阅读说明：本技术 一种基于码片级脉冲跳时的卫星导航信号生成方法 (Satellite navigation signal generation method based on chip-level pulse time hopping ) 是由 蒙艳松 严涛 王瑛 周昀 雷文英 王国永 边朗 于 2019-09-16 设计创作，主要内容包括：本发明涉及一种基于码片级脉冲跳时的卫星导航信号生成方法,包括基带扩频调制；信号伪码发生器生成信号伪码,进行码片赋形后,与编码后的电文调制在一起,得到基带扩频信号；码片跳时调制；跳频伪码发生器生成跳频伪码序列,控制码片选通脉冲发生器,生成码片选通脉冲,与所述基带扩频信号进行码片跳时调制,得到码片跳时信号；射频调制；载波发生器生成射频载波,与所述码片跳时信号进行射频调制,生成射频信号,经放大、滤波后,完成基于码片级脉冲跳时的卫星导航信号的生成,通过天线播发给用户。本发明实现抗干扰能力的提升,同时保持与现有卫星导航信号体制的兼容性,并支持基于载波相位测量的高精度应用。(The invention relates to a satellite navigation signal generating method based on chip-level pulse time hopping, which comprises baseband spread spectrum modulation; a signal pseudo code generator generates a signal pseudo code, and after chip shaping, the signal pseudo code and the coded text are modulated together to obtain a baseband spread spectrum signal; chip time hopping modulation; the frequency hopping pseudo code generator generates a frequency hopping pseudo code sequence, controls the chip gating pulse generator to generate chip gating pulses, and performs chip time hopping modulation with the baseband spread spectrum signal to obtain a chip time hopping signal; radio frequency modulation; and the carrier wave generator generates a radio frequency carrier wave, performs radio frequency modulation on the radio frequency carrier wave and the chip time hopping signal to generate a radio frequency signal, completes generation of a satellite navigation signal based on chip-level pulse time hopping after amplification and filtering, and broadcasts the satellite navigation signal to a user through an antenna. The invention realizes the improvement of the anti-interference capability, simultaneously keeps the compatibility with the existing satellite navigation signal system, and supports the high-precision application based on the carrier phase measurement.)

1. A satellite navigation signal generation method based on chip-level pulse time hopping is characterized by comprising the following steps:

(1) baseband spread spectrum modulation; a signal pseudo code generator generates a signal pseudo code, and after chip shaping, the signal pseudo code and the coded text are modulated together to obtain a baseband spread spectrum signal;

(2) chip time hopping modulation; the frequency hopping pseudo code generator generates a frequency hopping pseudo code sequence, controls the chip gating pulse generator to generate chip gating pulses, and performs chip time hopping modulation with the baseband spread spectrum signal to obtain a chip time hopping signal;

(3) radio frequency modulation; and the carrier wave generator generates a radio frequency carrier wave, performs radio frequency modulation on the radio frequency carrier wave and the chip time hopping signal to generate a radio frequency signal, completes generation of a satellite navigation signal based on chip-level pulse time hopping after amplification and filtering, and broadcasts the satellite navigation signal to a user through an antenna.

2. The method of claim 1, wherein the method further comprises: the baseband spread spectrum modulation is obtained by the following method:

(1.1) generating a signal pseudo code; the pseudo code sequence generated by the signal pseudo code generator is { c_l}，c_l∈{1,-1}，l＝0,1,2,…；

(1.2) shaping a chip waveform; carrying out chip waveform shaping on the pseudo code sequence to obtain a pseudo code waveform:

in the formula (I), the compound is shown in the specification,

(1.3) baseband spread spectrum modulation; modulating the text d (t) and the pseudo code waveform C (t) to obtain a baseband spread spectrum modulation signal s_b(t) ═ d (t) · c (t), text d (t) ∈ {1, -1 }.

