CN203658585U - Satellite signal capture device - Google Patents

Abstract

The utility model discloses a satellite signal capture device which comprises a local carrier generator, a local code generator, a multiplier, an integrator and a capture and detection module. The capture device divides input signals into an I path and a Q path; the local carrier generator generates local carrier waves to mix frequency of the I path of signals, the phase of local carrier waves is shifted for 90 degree, and frequency of the local carrier waves is then mixed with frequency of the Q path of signals; the local code generator generates spreading codes to multiply the signals after frequency mixing; the integrator carries out integration on spreading-code periods respectively on the multiplication results of the I path and the Q path to obtain single-period integration results of the I path and the Q path; and finally the capture and detection module carries out coherent, non-coherent or other processing on the single-period integration results of the I path and the Q path to detect and capture satellite signals. The satellite signal capture device overcomes the problem that coherent integration cannot be directly implemented due to the fact that phases of the single-period integration results are different; and the satellite signal capture device has a higher flexibility of satellite signal capture.

Description

A kind of satellite signal acquisition device

Technical field

The utility model relates to a kind of catching method of satellite-signal, relates in particular to a kind of acquisition equipment of highly sensitive Big Dipper satellite signal.

Background technology

Catching of satellite-signal is that the local spreading code reappearing of satellite-signal and satellite navigation receiver of input carries out related operation (related operation refers to that input signal and local signal multiply each other, then integration or cumulative), then according to the correlation properties of spreading code, detect accumulation result and whether occur peak value, whether exist and code phase location thereby detect satellite-signal.

In the time that satellite-signal is stronger, adopt the integration in 1 spreading code cycle obvious correlation peak just can be detected.In the time that satellite-signal is weak, need to adopt the integration in multiple spreading code cycles, improve storage gain, correlation peak just can be detected.

The integration in multiple spreading code cycles has coherent integration and two kinds of modes of non-coherent integration.Coherent integration has kept the phase information of signal, so need in coherent integration process to ensure that the polarity in multiple spreading code cycles is consistent, therefore the time span of coherent integration is subject to the restriction of modulation signal.Non-coherent integration is the phase information of holding signal not, is not therefore subject to the impact of modulation signal, but in the time that input signal is weak, because Squared Error Loss can reduce non-coherent integration to improving the effect of gain.So detect weak satellite-signal and be need to be longer the coherent integration time.

The general coherent integration that adopts multiple spreading code cycles of satellite navigation receiver coordinates non-coherent integration repeatedly again, then by integral result and thresholding comparison.For example, for the L1CA code satellite-signal of GPS, the spreading code cycle is 1 millisecond, Data Modulation rate is 50bps, and continuous 20 spreading code cycle polarity that data periodic packets contains are consistent, so can adopt the coherent integration of maximum 20ms to add the non-coherent integration of several times.

For Beidou satellite navigation system BDS, due to the difference of signal modulation feature, cannot implement above-mentioned traditional detection method.Big-dipper satellite is broadcast two kinds of navigation signals in B1 frequency, is respectively D1 signal and D2 signal.

The spreading code cycle of D1 signal is 1 millisecond, and Data Modulation rate is 50bps.A data periodic packets is drawn together 20 spreading code cycles.On D1 signal, modulate in addition NH code (Neumann Hoffman code), caused the polarity difference of 20 spreading codes that a data periodic packets contains.The D2 signal spread-spectrum code cycle is 1 millisecond, and Data Modulation rate is 500bps.A data periodic packets is drawn together 2 spreading code cycles, and the polarity of 2 spreading codes within a data cycle is identical.

For BDS satellite D1 signal, due to the existence of NH coding, even within the same modulating data cycle, continuous spreading code polarity is also different.Add repeatedly non-coherent integration so can only adopt the coherent integration in single spreading code cycle.The less coherent integration time (1 millisecond of single spreading code cycle), is difficult to detect weak signal, and restriction satellite navigation receiver is caught the sensitivity of Big Dipper satellite signal.

Therefore, for the spreading code polarity difference of Beidou satellite navigation system D1 signal, those skilled in the art is devoted to develop a kind of in the situation that continuous single spreading code periodic phase is different, still can carry out the coherent integration in multiple spreading code cycles, and coordinate repeatedly the Big Dipper satellite signal capture method and apparatus of non-coherent integration.

