CN110275189A - A chip time division navigation signal modulation method and system with mixed information rate - Google Patents

Abstract

A chip time-division navigation signal modulation method and system of mixed information rate, comprising (1) channel coding: channel coding low-speed telegrams and high-speed telegrams respectively, (2) PRN code mapping: mapping the channel-coded low-speed telegrams as One channel of PRN code sequence, the channel-coded high-speed message is mapped to N-1 channel of PRN code sequence, and N channels of PRN code sequence are obtained in total; (3) Chip time division: The N channels of PRN code sequence are divided into one signal by chip time; (4) Baseband waveform modulation: baseband waveform modulation is performed on a signal obtained after chip time division to obtain a baseband signal.

Description

A chip time division navigation signal modulation method and system with mixed information rate

technical field

The invention belongs to the field of satellite navigation, and mainly relates to a method and a system for modulating a chip time-division navigation signal with a mixed information rate.

Background technique

At present, the pattern of the four basic global satellite navigation systems (Global Navigation Satellite System, GNSS) has been formed, GNSS can meet people's most basic navigation, positioning and timing needs. In order to further improve the service performance of satellite navigation systems, some systems have begun to provide enhanced services: Japan's QZSS provides Centimeter Level Augmentation Service (CLAS) on its L6, and Galileo plans to provide precision positioning services on its E6 frequency.

This type of navigation enhancement service provides precise positioning services (Precise Point Positioning, PPP) by rapidly broadcasting precise telegrams or precise corrections. The precision correction number generally includes the correction number of orbit, clock error, carrier phase deviation, as well as parameters such as code deviation and URA. In order to achieve high-precision positioning, the broadcast interval of the precision correction number is short. Taking QZSS as an example, the broadcast interval of the clock error correction number is 5s, others are 30s.

In traditional GNSS signals, low-speed basic navigation messages are broadcast, and the information rate is usually only 50bps to 250bps. In the enhanced service, fast and precise corrections are broadcast, and the information rate is significantly improved. QZSS provides the L6 signal of CLAS, and the information rate reaches about 2kbps. Therefore, GNSS faces the need to broadcast low-speed basic navigation messages and high-speed precision messages at the same time.

The GNSS signal adopts direct spread spectrum modulation. In order to increase the information rate, there are traditionally two methods. The first method is to keep the code rate unchanged and increase the information rate, which reduces the number of chips in a symbol, reduces the spread spectrum gain, and deteriorates the cross-correlation performance. The second is to keep the spread spectrum gain unchanged and increase the information rate, which leads to an increase in the code rate and a larger bandwidth occupied by the signal.

In order to increase the information rate without changing the code rate and spreading gain, QZSS applies a code-shift keying (Code-Shift-Keying, CSK) modulation signal to its L6 signal. CSK is an M-ary quadrature modulation signal, there are M kinds of spread spectrum modulation signal waveforms, each waveform can represent k=log ₂ (M) bit information, these M kinds of spread spectrum modulation signal waveforms are the same basic Code cyclic shift is obtained. For a spreading code of code length L, each waveform represents at most bit information. However, the CSK modulated signal alone is not suitable for acquisition tracking measurements, only for data transmission.

In order to broadcast low-speed telegrams and high-speed telegrams at the same time, the patent "A Code Shift Keying Modulation Method and Its Demodulation Method with Repeated Phase Shifting" (Patent No.: CN 201811042847.0) proposes R-CSK signal, which is a special case of CSK signal , the information is modulated by different cyclic shifts of the same code, but the maximum information rate is limited by the code length. The patents "a double-rate composite message signal broadcast control method" (patent number: CN 201810947305.1) and "a R-CSK dual-rate composite message signal broadcast control method" (patent number: CN 201811078853.1) propose the use of phase quadrature QPSK For modulation, the traditional BPSK signal is used in the I branch to broadcast the low-rate basic navigation message, and the Q branch uses the CSK signal or R-CSK signal to broadcast the high-rate extended message. However, by means of phase separation, the I branch will consume a part of the power, and when the signal is tracked or demodulated, all the signal power cannot be used, which reduces the precision and the demodulation threshold.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a chip time-division navigation signal modulation method and system with a mixed information rate, which simultaneously realizes high-precision measurement and low/high data rate telegrams on a spread spectrum navigation signal. broadcast.

