CN101576612A - Method for estimating carrier-to-noise ratio of GPS signal and GPS receiver - Google Patents

Abstract

The invention discloses a method for estimating the carrier-to-noise ratio of a GPS signal and a GPS receiver. The method for estimating the carrier-to-noise ratio of the GPS signal comprises the following steps: a digital signal is divided into an in-phase component and an orthogonal component; the in-phase component and the orthogonal component respectively carry out correlation calculation with a local pseudo-random noise code so as to obtain an in-phase component signal and an orthogonal component signal, and phases of the local pseudo-random noise code and a pseudo-random noise code in the GPS signal are the same; on the basis of the in-phase component signal and the orthogonal component signal, a first estimation value and a second estimation value which are relevant to the GPS signal are estimated; the first estimation value is divided by the second estimation value to obtain the strength of the GPS signal; and a relative carrier-to-noise ratio value is found out from a preset lookup table according to the strength of the GPS signal. The invention obtains the carrier-to-noise ratio by the preset lookup table on the basis of the strength of the estimated GPS signal and can reduce the resource occupied by hardware and lower the computational complexity.

Description

The method of estimating GPS signal carrier-to-noise ratio and GPS receiver

Technical field

The present invention relates to a kind of method and GPS receiver of handling gps signal, particularly relate to a kind of method and GPS receiver of estimating GPS signal carrier-to-noise ratio.

Background technology

Gps signal is by the spread-spectrum signal of gps satellite in L1 or the transmission of L2 frequency.Civilian GPS receiver uses L1 frequency (1575.42MHZ) usually.The several signals that send on the L1 carrier wave are: thick catch code (C/A sign indicating number), P sign indicating number and navigation data.The detailed data of satellite orbit is included in the navigation data.The C/A sign indicating number is a kind of Pseudo-Random Noise Code (a PRN sign indicating number), is mainly used in the location purposes in the commercial receiver.Each satellite all has a unique C/A sign indicating number, and this C/A sign indicating number that circulates repeatedly.The C/A sign indicating number is one 0 and 1 (scale-of-two) sequence.Each 0 or 1 is considered to one " chip ".The C/A sign indicating number has 1023 chips long, and sends with the speed of per second 1.023 million chips, and promptly the one-period of C/A sign indicating number continues 1 millisecond.Those of ordinary skill in the art can think that " chip " is the unit of data length or time span.Navigation data also is one 0 and 1 (scale-of-two) sequence, and sends with the speed of per second 50 bits.

For realizing the location, the GPS receiver need be caught from different Satellite GPS signals, demodulates the navigation data of gps signal.C/A sign indicating number and different Doppler shifts that different Satellite GPS signals have different zero-times.Therefore, for searching for certain satellite-signal, the GPS receiver carries out two dimension search usually, on each possible frequency the different C/A sign indicating number of each zero-time is searched for.The GPS receiver comprises antenna, radio-frequency front-end and baseband signal processing unit.The gps signal of gps satellite emission sends radio-frequency front-end to after being received by antenna, radio-frequency front-end is converted to the radiofrequency signal that receives the signal with desired output frequency, and with predetermined sampling frequency will change signal digitalized, through the conversion and digitized signal be considered to intermediate-freuqncy signal.Then, this intermediate-freuqncy signal is sent to the trapping module of baseband signal processing unit.At trapping module, search for the Doppler shift of the starting point of C/A sign indicating number and the frequency of carrier wave, particularly gps signal by the related operation that intermediate-freuqncy signal and local C/A sign indicating number and local carrier carry out.If search module captures gps signal, for example the frequency error of carrier wave is in 1Hz, the C/A code phase error is 1/2 chip, the tracking module of baseband signal processing unit then enters tracking mode, make local C/A sign indicating number and local carrier follow the tracks of the C/A sign indicating number in the gps signal and the variation of carrier wave, thereby obtain phase shift of accurate C/A sign indicating number and Doppler shift.Tracking module comprises carrier tracking loop and C/A code tracking loop, respectively carrier wave in the gps signal and C/A sign indicating number is carried out real-time follow-up, to demodulate the navigation data that comprises in the gps signal.

