A method and system for simulating difference frequency signal of triangular wave frequency modulation fuze

Abstract

The present invention discloses a method and system for simulating the difference frequency signal of a triangular wave frequency modulation fuze, and relates to the technical field of radio fuze testing. The specific implementation method of the method includes: obtaining simulation parameters of the difference frequency signal to be simulated; inputting the simulation parameters including carrier frequency, frequency deviation, modulation period, sampling frequency, initial missile-target distance and missile-target relative motion speed into a triangular wave frequency modulation fuze difference frequency signal simulation model, the triangular wave frequency modulation fuze difference frequency signal simulation model includes a time domain phase formula of the difference frequency signal, an expression of the common coefficient of the time domain phase formula, an expression of the phase increment of the difference frequency signal and a phase calculation method of the difference frequency signal; according to the output of the triangular wave frequency modulation fuze difference frequency signal simulation model, the target difference frequency signal is obtained. This implementation method can realize the automatic generation of the difference frequency signal of the triangular wave frequency modulation fuze, shorten the test time, improve the test efficiency, reduce the test cost, and have strong test flexibility.

Description

Technical Field

[0001] The invention belongs to the technical field of radio fuze testing, and in particular relates to a method and system for simulating a difference frequency signal of a triangle wave frequency modulation fuze. Background Art

[0002] The fuze plays a key role in whether the weapon system can achieve the maximum destructive effect. The frequency modulation fuze is a type of radio fuze, which is used to transmit a frequency modulated sine wave signal and receive the echo signal reflected by the target. The echo signal and the transmission signal are mixed through a mixer to obtain a difference frequency signal. The distance between the projectile and the target is determined by analyzing the frequency of the difference frequency signal to achieve explosion height control.

[0003] In the test process of the existing frequency modulation fuze, the difference frequency signal with specific target information is usually collected or simulated first, and stored in the high-speed memory of the arbitrary signal generator; then, the arbitrary signal generator reads the difference frequency signal in the high-speed memory, and uses a high-speed DAC to convert the difference frequency signal into an analog signal, which is sent to the signal processing module of the frequency modulation fuze for testing.

[0004] However, on the one hand, the existing FM fuze test requires frequent import of test difference frequency signals into the arbitrary signal generator. The amount of data imported each time is very large, which is time-consuming and has poor test flexibility. On the other hand, since the arbitrary signal generator needs to use a high-speed digital processor, a high-speed large-capacity storage device and a high-speed DAC to convert the signal, the test cost is relatively high. Summary of the invention

[0005] In view of this, the present invention provides a method and system for simulating the difference frequency signal of a triangular wave frequency modulation fuze, which can realize the automatic generation of the difference frequency signal of the triangular wave frequency modulation fuze, shorten the test time, improve the test efficiency, and reduce the test cost at the same time, and has strong test flexibility.

[0006] The technical solution for implementing the present invention is as follows:

[0007] A method for simulating a difference frequency signal of a triangular wave frequency modulation fuze, comprising:

[0008] Acquire the simulation parameters of the difference frequency signal to be simulated, the simulation parameters include the carrier frequency f c , frequency deviation ΔF, modulation period T m , sampling frequency f s , the initial projectile-target distance R0 and the projectile-target relative motion speed v;

[0009] The carrier frequency f c , frequency deviation ΔF, modulation period T m , sampling frequency f s, the initial missile-target distance R0 and the missile-target relative motion speed v are input into a triangular wave frequency modulation fuze difference frequency signal simulation model, wherein the triangular wave frequency modulation fuze difference frequency signal simulation model includes a time domain phase formula of the difference frequency signal, an expression of a common coefficient of the time domain phase formula, an expression of a phase increment of the difference frequency signal and a phase calculation method of the difference frequency signal;

[0010] According to the output of the triangle wave frequency modulation fuze difference frequency signal simulation model, the target difference frequency signal is obtained.

