave, between first via signal and the second road signal carrier, there is the phase shift of 90 degree, the signal after two-way carrier modulation is added by adder, finally go out by antenna transmission.
With reference to figure 2, the present invention has used the equivalent low pass model of bandpass signal to carry out the design of another kind of simulating scheme: the frequency content of supposing a real-valued signal concentrates on frequency f
cin near narrowband frequency range, its analytic signal frequency-domain expression is: S
+(f)=2u (f) S (f); Time-domain expression is: s
+(t)=F
-1[2u (f)] * F
-1[S (f)]; Analytic signal is bandpass signal, and the frequency-domain expression of its equivalent low pass is: S
l(f)=S
+(f+f
c); The time-domain expression of equivalence low pass is:
in sum, the relation of bandpass signal and equivalent low-pass signal can be expressed as:
Transmit and energy can be covered completely on the gps signal frequency spectrum of L1 carrier frequency, carry out barrage jamming, represent by ± A the random binary signal that 0 and 1 sequence forms respectively, the auto-correlation function of this random process has leg-of-mutton waveform, can be represented by the formula:
Therefore the power spectral density of this random process is:
Expression formula, can find out S
x(f) be ± 1/T first zero point, because C/A code is a kind of Pseudo-Random Noise Code, and code check is 1.023Mb/s, and the data transfer rate of navigation message is 50b/s, so have the feature of random binary signal by the navigation message after the modulation of C/A code, mainly concentrate on-1.023MHz of its base band energy (uses rectangular window to form filtering) within the scope of 1.023MHz; In like manner can be through the mainly concentrate on-10.23MHz of its base band energy of navigation message after P code modulation within the scope of 10.23MHz, two paths of signals passes through carrier modulation after being added, can form the wideband interferer signal that on L1 frequency, bandwidth is 20.46MHz, its main energy covers the L1 frequency working range of GPS completely, thereby forms very strong barrage jamming.
Claims (8)
1. a method for designing for the gps signal jammer of L1 carrier frequency, is characterized in that comprising step:
Step 1), first at baseband design C/A code microwave circuit, is used for generating C/A code; Then use C/A code modulating data code, obtain the first via signal after band spectrum modulation; Described C/A code is easy catch code;
Step 2) design P code microwave circuit simultaneously, be used for generating P code, then with P code, numeric data code is carried out to band spectrum modulation, obtain the second road signal after band spectrum modulation; Described P code is accurate measurement code;
Finally design microwave circuit, the two paths of signals that above-mentioned steps is obtained uses respectively carrier modulation orthogonal in two phase places to the L1 carrier frequency of GPS, then goes out by antenna transmission.
2. method for designing according to claim 1, is characterized in that the C/A code microwave circuit of described step 1) produces 37 kinds of C/A codes, the real C/A code of respectively corresponding each satellite; Described 37 kinds of C/A codes are designed to manually to adjust;
Described step 2) P code microwave circuit be to simulate P code by the random sequence of 10.23MHz chip rate.
3. method for designing according to claim 1, is characterized in that described C/A code microwave circuits becomes two shift registers, and it is N=2 that these two shift registers produce respectively code length
10-1=1023, cycle are two m sequences of 1 millisecond;
Wherein, the output of second shift register selection is to carry out exporting after XOR in two memory cell of non-last memory cell; Again the m sequence of the output of itself and first shift register is carried out to XOR, can obtain the C/A code of 1023 kinds of different structures;
These C/A codes have 1 millisecond of identical symbol width 0.98 microsecond and identical cycle; From these codes, select part code to use to navigation satellite.
4. a gps signal jammer for the L1 carrier frequency that described in claim 1, method design obtains, is characterized in that comprising: the gps signal jammer of L1 carrier frequency comprises base band band spectrum modulation module, BPSK modulator block and adder; Described base band band spectrum modulation module comprises C/A code generator, P code generator and data producer;
Described C/A code generator generates a certain the C/A code that satellite uses; Described P code generator generates P code;
The navigation message data that data producer produces, carry out band spectrum modulation by C/A code, obtain first via signal; Described in , navigation message data are carried out band spectrum modulation by P code, obtain broadband signal, and this broadband signal is as the second road signal;
First via signal and the second road signal are modulated on L1 carrier wave by BPSK modulator block respectively; On L1 carrier wave, between first via signal and the second road signal carrier, there is the phase shift of 90 degree; Signal after first and second road carrier modulation is gone out by antenna transmission after being added by adder.
5. gps signal jammer according to claim 4, is characterized in that the C/A code that C/A code generator uses by a certain satellite of two 10 grades of feedback shift register combination results.
6. gps signal jammer according to claim 4, is characterized in that
Described C/A code generator produces 37 kinds of C/A codes, the real C/A code of respectively corresponding each satellite; Described 37 kinds of C/A codes can manually be adjusted; Described P code generator is to simulate P code by the random sequence of 10.23MHz chip rate.
7. gps signal jammer according to claim 4, it is characterized in that being connected with rf modulations module between described BPSK modulator block and adder, two carrier waves that the utilization of described BPSK modulator block has the phase shift of 90 degree are modulated to the signal after the signal after C/A code baseband modulation and P code baseband modulation on L1 carrier frequency respectively, and then by rf modulations module, two paths of signals is modulated, then two paths of signals is added by adder, finally goes out by antenna transmission.
8. gps signal jammer according to claim 4, it is characterized in that being connected with multiple rf modulations module and real part extraction module after described adder, complex baseband signal is modulated and is then got real part by multiple rf modulations module, has realized bandpass signal by Equivalent Base-Band pattern.
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| CN102866406B (en) * | 2012-09-21 | 2014-04-30 | 桂林电子科技大学 | Global position system (GPS) deception jamming method and system |
| WO2018184231A1 (en) | 2017-04-07 | 2018-10-11 | SZ DJI Technology Co., Ltd. | Jamming device and jamming method |
| CN108562915A (en) * | 2018-01-25 | 2018-09-21 | 扬州市职业大学 | A kind of GPS pressing types conflicting mode |
| CN114866128B (en) * | 2022-04-07 | 2023-09-05 | 中国人民解放军战略支援部队信息工程大学 | Satellite communication critical interference power threshold estimation method and system based on spread spectrum signal |
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| CN101246207A (en) * | 2007-12-18 | 2008-08-20 | 上海复控华龙微系统技术有限公司 | Implementing method for generating data code stream after scrambling in GPS disturbance system |
| CN101943756A (en) * | 2010-08-13 | 2011-01-12 | 费杰 | GPS signal interference method |
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| CN101246207A (en) * | 2007-12-18 | 2008-08-20 | 上海复控华龙微系统技术有限公司 | Implementing method for generating data code stream after scrambling in GPS disturbance system |
| CN101943756A (en) * | 2010-08-13 | 2011-01-12 | 费杰 | GPS signal interference method |
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