Constant Envelope Modulation Method and Device Based on the Combination of Interplex and CSK

Abstract

The present invention relates to a constant envelope modulation method based on the combination of Interplex and CSK, comprising: generating at least one set of CSK authentication signals according to the authentication information rate and the authentication time interval; calculating a modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio; generating a transmission signal according to a preset signal system; respectively using each set of the authentication signals as an input signal and modulating the transmission signal on the same carrier through Interplex phase modulation; calculating the modulation coefficient when the authentication signal is located at the frame header position of the carrier signal, and setting the modulation coefficients of other carrier signals to 0. Through the technical solution of the present invention, the generation rate of the authentication signal is further improved, and authenticating at the frame header position can reduce the impact on the original signal and further reduce the bit error rate of authentication.

Description

Technical Field

[0001] The present invention relates to the technical field of signal modulation, and in particular, to a constant envelope modulation method and system, a readable storage medium, and a computer device based on the combination of Interplex and CSK. Background Art

[0002] With the wide application of navigation systems, their role in ensuring national security and improving people's living standards has become increasingly important. Navigation signals are vulnerable to spoofing during propagation, resulting in receivers being deceived and unable to receive correct satellite signals, thus unable to perform correct positioning. Spoofing attacks pose a serious threat to satellite navigation applications and can even lead to catastrophic consequences.

[0003] With the development and application of GNSS technology, spoofing interference technology has gradually matured. Since the signal structure of GNSS civil services is public, some navigation data can be predicted. Spoofers can forge or change navigation information according to the public signal regime, causing spatial and temporal errors by forging the code phase and navigation information in the signal to disrupt navigation and communication systems and affect receiver positioning, resulting in incorrect positioning results. Currently, navigation interference has shifted from jamming interference to spoofing interference, that is, directly changing or forging navigation signals. Compared with jamming interference, spoofing interference is more concealed and more harmful.

[0004] At present, the protection against spoofing attacks mainly has two implementation directions: navigation signal feature detection and navigation information anti-counterfeiting authentication. Relatively speaking, the method of navigation information anti-counterfeiting authentication detects spoofed signals with more accurate results.

[0005] Signal authentication technology is an effective anti-spoofing means. By attaching authentication information to satellite navigation signals, receivers can determine the validity of the received navigation information based on the authenticity of the demodulated authentication information. Navigation signal authentication is also one of the directions for the evolution and development of future satellite navigation signals. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0007] To this end, the object of the present invention is to provide a constant envelope modulation method and device based on the combination of Interplex and CSK, which can not only improve signal security and a relatively high authentication information rate, but also ensure the constant envelope characteristic of the signal.

[0008] To achieve the above object, the technical solution of the first aspect of the present invention provides a constant envelope modulation method based on the combination of Interplex and CSK, including:

[0009] Generate at least one set of CSK authentication signals according to the authentication information rate and the authentication time interval;

[0010] Calculate the modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio;

[0011] Generate a transmission signal according to a preset signal system;

[0012] Take each set of the authentication signals as an input signal respectively and modulate them with the transmission signal on the same carrier through Interplex phase modulation;

[0013] Calculate the modulation coefficient when the authentication signal is located at the header position of the carrier signal frame, and set the modulation coefficients of other carrier signals to 0.

[0014] In the above technical solution, preferably, the expression of the CSK authentication signal is:

[0015] c x，y (t) = c x，0 (t0), t0 = (mod[t - y·T c +C·T c , C·T c )

[0016] c x，y [m] = c x，0 (m0), m0 = (mod[m - y + C, C]);

[0017] Among them, after the integer phase shift of the original pseudo-code sequence, M groups of CSK sequences are obtained, where M = 2 U , denoted as c x，y (t), x represents the x-th group of authentication spreading codes, y represents the phase shift of y bits, the value range of y is from 0 to M - 1, denoted as c x，0 (t) to c x，M-1 (t), the basic code c x，0 (t) in CSK modulation has C chip numbers in one spreading code period, and one chip time is T c , then the code period is T = C·T c , mod(a, b) represents a modulo b.