The C/A code tracking loop adopts the phaselocked loop (early-late ring) that shift to an earlier date-lags usually, and it comprises C/A sign indicating number generator, integration module, phase detector and wave filter.C/A sign indicating number generator produces two signals with predetermined phase difference based on the C/A sign indicating number phase shift of trapping module output, promptly shifts to an earlier date (early) and (late) C/A sign indicating number that lags, and the predetermined phase difference can be set to a chip.In advance and the intermediate-freuqncy signal of lag C/A sign indicating number and input export two paths of signals after in integration module, finishing related operation, this two paths of signals is through the processing of phase detector and wave filter, produce a control signal and regulate the local C/A sign indicating number that C/A sign indicating number generator produces, C/A code phase in the gps signal that makes the phase place of local C/A sign indicating number and receive keeps homophase, and the local C/A sign indicating number of this moment is instant (prompt) C/A sign indicating number.This instant C/A sign indicating number offers carrier tracking loop.Carrier tracking loop comprises carrier oscillator, integration module, phase detector and wave filter.Carrier oscillator produces a local carrier based on the Doppler shift of trapping module output, and the intermediate-freuqncy signal of this local carrier, instant C/A sign indicating number and input is carried out integration in integration module.The output of integration module produces a control signal and regulates carrier oscillator through the processing of phase detector and wave filter, with the local carrier of carrier synchronization in generation and the gps signal.

Because various interference, the radiofrequency signal that receives from antenna comprises useful signal and noise.Useful signal is from the gps signal of gps satellite to the receiver transmission, finishes functions such as location to help receiver.Carrier-to-noise ratio (CN0) is (the NationalMarine Electronics Association of American National ocean Institution of Electronics; NMEA) standard format that requires the GPS receiver to export.Carrier-to-noise ratio is a kind of expression mode of signal intensity, is meant the ratio of the noise power in carrier power and unit hertz (Hz) noise bandwidth, and the general decibel-hertz (dB-Hz) of using is as unit.When carrier-to-noise ratio was higher, the expression gps signal was stronger.Otherwise, when carrier-to-noise ratio is low, the expression gps signal a little less than.

Shown in Figure 1 is square frame Figure 100 that traditional carrier-to-noise ratio to gps signal provides estimation.The GPS receiver is converted to the signal with desired output frequency with the gps signal that receives, and with predetermined sampling frequency will change signal digitalized.Be considered to intermediate-freuqncy signal through conversion and digitized signal.Utilize the local carrier of local carrier generator 104 outputs in Doppler shift removal module 102, intermediate-freuqncy signal to be transformed to base band, obtain in-phase component I and quadrature component Q.Two local quadrature carrier signals of local carrier generator 104 outputs a: sinusoidal signal and a cosine signal.One of them of two carrier signals (claiming first local reference signal again) produced by carrier wave NCO 106.Another carrier signal (claiming second local reference signal again) obtains by the phase shift to first local reference signal.The phase shift operation is carried out by pi/2 phase shift module 108.In-phase component I and quadrature component Q carry out the integration of schedule time length K respectively in first integral module 112 with the local C/A sign indicating number of sign indicating number generator 110 outputs, obtain the homophase behind the integration and component of signal I (P), the Q (P) of quadrature two-way, the phase place of the C/A sign indicating number in wherein local C/A sign indicating number and the intermediate-freuqncy signal is identical.First integral module 112 is the integration module in the track loop.Local C/A sign indicating number is this locality (Prompt) C/A sign indicating number immediately of the C/A sign indicating number generator output in the phaselocked loop (early-late ring) of shift to an earlier date-lagging.In first square of summation module 114, the component of signal of the homophase of first integral module 112 output and quadrature two-way is asked respectively square, and, obtained signal power C the square value addition.

In the noise power calculation module, calculate noise power N based on in-phase component I and quadrature component Q.The noise power calculation module comprises second integral module 116 and second square of summation module 118.In-phase component I and quadrature component Q carry out the integration of schedule time length K in second integral module 116, obtain the homophase behind the integration and the component of signal of quadrature two-way.In second square of summation module 118, the component of signal of the homophase of second integral module 116 output and quadrature two-way is asked respectively square, and, obtained noise power N the square value addition.K integral time of first integral module 112 and second integral module 116 can dynamically arrange according to applied environment.When having the navigation bit auxiliary, integral time, the value of K can be greater than 20 milliseconds.When the bit that do not navigate was auxiliary, integral time, the maximum occurrences of K was 20 milliseconds.