3. The method of claim 2, wherein the method further comprises: the step (1.2) of shaping the pseudo code sequence by the chip waveform specifically comprises the following steps:

in the satellite navigation signal, a rectangular chip waveform or a binary offset carrier waveform is adopted;

for a rectangular chip waveform, there are:

the binary offset carrier waveform is a sinusoidal BOC chip waveform, for which

In the formula (f)_sSubcarrier frequency modulated for BOC, 2f_s/R_cAre integers.

4. The method of claim 2, wherein the method further comprises: and (2) chip time hopping modulation, which specifically comprises the following steps:

(2.1) spread spectrum modulating signal s of base band_b(T) in time domain by chip width T_cGrouping, wherein every N chips are divided into a group, the group is marked as 0,1,2, … and N-1, only one chip in every N chips is gated, and the power of the N chips is concentrated on one chip; wherein N is an integer greater than 1 and represents the number of chips contained in each packet;

(2.2) the time hopping pseudo code generator generates a time hopping pseudo code sequence c_TH,lMapped by time hopping pseudo code sequence, corresponding to every NT_cTime, in the ith chip packet, a number L belonging to {0,1,2, …, N-1} is output_iControlling the chip strobe generator to generate the chip strobe p_pulse(t)；

(2.3) at time T ∈ [ i.N.T ]_c,(i+1)·N·T_c) The pseudo-random number generated by the time-hopping pseudo-code generator is L_i(ii) a Where i denotes the ith packet, the chip strobe p generated by the chip strobe generator_pulse(t) is:

(2.4) spreading the baseband spread Signal s_b(t) and chip strobe p_pulse(t) multiplying to realize chip time-hopping modulation to obtain a chip time-hopping signal s_TH(t)：

s_TH(t)＝s_b(t)·p_pulse(t)。

5. The method of claim 4, wherein the method further comprises: the time hopping pseudo code sequence mapping in the step (2.2) is realized by the following method:

(2.2.1) time hopping pseudo code sequence { c_TH,l}，c_TH,lE {1,0}, l ═ 0,1,2, …, and is converted from serial to parallel

(2.2.2) the decoder translates the M binary chip values corresponding to the ith packet to a value belonging to {0,1,2, …,2 }^MDecimal number of-1 }, i.e.

(2.2.3) adding L_M,iModulo N to obtain the number L belonging to {0,1,2, …, N-1}_iI.e. by

L_i＝L_M,imod N。

6. The method of claim 4, wherein the method further comprises: radio frequency modulation in the step (3) is realized by the following method:

(3.1) carrier generator for generating radio frequency carrier cos (2 pi f)_RFt)；f_RFIs the radio frequency carrier frequency, t is the time variable;

(3.2) chip time-hopping signal s_TH(t) multiplied by the radio frequency carrier, having s_TH,RF(t)＝s_TH(t)·cos(2πf_RFt)；

s_TH,RFAnd (t) after being amplified by the pulse amplifier and filtered by the filter, the signal is broadcasted to the user through the antenna.

7. A satellite navigation signal generating system based on chip-level pulse time hopping realized according to the satellite navigation signal generating method of claim 1, comprising:

a baseband spread spectrum modulation module: generating a signal pseudo code by a signal pseudo code generator, carrying out chip shaping, and modulating the signal pseudo code and a coded text together to obtain a baseband spread spectrum signal;

chip time hopping modulation module: generating a frequency hopping pseudo code sequence through a frequency hopping pseudo code generator, controlling a chip gating pulse generator to generate a chip gating pulse, and performing chip time hopping modulation on the chip gating pulse and a baseband spread spectrum signal generated by a baseband spread spectrum modulation module to obtain a chip time hopping signal;

the radio frequency modulation module: and generating a radio frequency carrier wave by a carrier wave generator, carrying out radio frequency modulation on the radio frequency carrier wave and the chip time hopping signal to generate a radio frequency signal, amplifying and filtering the radio frequency signal to finish the generation of the satellite navigation signal based on the chip-level pulse time hopping, and broadcasting the satellite navigation signal to a user through an antenna.