[0018] In the above technical solution, preferably, the expression of taking each set of the authentication signals as an input signal respectively and modulating them with the transmission signal on the same carrier through Interplex phase modulation is:

[0019]

[0020] Among them, P is the total transmission power, β n is the modulation coefficient, which determines the power distribution of each path of signals, f cis the carrier frequency, is the initial phase, s1(t), s2(t),......, s N (t) are N input signals.

[0021] In the above technical solution, preferably, s1(t) to s N-1 (t) is the original signal, taking values of ±1, s N (t) is the newly added authentication signal, expressed as where k i represents the phase shift of the i-th group of spreading codes, i = 1, 2,..., r.

[0022] In the above technical solution, preferably, the attenuation degree of the signal carrier-to-noise ratio is expressed as: ΔC / N0 = -20log 10 (cos r (β N ), where r represents the number of CSK combinations, C / N0 is the carrier-to-noise ratio, ΔC / N0 represents the change in the carrier-to-noise ratio, and the modulation coefficient calculated according to the attenuation degree of the signal carrier-to-noise ratio is expressed as:

[0023] The technical solution of the second aspect of the present invention provides a constant envelope modulation system based on the combination of Interplex and CSK, including:

[0024] A CSK authentication module, configured to generate at least one group of CSK authentication signals according to the authentication information rate and the authentication time interval;

[0025] A modulation coefficient calculation module, configured to calculate the modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio;

[0026] A signal generation module, configured to generate a transmission signal according to a preset signal system;

[0027] An Interplex phase modulation module, configured to use each group of the authentication signals as an input signal respectively and modulate the transmission signal on the same carrier through Interplex phase modulation;

[0028] A modulation coefficient control module, configured to calculate the modulation coefficient when the authentication signal is located at the header position of the carrier signal, and set the modulation coefficients of other carrier signals to 0.

[0029] In the above technical solution, preferably, the expression of the CSK authentication signal is:

[0030] c x，y (t) = c x，0 (t0), t0 = (mod[t - y·T c +C·Tc , C·T c );

[0031] c x，y [m]=c x，0 (m0), m0=(mod[m - y + C, C]);

[0032] Among them, after the integer phase shift of the original pseudo - code sequence, M groups of CSK sequences are obtained, where M = 2 U , denoted as c x，y (t), x represents the x - th group of authentication spreading codes, y represents the phase shift of y bits, and the value range of y is from 0 to M - 1, denoted as c x，0 (t) to c x，M-1 (t), the basic code c x，0 (t) in CSK modulation, the number of chips in one spreading code period is C, and one chip time is T c , then the code period is T = C·T c , mod(a, b) represents a modulo b

[0033] In the above - mentioned technical solution, preferably, the expression for taking each group of the authentication signals as an input signal and modulating it with the transmission signal on the same carrier through Interplex phase modulation is:

[0034]

[0035] Among them, P is the total transmission power, β n is the modulation coefficient, which determines the power distribution of each path of signals, f c is the carrier frequency, is the initial phase, s1(t), s2(t),......, s N (t) are N paths of input signals

[0036] The technical solution of the third aspect of the present invention provides a readable storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the steps of the constant - envelope modulation method based on the combination of Interplex and CSK provided by the technical solution of the first aspect above

[0037] The technical solution of the fourth aspect of the present invention provides a computer device, including a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to implement the steps of the constant - envelope modulation method based on the combination of Interplex and CSK provided by the technical solution of the first aspect above