[0011] Optionally, generating the triangle wave frequency modulation fuse difference frequency signal simulation model includes:

[0012] Determine the time domain expression of the transmission signal of the triangular wave frequency modulation fuze according to the law of the signal frequency of the triangular wave frequency modulation fuze changing with time;

[0013] Determine the time domain expression of the echo signal of the triangular wave frequency modulation fuze by using the time delay between the transmission signal and the echo signal of the triangular wave frequency modulation fuze;

[0014] Mixing the transmission signal and the echo signal to obtain a time domain expression of a difference frequency signal of the triangular wave frequency modulation fuse;

[0015] The time domain expression of the difference frequency signal is organized into a time polynomial. For the coefficients of each term in the time polynomial, the common coefficients are extracted for a primary simplification process. The common coefficients of the first simplified polynomials in different regular areas are subjected to a secondary simplification process. The time of the secondary simplified polynomial is represented by a sampling period, and the time domain formula of the difference frequency signal is obtained:

[0016]

[0017] In the above formula, U b represents the amplitude of the difference frequency signal; b0 = (1 / 2) β; β is the slope of the triangular wave frequency modulation, k is the serial number of the sampling point, which is a non-negative integer; n is a natural number; Represents a frequency modulation period T m The number of sampling points within represents the number of sampling points in the irregular area within the nth frequency modulation period; a1=(f c -ΔF / 2)*2v / c, c is the speed of light; d1=β*2R0 / c; a2=4ΔFv / c; b 00 =β*2v / c;

[0018] c2=4ΔFR0 / c;

[0019] Extract the time domain phase formula of the difference frequency signal from the time domain formula of the difference frequency signal, and perform segmented phase expression

[0020]

[0021]

[0022]

[0023]

[0024] The phase increment of the difference frequency signal is calculated, and the change rule of the difference frequency signal is determined by using the phase calculation method of the difference frequency signal to obtain the simulation model of the difference frequency signal of the triangle wave frequency modulation fuse.

[0025] Optionally, the expression of the phase increment of the difference frequency signal in each of the segments is:

[0026]

[0027]

[0028]

[0029]

[0030] Optionally, the difference frequency signal Segmentation, The segmented phase calculation method includes:

[0031] For the difference frequency signal Segment by segment, loop through the following steps:

[0032] Determine the current phase at the current sampling period k and the current phase increment

[0033] According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1

[0034] Using the current phase increment and stated The second-order phase increment 2b0 of the segment is used to calculate the phase increment at the next sampling period k+1.

[0035] The phase of the next sampling period k+1 is As the current phase The phase increment at the next sampling period k+1 As the current phase increment

[0036] or,

[0037] For the difference frequency signal Segment by segment, loop through the following steps:

[0038] Determine the current phase at the current sampling period k and the current phase increment

[0039] According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1

[0040] Using the current phase increment and stated The second-order phase increment of the segment is -2b0, and the phase increment at the next sampling period k+1 is calculated.

[0041] The phase of the next sampling period k+1 is As the current phase The phase increment at the next sampling period k+1 As the current phase increment

[0042] Optionally, the difference frequency signal Segmentation, The segmented phase calculation method includes:

[0043] For the difference frequency signal Segment by segment, loop through the following steps:

[0044] A1: The current sampling period k is the initial moment, that is, when k = 0, the phase Phase increment

[0045] A2: According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1

[0046] A3: Take the next sampling period k+1 as the current sampling period k time k=k+1, and determine whether the current sampling period k time satisfies k=K T -1+nK T If yes, go to step A4; if no, go to step A7;

[0047] A4: According to the phase of the current sampling period k and stated The current variable period increment of the current frequency modulation period of the segment Calculate the phase at the next sampling period k+1

[0048]

[0049] A5: Using the current phase increment and stated Segmented second-order phase increment a2-2b 00 , calculate the phase increment at the next sampling period k+1

[0050] A6: By the current variable cycle increment and stated The second-order phase increment a2K T +a2, calculate the variable period increment of the next frequency modulation period Go to step A2;

[0051] A7: Using the current phase increment and stated Segmented second-order phase increment-2b 00 , calculate the phase increment at the next sampling period k+1 Go to step A2;

[0052] or,

[0053] For the difference frequency signal Segment by segment, loop through the following steps:

[0054] B1: The current sampling period k is the initial time, that is, when k = 0, the phase Phase increment

[0055] B2: According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1

[0056] B3: Take the next sampling period k+1 as the current sampling period k time k=k+1, and determine whether the current sampling period k time satisfies k=K T -1+nK T If yes, go to step B4; if no, go to step B7;

[0057] B4: According to the phase of the current sampling period k and stated The current variable period increment of the current frequency modulation period of the segment Calculate the phase at the next sampling period k+1

[0058]

[0059] B5: Using the current phase increment and stated Segmented second-order phase increment 2b 00 -a2, calculate the phase increment at the next sampling period k+1

[0060] B6: By the current variable cycle increment and stated The second-order phase increment a2K T +a2, calculate the variable period increment of the next frequency modulation period Go to step B2;

[0061] B7: Using the current phase increment and stated Segmented second-order phase increment 2b 00 , calculate the phase increment at the next sampling period k+1 Go to step B2.