First wave filter 120 and second wave filter 122 are used for signal power C that calculates and the result of noise power N are carried out Filtering Processing, obtain comparatively stable signal power C and noise power N.First and second wave filters 120,122 can be low-pass filters.In carrier-to-noise ratio estimation block 124, utilize following formula (a) to calculate the carrier-to-noise ratio CN0 of gps signal:

CN0＝[10*lg10(C/N-1)+10*lgK]dB-Hz (a)

Wherein, C, N are respectively above-mentioned signal power and noise power, and K is the integral time of signal calculated power C and noise power N.

Utilize following formula (b), can obtain the sensitivity (Sensitivity) of GPS receiver based on carrier-to-noise ratio CN0:

Sensitivity＝CN0-174(dBm) (b)

As seen from the above description, the method of traditional calculating gps signal carrier-to-noise ratio need be provided with the noise power calculation module in addition to calculate noise power, then, in carrier-to-noise ratio estimation block 124,, utilize above-mentioned formula (a) to calculate carrier-to-noise ratio again based on signal power and noise power.Therefore, not only computation process is complicated but also can expend a large amount of hardware resources for this traditional carrier-to-noise ratio evaluation method.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of carrier-to-noise ratio to gps signal that estimation approach and GPS receiver are provided, and can reduce hardware resource and reduce computation complexity.

For solving the problems of the technologies described above, the invention provides a kind of method of estimating GPS signal carrier-to-noise ratio, gps signal is converted into digital signal, and this method comprises: utilize predefined local reference signal, digital signal is divided into in-phase component and quadrature component; In-phase component and quadrature component are carried out related operation with local Pseudo-Random Noise Code respectively, obtain an in-phase component signal and an orthogonal component signal, the phase place of the Pseudo-Random Noise Code in this this locality Pseudo-Random Noise Code and the gps signal is identical; Based on in-phase component signal and orthogonal component signal, estimate first estimated value and second estimated value relevant with gps signal; Described first estimated value divided by described second estimated value, is obtained the intensity of gps signal; And, from the look-up table that pre-sets, find the value of corresponding carrier-to-noise ratio according to the intensity of described gps signal.

The present invention also provides a kind of GPS receiver of estimating GPS signal carrier-to-noise ratio, and this GPS receiver is converted to digital signal with gps signal.This GPS receiver comprises Doppler shift removal module, integration module, intensity estimation signal module and modular converter.Doppler shift is removed module digital signal is divided into in-phase component and quadrature component; Integration module is carried out related operation with local Pseudo-Random Noise Code respectively with in-phase component and quadrature component, obtains an in-phase component signal and an orthogonal component signal, and the phase place of the Pseudo-Random Noise Code in this this locality Pseudo-Random Noise Code and the gps signal is identical.The intensity estimation signal module estimates first estimated value relevant with gps signal and second estimated value, and based on this first estimated value and second estimated value, calculates the intensity of gps signal according to the in-phase component signal and the orthogonal component signal of integration module output.Modular converter finds the value of corresponding carrier-to-noise ratio based on the intensity of gps signal from the look-up table that pre-sets.

Compared with prior art, the present invention is based on the intensity of the gps signal that estimates,, obtain the carrier-to-noise ratio of gps signal, can reduce hardware and take resource and reduce computation complexity by the look-up table that pre-sets.

Below in conjunction with the drawings and specific embodiments technical scheme of the present invention is described in detail, so that characteristic of the present invention and advantage are more obvious.

Description of drawings

Fig. 1 is the block scheme that traditional carrier-to-noise ratio to gps signal provides estimation.

Fig. 2 is the present invention provides estimation to the carrier-to-noise ratio of gps signal a block scheme.

Fig. 3 is the block scheme that the intensity estimation signal module among Fig. 2 is estimated the intensity of gps signal in one embodiment.

Fig. 4 is the gps signal intensity that estimates among Fig. 3 and the simulation curve figure of sensitivity corresponding relation.

Fig. 5 is the gps signal intensity look-up table corresponding with carrier-to-noise ratio that estimates among Fig. 3.