[0038] Compared with the prior art, the advantages of the constant envelope modulation method and device provided by the present invention based on the combination of Interplex and CSK are as follows: compared with the traditional spread spectrum code authentication scheme, the present invention can further improve the generation rate of the authentication signal. At the same time, performing authentication at the frame header position can reduce the impact on the original signal and further reduce the bit error rate of authentication; by adjusting the modulation coefficient, no greater carrier-to-noise ratio attenuation will occur during multiple CSK modulations; at the same time, the Interplex scheme proposed by the present invention modulates the authentication signal and the navigation signal on the same carrier, ensuring the constant envelope characteristic of the signal. Therefore, the method used in the present invention is more adaptable to the market demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0040] Figure 1 FIG. shows a schematic diagram of a constant envelope modulation system based on the combination of Interplex and CSK according to an embodiment of the present invention;

[0041] Figure 2 FIG. shows a schematic diagram of CSK(U,F) modulation according to an embodiment of the present invention;

[0042] (a) shows the number of modulated bits U;

[0043] (b) shows the number of repetitions F of the sequence after the original pseudo-code phase shift;

[0044] Figure 3 FIG. shows a flowchart of a constant envelope modulation method based on the combination of Interplex and CSK according to an embodiment of the present invention;

[0045] Figure 4 FIG. shows a schematic diagram of the L5 signal frame format according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

[0047] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention may be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the limitations of the specific embodiments disclosed below.

[0048] Such as Figure 3As shown, a constant envelope modulation method based on the combination of Interplex and CSK according to an embodiment of the present invention includes:

[0049] Generating at least one group of CSK authentication signals according to the authentication information rate and the authentication time interval;

[0050] In this step, the CSK combination method is determined according to parameter requirements such as the authentication information rate and the authentication time interval, that is, the parameter r is determined. A CSK sequence is generated according to the authentication information. As shown in formula (4), multiple groups of combined signals s N (t) are generated.

[0051] In this step, the authentication signal is generated by code shift keying (CSK) modulation. Multiple combinations of CSK signals can be performed. The CSK modulation is a direct sequence spread spectrum modulation, which uses the original pseudo-code sequence to obtain sequences with different phases through integer phase shifts, overcoming the limitations of the spreading gain and the data rate, and can dynamically change the bit rate of the authentication signal.

[0052] Calculating the modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio;

[0053] In this step, according to the number of groups of CSK modulation and the modulation coefficient, the attenuation value of the carrier-to-noise ratio of the original signal can be controlled, and almost the same signal-to-noise ratio loss can be ensured.

[0054] Generating a transmission signal according to a preset signal system;

[0055] In this step, the preset signal system is a navigation signal system, and the transmission signal is a navigation signal, that is, signals s1(t) to s N-1 (t) are generated.

[0056] Taking each group of the authentication signals as an input signal respectively and performing Interplex phase modulation on the same carrier with the transmission signal;

[0057] Calculating the modulation coefficient when the authentication signal is located at the header position of the carrier signal, and setting the modulation coefficients of other carrier signals to 0;

[0058] In this step, the authentication signal can be selected to be added at the header position of the original signal to reduce the impact on the original signal, and the fixed bit of the header is used to further reduce the error rate of authentication.

[0059] In the above embodiment, preferably, the expression of the CSK authentication signal is:

[0060] c x，y (t) = c x，0 (t0), t0 = (mod[t - y·T c +C·T c , C·Tc ) (1);

[0061] c x，y [m]=c x，0 (m0), m0=(mod[m - y + C, C]) (2);

[0062] Among them, after the integer phase shift of the original pseudo - code sequence, M groups of CSK sequences are obtained, where M = 2 U , denoted as c x，y (t), x represents the x - th group of authentication spreading codes, y represents the phase shift of y bits, and the value range of y is from 0 to M - 1, denoted as c x，0 (t) to c x，M-1 (t), the basic code c x，0 (t) in CSK modulation, the number of chips in one spreading code period is C, and one chip time is T c , then the code period is T = C·T c , mod(a, b) represents a modulo b

[0063] In the above - mentioned embodiment, preferably, the expression for taking each group of the authentication signals as an input signal and modulating it with the transmission signal on the same carrier through Interplex phase modulation is:

[0064]

[0065] Among them, P is the total transmission power, β n is the modulation coefficient, which determines the power distribution of each path of signals, f c is the carrier frequency, is the initial phase, s1(t), s2(t),......, s N (t) are N paths of input signals