[0062] A simulation system for a difference frequency signal of a triangular wave frequency modulation fuse applied to a simulation method for a difference frequency signal of a triangular wave frequency modulation fuse, characterized in that it comprises: a k accumulator, a segmented phase calculation module of the difference frequency signal, a four-to-one selector, a truncated position quantization module and a cosine lookup table, wherein:

[0063] In each sampling period, the segment phase calculation module of the difference frequency signal outputs the current phase value of each segment respectively.

[0064] According to the value of the k accumulator and the phase value of each segment The phase of the difference frequency signal at the current time k is selected by the four-to-one selector Among them, the phase of the difference frequency signal The bit width is

[0065] The truncation quantization module performs a phase quantization on the difference frequency signal. Perform bit truncation quantization to obtain a bit width of B Φ(k) The target phase Φ(k);

[0066] According to the target phase Φ(k), the cosine lookup table is searched to obtain the target difference frequency signal cos(Φ(k)).

[0067] Optionally, the segment phase calculation module of the difference frequency signal outputs the current phase value of each segment respectively. include:

[0068] Using the simulation parameters, calculate the common coefficient b0=(1 / 2)β; β is the slope of the triangular wave frequency modulation, a1=(f c -ΔF / 2)*2v / c, c is the speed of light, d1=β*2R0 / c, a2=4ΔFv / c, b 00 =β*2v / c and c2=4ΔFR0 / c;

[0069] The common coefficients b0, a1, d1, a2, b 00 , c2 pseudo-parameters are substituted into the segmented phase expression of the difference frequency signal And the expression of the phase increment of the difference frequency signal

[0070] According to the segmented phase expression of the difference frequency signal The expression of phase increment is The phase value of each segment is calculated by the phase calculation method of the difference frequency signal of each segment

[0071] Beneficial effects:

[0072] (1) The method for simulating the difference frequency signal of a triangular wave frequency modulation fuze of the present invention can also be applied to the test of the signal processing module of the frequency modulation fuze to generate the difference frequency signal for the signal processing module, thereby reducing the complexity of the radio fuze test and experimental work throughout the development and production process of the radio fuze. Even if the radio fuze is in a high-speed rendezvous state between the missile and the target and the type and electromagnetic scattering characteristics of the target are very complex, the difference frequency signal can still be accurately simulated, thereby improving the test efficiency and accuracy and ensuring the quality and reliability of the radio fuze product.

[0073] (2) The present invention proposes a flexible, low-complexity, strong real-time, low-cost simulation system for the difference frequency signal of a triangular wave FM fuze. The system only uses an adder and only needs to obtain the modulation period, carrier frequency and other parameters of the FM fuze according to the actual working environment. The concise and accurate time domain formula of the difference frequency signal of the triangular wave FM fuze of the present invention can be used to generate the corresponding difference frequency signal in real time, and the requirements on the computing power of the digital signal processor and the conversion speed of the DAC are relatively low.

[0074] (3) When the present invention is applied to a radio fuze test device, a target difference frequency signal can be directly generated and sent to a signal processing module of the radio fuze, so that the signal processing module sends a detonation signal according to the target difference frequency signal to detonate the warhead at a set blast height. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 Schematic diagram of the main process of the method for simulating the difference frequency signal of the triangle wave frequency modulation fuse according to an embodiment of the present invention.

[0076] Figure 2 It is a schematic diagram of the signal variation law of the triangular wave frequency modulation fuze under different working conditions according to an embodiment of the present invention.

[0077] Figure 3 is the phase of the difference frequency signal of the triangular wave frequency modulation fuse according to the embodiment of the present invention Schematic diagram of the main flow of the computational method.

[0078] Figure 4 is the phase of the difference frequency signal of the triangular wave frequency modulation fuse according to the embodiment of the present invention Schematic diagram of the main flow of the computational method.