The technical solution of the present invention is:

A method for modulating a chip time-division navigation signal with a mixed information rate, the steps are as follows:

(1) Channel coding: channel coding the low-speed telegram and the high-speed telegram respectively,

(2) PRN code mapping: map the channel-coded low-speed telegrams to one PRN code sequence, and the channel-coded high-speed telegrams to N-1 PRN code sequences to obtain N PRN code sequences in total;

(3) Chip time division: The N-way PRN code sequence is divided into one signal by chip time;

(4) Baseband waveform modulation: baseband waveform modulation is performed on a signal obtained after chip time division to obtain a baseband signal.

The original information rate of the low-speed message is R _b,L , the symbol rate after channel coding is R _s,L , the symbol width of the low-speed message is T _s,L =1/R _s,L , and the coding efficiency is R _b,L /R _s,L , the information symbol stream after channel coding is {d _L,m }, d _L,m ∈{0,1};

The original information rate of the high-speed message is R _b,H , the symbol rate after channel coding is R _s,H , the symbol width of the high-speed message is T _s,H =1/R _s,H , and the coding efficiency is R _b,H /R _s,H , the channel-coded information symbol stream is {d _H,m }, d _H,m ∈ {0,1}.

Low-speed message PRN code mapping, specifically:

(2.11) Generate the PRN code sequence of the low-speed message, the spreading code sequence is {c _{L, i} }, i = 0, 1, 2,..., L _c -1, c _{L, i} ∈ {0, 1}, the code rate is R _c ;

(2.12) Determine the code period: a low-speed data symbol has code period, that is, T _{s, L} is an integer multiple of L _c ·T _c , L _c is the code length of the spreading code, T _c =1/R _c , is the chip width,

(2.13) XOR the low-speed message {d _{L, m} } with the spreading code sequence {c _{L, i} } to obtain the code sequence after mapping; that is, when the data symbol d _{L, m} is 0, the output code sequence is {c _{L, i} }, when the data symbol d _{L, m} is 1, the output code sequence is the inverse sequence of {c _{L, i} } The code sequence obtained by mapping is denoted as {C _L,i }.

High-speed message PRN code mapping, specifically:

(2.21) Generate a set of PRN code sequences for high-speed telegrams;

The number of different orthogonal spreading code sequences generated is N _c , which are The code length of each spreading code is L _c ; each spreading code is cyclically shifted to obtain a new orthogonal spreading code sequence, and at most N _c ·L _c orthogonal spreading code sequences are obtained. A spreading code sequence represents bit;

(2.22) According to the rate of high-speed telegram, each spreading code sequence represents U bits, A total of M = 2 ^U orthogonal code sequences are required, expressed as These orthogonal code sequences come from and their cyclic shifts;

(2.23) After the serial-to-parallel conversion of the high-speed telegram {d _H,m }, the (N-1)·U parallel telegram symbol stream is output, denoted as d _(N-1)·U,k =[d _1,k d _2,k … d _{(N-1) U,k} ] ^T , d _u,k represents the k-th symbol value of the u-th message symbol stream; after serial-parallel conversion, the symbol rate is reduced to

(2.24) Each column has (N-1) U-bit message symbols, and each U row of message symbols is mapped to a code sequence, and a total of N-1 code sequences are obtained; (n-1) U+1 to n. The code sequence of U-channel message symbol mapping is expressed as

The mapping relationship between U parallel message symbols and spreading codes is as follows:

