Constant envelope modulation method and device based on combination of Interplex and CSK

Abstract

The invention relates to a constant envelope modulation method based on the combination of Interplex and CSK. The method comprises the following steps: generating at least one group of CSK authentication signals according to an authentication information rate and an 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; taking each group of authentication signals as an input signal and modulating the input signal and the transmission signal on the same carrier through Interplex phase modulation; and 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 be 0. Through the technical scheme of the invention, the generation rate of the authentication signal is further improved, the influence on the original signal can be reduced by performing authentication at the frame header position, and the error rate of authentication is further reduced.

Description

Technical Field

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

[0002] With the widespread application of navigation systems, their role in ensuring national security and improving people's living standards has become increasingly important. Navigation signals are easily deceived during transmission, causing the receiver to be deceived and unable to receive the correct satellite signals, thus failing to perform correct positioning. Deception attacks pose a serious threat to satellite navigation applications and may even lead to catastrophic consequences.

[0003] With the development and application of GNSS technology, deception jamming technology has gradually matured. Since the structure of GNSS civil service signals is public, some navigation data can be predicted. Spoofers can forge or change navigation information based on the public signal system, and forge the code phase and navigation information in the signal to cause errors in space and time to disrupt the navigation and communication systems, affect the positioning of the receiver, and calculate the wrong positioning results. At present, navigation jamming has changed from suppression jamming to deception jamming, that is, directly changing or forging navigation signals. Compared with suppression jamming, deception jamming is more concealed and more harmful.

[0004] At present, there are two main implementation directions for spoofing attack protection: navigation signal feature detection and navigation information anti-counterfeiting authentication. In comparison, the results of spoofing signal detection by navigation information anti-counterfeiting authentication are more accurate.

[0005] Signal authentication technology is an effective anti-spoofing method. Signal authentication attaches authentication information to the satellite navigation signal. The receiver can judge 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 future evolution and development of 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 art.

[0007] To this end, the purpose 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 higher authentication information rate, but also ensure the constant envelope characteristics 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, comprising:

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

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

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

[0012] Each group of the authentication signals is used as an input signal and the transmission signal is interplexed and phase modulated on the same carrier;

[0013] 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.

[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[ty·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, 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.

[0018] In the above technical solution, preferably, each group of the authentication signals is respectively used as an input signal and the transmission signal is interplex phase modulated on the same carrier as follows:

[0019]

[0020] Where P is the total transmit power, β n is the modulation coefficient, which determines the power distribution of each signal. cis the carrier frequency, is the initial phase, s1(t), s2(t), ..., s N (t) is N input signals.

[0021] In the above technical solution, preferably, 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.

[0022] In the above technical solution, preferably, 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:

[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 is configured to generate at least one set of CSK authentication signals according to an authentication information rate and an authentication time interval;

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

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

[0027] An 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;

[0028] 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.

[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[ty·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, 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.

[0033] In the above technical solution, preferably, each group of the authentication signals is respectively used as an input signal and the transmission signal is interplex phase modulated on the same carrier as follows:

[0034]

[0035] 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.

[0036] The technical solution of the third aspect of the present invention provides a 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 provided by the technical solution of the first aspect are implemented.

[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 based on the combination of Interplex and CSK provided by the present invention are: compared with the traditional spread spectrum code authentication scheme, the present invention can further improve the generation rate of the authentication signal, and at the same time, authentication at the frame header position can reduce the impact on the original signal and further reduce the authentication bit error rate; by adjusting the modulation coefficient, no greater carrier-to-noise ratio attenuation will be generated when performing multiple CSK modulation; 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 characteristics of the signal, so the method used by the present invention is more adaptable to market needs. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0041] Figure 2 A schematic diagram of CSK (U, F) modulation involved in an embodiment of the present invention is shown;

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

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

[0044] Figure 3 A flow chart of a constant envelope modulation method based on the combination of Interplex and CSK according to an embodiment of the present invention is shown;

[0045] Figure 4 A schematic diagram showing the L5 signal frame format involved in an embodiment of the present invention is shown. DETAILED DESCRIPTION

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

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

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

[0049] generating at least one set of CSK authentication signals according to an authentication information rate and an authentication time interval;

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

[0051] In this step, the authentication signal is generated by code shift keying CSK modulation, and 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, overcomes the limitations of spread spectrum gain and data rate, and can dynamically change the bit rate of the authentication signal.