[0079] Figure 5 is the phase of the difference frequency signal of the triangular wave frequency modulation fuse according to the embodiment of the present invention Schematic diagram of the main flow of the computational method.

[0080] Figure 6 is the phase of the difference frequency signal of the triangular wave frequency modulation fuse according to the embodiment of the present invention Schematic diagram of the main flow of the computational method.

[0081] Figure 7 Schematic diagram of a simulation system for a difference frequency signal of a triangle wave frequency modulation fuse according to an embodiment of the present invention.

[0082] Figure 8 4 is a schematic diagram of a time domain comparison result between a target difference frequency signal and an actual difference frequency signal according to an embodiment of the present invention.

[0083] Fig. 9 4 is a schematic diagram of a frequency domain comparison result between a target difference frequency signal and an actual difference frequency signal according to an embodiment of the present invention. DETAILED DESCRIPTION

[0084] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0085] In modern warfare, the increasing complexity of targets on the battlefield, the increasingly harsh electromagnetic environment, and the widespread application of information technology in the military have put forward higher requirements for the precise ranging performance and anti-interference performance of the fuze. Relying on the difference frequency signal frequency ranging rather than the signal amplitude is conducive to improving the ranging accuracy and reducing the explosion height dispersion. In addition, the frequency modulation signal has a large bandwidth and many signal characteristics, which increases the difficulty of the jammer to implement interference, making the frequency modulation fuze have great advantages in ranging accuracy and anti-interference. Frequency modulation fuzes mainly include sawtooth wave frequency modulation and triangle wave frequency modulation, which are the two most widely used frequency modulation systems. The present invention provides a method for simulating the difference frequency signal of a triangle wave frequency modulation fuze, such as Figure 1 As shown, the method for simulating the difference frequency signal of the triangular wave frequency modulation fuse of the present invention comprises the following steps:

[0086] Step 11, obtaining simulation parameters of the difference frequency signal to be simulated, wherein the simulation parameters include carrier frequency, frequency deviation, modulation period, sampling frequency, initial projectile-target distance and projectile-target relative motion speed.

[0087] In the embodiment of the present invention, the simulation parameters of the triangular wave frequency modulation fuse difference frequency signal to be simulated include the carrier frequency f c , frequency deviation ΔF, modulation period T m , sampling frequency f s , initial missile-target distance R0, missile-target relative motion speed v; where frequency deviation ΔF represents the bandwidth of the transmission signal of the triangular wave frequency modulation fuze; T m is the modulation period of the triangle wave frequency modulation fuze.

[0088] Step 12, input the carrier frequency, frequency deviation, modulation period, sampling frequency, initial missile-target distance and missile-target relative motion speed into the triangle wave frequency modulation fuze difference frequency signal simulation model, the triangle wave frequency modulation fuze difference frequency signal simulation model includes the time domain phase formula of the difference frequency signal, the expression of the common coefficient of the time domain phase formula, the expression of the phase increment of the difference frequency signal and the phase calculation method of the difference frequency signal.

[0089] In an embodiment of the present invention, when generating a triangular wave frequency modulation fuse difference frequency signal simulation model, firstly, the law of the signal frequency of the triangular wave frequency modulation fuse changing with time is analyzed to obtain the time domain expression of the difference frequency signal; then, the time domain expression is expressed as a time polynomial, the common coefficients of the polynomial are extracted, and the polynomial is sorted into a first-order simplified polynomial; the common coefficients of different regular areas are compared, and the common coefficients are subjected to a secondary simplification process including merging and removal to obtain a quadratic simplified polynomial; the time of the quadratic simplified polynomial is expressed by a sampling period to obtain a time domain formula of the difference frequency signal, from which the time domain phase formula of the difference frequency signal of each segment is extracted; the phase increment of each segment is calculated to determine the phase calculation method of each segment; the expression of the common coefficient, the time domain phase formula, the phase increment and the phase calculation method constitute the triangular wave frequency modulation fuse difference frequency signal simulation model.

[0090] Step 21, determining the time domain expression of the transmission signal of the triangular wave frequency modulation fuze according to the law of the signal frequency of the triangular wave frequency modulation fuze changing with time.