[0066] In this embodiment, taking N = 3 as an example for step - by - step explanation, at this time, it is described that the original satellite navigation signal contains two paths (for example, the GPS L5 signal includes L5I and L5Q signals), and a new authentication signal and the original two signals form 3 signals, so N = 3. When N = 3, the above formula is expressed as:

[0067]

[0068] In the formula, s1(t), s2(t) are binary data streams modulated through spreading codes, BOC modulation, data - coding symbols, etc., that is, the original satellite navigation signals, taking values of ±1, s3(t) is the authentication signal after multi - group CSK combined modulation, and s3(t) can be expressed as The parameter β2 can control the power ratio of s1(t) and s2(t), and the parameter β3 can control the proportion of the authentication signal power distribution. When used in combination with r, see the expression for calculating the modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio. Adjusting β3 according to the CSK combination can control the same signal-to-noise ratio loss.

[0069] The navigation message of the GPS L5 signal adopts the CNAV message structure. The message is composed of a basic frame structure with a length of 300 bits and a duration of 12 s. The message frame header includes an 8-bit frame synchronization header, a 6-bit PRN number, a 6-bit frame type number, a 17-bit time synchronization word (Time Of Word, TOW), and a 1-bit warning flag bit. The message frame tail includes 24-bit check bits, as Figure 4 shown. Therefore, adding the authentication signal at the frame synchronization header position can reduce the impact on the original signal.

[0070] Working principle: The present invention provides a constant envelope modulation scheme based on the combination of Interplex and CSK. The authentication signal is modulated by CSK, and the generation rate can be flexibly changed by adjusting the parameters of CSK. The authentication signal is used as one input signal and is modulated on the same carrier as the navigation signal through Interplex. By changing the modulation coefficient of the authentication signal, that is, the proportion of power distribution, multiple groups of CSK authentication can be realized without increasing additional carrier-to-noise ratio attenuation.

[0071] In the above embodiment, preferably, s1(t) to s N-1 (t) is the original signal, taking values of ±1, and s N (t) is the newly added authentication signal, expressed as where k i represents the phase shift of the i-th spreading code, and i = 1, 2,..., r.

[0072] In the above embodiment, preferably, the attenuation degree of the signal carrier-to-noise ratio is expressed as:

[0073] ΔC / N0 = -20log 10 (cos r (β N )) (5);

[0074] where r represents the number of CSK combinations, C / N0 is the carrier-to-noise ratio, simply referred to as the carrier-to-noise ratio, ΔC / N0 represents the change in the carrier-to-noise ratio, which refers to the attenuation of the carrier-to-noise ratio here. The expression for calculating the modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio is:

[0075] Specific example

[0076] Taking N = 3 as an example to illustrate the source of the formula in this patent, formula (3) is further simplified as:

[0077]

[0078]

[0079] Since the values of s1(t) and s2(t) are ±1, then

[0080]

[0081] sin(β2·s1(t)s2(t)) = s1(t)s2(t)·sin(β2) (10);

[0082] cos(β2·s1(t)s2(t)) = cos(β2) (11);

[0083] sin(β3·s1(t)s3(t)) = s1(t)·sin(β3s3(t)) (12);

[0084] cos(β3·s1(t)s3(t)) = cos(β3s3(t)) (13);

[0085] Therefore, formula (7) can be expressed as:

[0086]

[0087] When the authentication signal uses single - group CSK modulation and the value of s3(t) is ±1, formula (14) can be written as:

[0088]

[0089] The equivalent complex baseband is:

[0090]

[0091] Denote P1 as the power of s1(t), P2 as the power of s2(t), and P3 as the power of s3(t). To ensure the constant - envelope characteristic of the signal, there is an inter - modulation term s1(t)s2(t)·sin(β2)sin(β3s3(t)), and its power is P IM

[0092] P1 = P·cos 2 (β2)·cos 2 (β3s3(t)) (17);