Embodiment

Fig. 2 is the present invention provides estimation to the carrier-to-noise ratio of gps signal square frame Figure 200.The GPS receiver is converted to the signal with desired output frequency with the gps signal that receives, and with predetermined sampling frequency will change signal digitalized.Be considered to intermediate-freuqncy signal through conversion and digitized signal.Utilize the local carrier of local carrier generator 204 outputs in Doppler shift removal module 202, intermediate-freuqncy signal to be transformed to base band, obtain in-phase component I and quadrature component Q.Two local quadrature carrier signals of local carrier generator 204 outputs a: sinusoidal signal and a cosine signal.One of them of two carrier signals (claiming first local reference signal again) produced by carrier wave NCO 206.Another carrier signal (claiming second local reference signal again) obtains by the phase shift to first local reference signal, and the phase shift operation is carried out by pi/2 phase shift module 208.In-phase component I and quadrature component Q carry out related operation in the schedule time length with the local C/A sign indicating number of sign indicating number generator 210 output respectively in integration module 212, finish integration to in-phase component I and quadrature component Q, thereby obtain in-phase component signal I (P) and orthogonal component signal Q (P), the phase place of the C/A sign indicating number in wherein local C/A sign indicating number and the intermediate-freuqncy signal is identical.In one embodiment of the invention, local C/A sign indicating number is local instant (Prompt) C/A sign indicating number of the C/A sign indicating number generator output in the phaselocked loop (early-late ring) of shift to an earlier date-lagging, and integration module 212 is the integration module in the track loop.

Intensity estimation signal module 300 estimates the intensity of gps signal based on in-phase component signal I (P) and orthogonal component signal Q (P).In one embodiment of the invention, the specific implementation block diagram estimated of the intensity of 300 pairs of gps signals of intensity estimation signal module as shown in Figure 3.Intensity estimation signal module 300 is estimated the intensity of gps signal based on following formula (1).

$\left\{\begin{array}{c}\mathrm{SL}={\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{I}_i\right)}^2+{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{Q}_i\right)}^2\\ \mathrm{NL}=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}(I_i^2+Q_i^2)\end{array}\right.---\left(1\right)$

In the following formula, M is the integral time of in-phase component signal and orthogonal component signal, and SL is first estimated value relevant with gps signal, and NL is second estimated value relevant with gps signal.

With reference to figure 3, in first integral unit 302, respectively in-phase component signal I (P) and orthogonal component signal Q (P) are carried out integral operation in the length M at the fixed time.Then, in square sum unit 304, the integration of the integration of the in-phase component signal of first integral unit 302 output and orthogonal component signal is asked respectively square, and, obtained the first estimated value SL relevant with gps signal with the square value addition.

In squaring cell 306, respectively in-phase component signal I (P) and orthogonal component signal Q (P) are carried out square operation.Then, in second integral unit 308, the quadratic sum orthogonal component signal of the in-phase component signal of squaring cell 306 output square carried out integral operation in the length M at the fixed time.Then, in sum unit 310, the two-way integral result addition with 310 outputs of second integral unit obtains the second estimated value NL relevant with gps signal.

The present invention is not limited to utilize above-mentioned formula (1) to estimate the first estimated value SL relevant with gps signal and the second estimated value NL.In other embodiments of the invention, intensity estimation signal module 300 also can adopt following formula (2) or (3), estimates the first estimated value SL relevant with gps signal and the second estimated value NL.

$\left\{\begin{array}{c}\mathrm{SL}=\left|\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{I}_i\right|+\left|\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{Q}_i\right|\\ \mathrm{NL}=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\left(\right|I_i|+|Q_i\left|\right)\end{array}\right.---\left(2\right)$

$\left\{\begin{array}{c}\mathrm{SL}=\sqrt{{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{I}_i\right)}^2+{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{Q}_i\right)}^2}\\ \mathrm{NL}=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\left(\sqrt{I_i^2+Q_i^2}\right)\end{array}\right.---\left(3\right)$

The first estimated value SL and the second estimated value NL are nonlinear relationship.First estimated value and second estimated value the inside have all comprised the influence and the The noise of signal.

In above-mentioned formula (1), (2) and (3) integral time M value can be according to signal intensity, be provided with flexibly.When signal was strong, integral time, the value of M was less; When signal was more weak, integral time, the value of M was bigger.For example, when having the navigation bit auxiliary, can dynamically arrange M integral time, make the value of M greater than 20 milliseconds according to applied environment.When the bit that do not navigate was auxiliary, integral time, the maximum occurrences of M was 20 milliseconds.

