CN106028442B - A kind of signal acquisition methods and device - Google Patents
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Abstract
The embodiment of the invention discloses a kind of signal acquisition methods and devices, demal point orthogonal frequency division multiplexing TC-OFDM system when this method and device are applied to, this method comprises: carrying out incoherent loss balancing to non-coherent integration results Z (n), whether the non-coherent integration results after judging incoherent loss balancing meet preset thresholding decision condition；If satisfied, then carrying out signal capture.This method and device are combined by relevant/non-coherent integration and carry out loss balancing to non-coherent integration results, signal is captured, opposite capture peak value can be effectively improved, reduce the leakage probability of weak signal, to improve capture ability of the location receiver to weak signal of TC-OFDM system, effective capture to weak signal is realized.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a signal capturing method and a signal capturing device applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system.
Background
With the rapid development of wireless networks, Location Based Service (LBS) has gradually merged into people's daily life. Currently, the Global Navigation Satellite System (GNSS) can provide accurate position information for our outdoor activities. With the increasing number of large buildings in cities, the activity space of people has been changed from outdoor to indoor, and thus accurate positioning in indoor environments has become more important.
A time division code division orthogonal frequency division multiplexing (TC-OFDM) system is developed aiming at the accurate positioning of indoor environment, and can provide wide-area high-accuracy indoor and outdoor location service. The TC-OFDM system is also based on Code Division Multiple Access (CDMA), and superimposes a CDMA signal on a mobile broadcast signal, as in most high-precision positioning systems, and provides a precise location service for a user without affecting the reception of the mobile broadcast signal by the user.
In the signal transmission process of the TC-OFDM system, the signal intensity of the TC-OFDM system is greatly weakened due to the reasons of barrier shielding, same-frequency signal interference and the like. When the Carrier to Noise Ratio (CNR) of a signal is lower than a certain value, a weak TC-OFDM system signal cannot be detected by a common parallel code acquisition algorithm.
Disclosure of Invention
The embodiment of the invention discloses a signal capturing method and a signal capturing device applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system, which are used for improving the capturing capability of a positioning receiver of the TC-OFDM system to weak signals.
In order to achieve the above object, an embodiment of the present invention discloses a signal acquisition method applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system, the method including:
receiving a TC-OFDM base station radio frequency signal, and performing down-conversion and low-pass filtering on the radio frequency signal to obtain a complex signal r (t);
performing A/D conversion on the complex signal r (t) to obtain i paths of discrete digital intermediate frequency signals i (n) and q paths of discrete digital intermediate frequency signals q (n);
coherent integration is carried out on the i paths of discrete digital intermediate frequency signals i (n) and the q paths of discrete digital intermediate frequency signals q (n) to obtain i paths of power output V (n) related to q paths of power output;
performing non-coherent integration on the power output V (n) to obtain a non-coherent integration result Z (n);
calculating a loss compensation value P according to the value obtained by dividing the maximum value and the second maximum value in the non-coherent integration result Z (n)noise；
Compensating for value P by said lossnoisePerforming loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n); and
judging whether the loss compensated non-coherent integration result Z' (n) meets a preset threshold judgment condition or not; if yes, the signal acquisition is successful.
Optionally, said compensating value P for said lossnoisePerforming loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n), including:
subtracting loss compensation from the non-coherent integration result Z (n)Compensation value PnoiseAnd obtaining the loss compensated incoherent integration result Z' (n).
Optionally, the loss compensation value PnoiseCalculated by the following formula:
Pnoise＝αP′noise
wherein max (z (n)) represents the maximum value in the non-coherent integration result z (n), second (z (n)) represents the second largest value in the non-coherent integration result z (n), len represents the GOLD code length, and α is a preset constant.