Utility model content

Because the above-mentioned defect of prior art, technical problem to be solved in the utility model is to provide a kind of catching method and device of high sensitivity Big Dipper satellite signal.

For achieving the above object, the utility model provides a kind of high sensitivity Big Dipper satellite signal capture method, it is characterized in that, comprising:

Step (401) input input signal;

Described input signal and local carrier signal are carried out mixing by step (402), obtains the baseband signal on I road and the baseband signal on Q road;

The baseband signal on the baseband signal of step (403) to described I road and described Q road is carried out respectively spreading code modulation and spreading code monocycle integration;

Step (404) is carried out leggy coherent integration to the result of described monocycle integration, and integral result is asked to amplitude or power;

Step (405), to the described amplitude of trying to achieve in step (404) or described power data, carries out noncoherent accumulation computing jointly;

Step (406), compares the accumulated value after noncoherent accumulation and thresholding, detects and capturing satellite signal.

Further, described input signal is the digital medium-frequency signal that arrive of the satellite-signal that receives of satellite navigation receiver after radio frequency amplification, down coversion and quantification treatment.

Further, in described step (402), described local carrier signal is identical with the phase place of described input signal, and described I roadbed band signal is described input signal and described local carrier signal mixing gained; The orthogonal signal mixing gained that described Q roadbed band signal is described input signal and described local carrier signal.

Further, described step (404) the result of described monocycle integration is carried out to leggy coherent integration, and integral result is asked to amplitude or power, comprising:

First the result of the single spreading code cycle integrated to described I road and described Q road is converted to respectively several data groups of parallel output, and each data group comprises m data, and a data group on described I road is [I ₁..., I _m], a data group on described Q road is [Q ₁..., Q _m];

Then respectively data group described in each of described I road and described Q road is carried out to leggy coherent integration, each data group obtains the phase-group that k kind is different, k=2 after leggy coherent integration ^m-1;

Finally the different described phase-group of k kind is asked to amplitude and power, obtain k data.

Further, described m changes according to satellite-signal or specific design.

A kind of satellite signal acquisition device that uses catching method of the present utility model, it is characterized in that, comprise local carrier generator (102), local code generator (103), the first multiplier (108a), the second multiplier (108b), the 3rd multiplier (109a), the 4th multiplier (109b), first integrator (104a) and second integral device (104b) and Acquisition Detection module (106);

Local carrier generator (102) for generation of with the synchronous local carrier of input signal, described local code generator is for generation of local spreading code; Described Acquisition Detection module is for capturing satellite signal;

Input signal is divided into I road and Q road signal enters described acquisition equipment, the output signal of described I road input signal and described local carrier generator (102) is linked in described the first multiplier (108a), the output terminal of the output terminal of described the first multiplier (108a) and described local code generator (103) is connected with described the 3rd multiplier (109a), and described the 3rd multiplier (109a) is connected by described first integrator (104a) with described Acquisition Detection module (106); Described Q road input signal and described local carrier generator (102) are linked in described the second multiplier (108b) through the dephased output signal of 90 degree, the output terminal of described the second multiplier (108b) is connected with described the 4th multiplier (109b) with the output terminal of described local code generator (103), and described the 4th multiplier (109b) is connected by described second integral device (104b) with described Acquisition Detection module (106).

Further, described input signal is the digital medium-frequency signal that arrive of the satellite-signal that receives of satellite navigation receiver after radio frequency amplification, down coversion and quantification treatment.

Further, described Acquisition Detection module (106) comprises the first buffer (301a), the second buffer (301b), the first leggy coherent integration device (302a), the second leggy coherent integration device (302b), asks amplitude module (308), asks for maximal value module (310), compares detection module (305) and noncoherent accumulation module (304);

Two input ends of described Acquisition Detection module (106) are connected with described the first buffer (301a) and described the second buffer (301b) respectively; The output terminal of described the first buffer (301a) outputs to the input end of described the first leggy coherent integration device (302a), and the output terminal of described the first leggy coherent integration device (302a) outputs to described in some and asks amplitude module (308); The output terminal of described the second buffer (301b) outputs to described the second leggy coherent integration device (302b), the output terminal of described the second leggy coherent integration device (302b) with some described in ask amplitude module (308) to be connected; The output terminal of some described amplitude module (308) is connected with the input end of described maximal value module (310), and the output terminal of described maximal value module (310) is connected with described noncoherent accumulation module (304) input end; The output terminal of described noncoherent accumulation module (304) is connected with the described relatively input end of detection module (305), and the signal of the output terminal output of described relatively detection module (305) is the satellite-signal of catching.