In the formula, x _n,k is the decimal number representation of the binary number [d _(n-1)U+1,k d _(n-1)U+2,k … d _{n U+1,k} ] ^T , namely

The chip time division is obtained by the following methods:

(3.1) One channel of spreading code {C _{L, i} } mapped to low-speed message and N-1 channel of spreading code mapped to high-speed message As an N-way parallel code sequence, 1≤n≤N-1;

(3.2) According to the chip-by-chip time division method, the N parallel code sequences are synthesized into one spread spectrum code sequence, and the spread spectrum code sequence after chip time division multiplexing is recorded as: { _CM,l }, when (i-1 )N+1≤l≤i·N,

(3.3) After passing the chip time division, the code rate of {C _M,l } is increased to N times of the original, which is denoted as N·R _c .

Baseband waveform modulation, obtained by:

(4.1) Design the chip waveform p(t) according to the signal performance and compatibility requirements;

(4.2) The code sequence {C _M,l } after chip time division is modulated with the chip waveform p(t), and the modulated signal of the baseband waveform is expressed as:

The chip waveform p(t) adopts a rectangular chip waveform or a binary offset carrier waveform.

For rectangular chip waveforms, there are:

For binary offset carrier waveforms, we have

In the formula, f _s is the sub-carrier frequency of BOC modulation, and 2f _s /(N·R _c ) is an integer.

Further, the present invention also proposes a navigation signal modulation system based on the mixed information rate chip time division navigation signal modulation method, including:

Channel coding module: channel coding low-speed telegrams and high-speed telegrams respectively, and interleaving after channel coding to improve the ability to resist channel fading.

PRN code mapping module: maps the channel-coded low-speed telegrams to one PRN code sequence, and the channel-encoded high-speed telegrams to N-1 PRN code sequences to obtain N PRN code sequences in total;

Chip time division module: divide the N-way PRN code sequence into one signal chip by chip time;

Baseband waveform modulation module: perform baseband waveform modulation on a signal obtained after chip time division to obtain a baseband signal.

The beneficial effects of the present invention compared with the prior art are:

(1) Compared with the hybrid structure of BPSK and R-CSK using QPSK modulation, this method adopts the chip time division technology, which modulates one signal of the low-speed telegram and the multi-channel signal of the modulated high-speed telegram, and broadcasts the time-division chip by chip. When performing signal tracking and demodulation, the full power can be used, which improves the signal tracking accuracy.

(2) The existing chip time division is usually the chip time division of the two-channel signal, and the present patent adopts the chip time division of the multi-channel signal to improve the data rate.

(3) The traditional CSK modulation signal is only suitable for broadcasting data, not suitable for tracking and code ranging. In a composite signal, the present invention combines a code sequence with high-precision ranging capability with a code sequence for modulating high-speed telegrams. Chip-by-chip time division realizes the combination of high-precision navigation ranging and high-speed data broadcasting.

(4) The existing CSK only uses the cyclic shift modulation data of one spreading code, and the maximum data rate is limited by the code length and code rate of the spreading code. The present invention can use multiple different spreading codes and their cyclic shifts. The shift realizes the mapping of more bits, the maximum data rate breaks through the limitation of the code length, and further improves the information rate.

(5) In the existing CSK modulation mode, the chip waveforms are all rectangular chips, and the spectrum and ranging performance of the signal are limited. The present invention points out that rectangular or BOC chip waveforms and other chip waveforms can be used to achieve high performance and high compatibility.

Description of drawings

Fig. 1 is the mixed information rate chip time division navigation signal modulation scheme disclosed by the present invention;

Figure 2 is a schematic diagram of PRN code mapping of low-speed telegrams

Figure 3 is a schematic diagram of the parallel conversion of high-speed telegram serial to (N-1) U-channel parallel

FIG. 4 is a schematic diagram of chip time division.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The present invention broadcasts the code sequence of the modulated low-speed telegram and the code sequence modulated with the high-speed telegram in time division through the chip-by-chip time division technique. For the convenience of description, in this patent, the logic level and the signal level are equivalent, adopting the convention in satellite navigation signals, the logic 0 is mapped to the signal level 1.0, and the logic 1 is mapped to the signal level -1.0.