Because The noise, there are some shakes in the intensity estimation signal module 300 first estimated value SLs relevant with gps signal that estimate and the second estimated value NL, through the filtering smoothing processing of first wave filter 312 and second wave filter 314, obtain the first comparatively stable estimated value and second estimated value respectively.

The ratio SNR_Level of the first estimated value SL and the second estimated value NL is a numerical value that becomes nonlinear relationship with signal to noise ratio (S/N ratio), and this ratio is big more, and signal to noise ratio (S/N ratio) is just big more.Therefore, in estimation module 316, the first estimated value SL divided by the second estimated value NL, is obtained the ratio of the first estimated value SL and the second estimated value NL, the intensity that this ratio can indirect reaction Current GPS signal.

Fig. 4 is the gps signal strength S NR_Level that estimates among Fig. 3 and simulation curve Figure 40 0 of sensitivity corresponding relation, and wherein transverse axis is sensitivity, and unit is a decibel milli (dBm), and the longitudinal axis is gps signal strength S NR_Level.As shown in Figure 4, the gps signal intensity that estimates according to above-mentioned formula (1) becomes nonlinear relationship with the sensitivity of GPS receiver, and gps signal is strong more, and sensitivity is just high more.Persons of ordinary skill in the art may appreciate that also be nonlinear relationship according to the gps signal intensity that estimates of above-mentioned formula (2) or (3) with the sensitivity of GPS receiver, and gps signal is strong more, sensitivity is just high more.Different is that numerical value and Fig. 4 of the intensity of the gps signal at certain some place and sensitivity are variant on the corresponding curve map.

According to the curve map of Fig. 4, corresponding different gps signal strength S NR_Level can obtain a corresponding sensitivity.And there are certain relation in sensitivity and carrier-to-noise ratio CN0, shown in the formula (b) of background technology part, sensitivity are added numerical value 174, just can obtain carrier-to-noise ratio CN0.That is to say, have relation one to one between carrier-to-noise ratio and the gps signal intensity.Carrier-to-noise ratio becomes nonlinear relationship with gps signal intensity, and gps signal is strong more, and carrier-to-noise ratio is just big more.Fig. 5 is the gps signal intensity look-up table 500 corresponding with carrier-to-noise ratio that estimates among Fig. 3.In look-up table, corresponding different gps signal intensity has the carrier-to-noise ratio of different numerical value.Those of ordinary skill in the art is appreciated that equally, if according to above-mentioned formula (2) or (3) estimation gps signal intensity, the gps signal intensity that then estimates and the corresponding relation of carrier-to-noise ratio can change, and the numerical value in the look-up table promptly shown in Figure 5 can produce corresponding variation.

Referring again to Fig. 2, modular converter 320 is according to the look-up table as shown in Figure 5 that pre-sets, and the Current GPS signal intensity SNR_Level of respective signal strength estimation module 300 outputs finds the value of corresponding carrier-to-noise ratio, thereby obtains the carrier-to-noise ratio of gps signal.

The present invention is based on the in-phase component signal I (P) and the orthogonal component signal Q (P) that produce in the track loop, estimate the intensity of gps signal, utilize the look-up table that pre-sets to obtain the carrier-to-noise ratio of gps signal again, can reduce hardware and take resource and reduce computation complexity.

It should be noted last that: above embodiment is only unrestricted in order to explanation the present invention, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement the present invention, and not breaking away from the spirit and scope of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (10)

1. the method for an estimating GPS signal carrier-to-noise ratio, described gps signal is converted into digital signal, it is characterized in that, and described method comprises:

1) utilizes predefined local reference signal, described digital signal is divided into in-phase component and quadrature component;

2) in-phase component and quadrature component are carried out related operation with local Pseudo-Random Noise Code respectively, obtain an in-phase component signal and an orthogonal component signal, the phase place of the Pseudo-Random Noise Code in this this locality Pseudo-Random Noise Code and the gps signal is identical;

3), estimate first estimated value and second estimated value relevant with gps signal based on described in-phase component signal and orthogonal component signal;

4) with described first estimated value divided by described second estimated value, obtain the intensity of gps signal; And

5), from the look-up table that pre-sets, find the value of corresponding carrier-to-noise ratio according to the intensity of described gps signal.