Further, the spatial cache of described the first buffer (301a) and described the second buffer (301b) is m.

Further, described m changes according to satellite-signal or specific design.

First high sensitivity Big Dipper satellite signal capture method and apparatus of the present utility model carries out the despreading of the spreading code in down coversion and single cycle to input digital intermediate frequency signal, obtains the integral result in the single code cycle of I, Q two-way.I, m monocycle integral result of Q two-way are carried out respectively to buffer memory, obtain the monocycle integral result sequence [I of I, Q two-way ₁..., I _m] and [Q ₁..., Q _m].Then may exist m in sequence monocycle integral result 2 ^m-1plant phase combination and carry out respectively coherent integration, obtain 2 ^m-1to integration branch road.Monocycle integral result to I, Q two-way same phase integration branch road is asked amplitude, then gets the maximal value wherein result as a leggy coherent integration.Finally n leggy coherent integration result carried out to noncoherent accumulation.Last and thresholding comparison, detection satellite-signal.

The utility model has the advantages that: in without any supplementary situation, can carry out multiply periodic coherent integration to the big-dipper satellite D1 navigation signal that has the modulation of NH code, compare traditional monocycle coherent integration detection method, there is higher acquisition sensitivity.

Below with reference to accompanying drawing, the technique effect of design of the present utility model, concrete structure and generation is described further, to understand fully the purpose of this utility model, feature and effect.

Brief description of the drawings

Fig. 1 is the process flow diagram of a kind of high sensitivity Beidou satellite system catching method of the present invention;

Fig. 2 is the structural drawing of Big Dipper satellite signal capture device of the present invention;

Fig. 3 is the structural drawing of the Acquisition Detection module of Big Dipper satellite signal capture device of the present invention;

Fig. 4 is the structural drawing that Beidou satellite navigation system D1 signal adopts traditional coherent joint to divide;

Fig. 5 is in Big Dipper satellite signal capture method and apparatus of the present invention when m=3, the structural drawing of leggy coherent integration.

Embodiment

Below in conjunction with accompanying drawing, embodiment of the present utility model is elaborated: the present embodiment is implemented under with technical solutions of the utility model prerequisite; provided detailed embodiment and concrete operating process, but protection domain of the present utility model is not limited to following embodiment.

As shown in Figure 1, Big Dipper satellite signal capture method of the present utility model is caught in accordance with the following steps:

Step 401, input input signal, the digital medium-frequency signal that the satellite-signal that satellite navigation receiver is received obtains after radio frequency amplification, down coversion and quantification treatment is as input signal.

Step 402, carries out mixing by local carrier signal to input signal, obtains I roadbed band signal and Q roadbed band signal: the local carrier signal identical with input signal phase place and input signal are carried out to mixing, obtain the baseband signal on I road; Local carrier signal is carried out to (being the orthogonal signal of local carrier signal) after 90 ° of phase shifts and carry out mixing with input signal, obtain the baseband signal on Q road.Wherein, I roadbed band signal and input signal homophase, Q roadbed band signal is different from the phase place of input signal.

Step 403, carries out respectively spreading code modulation and the integration in single spreading code cycle to I roadbed band signal and Q roadbed band signal.

Step 404, the result of the monocycle integration to I road and Q road is carried out leggy coherent integration, and integral result is asked to amplitude or power: first the result of the single spreading code cycle integrated to I road and Q road is converted to respectively several data groups of parallel output, each data group comprises m data, m changes according to satellite-signal or specific design, and a data group on I road is [I ₁..., I _m], a data group on Q road is [Q ₁..., Q _m]; Then respectively each data group on I road and Q road is carried out to leggy coherent integration, each data group obtains 2 after leggy coherent integration ^mindividual different phase combination, owing to asking the result of amplitude or power the same to contrary each other combinations of polarities, so only need to calculate the phase-group that k kind is different, k=2 ^m-1; Finally the different phase-group of k kind is asked to amplitude and power, obtain k data.

Step 405, k amplitude that I road and Q road are calculated or power data, carry out noncoherent accumulation computing jointly.

Step 406, compares the accumulated value after noncoherent accumulation and thresholding, detects and capturing satellite signal.