In order to achieve the above object, the present invention discloses a chip time division signal modulation method with mixed information rate.

1. The chip time division signal modulation method of mixed information rate includes the following steps, as shown in Figure 1:

(1) Channel coding. The low-speed message and the high-speed message are channel-coded respectively, the original information rate of the low-speed message is R _b,L , the symbol rate after channel coding is R _s,L , and the symbol width of the low-speed message is T _s,L =1/R _{s, L} , the coding efficiency is R _b,L /R _s,L , the information symbol stream after channel coding is {d _L,m }, d _L,m ∈{0,1}. The original information rate of the high-speed message is R _b,H , the symbol rate after channel coding is R _s,H , the symbol width of the high-speed message is T _s,H =1/R _s,H , and the coding efficiency is R _b,H /R _s,H , the channel-coded information symbol stream is {d _H,m }, d _H,m ∈ {0,1}. After channel coding, interleaving technology can be used to improve the ability to resist channel fading.

(2) PRN code mapping. The low-speed telegram is mapped to one PRN code sequence, and the high-speed telegram is mapped to N-1 PRN code sequence, and a total of N PRN code sequences are obtained.

(3) Chip time division. The N-way PRN code sequence is divided into one signal by chip time.

(4) Baseband waveform modulation. Baseband waveform modulation is performed on a signal obtained after chip time division to obtain a baseband signal.

2. The low-speed message PRN code mapping described in (2) in step 1 is obtained by the following methods:

1) Generate the PRN code sequence of the low-speed message, the spreading code sequence is {c _{L, i} }, i = 0, 1, 2, ..., L _c -1, c _{L, i} ∈ {0, 1}, the code rate is R _c .

2) A low-speed data symbol has A code period, that is, T _{s, L} is an integer multiple of L _c ·T _c .

3) XOR the low-speed message {d _{L, m} } with the spreading code sequence {c _{L, i} } to obtain the post-mapping code sequence. That is, when the data symbol d _{L, m} is 0, the output code sequence is {c _{L, i} }, and when the data symbol d _{L, m} is 1, the output code sequence is the inverted sequence of {c _{L, i} } The code sequence obtained by mapping is denoted as {C _L,i }.

3. The high-speed message PRN code mapping described in (2) in step 1 is obtained by the following methods:

1) Generate a set of PRN code sequences for high-speed telegrams. The number of different orthogonal spreading code sequences generated is N _c , which are The code length of each spreading code is L _c . By cyclically shifting each spreading code, a new orthogonal spreading code sequence can be obtained. In theory, at most N _c · L _c orthogonal spreading code sequences can be obtained. Each spreading code sequence can represent bits.

2) According to the rate of the high-speed message, it is determined that each spreading code sequence needs to represent U bits, A total of M = 2 ^U orthogonal code sequences are required, expressed as These orthogonal code sequences come from and their cyclic shifts.

3) After the serial-to-parallel conversion of the high-speed telegram {d _H,m }, the (N-1)·U parallel telegram symbol stream is output, denoted as d _(N-1)·U,k =[d _1,k d _{2 ,k} … d _(N-1)·U,k ] ^T , d _u,k represents the k-th symbol value of the u-th message symbol stream. After serial-to-parallel conversion, the symbol rate is reduced to

4) Each column has (N-1) U-bit message symbols, and each U row of message symbols is mapped to a code sequence, and the code sequence mapped by the (n-1)th U+1 to n-U message symbols is expressed as The mapping relationship between U parallel message symbols and spreading codes is as follows:

In the formula, x _n,k is the decimal number representation of the binary number [d _(n-1)U+1,k d _(n-1)U+2,k … d _{n U+1,k} ] ^T , namely

4. The chip time division described in (3) in step 1 is obtained by the following method:

1) One channel of spreading code {C _{L, i} } mapped to low-speed message and (N-1) channel of spreading code mapped to high-speed message (1≤n≤N-1) as the N-way parallel code sequence.