2. the method for estimating GPS signal carrier-to-noise ratio according to claim 1 is characterized in that, described first estimated value and second estimated value are obtained by following formula:

$\left\{\begin{array}{c}\mathrm{SL}={\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{I}_i\right)}^2+{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{Q}_i\right)}^2\\ \mathrm{NL}=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}(I_i^2+Q_i^2)\end{array}\right.$

Wherein SL, NL are respectively described first estimated value and second estimated value; Ii, Qi are respectively described in-phase component signal and orthogonal component signal; M is integral time.

3. the method for estimating GPS signal carrier-to-noise ratio according to claim 1 is characterized in that, described first estimated value and second estimated value are obtained by following formula:

$\left\{\begin{array}{c}\mathrm{SL}=\left|\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{I}_i\right|+\left|\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{Q}_i\right|\\ \mathrm{NL}=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\left(\right|I_i|+|Q_i\left|\right)\end{array}\right.$

Wherein SL, NL are respectively described first estimated value and second estimated value; Ii, Qi are respectively described in-phase component signal and orthogonal component signal; M is integral time.

4. the method for estimating GPS signal carrier-to-noise ratio according to claim 1 is characterized in that, described first estimated value and second estimated value are obtained by following formula:

$\left\{\begin{array}{c}\mathrm{SL}=\sqrt{{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{I}_i\right)}^2+{\left(\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{Q}_i\right)}^2}\\ \mathrm{NL}=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\left(\sqrt{I_i^2+Q_i^2}\right)\end{array}\right.$

Wherein SL, NL are respectively described first estimated value and second estimated value; Ii, Qi are respectively described in-phase component signal and orthogonal component signal; M is integral time.

5. according to the method for each described estimating GPS signal carrier-to-noise ratio of claim 1-4, it is characterized in that described local Pseudo-Random Noise Code is the local instant Pseudo-Random Noise Code by the output of the Pseudo-Random Noise Code generator in the code tracking loop.

6. according to the method for each described estimating GPS signal carrier-to-noise ratio of claim 1-4, it is characterized in that, before the step of the intensity of described calculating gps signal, also comprise the step of described first estimated value and described second estimated value being carried out Filtering Processing.

7. the GPS receiver of an estimating GPS signal carrier-to-noise ratio, this GPS receiver is converted to digital signal with described gps signal, it is characterized in that, and described GPS receiver comprises:

Doppler shift is removed module, and it is divided into in-phase component and quadrature component with described digital signal;

Integration module, described in-phase component and quadrature component are carried out related operation with local Pseudo-Random Noise Code respectively, obtain an in-phase component signal and an orthogonal component signal, the phase place of the Pseudo-Random Noise Code in this this locality Pseudo-Random Noise Code and the gps signal is identical;

The intensity estimation signal module, it is according to the described in-phase component signal and the orthogonal component signal of described integration module output, estimate first estimated value relevant and second estimated value, and, calculate the intensity of gps signal based on this first estimated value and second estimated value with gps signal; And

Modular converter, it finds the value of corresponding carrier-to-noise ratio based on the intensity of described gps signal from the look-up table that pre-sets.

8. the GPS receiver of estimating GPS signal carrier-to-noise ratio according to claim 7 is characterized in that, described intensity estimation signal module comprises:

The first integral unit is used for described in-phase component signal and orthogonal component signal are made integration in the length at the fixed time;

Square sum unit is used for the integration of the in-phase component signal of described first integral unit output and orthogonal component signal is asked respectively square and with the square value addition, obtained described first estimated value;

Squaring cell is asked respectively square described in-phase component signal and orthogonal component signal;

Integration square is made to the in-phase component signal of described squaring cell output and orthogonal component signal in the second integral unit in described schedule time length;

Sum unit with the in-phase component signal of described second integral unit output and the integration addition of orthogonal component signal, obtains described second estimated value; And

Estimation module based on described first estimated value and second estimated value, calculates the intensity of gps signal.

9. the GPS receiver of estimating GPS signal carrier-to-noise ratio according to claim 8, it is characterized in that, described intensity estimation signal module also comprises first wave filter and second wave filter, respectively described first estimated value and described second estimated value is carried out Filtering Processing.

10. the GPS receiver of estimating GPS signal carrier-to-noise ratio according to claim 9 is characterized in that, described first wave filter and second wave filter are low-pass filters.

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