Optionally, the non-coherent integration result z (n) is subtracted by a loss compensation value PnoiseObtaining the loss-compensated incoherent integration result Z' (n), including:
subtracting a loss compensation value P from a maximum value max (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a first loss-compensated incoherent integration result Z'1(n)；
Subtracting a loss compensation value P from a second largest value second (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a second loss-compensated incoherent integration result Z'2(n)。
Optionally, the determining whether the loss-compensated non-coherent integration result Z' (n) meets a preset threshold determination condition includes:
judging the non-coherent integration result Z 'after the first loss compensation'1(n) and the second loss-compensated incoherent integration result Z'2(n) ratio to detection threshold RthIf the ratio is greater than or equal to the detection threshold value RthThen the threshold decision condition is satisfied.
In order to achieve the above object, an embodiment of the present invention discloses a signal capturing apparatus, which is applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system, and includes:
a receiving unit, configured to receive a TC-OFDM base station radio frequency signal;
the first conversion unit is used for carrying out down-conversion and low-pass filtering on the radio-frequency signal to obtain a complex signal r (t);
the second conversion unit is used for carrying out A/D conversion on the complex signal r (t) to obtain i paths of discrete digital intermediate frequency signals i (n) and q paths of discrete digital intermediate frequency signals q (n);
a coherent integration unit, configured to perform coherent integration on the i channels of discrete digital intermediate frequency signals i (n) and the q channels of discrete digital intermediate frequency signals q (n), so as to obtain i channels of power output v (n) related to q channels of power output v (n);
the non-coherent integration unit is used for performing non-coherent integration on the power output V (n) to obtain a non-coherent integration result Z (n);
a calculation unit for calculating a loss compensation value P according to a value obtained by dividing the maximum value and the second maximum value in the non-coherent integration result Z (n)noise；
A loss compensation unit for compensating the value P with the lossnoisePerforming loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n);
the judging unit is used for judging whether the loss compensated non-coherent integration result Z' (n) meets a preset threshold judging condition or not;
and the signal capturing unit is used for successfully capturing the signal if the loss compensated non-coherent integration result Z' (n) meets a preset threshold judgment condition.
Optionally, the loss compensation unit is specifically configured to:
subtracting a loss compensation value from the non-coherent integration result Z (n)PnoiseAnd obtaining the loss compensated incoherent integration result Z' (n).
Optionally, the computing unit is specifically configured to:
calculating the loss compensation value P according to the following expressionnoise：
Pnoise＝αP′noise
Wherein max (z (n)) represents the maximum value in the non-coherent integration result z (n), second (z (n)) represents the second largest value in the non-coherent integration result z (n), len represents the GOLD code length, and α is a preset constant.
Optionally, the loss compensation unit is specifically configured to:
subtracting a loss compensation value P from a maximum value max (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a first loss-compensated incoherent integration result Z'1(n)；
Subtracting a loss compensation value P from a second largest value second (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a second loss-compensated incoherent integration result Z'2(n)。
Optionally, the determining unit is specifically configured to:
judging the non-coherent integration result Z 'after the first loss compensation'1(n) and the second loss-compensated incoherent integration result Z'2(n) ratio to detection threshold RthIf the ratio is greater than or equal to the detection threshold value RthThen the threshold decision condition is satisfied.
The signal capturing method and the signal capturing device applied to the time division code division orthogonal frequency division multiplexing TC-OFDM system provided by the embodiment of the invention can effectively improve the relative capturing peak value and reduce the capturing missing probability of the weak signal by combining coherent integration and incoherent integration and performing loss compensation on the incoherent integration result to capture the signal, thereby improving the capturing capability of a positioning receiver of the TC-OFDM system on the weak signal and realizing the effective capturing of the weak signal.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flowchart of a signal acquisition method according to an embodiment of the present invention;
FIG. 2 shows the results of the capture success rate test at different SNR;
fig. 3 is a schematic structural diagram of a signal capturing apparatus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic flow chart of a signal acquisition method according to an embodiment of the present invention, where the signal acquisition method is applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system, and includes the following steps:
s101: receiving a TC-OFDM base station radio frequency signal, and performing down-conversion and low-pass filtering on the radio frequency signal to obtain a complex signal r (t).