2) According to the chip-by-chip time division method, the N parallel code sequences are synthesized into one spread spectrum code sequence, and the spread spectrum code sequence after chip time division multiplexing is recorded as: { _CM,l }, when (i-1) N+1≤l≤i·N,

3) After passing the chip time division, the code rate of {C _M,l } is increased to N times of the original, denoted as N·R _c .

5. The baseband waveform modulation described in (4) in step 1 is obtained by the following method:

1) According to the signal performance and compatibility requirements, design the chip waveform, p(t). A rectangular chip waveform or a binary offset carrier (BOC) waveform may be employed. For rectangular chip waveforms, there are:

For a sinusoidal BOC chip waveform, we have

In the formula, f _s is the sub-carrier frequency of BOC modulation, and 2f _s /(N·R _c ) is an integer.

2) The code sequence {C _M,l } after chip time division is modulated with the chip waveform p(t), and the modulated signal of the baseband waveform is expressed as:

Embodiment: The operation steps of the mixed information rate chip time division navigation signal modulation method disclosed by the present invention are as follows:

(1) Channel coding.

The low-speed message and high-speed message are channel-coded respectively. The original information rate of the low-speed message is R _{b, L} = 50bps, the symbol rate after channel coding is R _{s, L} = 100sps, the symbol width of the low-speed message is 10ms, and the coding efficiency is 1 /2, the information symbol stream after channel coding is {d _L,m }, d _L,m ∈ {0,1}. The original information rate of the high-speed message is R _b,H =2.4kbps, the symbol rate after channel coding is R _s,H =4.8ksps, the coding efficiency is 1/2, and the information symbol stream after channel coding is {d _H,m }, d _H,m ∈ {0,1}.

(2) PRN code mapping.

The PRN code sequence sequence of the low-speed message is {c _L,i }, i=0,1,2,...,1022, c _L,i ∈{0,1}, the code length is L _c =1023, and the code rate is R _c = 1.023 Mcps. A low-speed data symbol has 10 code periods. The low-speed message {d _L,m } is XORed with the spreading code sequence {c _{L, i} } to obtain the post-mapping code sequence {C _{L, i} }, and the mapping process is shown in FIG. 2 .

Generates a set of PRN code sequences for high-speed telegrams. The number of generated different orthogonal spreading code sequences is N _c =1, and the code lengths of the spreading codes are all L _c =1023. By cyclically shifting the spreading code, M=32 orthogonal spreading code sequences are obtained, which are expressed as Each spreading code sequence can represent U=6 bits. After converting the high-speed message {d _H,m } to serial and parallel, output 4×6=24 parallel message symbol streams, denoted as d _24,k =[d _1,k d _2,k … d _24,k ] ^T , d _u,k represents the k-th symbol value of the u-th message symbol stream, and the symbol rate is reduced to 200sps after serial-to-parallel conversion. Figure 3 shows a schematic diagram of the high-speed telegram serial-to-parallel conversion into (N-1)·U-channel parallel.

Each column has 4×6=24-bit message symbols, and each group of 6 is mapped to a code sequence. The code sequence mapped by the 6(n-1)+1 to 6nth message symbols is expressed as The mapping relationship between the six parallel message symbols and the spreading code is as follows:

In the formula, x _n,k is the decimal representation of the binary number [d _6(n-1)+1,k d _6(n-1)+2,k … d _6n+1,k ] ^T , namely

(3) Chip time division.