[0091] The signal frequency of the triangular wave frequency modulation fuse simulated by the present invention changes with time as shown in the following figure: Figure 2 As shown, the horizontal axis represents time and the vertical axis represents the carrier frequency f c ,in:

[0092] The solid line shows how the instantaneous frequency of the transmitted signal changes with time;

[0093] Under the condition that the FM fuze and the target are relatively stationary, the dotted line represents the law of the instantaneous frequency of the echo signal changing with time, and the alternating long and short dashes represent the law of the instantaneous frequency of the difference frequency signal changing with time;

[0094] Under the condition that the frequency modulation fuze and the target are in relative motion, the double-dotted line represents the law of change of the instantaneous frequency of the echo signal with time, and the single-dotted line represents the law of change of the instantaneous frequency of the difference frequency signal with time.

[0095] Furthermore, if Figure 2 As shown, τ is the time delay of the echo signal relative to the transmitted signal; β is the slope of the triangular wave frequency modulation,

[0096] In the embodiment of the present invention, Figure 2 The variation law of the signal frequency of the triangular wave frequency modulation fuze over time can be used to obtain the instantaneous frequency of the transmitting signal of the triangular wave frequency modulation fuze in the nth cycle, as shown in the following formula (1):

[0097]

[0098] In the above formula, f1 n (t) represents the transmitted signal in nT mto (n+1 / 2)T m The instantaneous frequency within the period;

[0099] f2 n (t) indicates the transmitted signal at (n+1 / 2)T m to (n+1)T m The instantaneous frequency within a period; where n is a natural number, that is, n≥0 and n is an integer.

[0100] In the embodiment of the present invention, the instantaneous frequency of the transmitting signal is integrated to obtain the instantaneous phase variation law of the transmitting signal, and then the time domain expression s of the transmitting signal of the triangular wave frequency modulation fuse is obtained. t (t), as shown in the following formula (2):

[0101]

[0102] In the above formula, U t Indicates the amplitude of the transmitted signal.

[0103] Step 22, using the time delay between the transmitting signal and the echo signal of the triangular wave frequency modulation fuse, determine the time domain expression of the echo signal.

[0104] In the embodiment of the present invention, the difference between the echo signal and the transmitted signal is only the time delay τ between the signals and the phase shift introduced by the reflection characteristics of the target. When the FM fuze and the target are relatively stationary, τ(t) = 2R / c is a constant, where R is the distance between the projectile and the target, and c is the speed of light. When the FM fuze and the target are in relative motion, τ(t) = 2R0 / c-2vt / c, where R0 is the initial distance between the projectile and the target; v is the relative speed of the projectile and the target, v is positive when the projectile and the target are close, and v is negative when the projectile and the target are far away. Thus, the time domain expression of the echo signal of the triangular wave FM fuze can be obtained, as shown in the following formula (3):

[0105]

[0106] In the above formula, U r Indicates the amplitude of the echo signal.

[0107] Step 23, mixing the transmission signal and the echo signal to obtain the time domain expression of the difference frequency signal of the triangle wave frequency modulation fuse.

[0108] In the embodiment of the present invention, the difference frequency signal of the triangular wave frequency modulation fuse is obtained by mixing the transmission signal and the echo signal. Therefore, the time domain expression of the transmission signal of the triangular wave frequency modulation fuse is: t (t) and the time domain expression of the echo signal s rAfter multiplying (t) and removing the high-frequency term, the time domain expression of the difference frequency signal of the triangular wave frequency modulation fuse is obtained, as shown in the following formula (4):

[0109]

[0110] In the above formula, U b Indicates the amplitude of the difference frequency signal. Figure 2 As shown, the difference frequency signal has regular and irregular areas, ①nT m ≤t<τ(t)+nT m With ③T m / 2+nT m ≤t<T m / 2+τ(t)+nT m For irregular segmentation, ②τ(t)+nT m ≤t<T m / 2+nT m With ④T m / 2+τ(t)+nT m ≤t<T m +nT m Divide the rules into segments.

[0111] Step 24: Arrange the time domain expression of the difference frequency signal into a time polynomial.

[0112] In the embodiment of the present invention, the simulation system of the triangular wave frequency modulation fuse beat frequency signal is a digital system. In order to facilitate the calculation of the triangular wave frequency modulation fuse beat frequency signal simulation model in the actual digital system, the time domain expression of the beat frequency signal is organized into a polynomial of time t, as shown in the following formula (5):

[0113]

[0114] Step 25, extracting common coefficients from the coefficients of each term in the time polynomial and performing a simplification process to obtain a simplified polynomial.