Wherein the complex signal r (t) can be represented by the following formula:
where t denotes time, a denotes signal amplitude, D (t) denotes data code, S (t- τ) denotes GOLD code, τ denotes propagation delay, fIFRepresenting residual carrier frequency, fdRepresents the frequency deviation of the intermediate frequency, theta, caused by Doppler and crystal oscillation deviationIFIndicating the initial phase of the carrier and n (t) the noise signal.
S102: and performing A/D conversion on the complex signal r (t) to obtain i paths of discrete digital intermediate frequency signals i (n) and q paths of discrete digital intermediate frequency signals q (n).
Wherein, the i discrete digital intermediate frequency signals i (n) and the q discrete digital intermediate frequency signals q (n) can be respectively represented by the following formulas:
i(n)＝aD(n-τ)S(n-τ)sin(2π(fIF+fd)t(n)+θIF)+ni(n)
q(n)＝aD(n-τ)S(n-τ)cos(2π(fIF+fd)t(n)+θIF)+nq(n)
where n denotes discrete time, a denotes signal amplitude, D (n- τ) denotes data code, S (n- τ) denotes GOLD code, τ denotes propagation delay, fIFRepresenting residual carrier frequency, fdRepresents the frequency deviation of the intermediate frequency, theta, caused by Doppler and crystal oscillation deviationIFIndicating the initial phase of the carrier, ni(n) represents the i-channel noise signal, nqAnd (n) represents q paths of noise signals, and the noise signals conform to Gaussian white noise distribution.
S103: and performing coherent integration on the i paths of discrete digital intermediate frequency signals i (n) and the q paths of discrete digital intermediate frequency signals q (n) to obtain i paths of power output V (n) related to q paths of power output V (n).
The I discrete digital intermediate frequency signals I (n) and the Q discrete digital intermediate frequency signals Q (n) are multiplied by local codes in a parallel-to-serial conversion module respectively and then added to obtain coherent integration results I '(n) and Q' (n), and then the coherent integration results I '(n) and Q' (n) are subjected to a serial-to-parallel conversion module and then subjected to square sum processing to obtain I and Q correlated power outputs v (n).
The coherent integration results I '(n), Q' (n) can be represented by the following formula:
where N represents discrete time, k represents integration time, N represents code length, c (k) represents local code, a represents signal amplitude, R (τ) represents corresponding autocorrelation function, f (τ) represents correlation functioneIndicating a frequency error, TcohRepresents the integration time, phieRepresenting the phase error, nIRepresenting i noise signals, nQRepresenting a q-way noise signal.
Wherein the power output V (n) may be represented by:
wherein n isIAnd nQAll are normal noise with zero mean and equal variance; the first term to the right of the second equal sign is the autocorrelation power value of the received signal, the mean value of the second term is zero, the second term isThree itemsIs not equal to zero.
The power output v (n) may be further expressed as:
where n denotes the discrete time, a denotes the signal amplitude, R (τ) denotes the corresponding autocorrelation function, feIndicating a frequency error, TcohRepresents the integration time, phieRepresenting the phase error, nIRepresenting i noise signals, nQRepresenting a q-way noise signal.
S104: and carrying out non-coherent integration on the power output V (n) to obtain a non-coherent integration result Z (n).
Wherein the non-coherent integration result z (n) can be represented by the following formula:
where x represents the number of integrations, l represents the integration variable, and n represents the discrete time.
The non-coherent integration accumulates the energy power amplitude of the noise, and thus causes non-coherent loss.
S105: calculating a loss compensation value P according to the value obtained by dividing the maximum value and the second maximum value in the non-coherent integration result Z (n)noise。
S106: compensating for value P by said lossnoiseAnd performing loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n).
Wherein the loss compensation may comprise the steps of:
subtracting a loss compensation value P from the non-coherent integration result Z (n)noiseAnd obtaining the loss compensated incoherent integration result Z' (n).