Further, the utility model also provides a kind of Big Dipper satellite signal capture device, specifically as shown in Figure 2.Comprise: local carrier generator 102, local code generator 103, first integrator 104a and the 2nd 104b, the first multiplier 108a, the second multiplier 108b, the 3rd multiplier 109a and the 4th multiplier 109b and Acquisition Detection module 106.

Input signal is divided into I road and Q road signal enters acquisition equipment, the output signal of I road input signal and local carrier generator 102 is linked in the first multiplier 108a, the output terminal of the output terminal of the first multiplier 108a and local code generator 103 is connected with the 3rd multiplier 109a, and the first multiplier 108a is connected by first integrator 104a with Acquisition Detection module 106; Q road input signal and local carrier generator 102 are linked in the second multiplier 108b through the dephased output signal of 90 degree, the output terminal of the output terminal of the second multiplier 108b and local code generator 103 is connected with the 4th multiplier 109b, and the 4th multiplier 109b is connected by second integral device 104b with Acquisition Detection module 106

First input signal 101 is digital medium-frequency signals of exporting after satellite navigation receiver antenna, radio frequency amplification, down coversion, quantification, and local carrier generator 102 generates local intermediate frequency carrier in-phase signal, produces orthogonal signal after 90 degree phase shifts simultaneously.Local intermediate frequency carrier homophase, orthogonal signal are carried out mixing with input signal 101 respectively, obtain the baseband signal of I, Q two-way.

Local code generation device 103 produces local spreading code, respectively with I, Q two-way baseband signal multiply each other.Integrator 104a, 104b carry out respectively the integration (1 millisecond of big-dipper satellite D1 signal spread-spectrum code cycle) in a spreading code cycle to the result multiplying each other, obtain the monocycle integral result I of I, Q two-way _ms105a, Q _ms105b.

Last Acquisition Detection module 106 is concerned with, after incoherent or other process, detect and whether have satellite-signal monocycle integral result 105a, the 105b of I, Q two-way.The frequency of the local carrier producing when local carrier generator 102 is identical with input satellite-signal 101 frequencies, when the spreading code that local code generation device 103 produces aligns with input satellite-signal spreading code, in the monocycle, integral result 105a there will be peak value, thereby realizes catching satellite-signal.

Further, as shown in Figure 3, Acquisition Detection module 106 comprises the first buffer 301a and the second buffer 301b, the first leggy coherent integration device 302a and the second leggy coherent integration device 302b, asks amplitude module 308, asks for maximal value module 310 and noncoherent accumulation module 304.

Two input ends of Acquisition Detection module 106 are connected with the first buffer 301a and the second buffer 301b respectively; The output terminal of the first buffer 301a outputs to the input end of the first leggy coherent integration device 302a, and the output terminal of the first leggy coherent integration device 302a outputs to some amplitude module 308 of asking; The output terminal of the second buffer 301b outputs to the second leggy coherent integration device 302b, and the output terminal of the second leggy coherent integration device 302b is connected with some amplitude module 308 of asking; The output terminal of some amplitude module 308 is connected with the input end of maximal value module 310, and the output terminal of maximal value module 310 is connected with noncoherent accumulation module 304 input ends; The output terminal of noncoherent accumulation module 304 is connected with the input end that compares detection module 305, and relatively the signal of the output terminal of detection module 305 output is the satellite-signal of catching.

First use buffer 301a to carry out buffer memory to I road monocycle integral result 105a, the second buffer 301b carries out buffer memory to Q road monocycle integral result 105b; And serial input data is become parallel output by the first buffer 301a and the second buffer 301b, and the spatial cache of the first buffer 301a and the second buffer 301b is m, fill up parallel output after m data, then wait next time and fill up output.The first buffer 301a is output as 306a[I ₁..., I _m], the second buffer 301b is output as 306b[Q ₁..., Q _m].Wherein m is variable element, can get different values according to design, as 3,5,10 etc.