One spread spectrum code {C _{L, i} } mapped to low-speed telegrams and four spread spectrum codes mapped to high-speed telegrams As a 5-way parallel code sequence. According to the chip-by-chip time division method, 5 parallel code sequences are synthesized into one spread spectrum code sequence, and the spread spectrum code sequence after chip time division multiplexing is recorded as: { _CM,l }, when 5(i-1)+ 1≤l≤5i, A schematic diagram of chip time division is shown in FIG. 4 . After chip time division, the code rate of {C _M,l } is increased by 5 times, that is, 5.115Mcps.

(4) Baseband waveform modulation.

The chip waveform p(t) is used for waveform modulation, and the baseband waveform modulated signal is expressed as:

For rectangular chip waveforms, there are:

In this example, low-speed telegrams with an information rate of 50 bps and high-speed telegrams with an information rate of 2.4 kbps are broadcast at the same time, realizing high information rate broadcast. In this example, only 32 cyclic shifts of a spreading code sequence are used for high-speed message modulation, and the information rate can be further improved by increasing the number of spreading code sequences. In addition, the spread spectrum code sequence for modulating low-speed telegrams and the spreading code sequence for modulating high-speed telegrams are combined into one signal according to the time division pattern, and the signal is tracked as a whole. When the full signal power is used, high-precision tracking can be achieved.

The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (10)

1. a kind of chip time-division navigation signal modulation method of mixed information rate, it is characterised in that steps are as follows:

(1) channel coding: low speed text and high speed text are respectively channel encoded；

(2) PRN code maps: the low speed text Jing Guo channel coding being mapped as PRN code sequence all the way, by the height of channel coding Fast text is mapped as the road N-1 PRN code sequence, and the road N PRN code sequence is obtained；

(3) the chip time-division: it is divided into signal all the way when by the road N PRN code sequence by chip；

(4) baseband waveform is modulated: the signal all the way obtained after the chip time-division being carried out baseband waveform modulation, obtains baseband signal.

2. a kind of chip time-division navigation signal modulation method of mixed information rate according to claim 1, feature exist In: the raw information rate of low speed text is R_b,L, it is R by character rate after channel coding_s,L, low speed text symbol intervals are T_s,L=1/R_s,L, code efficiency R_b,L/R_s,L, the information symbol stream after channel coding is { d_L,m, d_L,m∈{0,1}；

The raw information rate of high speed text is R_b,H, it is R by character rate after channel coding_s,H, high speed text symbol intervals For T_s,H=1/R_s,H, code efficiency R_b,H/R_s,H, the information symbol stream after channel coding is { d_H,m, d_H,m∈{0,1}。

3. a kind of chip time-division navigation signal modulation method of mixed information rate according to claim 2, feature exist In:

The mapping of low speed text PRN code, specifically:

(2.11) PRN code sequence of low speed text is generated, spread spectrum code sequence is { c_L,i, i=0,1,2 ..., L_c- 1, c_L,i∈{0, 1 }, bit rate R_c；

(2.12) determine the code period: a low speed data symbol hasA yard of period, i.e. T_s,LIt is L_c·T_cInteger Times, L_cIt is the code length of spreading code, T_c=1/R_c, it is chip width,

(2.13) by low speed text { d_L,mAnd spread spectrum code sequence { c_L,iExclusive or, code sequence after being mapped；Work as data symbol d_L,mWhen being 0, output code sequence is { c_L,i, as data symbol d_L,mWhen being 1, output code sequence is { c_L,iNegate sequenceIt maps obtained code sequence and is denoted as { C_L,i}。

4. a kind of chip time-division navigation signal modulation method of mixed information rate according to claim 2, feature exist In:

The mapping of high speed text PRN code, specifically:

(2.21) the PRN code sequence set of high speed text is generated；

The different orthogonal spread spectrum code sequence number of generation is N_cIt is a, respectivelyThe code length of each spreading code is L_c；By each spreading code cyclic shift, new orthogonal intersection sequence is obtained, N is at most obtained_c·L_cA orthogonal spreading code sequence Column, each spread spectrum code sequence indicateBit；