[0115] In the embodiment of the present invention, the corresponding relationship between the simplified mark and the common coefficient of a simplification process is shown in the following formula (6):

[0116]

[0117] It can be seen from the above formula that the common coefficient is only related to the carrier frequency f of the triangular wave frequency modulation fuze. c , frequency deviation ΔF, modulation period T m , the initial projectile-target distance R0, and the projectile-target relative motion speed v are related. By extracting the common coefficients, the time domain expression of the difference frequency signal can be simplified and intuitive, which is convenient for the analysis and simulation of the difference frequency signal. d1=β*2R0 / c;a2=4ΔFv / c;b00 =β*2v / c; c2=4ΔFR0 / c;

[0118] Substituting the correspondence between the simplified mark and the common coefficient into the polynomial of time t corresponding to the time domain expression of the difference frequency signal, a simplified polynomial is obtained, as shown in the following equation (7):

[0119]

[0120] Step 26, performing a secondary simplification process on the common coefficients of the first-order simplified polynomials in different regular areas to obtain a secondary simplified polynomial.

[0121] In an embodiment of the present invention, the secondary simplification processing method includes merging similar common coefficients, comparing and removing the minimum common coefficient terms and removing the initial phase common coefficient terms, etc. By ignoring the common coefficients that have little influence on the formula output result, the time domain expression of the difference frequency signal of the triangular wave frequency modulation fuse can be further simplified without affecting the time domain waveform and spectrum of the formula output result, which is convenient for realizing the calculation of the triangular wave frequency modulation fuse difference frequency signal simulation model in the actual digital system.

[0122] In the embodiment of the present invention, by observing the first-order simplified polynomials of the two regular regions, it can be found that among the common coefficients in the regular region, the common coefficients a1 and a2 representing the Doppler frequency component of the difference frequency signal are 11 The values ​​of are very close and can be combined into one, with the common coefficient a 11 It is expressed by the common coefficient a1; the common coefficients a3, b1, and c3 all contain 1 / c 2 , due to 1 / c 2 It is much smaller than other common coefficients, so it can be ignored directly. Remove the terms corresponding to the common coefficients a3, b1, and c3 in the simplified polynomial; the common coefficients c1, c 01 is the initial phase of the signal in the regular area. Since the initial phase cannot be determined in the actual signal and has little effect on the time domain waveform and spectrum of the signal, it can be ignored. The common coefficients c1 and c 01 The corresponding items.

[0123] By observing the simplified polynomials of the two irregular regions, we can find that among the common coefficients in the irregular region, the value of the common coefficient b0 is much larger than the other common coefficients a0, a1, a2, c0, so it can be ignored. The terms corresponding to the common coefficients a0, a1, a2, c0 in the simplified polynomial of the first order are removed; 1 / c 2It is much smaller than other common coefficients and can also be ignored directly. The terms corresponding to the common coefficients a3, b1, and c3 in the first-order simplified polynomial are removed. The common coefficients c1 and c2 are the initial phases of the signal in the irregular area, which cannot be determined in the actual signal and have little effect on the time domain waveform and spectrum of the signal. They can be ignored. The terms corresponding to the common coefficients c1 and c2 in the first-order simplified polynomial are removed. Accordingly, the common coefficients in the first-order simplified polynomial in the irregular area can only retain the b0 term.

[0124] Furthermore, the quadratic simplified polynomial obtained by the quadratic simplification of the first simplified polynomial is shown in the following formula (8):

[0125]

[0126] Step 27, expressing the time of the quadratic simplified polynomial with a sampling period to obtain a time domain formula of the difference frequency signal.

[0127] In the embodiment of the present invention, in order to facilitate the calculation of the time domain expression formula of the difference frequency signal of the triangular wave frequency modulation fuse in the digital system, the time is represented by the sampling period, that is, t = kT s , where k is a non-negative integer, T s is the sampling period. Accordingly, the time domain formula of the difference frequency signal is obtained by substituting the quadratic simplified polynomial into the following equation (9):

[0128]

[0129] In the above formula, Represents a frequency modulation period T m The number of sampling points within Express Round to the nearest integer; Indicates the number of sampling points in the irregular area within the nth frequency modulation cycle, Express The sampling period is the reciprocal of the sampling frequency.