8. The system according to claim 7, wherein the system further comprises: the baseband spread spectrum modulation is obtained by the following method:

(1.1) generating a signal pseudo code; the pseudo code sequence generated by the signal pseudo code generator is { c_l}，c_l∈{1,-1}，l＝0,1,2,…；

(1.2) shaping a chip waveform; carrying out chip waveform shaping on the pseudo code sequence to obtain a pseudo code waveform:

in the formula (I), the compound is shown in the specification,

in the satellite navigation signal, a rectangular chip waveform or a binary offset carrier waveform is adopted;

for a rectangular chip waveform, there are:

the binary offset carrier waveform is a sinusoidal BOC chip waveform, for which

In the formula (f)_sSubcarrier frequency modulated for BOC, 2f_s/R_cIs an integer;

(1.3) baseband spread spectrum modulation; modulating the text d (t) and the pseudo code waveform C (t) to obtain a baseband spread spectrum modulation signal s_b(t) ═ d (t) · c (t), text d (t) ∈ {1, -1 }.

9. The system according to claim 7, wherein the system further comprises: the chip time hopping modulation specifically comprises the following steps:

(2.1) spread spectrum modulating signal s of base band_b(T) in time domain by chip width T_cGrouping, wherein every N chips are divided into a group, the group is marked as 0,1,2, … and N-1, only one chip in every N chips is gated, and the power of the N chips is concentrated on one chip; wherein N is an integer greater than 1 and represents the number of chips contained in each packet;

(2.2) time hopping pseudo code generationThe device generates a time-hopping pseudo code sequence c_TH,lMapped by time hopping pseudo code sequence, corresponding to every NT_cTime, in the ith chip packet, a number L belonging to {0,1,2, …, N-1} is output_iControlling the chip strobe generator to generate the chip strobe p_pulse(t)；

The time hopping pseudo code sequence mapping is realized by the following method:

(2.2.1) time hopping pseudo code sequence { c_TH,l}，c_TH,lE {1,0}, l ═ 0,1,2, …, and is converted from serial to parallel

(2.2.2) the decoder translates the M binary chip values corresponding to the ith packet to a value belonging to {0,1,2, …,2 }^MDecimal number of-1 }, i.e.

(2.2.3) adding L_M,iModulo N to obtain the number L belonging to {0,1,2, …, N-1}_iI.e. by

L_i＝L_M,imod N；

(2.3) at time T ∈ [ i.N.T ]_c,(i+1)·N·T_c) The pseudo-random number generated by the time-hopping pseudo-code generator is L_i(ii) a Where i denotes the ith packet, the chip strobe p generated by the chip strobe generator_pulse(t) is:

(2.4) spreading the basebandSignal s_b(t) and chip strobe p_pulse(t) multiplying to realize chip time-hopping modulation to obtain a chip time-hopping signal s_TH(t)：

s_TH(t)＝s_b(t)·p_pulse(t)。

10. The system according to claim 7, wherein the system further comprises: radio frequency modulation is realized by the following method:

(3.1) the carrier generator generates a radio frequency carrier cos (2 π f)_RFt)；f_RFIs the radio frequency carrier frequency, t is the time variable;

(3.2) chip time-hopping signal s_TH(t) multiplied by the radio frequency carrier, having s_TH,RF(t)＝s_TH(t)·cos(2πf_RFt)；

s_TH,RFAnd (t) after being amplified by the pulse amplifier and filtered by the filter, the signal is broadcasted to the user through the antenna.

Technical Field

The invention belongs to the field of satellite navigation, and particularly relates to a satellite navigation signal generation method based on chip-level pulse time hopping.

Background

Current satellite navigation signals are susceptible to interference and shadowing, primarily because the average transmit power of the signal is limited because the navigation satellite is a power limited system. The satellite navigation signal mainly adopts a continuous broadcast signal modulated by direct sequence spread spectrum, and the ground level of the satellite navigation signal is low, generally about-160 dBW. Moreover, the frequency and modulation mode of the satellite navigation signal are public, and are particularly easily affected by matching spectrum interference.