[0093] P2 = P·sin 2 (β2)·cos 2 (β3s3(t)) (18);

[0094] When β3 is small, sin(β3s3(t)) ≈ s3(t)sin(β3), then

[0095] P3 ≈ P·cos 2 (β2)·sin 2 (β3s3(t)) (19);

[0096] where P = P1 + P2 + P3 + P IM , then the modulation efficiency is

[0097]

[0098] Taking the GPS L5 signal as an example, it consists of two signals, I and Q. The I branch is the data channel, represented by s1(t), and the Q branch is the pilot channel, represented by s2(t). The power ratio of the I and Q branches is 1:1. Therefore β3 = 0. Add a s3(t) signal as the authentication signal based on the L5 signal, and at this time β3 is not zero.

[0099] During reception, assume that the locally generated s1(t) signal is completely aligned with the received signal. Let ∫s1(t)·s1(t)dt = H, and the correlation for one spreading code period is obtained as

[0100] ∫s1(t)cos(β2)cos(β3s3(t))·s1(t)dt (21);

[0101] When the authentication signal uses single - weight CSK modulation, s3(t) takes values of ±1. At this time, the correlation for one spreading code period is obtained as follows:

[0102] ∫s1(t)cos(β2)cos(β3s3(t))·s1(t)dt = ∫s1(t)·s1(t)dtcos(β2)cos(β3) = Hcos(β2)cos(β3) (22);

[0104] Compared with when the authentication signal is not modulated, the carrier - to - noise ratio of the s1(t) signal attenuates by - 20log 10 (cos(β3)).

[0105] When the authentication signal uses two - group CSK modulation, s3(t) is the superposition of the spreading codes after two - group CSK modulation, and its values can only be ±2, 0. The value of ±2 accounts for 50%, and the value of 0 accounts for 50%. At this time, the correlation for one spreading code period is obtained as follows:

[0106]

[0107] Compared with when the authentication signal is not modulated, the carrier-to-noise ratio of the s1(t) signal decays by -20log 10 (cos 2 (β3)).

[0108] When the authentication signal uses three groups of CSK modulation, the value of s3(t) is ±3 (accounting for 25%) and ±1 (accounting for 75%). After completing the correlation of one spreading code period, we get:

[0109]

[0110] Compared with when the authentication signal is not modulated, the carrier-to-noise ratio of the s1(t) signal decays by -20log 10 (cos 3 (β3)).

[0111] When the authentication signal uses four groups of CSK modulation, the value of s3(t) is ±4 (accounting for 12.5%), 0 (accounting for 37.5%), and ±2 (accounting for 50%). After completing the correlation of one spreading code period, we get:

[0112]

[0113] Compared with when the authentication signal is not modulated, the carrier-to-noise ratio of the s1(t) signal decays by -20log 10 (cos 4 (β3)).

[0114] In summary, the carrier-to-noise ratio decay can be recorded as ΔC / N0 = -20log 10 (cos r (β3)) (27);

[0115] where r represents the number of CSK combinations.

[0116]

[0117] If the carrier-to-noise ratio decay is set to 0.033115 dB, that is, ΔC / N0 = 0.033115 dB, then according to formula (28), the modulation coefficients β3 corresponding to single-group CSK, two-group CSK, three-group CSK, and four-group CSK can be calculated, as shown in Table 1:

[0118] Table 1 CSK modulation coefficients of single-group, two-group, three-group, and four-group authentication signals

[0119]

[0120]

[0121] Such as Figure 2Shown is a schematic diagram of CSK modulation. By using the original pseudo-code sequence, sequences with different phases are obtained through integer phase shifts. CSK modulation is affected by two parameters: the number of bits U modulated by each CSK symbol and the number of repetitions F of the sequence after the original pseudo-code phase shift in each CSK symbol.