Wherein the loss compensation value PnoiseCalculated by the following formula:
Pnoise＝αP′noise
wherein max (z (n)) represents the maximum value in the non-coherent integration result z (n), second (z (n)) represents the second largest value in the non-coherent integration result z (n), len represents the GOLD code length, and α is a preset constant.
α is a preset constant, and within a certain error tolerance range, the constant can be used to approximate the value (denoted as P ') of the non-correlated integration result divided by the maximum value and the second largest value'noise) And the loss compensation value PnoiseCan be in accordance with P'noiseTo obtain the loss compensation value Pnoise。
It should be noted that the embodiment of the present invention does not need to be limited to α, and those skilled in the art can make reasonable arrangement according to the empirical values obtained from a large amount of experimental data and the practical situation.
Wherein the subtracting of the loss compensation value P from the non-coherent integration result Z (n)noiseObtaining the loss-compensated incoherent integration result Z' (n) may include the following steps:
subtracting a loss compensation value P from a maximum value max (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a first loss-compensated incoherent integration result Z'1(n)；
Subtracting a loss compensation value P from a second largest value second (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a second loss-compensated incoherent integration result Z'2(n)。
S107: and judging whether the loss compensated non-coherent integration result Z' (n) meets a preset threshold judgment condition, if so, successfully capturing the signal.
The determining whether the loss-compensated non-coherent integration result Z' (n) meets a preset threshold determination condition may include the following steps:
judging the non-coherent integration result Z 'after the first loss compensation'1(n) and the second loss-compensated incoherent integration result Z'2(n) ratio to detection threshold RthIf the ratio is greater than or equal to the detection threshold value RthThen the threshold decision condition is satisfied.
In one implementation, the GOLD code may be captured as follows: the local GOLD codes are used for matching with the received signal, for example, the system has 100 GOLD codes in total, the received radio frequency signal contains a certain group of GOLD codes, in the acquisition process, the local system uses all GOLD codes to respectively perform matching operation with the received signal, when a peak value occurs (the peak value can be found only by matching the same GOLD codes), which group of GOLD codes is contained in the received signal is determined, and simultaneously, the phase of the GOLD code at the moment is determined. Of course, a specific implementation for capturing GOLD codes and GOLD code phases is merely illustrated, and the present invention is not limited thereto, and any feasible implementation can be applied to the present invention.
It can be seen from the foregoing embodiments that, the signal acquisition method applied to the TC-OFDM system based on time division code division orthogonal frequency division multiplexing according to the embodiments of the present invention acquires a signal by combining coherent integration and non-coherent integration and performing loss compensation on a non-coherent integration result, and can effectively improve a relative acquisition peak value and reduce a weak signal missing probability, thereby improving an acquisition capability of a positioning receiver of the TC-OFDM system for a weak signal and realizing effective acquisition of the weak signal.
FIG. 2 shows the capture success rate test under different SNR, i.e. under any SNR condition, 500 times of continuous capture operations are performed on TC-OFDM signals, wherein the capture threshold is set as RthThe percentage of acquisition success before and after noncoherent integration loss compensation was recorded as 1.5. As can be seen from fig. 2, the acquisition success rate after the non-coherent integration compensation is higher than that before the compensation. Therefore, the improved capturing method combining coherent integration and non-coherent integration can effectively reduce the capturing missing probability and realize the capturing of weak signals.