In order to improve the anti-interference capability of signals, the most effective and direct method is to increase the transmission power of the signals, and therefore, in the process of GPS modernization, a spot beam power enhancement mode is designed for M code signals, and the power of an area can be enhanced by more than 20 dB. The other method is to adopt an anti-interference signal system, such as a direct sequence spread spectrum frequency hopping signal or a direct sequence spread spectrum time hopping signal, and to improve the anti-interference capability by separating the anti-interference signal from the interference signal in a time domain or a frequency domain.

In the aspect of anti-interference signal system, the radio navigation system of spread spectrum and frequency hopping system (patent number: CN200910072086.8) provides a radio navigation system of hopping spread spectrum system, the navigation message is directly spread spectrum modulated and frequency hopping modulated in the spread spectrum and frequency hopping modulation module, and then is transmitted from the antenna through the high pass filter and the power amplifier. The patent "a burst navigation signal system and receiving method" (patent number: CN 201019114075.1) relates to a burst satellite navigation beacon broadcasted by a direct-transmitting satellite navigation system or a repeater satellite navigation system satellite, or a gap satellite navigation signal. The patent "a navigation signal generation method of time division system" (patent number: CN 201810245853.X) discloses a navigation signal generation method of time division system, which realizes two-way transmission between satellites by way of time division multiplexing and improves the utilization rate of frequency band. The document 'navigation satellite anti-interference technology based on mixed spread spectrum' combines the DS/TH mixed spread spectrum technology with the existing navigation satellite, after the navigation signal is subjected to DS code spread spectrum, each code piece after direct spread is divided into a plurality of time slots, and the time slots are selected according to a time hopping sequence to transmit the navigation signal.

It can be seen that the above patent adopts a hybrid spread spectrum scheme including direct sequence spread spectrum (DS/FH) and direct sequence spread spectrum (DS/TH) signals in order to improve the interference resistance of the navigation signals. The center frequency of the direct spread spectrum frequency hopping signal jumps along with time, the frequency hopping code controls the frequency at which the signal is broadcast, and the frequency and the interference signal are separated, so that the anti-interference capability is improved. However, the direct sequence spread spectrum frequency hopping has two disadvantages, firstly, the frequency hopping system signal is incompatible with the existing satellite navigation signal, and secondly, the high-precision measurement of the carrier phase of the frequency modulation signal has certain problems. The traditional direct sequence spread time hopping signal is incompatible with the current satellite navigation signal and can not be directly received by the existing receiving method. When a chip is divided into a plurality of time slots, the power spectrum of the signal is changed, and the bandwidth of the signal is increased.

Disclosure of Invention

The invention aims to: the method overcomes the defects of the prior art, and provides a chip-level pulse time hopping-based satellite navigation signal generation method under the conditions that the power of a satellite platform is limited and the average power of a transmitted signal is given, so that the improvement of the anti-interference capability is realized, the compatibility with the conventional satellite navigation signal system is kept, and the high-precision application based on carrier phase measurement is supported.

The technical solution of the invention is as follows:

a satellite navigation signal generation method based on chip-level pulse time hopping comprises the following steps:

(1) baseband spread spectrum modulation; a signal pseudo code generator generates a signal pseudo code, and after chip shaping, the signal pseudo code and the coded text are modulated together to obtain a baseband spread spectrum signal;

(2) chip time hopping modulation; the frequency hopping pseudo code generator generates a frequency hopping pseudo code sequence, controls the chip gating pulse generator to generate chip gating pulses, and performs chip time hopping modulation with the baseband spread spectrum signal to obtain a chip time hopping signal;

(3) radio frequency modulation; and the carrier wave generator generates a radio frequency carrier wave, performs radio frequency modulation on the radio frequency carrier wave and the chip time hopping signal to generate a radio frequency signal, completes generation of a satellite navigation signal based on chip-level pulse time hopping after amplification and filtering, and broadcasts the satellite navigation signal to a user through an antenna.