(2.22) according to the rate of high speed text, each spread spectrum code sequence indicates U bit,M is needed altogether =2^UOrthogonal code sequence is expressed asThese orthogonal code sequences fromAnd their cyclic shift；

(2.23) high speed text { d_H,mAfter serioparallel exchange, the parallel text symbol stream in the road (N-1) U is exported, d is denoted as_(N-1)·U,k =[d_1,k d_2,k … d_(N-1)·U,k]^T, d_u,kIndicate k-th of value of symbol of the road u text symbol stream；Symbol speed after serioparallel exchange Rate is reduced to

(2.24) each to show (N-1) U bit text symbol, every U row text symbol is mapped as a kind of yard of sequence, N- is obtained 1 kind of code sequence；The code sequence of the road (n-1) U+1 to nU text symbol mapping is expressed as

U parallel text symbols are as follows: with spreading code mapping relations

In formula, x_n,kFor binary numberDecimal number indicate, i.e.,

5. a kind of chip time-division navigation signal modulation method of mixed information rate according to claim 4, feature exist In: it the chip time-division, obtains by the following method:

(3.1) spreading code { C all the way for mapping low speed text_L,iAnd high speed text mapping the road N-1 spreading codeAs N The parallel code sequence in road, 1≤n≤N-1；

(3.2) in the way of by the chip time-division, by the parallel code sequent synthesis in the road N, spread spectrum code sequence, chip are time-multiplexed all the way Spread spectrum code sequence afterwards is denoted as: { C_M,l, as (i-1) N+1≤l≤iN,

(3.3) after passing through the chip time-division, { C_M,lBit rate increase be original N times, be denoted as NR_c。

6. a kind of chip time-division navigation signal modulation method of mixed information rate according to claim 4, feature exist In: baseband waveform modulation obtains by the following method:

(4.1) it according to signal performance and compatibility requirement, designs Chip Waveform p (t)；

(4.2) by the code sequence { C after the chip time-division_M,lBe modulated with Chip Waveform p (t), the modulated signal of baseband waveform It indicates are as follows:

7. a kind of chip time-division navigation signal modulation method of mixed information rate according to claim 6, feature exist In: Chip Waveform p (t) uses rectangle Chip Waveform or binary offset carrier waveform.

8. a kind of chip time-division navigation signal modulation method of mixed information rate according to claim 7, feature exist In:

For rectangle Chip Waveform, have:

For binary offset carrier waveform, have

In formula, f_sFor the sub-carrier frequencies of BOC modulation, 2f_s/(N·R_c) it is integer.

9. a kind of navigation that the chip time-division navigation signal modulation method based on mixed information rate described in claim 1 is realized Signal modulating system, characterized by comprising:

Channel coding module: low speed text and high speed text are respectively channel encoded,

PRN code mapping block: the low speed text Jing Guo channel coding is mapped as PRN code sequence all the way, by channel coding High speed text is mapped as the road N-1 PRN code sequence, and the road N PRN code sequence is obtained；

Sub-module when chip: it is divided into signal all the way when by the road N PRN code sequence by chip；

Baseband waveform modulation module: the signal all the way obtained after the chip time-division is subjected to baseband waveform modulation, obtains baseband signal.

10. navigation signal modulating system according to claim 9, it is characterised in that: the raw information rate of low speed text For R_b,L, it is R by character rate after channel coding_s,L, low speed text symbol intervals are T_s,L=1/R_s,L, code efficiency R_b,L/ R_s,L, the information symbol stream after channel coding is { d_L,m, d_L,m∈{0,1}；

The raw information rate of high speed text is R_b,H, it is R by character rate after channel coding_s,H, high speed text symbol intervals For T_s,H=1/R_s,H, code efficiency R_b,H/R_s,H, the information symbol stream after channel coding is { d_H,m, d_H,m∈{0,1}；Channel It is interleaved after coding to promote anti-channel fading ability.