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

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

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

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

[0056] Each group of the authentication signals is used as an input signal and the transmission signal is interplexed and phase modulated on the same carrier;

[0057] 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;

[0058] In this step, the authentication signal can be selectively added to the original signal frame header position to reduce the impact on the original signal, and the authentication bit error rate can be further reduced by using the fixed position of the frame header.

[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[ty·T c +C·T c , C.T.c ]) (1);

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

[0062] 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.

[0063] In the above embodiment, preferably, each group of the authentication signals is respectively used as an input signal and the transmission signal is interplex phase modulated on the same carrier as follows:

[0064]

[0065] 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.

[0066] In this embodiment, N=3 is used as an example to illustrate the steps. At this time, it is explained that the original satellite navigation signal includes two channels (for example, the GPS L5 signal includes L5I and L5Q signals), and a new authentication signal and the original two channels constitute three signals, so N=3. When N=3, the above formula is expressed as:

[0067]

[0068] Where s1(t) and s2(t) are binary data streams modulated by spreading codes, BOC modulation and data coding symbols, i.e., the original satellite navigation signal, with a value of ±1. s3(t) is the authentication signal after multiple groups of CSK combined modulation. s3(t) can be expressed as Parameter β2 can control the power ratio of s1(t) and s2(t), and parameter β3 can control the power allocation ratio of the authentication signal. When used in combination with r, see the expression for calculating the modulation coefficient based on the attenuation degree of the signal-to-noise ratio. By adjusting β3 according to the CSK combination, the signal-to-noise ratio loss can be controlled to be the same.

[0069] The GPS L5 signal navigation message adopts the CNAV message structure. The message consists of a basic frame structure of 300 bits in length and 12 seconds in duration. 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. The message frame tail includes a 24-bit check bit, such as Figure 4 Therefore, adding the authentication signal to 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. The generation rate can be flexibly changed by adjusting the parameters of CSK. The authentication signal is used as an input signal and is modulated on the same carrier with the navigation signal through Interplex. By changing the modulation coefficient of the authentication signal, that is, the power allocation ratio, multiple groups of CSK authentication can be achieved 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, 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.

[0072] In the above embodiment, preferably, the attenuation degree of the signal-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 carrier-to-noise ratio, referred to as carrier-to-noise ratio, ΔC / N0 represents the change of carrier-to-noise ratio, which here refers to the attenuation of the carrier-to-noise ratio. The modulation coefficient is calculated according to the attenuation degree of the signal carrier-to-noise ratio and is expressed as:

[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 to:

[0077]

[0078]

[0079] Since s1(t) and s2(t) are ±1,

[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 adopts a single group CSK modulation, s3(t) takes the value of ±1, and formula (14) can be written as:

[0088]

[0089] The equivalent complex baseband is:

[0090]

[0091] Let P1 be the power of s1(t), P2 be the power of s2(t), and P3 be the power of s3(t). In order to ensure the constant envelope characteristics of the signal, there is an intermodulation term s1(t)s2(t)·sin(β2)sin(β3s3(t)), whose 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 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, so β3=0, an s3(t) signal is added to the L5 signal as an authentication signal, and β3 is not zero at this time.