Further, the baseband spread spectrum modulation is specifically obtained by the following method:

(1.1) generating a signal pseudo code; the pseudo code sequence generated by the signal pseudo code generator is { c_l}，c_l∈{1,-1}，l＝0,1,2,…；

(1.2) shaping a chip waveform; carrying out chip waveform shaping on the pseudo code sequence to obtain a pseudo code waveform:

in the formula, p_Tc(T) is a chip waveform, T_c＝1/R_cIs chip width, R_cIs the code rate, t is the time variable;

(1.3) baseband spread spectrum modulation; modulating the text d (t) and the pseudo code waveform C (t) to obtain a baseband spread spectrum modulation signal s_b(t) ═ d (t) · c (t), text d (t) ∈ {1, -1 }.

Further, the step (1.2) performs chip waveform shaping on the pseudo code sequence, specifically:

in the satellite navigation signal, a rectangular chip waveform or a binary offset carrier waveform is adopted;

for a rectangular chip waveform, there are:

the binary offset carrier waveform is a sinusoidal BOC chip waveform, for which

In the formula (f)_sFor seed modulated by BOCCarrier frequency, 2f_s/R_cAre integers.

Further, the chip time hopping modulation in step (2) specifically includes:

(2.1) spread spectrum modulating signal s of base band_b(T) in time domain by chip width T_cGrouping, wherein every N chips are divided into a group, the group is marked as 0,1,2, … and N-1, only one chip in every N chips is gated, and the power of the N chips is concentrated on one chip; wherein N is an integer greater than 1 and represents the number of chips contained in each packet;

(2.2) the time hopping pseudo code generator generates a time hopping pseudo code sequence c_TH,lMapped by time hopping pseudo code sequence, corresponding to every NT_cTime, in the ith chip packet, a number L belonging to {0,1,2, …, N-1} is output_iControlling the chip strobe generator to generate the chip strobe p_pulse(t)；

(2.3) at time T ∈ [ i.N.T ]_c,(i+1)·N·T_c) The pseudo-random number generated by the time-hopping pseudo-code generator is L_i(ii) a Where i denotes the ith packet, the chip strobe p generated by the chip strobe generator_pulse(t) is:

(2.4) spreading the baseband spread Signal s_b(t) and chip strobe p_pulse(t) multiplying to realize chip time-hopping modulation to obtain a chip time-hopping signal s_TH(t)：

s_TH(t)＝s_b(t)·p_pulse(t)。

Further, the time hopping pseudo code sequence mapping in step (2.2) is implemented by the following method:

(2.2.1) time hopping pseudo code sequence { c_TH,l}，c_TH,lE {1,0}, l ═ 0,1,2, …, and is converted from serial to parallelThe way of the road is that the road is,meaning rounding up, i.e. mapping an integer L every M chips_iThe ith group has corresponding M binary code sequences of { c }_1,i}、{c_2,i}、…、{c_M,i}。

(2.2.2) the decoder translates the M binary chip values corresponding to the ith packet to a value belonging to {0,1,2, …,2 }^MDecimal number of-1 }, i.e.

(2.2.3) adding L_M,iModulo N to obtain the number L belonging to {0,1,2, …, N-1}_iI.e. by

L_i＝L_M,imod N。

Further, the radio frequency modulation in the step (3) is realized by the following method:

(3.1) the carrier generator generates a radio frequency carrier cos (2 π f)_RFt)；f_RFIs the radio frequency carrier frequency, t is the time variable;

(3.2) chip time-hopping signal s_TH(t) multiplied by the radio frequency carrier, having s_TH,RF(t)＝s_TH(t)·cos(2πf_RFt)；

s_TH,RFAnd (t) after being amplified by the pulse amplifier and filtered by the filter, the signal is broadcasted to the user through the antenna.