Fig. 3 is a schematic structural diagram of a signal acquisition apparatus according to an embodiment of the present invention, which corresponds to the flow shown in fig. 1, and the signal acquisition apparatus is applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system, and includes:
a receiving unit 301, configured to receive a TC-OFDM base station radio frequency signal;
a first conversion unit 302, configured to perform down-conversion and low-pass filtering on the radio frequency signal to obtain a complex signal r (t);
a second conversion unit 303, configured to perform a/D conversion on the complex signal r (t) to obtain i channels of discrete digital intermediate frequency signals i (n) and q channels of discrete digital intermediate frequency signals q (n);
a coherent integration unit 304, configured to perform coherent integration on the i channels of discrete digital intermediate frequency signals i (n) and the q channels of discrete digital intermediate frequency signals q (n), so as to obtain i channels of power output v (n) related to q channels of power output v (n);
a non-coherent integration unit 305, configured to perform non-coherent integration on the power output v (n) to obtain a non-coherent integration result z (n);
a calculating unit 306, configured to calculate a loss compensation value P according to a value obtained by dividing the maximum value and the second maximum value in the non-coherent integration result z (n)noise。
A loss compensation unit 307, configured to perform loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n);
a determining unit 308, configured to determine whether the loss compensated non-coherent integration result Z' (n) meets a preset threshold determination condition.
A signal capturing unit 309, configured to successfully capture the signal if the loss-compensated non-coherent integration result Z' (n) meets a preset threshold determination condition.
Specifically, the loss compensation unit is specifically configured to:
subtracting a loss compensation value P from the non-coherent integration result Z (n)noiseAnd obtaining the loss compensated incoherent integration result Z' (n).
Specifically, the computing unit is specifically configured to:
calculating the loss compensation value P according to the following expressionnoise：
Pnoise＝αP′noise
Wherein max (z (n)) represents the maximum value in the non-coherent integration result z (n), second (z (n)) represents the second largest value in the non-coherent integration result z (n), len represents the GOLD code length, and α is a preset constant.
Specifically, the loss compensation unit is specifically configured to:
subtracting a loss compensation value P from a maximum value max (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a first loss-compensated incoherent integration result Z'1(n)；
For the non-coherent integration resultThe second largest value of Z (n) second (Z (n)) minus the loss compensation value PnoiseObtaining a second loss-compensated incoherent integration result Z'2(n)。
Specifically, the determining unit is specifically configured to:
judging the non-coherent integration result Z 'after the first loss compensation'1(n) and the second loss-compensated incoherent integration result Z'2(n) ratio to detection threshold RthIf the ratio is greater than or equal to the detection threshold value RthThen the threshold decision condition is satisfied.
It can be seen from the foregoing embodiments that, the signal capturing apparatus applied to the TC-OFDM system based on time division code division orthogonal frequency division multiplexing provided in the embodiments of the present invention captures signals by combining coherent integration and non-coherent integration and performing loss compensation on non-coherent integration results, and can effectively improve relative capture peak values and reduce the capture missing probability of weak signals, thereby improving the capturing capability of a positioning receiver of the TC-OFDM system on weak signals and realizing effective capture of weak signals.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the apparatus embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
Those skilled in the art will appreciate that all or part of the steps in the above method embodiments may be implemented by a program to instruct relevant hardware to perform the steps, and the program may be stored in a computer-readable storage medium, which is referred to herein as a storage medium, such as: ROM/RAM, magnetic disk, optical disk, etc.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (2)
1. A signal acquisition method applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system, the method comprising:
receiving a TC-OFDM base station radio frequency signal, and performing down-conversion and low-pass filtering on the radio frequency signal to obtain a complex signal r (t);
performing A/D conversion on the complex signal r (t) to obtain i paths of discrete digital intermediate frequency signals i (n) and q paths of discrete digital intermediate frequency signals q (n);
coherent integration is carried out on the i paths of discrete digital intermediate frequency signals i (n) and the q paths of discrete digital intermediate frequency signals q (n) to obtain i paths of power output V (n) related to q paths of power output;
performing non-coherent integration on the power output V (n) to obtain a non-coherent integration result Z (n);