The first leggy coherent integration device 302a, the second leggy coherent integration device 302b carry out respectively the coherent integration of leggy to two buffer memory sequence 306a, 306b of I, Q two-way.M monocycle integral result, as the input of leggy coherent integration, always has 2 ^mkind different phase combination, considers that to ask the rear result of amplitude module 308 be the same to contrary each other combinations of polarities by follow-up, only needs to calculate the phase-group different with considering k kind and export, wherein k=2 ^m-1.Taking I circuit-switched data, m=3 as example, originally have 2 ³=8 different phase combination:

CI ₁=I ₁+I ₂+I ₃;CI ₅=-I ₁-I ₂-I ₃；

CI ₂=I ₁+I ₂-I ₃;CI ₆=-I ₁-I ₂+I ₃；

CI ₃=I ₁-I ₂+I ₃;CI ₇=-I ₁+I ₂-I ₃；

CI ₄=I ₁-I ₂-I ₃;CI ₈=-I ₁+I ₂+I ₃。

Wherein be divided between two one group, inverse value each other,

CI ₅=-I ₁-I ₂-I ₃=-(I ₁+I ₂+I ₃)=-CI ₁；

CI ₆=-I ₁-I ₂+I ₃=-(I ₁+I ₂-I ₃)=-CI ₂；

CI ₇=-I ₁+I ₂-I ₃=-(I ₁-I ₂+I ₃)=-CI ₃；

CI ₈=-I ₁+I ₂+I ₃=-(I ₁-I ₂-I ₃)=-CI ₄。

Two inverse values are asked after amplitude module 308 through follow-up, and result is identical, so only need to calculate and consider k=2 ^3-1different phase combination Output rusults in=4:

CI ₁=I ₁+I ₂+I ₃；

CI ₂=I ₁+I ₂-I ₃；

CI ₃=I ₁-I ₂+I ₃；

CI ₄=I ₁-I ₂-I ₃。

After leggy coherent integration, obtain I, Q two-way leggy coherent integration result sequence 307a[CI ₁, CI ₂..., CI _k], 307b[CQ ₁, CQ ₂..., CQ _k].Same phase I in above-mentioned two sequences, Q result, respectively through asking after amplitude module 308, obtain leggy coherent integration range value 309[P ₁, P ₂..., P _k], with m=3, k=4 is example:

${\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="HDA0000423627000000032.png"\; state="\{\{state\}\}">P</figure-callout>}}_1=\sqrt{{\left({\mathrm{CI}}_1\right)}^2+{\left({\mathrm{CQ}}_1\right)}^2}$

${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA0000423627000000032.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=\sqrt{{\left({\mathrm{CI}}_2\right)}^2+{\left({\mathrm{CQ}}_2\right)}^2}$

${\mathrm{<figure-callout\; id="3"\; label="P"\; filenames="HDA0000423627000000032.png"\; state="\{\{state\}\}">P</figure-callout>}}_3=\sqrt{{\left({\mathrm{CI}}_3\right)}^2+{\left({\mathrm{CQ}}_3\right)}^2}$

${\mathrm{<figure-callout\; id="4"\; label="P"\; filenames="HDA0000423627000000032.png"\; state="\{\{state\}\}">P</figure-callout>}}_4=\sqrt{{\left({\mathrm{CI}}_4\right)}^2+{\left({\mathrm{CQ}}_4\right)}^2}$

Total k the data of leggy coherent integration range value 309, module 310 is got wherein maximal value and is exported as the amplitude of a coherent integration.Follow-uply can carry out noncoherent accumulation 304, then by accumulated value and thresholding comparison, detect and capturing satellite signal.

Fig. 4 Big Dipper satellite signal adopts the structural drawing of traditional coherent integration, and as shown in Figure 4, big-dipper satellite D1 signal data modulation rate is 50Hz, and the cycle is 20 milliseconds; NH code modulation rate is 1kHz, and the cycle is 20 milliseconds; Spread-spectrum code rate is 2.046MHz, and the cycle is 1 millisecond.Continuous 5 milliseconds of times shown in Fig. 4, be positioned at the same data cycle, so data phase is consistent (+1).NH code is [+1 ,+1 ,-1 ,+1 ,-1] in the continuous phase place of 5 milliseconds.5 monocyclic spreading code correlated results are respectively 201a～201e.Due to the modulating action of NH code, cause the phase place difference of single spreading code correlated results 201a～201e, 201a, 201b, 201d relevant peaks are positive number, 201c, 201e relevant peaks are negative.Traditional multicycle coherent integration is directly cumulative by these 5 correlated results, and because positive and negative peak energy is offset, the peak value of the correlation 202 in last 5 cycles is the same with the peak value of monocyclic correlated results 201a size.Although used 5 milliseconds relevant, the difference of each spreading code phase place, causes the energy of signal to be cancelled out each other, the peak value of net result does not increase than monocycle correlation peak.