Further, the present invention provides a satellite navigation signal generating system based on chip-level pulse time hopping according to the satellite navigation signal generating method of claim 1, comprising:

a baseband spread spectrum modulation module: generating a signal pseudo code by a signal pseudo code generator, carrying out chip shaping, and modulating the signal pseudo code and a coded text together to obtain a baseband spread spectrum signal;

chip time hopping modulation module: generating a frequency hopping pseudo code sequence through a frequency hopping pseudo code generator, controlling a chip gating pulse generator to generate a chip gating pulse, and performing chip time hopping modulation on the chip gating pulse and a baseband spread spectrum signal generated by a baseband spread spectrum modulation module to obtain a chip time hopping signal;

the radio frequency modulation module: and generating a radio frequency carrier wave by a carrier wave generator, carrying out radio frequency modulation on the radio frequency carrier wave and the chip time hopping signal to generate a radio frequency signal, amplifying and filtering the radio frequency signal to finish the generation of the satellite navigation signal based on the chip-level pulse time hopping, and broadcasting the satellite navigation signal to a user through an antenna.

Compared with the prior art, the invention has the beneficial effects that:

the invention discloses a satellite navigation signal based on chip-level pulse time hopping and a generation method thereof, which realize the improvement of the anti-interference capability on the premise of certain average transmitting power, compared with the prior method, the method disclosed by the invention has the following advantages:

(1) the current anti-interference navigation signal system usually adopts a mixed spread spectrum mode and is incompatible with the current satellite navigation signal receiving mode; the satellite navigation signal based on chip-level pulse time hopping provided by the invention is completely compatible with the existing satellite navigation signal system, and can be received by using the existing receiving method.

(2) In the existing direct sequence spread time hopping signal system, a chip is divided into a plurality of time slots, and through time slot hopping, a signal is only broadcast in one time slot each time, so that the power spectrum of the signal is changed, and the bandwidth of the signal is increased. The invention adopts the mode of chip gating pulse to change the position of gating one chip in each group of N chips, thereby realizing the effect of equivalent chip time hopping without changing the frequency spectrum of signals.

(3) The invention realizes the conversion of continuous signals with low average power into random pulse position quasi-continuous signals with high instantaneous power when realizing chip-level pulse skipping at the chip level. Specifically, the power of N chips is concentrated on one chip, and the carrier phase is continuous for one code period processing, so that high-precision application based on carrier phase measurement can be supported. For users with time-hopping code sequences, the anti-interference capability can be improved by 10lg (N) dB. The improvement of the anti-interference capability can be flexibly adjusted by changing the value of N.

Drawings

FIG. 1 is a schematic diagram of a satellite navigation signal based on chip-level pulse time hopping according to the present disclosure;

FIG. 2 is a pseudo code sequence mapping method for time hopping

FIG. 3 is a diagram of chip-level pulse time-hopping signal generation

FIG. 4 shows the baseband waveform of a chip-hopping signal

FIG. 5 is a power spectrum of a chip-hopping signal

Fig. 6 is a correlation function of a chip-hopping signal.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

The average power of the transmitted signal is constant, in order to improve the anti-interference capability of the signal, the invention adopts a chip-level pulse time hopping scheme, namely, a spread spectrum code sequence is grouped according to chips, each group of N chips has only one chip to gate, the position of the gated chip is determined by a gating pulse, and the gating pulse can be generated by a time hopping code and is pseudo-random. In the scheme of the invention, the power of N original chips is concentrated on one chip, and for a user without a time hopping code, a traditional navigation signal receiving and processing method can be adopted, so that the invention is compatible with the existing satellite navigation signal; for the users with the time hopping codes, after matched receiving can be carried out, the signal power is improved by N times, and the anti-interference capability is improved by 10lg (N) dB.

In order to achieve the above object, the present invention discloses a method for generating a satellite navigation signal based on chip-level pulse time hopping, and the specific flow is shown in fig. 1.