calculating a loss compensation value P according to the value obtained by dividing the maximum value and the second maximum value in the non-coherent integration result Z (n)noise；
Compensating for value P by said lossnoisePerforming loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n); and
judging whether the loss compensated non-coherent integration result Z' (n) meets a preset threshold judgment condition or not; if yes, the signal acquisition is successful;
the loss compensation value PnoiseCalculated by the following formula:
Pnoise＝αP′noise
wherein max (z (n)) represents the maximum value in the non-coherent integration result z (n), second (z (n)) represents the second largest value in the non-coherent integration result z (n), len represents the GOLD code length, and α is a preset constant;
using said loss compensation value PnoisePerforming loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n), including:
subtracting a loss compensation value P from the non-coherent integration result Z (n)noiseObtaining a loss-compensated incoherent integration result Z' (n); wherein,
the subtraction of a loss compensation value P from the non-coherent integration result Z (n)noiseObtaining the loss-compensated incoherent integration result Z' (n), including:
subtracting a loss compensation value P from a maximum value max (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a first loss-compensated incoherent integration result Z'1(n)；
Subtracting a loss compensation value P from a second largest value second (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a second loss-compensated incoherent integration result Z'2(n)；
The judging whether the loss compensated non-coherent integration result Z' (n) meets a preset threshold judgment condition includes:
judging the non-coherent integration result Z 'after the first loss compensation'1(n) and the second loss-compensated incoherent integration result Z'2(n) ratio to detection threshold RthIf the ratio is greater than or equal to the detection threshold value RthThen the threshold decision condition is satisfied.
2. A signal acquisition apparatus, applied to a time division code division orthogonal frequency division multiplexing TC-OFDM system, comprising:
a receiving unit, configured to receive a TC-OFDM base station radio frequency signal;
the first conversion unit is used for carrying out down-conversion and low-pass filtering on the radio-frequency signal to obtain a complex signal r (t);
the second conversion unit is used for carrying out A/D conversion on the complex signal r (t) to obtain i paths of discrete digital intermediate frequency signals i (n) and q paths of discrete digital intermediate frequency signals q (n);
a coherent integration unit, configured to perform coherent integration on the i channels of discrete digital intermediate frequency signals i (n) and the q channels of discrete digital intermediate frequency signals q (n), so as to obtain i channels of power output v (n) related to q channels of power output v (n);
the non-coherent integration unit is used for performing non-coherent integration on the power output V (n) to obtain a non-coherent integration result Z (n);
a calculation unit for calculating a loss compensation value P according to a value obtained by dividing the maximum value and the second maximum value in the non-coherent integration result Z (n)noise；
A loss compensation unit for compensating the value P with the lossnoisePerforming loss compensation on the incoherent integration result Z (n) to obtain a loss-compensated incoherent integration result Z' (n);
the judging unit is used for judging whether the loss compensated non-coherent integration result Z' (n) meets a preset threshold judging condition or not;
the signal capturing unit is used for successfully capturing the signal if the loss compensated non-coherent integration result Z' (n) meets a preset threshold judgment condition;
the computing unit is specifically configured to:
calculating the loss compensation value P according to the following expressionnoise：
Pnoise＝αP′noise
Wherein max (z (n)) represents the maximum value in the non-coherent integration result z (n), second (z (n)) represents the second largest value in the non-coherent integration result z (n), len represents the GOLD code length, and α is a preset constant;
the loss compensation unit is specifically configured to:
subtracting a loss compensation value P from the non-coherent integration result Z (n)noiseObtaining a loss-compensated incoherent integration result Z' (n);
the loss compensation unit is specifically configured to:
subtracting a loss compensation value P from a maximum value max (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a first loss-compensated incoherent integration result Z'1(n)；
Subtracting a loss compensation value P from a second largest value second (Z (n)) of the non-coherent integration result Z (n)noiseObtaining a second loss-compensated incoherent integration result Z'2(n)；
The judgment unit is specifically configured to:
judging the non-coherent integration result Z 'after the first loss compensation'1(n) and the second loss-compensated incoherent integration result Z'2(n) ratio to detection threshold RthIf the ratio is greater than or equal to the detection threshold value RthThen the threshold decision condition is satisfied.
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