The structural drawing of leggy correlation integral of the present utility model, as shown in Figure 5.Fig. 5 is the leggy coherent integration structural drawing of m=3.

Taking I road as example, investigate continuous 3 monocycle correlated results 306a (1) I that is input as of the first leggy coherent integration module 302a ₁, 306a (2) I ₂and 306a (3) I ₃, wherein I ₁and I ₃for positive polarity, I ₂for negative polarity.Leggy coherent integration module 302a calculates 4 different phase combination results:

307a(1)CI ₁=I ₁+I ₂+I ₃；

307a(2)CI ₂=I ₁+I ₂-I ₃；

307a(3)CI ₃=I ₁-I ₂+I ₃；

307a(4)CI ₄=I ₁-I ₂-I ₃。

Wherein only has [the I of the 3rd tunnel phase combination and input ₁, I ₂, I ₃] phase combination coincide, the peak value of the correlation 307a (3) obtaining is also the highest.Follow-uply the 3rd tunnel result can be extracted by asking after amplitude and maximizing module, reach the effect of the coherent integration accumulation signal energy in multiple spreading code cycles.

More than describe preferred embodiment of the present utility model in detail.The ordinary skill that should be appreciated that this area just can be made many modifications and variations according to design of the present utility model without creative work.Therefore, all technician in the art comply with design of the present utility model on the basis of existing technology by the available technical scheme of logical analysis, reasoning, or a limited experiment, all should be in by the determined protection domain of claims.

Claims (3)

1. a satellite signal acquisition device, it is characterized in that, comprise local carrier generator (102), local code generator (103), the first multiplier (108a), the second multiplier (108b), the 3rd multiplier (109a), the 4th multiplier (109b), first integrator (104a) and second integral device (104b) and Acquisition Detection module (106);

Local carrier generator (102) for generation of with the synchronous local carrier of input signal, described local code generator is for generation of local spreading code; Described Acquisition Detection module is for capturing satellite signal; Input signal is divided into I road and Q road by described acquisition equipment, the output signal of described I road input signal and described local carrier generator (102) is linked in described the first multiplier (108a), the output terminal of the output terminal of described the first multiplier (108a) and described local code generator (103) is connected with described the 3rd multiplier (109a), and described the 3rd multiplier (109a) is connected by described first integrator (104a) with described Acquisition Detection module (106); Described Q road input signal and described local carrier generator (102) are linked in described the second multiplier (108b) through the dephased output signal of 90 degree, the output terminal of the output terminal of described the second multiplier (108b) and described local code generator (103) is connected with described the 4th multiplier (109b), and described the 4th multiplier (109b) is connected by described second integral device (104b) with described Acquisition Detection module (106).

2. a kind of satellite signal acquisition device as claimed in claim 1, wherein, described input signal is the digital medium-frequency signal that satellite-signal that satellite navigation receiver receives obtains after radio frequency amplification, down coversion and quantification treatment.

3. a kind of satellite signal acquisition device as claimed in claim 1, wherein, described Acquisition Detection module (106) comprises the first buffer (301a), the second buffer (301b), the first leggy coherent integration device (302a), the second leggy coherent integration device (302b), asks amplitude module (308), asks for maximal value module (310), compares detection module (305) and noncoherent accumulation module (304); Two input ends of described Acquisition Detection module (106) are connected with described the first buffer (301a) and described the second buffer (301b) respectively; The output terminal of described the first buffer (301a) outputs to the input end of described the first leggy coherent integration device (302a), and the output terminal of described the first leggy coherent integration device (302a) outputs to respectively described in some and asks amplitude module (308); The output terminal of described the second buffer (301b) outputs to described the second leggy coherent integration device (302b), the output terminal of described the second leggy coherent integration device (302b) respectively with some described in ask amplitude module (308) to be connected; The output terminal of some described amplitude module (308) is connected with the input end of described maximal value module (310), and the output terminal of described maximal value module (310) is connected with described noncoherent accumulation module (304) input end; The output terminal of described noncoherent accumulation module (304) is connected with the described relatively input end of detection module (305), and the signal of the output terminal output of described relatively detection module (305) is the satellite-signal of catching.

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