Step 1, base band spread spectrum modulation. The signal pseudo code generator generates a signal pseudo code, carries out chip shaping and then modulates the signal pseudo code and the coded text together to obtain a baseband spread spectrum signal. The message d (t) is epsilon {1, -1}, t is a time variable, and the message symbol rate is R_sSymbol width of T_s＝1/R_s(ii) a Code rate of R_cChip width of T_c＝1/R_c。

The baseband spread spectrum modulation is obtained by the following method:

1) signal pseudo-code generation. The pseudo code sequence generated by the signal pseudo code generator is { c_lThe l-th chip c_l∈{1,-1}，l＝0,1,2,…；

2) And shaping a chip waveform. Carrying out chip waveform shaping on the code sequence to obtain a pseudo code waveform:

in the formula, p_TcAnd (t) is a chip waveform, and a rectangular chip waveform or a Binary Offset Carrier (BOC) waveform can be adopted in the satellite navigation signal. For a rectangular chip waveform, there are:

for a sinusoidal BOC chip waveform, there are

In the formula (f)_sSubcarrier frequency modulated for BOC, 2f_s/R_cAre integers.

3) And (4) baseband spread spectrum modulation. Modulating the text d (t) and the pseudo code waveform C (t) to obtain a baseband spread spectrum modulation signal s_b(t)：

s_b(t)＝d(t)·C(t)

And step 2, chip time hopping modulation. The frequency hopping pseudo code generator generates a frequency hopping pseudo code sequence, controls the chip gating pulse generator to generate chip gating pulses, and performs chip time hopping modulation with the baseband spread spectrum signal to obtain a chip time hopping signal.

The chip time hopping modulation is obtained by the following method:

(1) will s_b(T) in time domain by chip width T_cGrouping is carried out, N chips are divided into a group, which is marked as 0,1,2, … and N-1, only one chip in every N chips is gated, and the power of the N chips is concentrated on one chip, wherein N is an integer greater than 1 and represents the number of chips contained in each group.

(2) The time-hopping pseudo-code generator generates a time-hopping pseudo-code sequence c_TH,lMapped by time hopping pseudo code sequence, corresponding to every NT_cTime, in the ith chip packet, a number L belonging to {0,1,2, …, N-1} is output_iControlling the chip strobe generator to generate the chip strobe p_pulse(t)。

The time hopping pseudo code sequence mapping can be obtained by the following method:

(2.1) time hopping pseudo code sequence { c_TH,l}，c_TH,lE {1,0}, l ═ 0,1,2, …, and is converted from serial to parallel

The way of the road is that the road is,

meaning rounding up, i.e. mapping an integer L every M chips_i. In the ith group, the corresponding M-path binary code sequence is { c_1,i}、{c_2,i}、…、{c_M,i}，

(2.2) the decoder translates the M binary chip values corresponding to the ith packet to a value belonging to {0,1,2, …,2 }^MDecimal number of-1 }, i.e.

(2.3) mixing L_M,iModulo N to obtain the number L belonging to {0,1,2, …, N-1}_iI.e. by

L_i＝L_M,imod N

(3) At time T ∈ [ i.N.T_c,(i+1)·N·T_c) The pseudo-random number generated by the time-hopping pseudo-code generator is L_i. i denotes the ith packet, the chip strobe p generated by the chip strobe generator_pulse(t) is:

(4) will radicalWith spread spectrum signal s_b(t) and chip strobe p_pulse(t) multiplying to realize chip time-hopping modulation to obtain a chip time-hopping signal s_TH(t)：

s_TH(t)＝s_b(t)·p_pulse(t)

And 3, modulating the radio frequency. The carrier wave generator generates a radio frequency carrier wave, performs radio frequency modulation with the chip time hopping signal to generate a radio frequency signal, and broadcasts the radio frequency signal to a user after amplification, filtering and antenna.

The radio frequency modulation can be obtained by the following method:

(1) carrier generator for generating radio frequency carrier cos (2 pi f)_RFt)；

(2) Chip time hopping signal s_TH(t) multiplied by the radio frequency carrier, having s_TH,RF(t)＝s_TH(t)·cos(2πf_RFt)；

s_TH,RFAnd (t) after pulse amplifier amplification, filter filtering and antenna broadcasting to users.