[0099] When receiving, assume that the locally generated s1(t) signal is completely aligned with the received signal, let ∫s1(t)·s1(t)dt=H, and complete the correlation of one spread spectrum code cycle to obtain

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

[0101] When the authentication signal adopts single CSK modulation, s3(t) takes the value of ±1. At this time, the correlation of one spread spectrum code cycle is completed and the following is obtained:

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

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

[0105] When the authentication signal uses two groups of CSK modulation, s3(t) is the superposition of the spread spectrum codes after the two groups of CSK modulation. Its value can only be ±2 or 0. The value of ±2 accounts for 50% and the value of 0 accounts for 50%. At this time, the correlation of a spread spectrum code cycle is completed:

[0106]

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

[0108] When the authentication signal uses three groups of CSK modulation, s3(t) takes the values ​​of ±3 (accounting for 25%) and ±1 (accounting for 75%), and the correlation of one spread spectrum code cycle is completed to obtain:

[0109]

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

[0111] When the authentication signal adopts four groups of CSK modulation, s3(t) takes the values ​​of ±4 (accounting for 12.5%), 0 (accounting for 37.5%), and ±2 (accounting for 50%). After completing the correlation of one spread spectrum code cycle, the following is obtained:

[0112]

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

[0114] In summary, the carrier-to-noise ratio attenuation 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 is set to attenuate 0.033115 dB, that is, ΔC / N0 = 0.033115 dB, then the modulation coefficient β3 corresponding to single-group CSK, two-group CSK, three-group CSK, and four-group CSK can be calculated according to formula (28), as shown in Table 1:

[0118] Table 1 CSK modulation coefficients of single, double, triple and quadruple authentication signals

[0119]

[0120]

[0121] like Figure 2The figure shows a schematic diagram of CSK modulation, which uses the original pseudo code sequence to obtain sequences with different phases through integer bit phase shifts. CSK modulation is affected by two parameters: the number of bits U modulated by each CSK symbol and the number of sequence repetitions F after the original pseudo code phase shift in each CSK symbol.

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

[0123] 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;

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

[0125] A signal generating module, configured to generate a transmission signal according to a preset signal system;

[0126] An 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;

[0127] 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.

[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[ty·T c +C·T c , C.T. c ]);

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

[0131] 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.

[0132] In the above embodiment, preferably, each group of the authentication signals is respectively used as an input signal and the transmission signal is interplex phase modulated on the same carrier as follows:

[0133]

[0134] 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.

[0135] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. 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 this understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, USB flash drive, mobile hard disk, etc.), including a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods of various implementation scenarios of the present application.

[0137] An 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, a sensor, an audio circuit, a WI-FI module, etc. The user interface may include a display, an input unit such as a keyboard, etc., and the optional user interface may also 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 will appreciate that the computer device structure provided in this embodiment does not limit the computer device, and may include more or fewer components, or a combination of certain components, or different component arrangements.

[0140] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages and saves the hardware and software resources of the computer device, and supports the operation of information processing programs and other software and / or programs. The network communication module is used to realize communication between the components inside the storage medium, and communication with other hardware and software in the physical device.

[0141] In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed", etc. 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 is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are 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 understood as a limitation on the present invention.

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

[0144] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in 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; Calculate the modulation coefficient according to the attenuation degree of the signal-to-noise ratio; 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 interplexed and phase modulated on the same carrier; 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. The constant envelope modulation method based on the combination of Interplex and CSK according to claim 2, characterized in that: The expression for taking each group of the authentication signals as one input signal and the transmission signal through interplex phase modulation on the same carrier 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.

4. The constant envelope modulation method based on the combination of Interplex and CSK according to claim 3, characterized in that: 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.

5. The constant envelope modulation method based on the combination of Interplex and CSK according to claim 4, characterized in that: 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:

6. 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; A modulation coefficient calculation module is configured to calculate the modulation coefficient according to the attenuation degree of the signal carrier-to-noise ratio; A signal generating module, configured to generate a transmission signal according to a preset signal system; An 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; 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.

7. The constant envelope modulation system based on the combination of Interplex and CSK according to claim 6, 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.

8. The constant envelope modulation system based on the combination of Interplex and CSK according to claim 7, characterized in that: The expression for taking each group of the authentication signals as one input signal and the transmission signal through interplex phase modulation on the same carrier 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.

9. 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 described in any one of claims 1 to 5 are implemented.

10. A computer device, characterized in that: The invention 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 described in any one of claims 1 to 5.

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