[0122] As Figure 1 shown, a constant envelope modulation system based on the combination of Interplex and CSK according to another embodiment of the present invention includes:

[0123] A CSK authentication module, configured to generate at least one set of CSK authentication signals according to the authentication information rate and the authentication time interval;

[0124] A modulation coefficient calculation module, configured to calculate the modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio;

[0125] A signal generation module, configured to generate a transmission signal according to a preset signal regime;

[0126] An Interplex phase modulation module, configured to use each set of the authentication signals as an input signal and perform Interplex phase modulation on the transmission signal on the same carrier;

[0127] A modulation coefficient control module, configured to calculate the modulation coefficient when the authentication signal is located at the header position of the carrier signal, and set the modulation coefficients of other carrier signals to 0.

[0128] In the above embodiment, preferably, the expression of the CSK authentication signal is:

[0129] c x，y (t) = c x，0 (t0), t0 = (mod[t - y·T c + C·T c , C·T c )

[0130] c x，y [m] = c x，0 (m0), m0 = (mod[m - y + C, C]);

[0131] wherein, after integer phase shifts of the original pseudo-code sequence, M sets of CSK sequences are obtained, where M = 2 U , denoted as c x，y (t), x represents the x-th group of authentication spreading codes, y represents a phase shift of y bits, and the value range of y is from 0 to M - 1, denoted as c x，0 (t) to c x，M-1 (t), and the basic code c x，0(t) The number of chips in a spreading code period is C, and a chip time is T c , then the code period is T = C·T c , where mod(a, b) represents a modulo b.

[0132] In the above embodiment, preferably, the expression of using each group of the authentication signals as an input signal and the transmission signal through Interplex phase modulation on the same carrier is:

[0133]

[0134] where P is the total transmission power, β n is the modulation coefficient, which determines the power distribution of each path of signals, f c is the carrier frequency, is the initial phase, and s1(t), s2(t),......, s N (t) are N paths of input signals.

[0135] The embodiment of the present application also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the steps of the constant envelope modulation method based on the combination of Interplex and CSK in any of the above embodiments are implemented.

[0136] Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product. The software product can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods in various implementation scenarios of the present application.

[0137] The embodiment of the present application also provides a computer device, including a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to implement the steps of the constant envelope modulation method based on the combination of Interplex and CSK in any of the above embodiments.

[0138] Optionally, the computer device may further include a user interface, a network interface, a camera, a radio frequency (RF) circuit, sensors, an audio circuit, a WI-FI module, etc. The user interface may include a display screen (Display), an input unit such as a keyboard (Keyboard), etc. Optionally, the user interface may further include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a Bluetooth interface, a WI-FI interface), etc.

[0139] Those skilled in the art can understand that the structure of a computer device provided in this embodiment does not limit the computer device, and it may include more or fewer components, or combine some components, or have different component arrangements.

[0140] The storage medium may also include an operating system and a network communication module. The operating system is a program for managing and storing the hardware and software resources of a computer device, and supports the operation of information processing programs and other software and / or programs. The network communication module is used to implement communication between components inside the storage medium, as well as communication between other hardware and software in this entity device.

[0141] In the present invention, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance; the term "plural" means two or more, unless otherwise clearly defined. Terms such as "installed", "connected", "connected to", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0142] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

[0143] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0144] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A constant envelope modulation method based on the combination of Interplex and CSK, characterized in that: include: generating at least one set of CSK authentication signals according to an authentication information rate and an authentication time interval; The modulation coefficient is calculated according to the attenuation degree of the signal-to-noise ratio, and the attenuation degree of the signal-to-noise ratio is expressed as: ΔC / N0=-20log 10 (cos r (β N )), where r represents the number of CSK combinations, C / N0 is the carrier-to-noise ratio, ΔC / N0 represents the change in the carrier-to-noise ratio, and the modulation coefficient is calculated based on the attenuation degree of the signal carrier-to-noise ratio as follows: Generate a transmission signal according to a preset signal system; Each group of the authentication signals is used as an input signal and the transmission signal is interplex phase modulated on the same carrier. The expression is: Where P is the total transmit power, β n is the modulation coefficient, which determines the power distribution of each signal. c is the carrier frequency, is the initial phase, s1(t), s2(t), ..., s N (t) is N input signals; s1(t) to s N-1 (t) is the original signal, with a value of ±1, s N (t) is the newly added authentication signal, expressed as where k i represents the phase shift of the i-th group of spreading codes, i=1, 2, ..., r; The modulation coefficient when the authentication signal is located at the frame header position of the carrier signal is calculated, and the modulation coefficients of other carrier signals are set to 0.