The embodiment of the invention is as follows:

the operation steps of the satellite navigation signal based on chip-level pulse time hopping and the generation method disclosed by the invention are shown in fig. 1, and specifically are as follows:

(1) and (4) baseband spread spectrum modulation. The signal pseudo code generator generates a signal pseudo code, carries out chip shaping and then modulates the signal pseudo code and the coded text together to obtain a baseband spread spectrum signal. Message d (t) e {1, -1}, symbol rate R_s100sps, symbol width T_s＝10ms；

The pseudo code sequence generated by the signal pseudo code generator is { c_l}，c_lE {1, -1}, l ═ 0,1,2, …; code rate of R_c10.23Mcps, chip width T_c＝1/R_c。

Carrying out rectangular chip waveform shaping on the code sequence to obtain a pseudo code waveform:

in the formula, p_Tc(t) is a rectangular chip waveform having：

Modulating the text d (t) and the pseudo code waveform C (t) to obtain a baseband spread spectrum modulation signal s_b(t)：

s_b(t)＝d(t)·C(t)

(2) Chip hopping modulation. The frequency hopping pseudo code generator generates a frequency hopping pseudo code sequence, controls the chip gating pulse generator to generate chip gating pulses, and performs chip time hopping modulation with the baseband spread spectrum signal to obtain a chip time hopping signal.

Will s_b(T) in time domain by chip width T_cGrouping is carried out, every N-16 chips are divided into a group, which is marked as 0,1,2, … and 15, only one chip in every N-16 chips is gated, and the power of N chips is concentrated on one chip.

The time-hopping pseudo-code generator generates a time-hopping pseudo-code sequence c_TH,lMapped by time hopping pseudo code sequence, corresponding to every NT_cTime, in the ith packet, a number L belonging to {0,1,2, …,15} is output_iControlling the chip strobe generator to generate the chip strobe p_pulse(t) of (d). Fig. 2 shows a schematic diagram of a time hopping pseudo code sequence mapping method.

At time T ∈ [ i.N.T_c,(i+1)·N·T_c) The pseudo-random number generated by the time-hopping pseudo-code generator is L_i. Chip strobe p generated by a chip strobe generator_pulse(t) is:

spreading the baseband signal s_b(t) and chip strobe p_pulse(t) multiplying to realize chip time-hopping modulation to obtain a chip time-hopping signal s_TH(t)：

s_TH(t)＝s_b(t)·p_pulse(t)

Base band spread spectrum signal s_b(t), time hopping pseudo codeSequence c_TH,lChip strobe p_pulse(t) and chip time hopping signal s_THThe time domain diagram of (t) is shown in fig. 3. Chip time hopping signal s_THThe baseband waveform of (t) is shown in fig. 4, and the power spectrum is shown in fig. 5.

(3) And (4) radio frequency modulation. The carrier wave generator generates a radio frequency carrier wave, performs radio frequency modulation with the chip time hopping signal to generate a radio frequency signal, and broadcasts the radio frequency signal to a user after amplification, filtering and antenna.

For users with time hopping codes, matched reception can be performed, and the anti-interference capability is improved, for users without time hopping codes, non-matched reception can be performed by adopting a traditional receiving method, and a correlation function of the matched reception and the non-matched reception is shown in fig. 6.

The invention adopts the mode of chip gating pulse to change the position of gating one chip in each group of N chips, thereby realizing the effect of equivalent chip time hopping without changing the frequency spectrum of signals.

The invention realizes the conversion of continuous signals with low average power into random pulse position quasi-continuous signals with high instantaneous power when realizing chip-level pulse skipping at the chip level. Specifically, the power of N chips is concentrated on one chip, and the carrier phase is continuous for one code period processing, so that high-precision application based on carrier phase measurement can be supported. For users with time-hopping code sequences, the anti-interference capability can be improved by 10lg (N) dB. The improvement of the anti-interference capability can be flexibly adjusted by changing the value of N.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.