2. The constant envelope modulation method based on the combination of Interplex and CSK according to claim 1, characterized in that: The expression of the CSK authentication signal is: c x，y (t)=c x，0 (t0),t0=(mod[t-y·T c +C·T c ,C·T c ]); c x，y [m]=c x，0 (m0),m0=(mod[m-y+C,C]); Among them, the original pseudo code sequence is phase shifted by integer bits to obtain M groups of CSK sequences, where M = 2 U , denoted as c x，y (t), x represents the xth group of authentication spreading code, y represents the phase shift of y bits, and the value range of y is 0 to M-1, denoted by c x，0 (t) to c x，M-1 (t), basic code c in CSK modulation x，0 (t) The number of chips in a spread spectrum code period is C, and the time of a chip is T. c , then the code period is T = C·T c , mod(a, b) means a modulo b.

3. A constant envelope modulation system based on the combination of Interplex and CSK, characterized in that: include: A CSK authentication module is configured to generate at least one set of CSK authentication signals according to an authentication information rate and an authentication time interval; The modulation coefficient calculation module is configured to calculate the modulation coefficient according to the attenuation degree of the signal-to-noise ratio, wherein the attenuation degree of the signal-to-noise ratio is expressed as: ΔC / N0=-20log 10 (cos r (β N )), where r represents the number of CSK combinations, C / N0 is the carrier-to-noise ratio, ΔC / N0 represents the change in the carrier-to-noise ratio, and the modulation coefficient is calculated based on the attenuation degree of the signal carrier-to-noise ratio as follows: A signal generating module, configured to generate a transmission signal according to a preset signal system; The interplex phase modulation module is configured to use each group of the authentication signals as an input signal and the transmission signal on the same carrier through interplex phase modulation, and the expression is: Where P is the total transmit power, β n is the modulation coefficient, which determines the power distribution of each signal. c is the carrier frequency, is the initial phase, s1(t), s2(t), ..., s N (t) is N input signals; s1(t) to s N-1 (t) is the original signal, with a value of ±1, s N (t) is the newly added authentication signal, expressed as where k i represents the phase shift of the i-th group of spreading codes, i=1, 2, ..., r; The modulation coefficient control module is configured to calculate the modulation coefficient when the authentication signal is located at the frame header position of the carrier signal, and the modulation coefficients of other carrier signals are set to 0.

4. The constant envelope modulation system based on the combination of Interplex and CSK according to claim 3, characterized in that: The expression of the CSK authentication signal is: c x，y (t)=c x，0 (t0),t0=(mod[t-y·T c +C·T c ,C·T c ]); c x，y [m]=c x，0 (m0),m0=(mod[m-y+C,C]); Among them, the original pseudo code sequence is phase shifted by integer bits to obtain M groups of CSK sequences, where M = 2 U , denoted as c x，y (t), x represents the xth group of authentication spreading code, y represents the phase shift of y bits, and the value range of y is 0 to M-1, denoted by c x，0 (t) to c x，M-1 (t), basic code c in CSK modulation x，0 (t) The number of chips in a spread spectrum code period is C, and the time of a chip is T. c , then the code period is T = C·T c , mod(a, b) means a modulo b.

5. A readable storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the steps of the constant envelope modulation method based on the combination of Interplex and CSK as claimed in claim 1 or 2 are implemented.

6. A computer device, characterized in that: It comprises a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to implement the steps of the constant envelope modulation method based on the combination of Interplex and CSK as claimed in claim 1 or 2.

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