[0130] Step 28: extracting the time domain phase formula of the difference frequency signal from the time domain formula of the difference frequency signal.

[0131] In the embodiment of the present invention, in an actual digital system, the difference frequency signal is usually represented by a phase. Therefore, the time domain phase formula of the difference frequency signal is extracted from equation (9) to represent the phase of the difference frequency signal, as shown in equation (10):

[0132]

[0133] The segments in the above formula are respectively expressed by segment phase It is expressed as shown in the following formula (11):

[0134]

[0135] Step 29, calculating the phase increment of the difference frequency signal, using the phase calculation method of the difference frequency signal to determine the change rule of the difference frequency signal, and obtaining the triangle wave frequency modulation fuse difference frequency signal simulation model.

[0136] In the embodiment of the present invention, since the resources and time cost consumed by addition calculation in the actual digital system are much smaller than those of multiplication calculation, the phase calculation method of the difference frequency signal of the present invention is the accumulation method, and the accumulation method is used to complete the calculation of the time domain phase formula of the difference frequency signal, wherein the phase increment of the difference frequency signal in each segment is shown in the following formula (12):

[0137]

[0138] In the above formula, Figure 3 and Figure 5 As shown, for the phase of the two irregular regions in the difference frequency signal The phase at the next sampling period k+1 is the phase at the current sampling period k Accumulate a phase increment What we get is, And the phase increment at the next sampling period k+1 is Constantly changing, it is the phase increment at the current sampling period k It is obtained by accumulating a second-order phase increment 2b0, -2b0, that is, Among them, the current sampling period k is the initial moment, that is, when k = 0, the phase Phase increment

[0139] like Figure 4 and Figure 6 As shown, for the phase in the two regular regions of the difference frequency signal The current sampling period k is the initial moment, that is, when k = 0, the phase Phase increment Variable cycle increment The phase at the next sampling period k+1 is the phase at the current sampling period k Accumulate a phase increment What we get is, The next sampling period k+1 is taken as the current sampling period k. It is necessary to determine whether the current sampling period k is at the moment when the frequency modulation period changes, that is, k=K T -1+nK T Is it true? If so, the phase and phase increment Do special processing, specifically:

[0140] When k=K T -1+nK T When the phase of the next sampling period k+1 is is the phase at the current sampling period k Accumulate a variable period increment What we get is, The phase increment at the next sampling period k+1 is the phase increment at the current sampling period k Accumulate a second-order phase increment a2-2b 00 、2b 00 -a2, that is, The variable period increment of the next frequency modulation period It is the variable period increment of the current frequency modulation period. Accumulate a second-order phase increment a2K T +a2, that is,

[0141] When k≠K T -1+nK T When the phase increment at the next sampling period k+1 is Constantly changing, it is the phase increment at the current sampling period k Accumulate a second-order phase increment -2b 00 , 2b 00 What we get is,

[0142] In the embodiment of the present invention, the final triangular wave frequency modulation fuse difference frequency signal simulation model includes the common coefficient expression (6), the segmented phase expression (11), the phase increment expression (12) and Figure 3-Figure 6 Phase calculation method for each segment.

[0143] In the embodiment of the present invention, Figure 7As shown, the simulation system of the difference frequency signal of the triangular wave frequency modulation fuse of the present invention includes a k accumulator, a segmented phase calculation module of the difference frequency signal, a four-to-one data selector (referred to as a four-to-one selector), a truncation quantization module and a cosine lookup table, a total of five modules, wherein the segmented phase calculation module of the difference frequency signal also includes Segment phase calculation, Segment phase calculation,

[0144] Segment phase calculation, The segmented phase calculation has 4 submodules. Specifically:

[0145] Step 71: In each sampling period, the segment phase calculation module of the difference frequency signal outputs the current phase value of each segment respectively.

[0146] In the embodiment of the present invention, the simulation parameters of the triangular wave frequency modulation fuse difference frequency signal to be simulated include the carrier frequency f c =35.25GHz, frequency deviation ΔF=50MHz, modulation period T m =4us, sampling frequency f s =184.32MHz, initial projectile-target distance R0=80m, projectile-target relative motion speed v=300m / s as an example, each phase calculation module includes the following steps when calculating the phase value:

[0147] Step 711, using the simulation parameters, calculate the common coefficients b0, a1, d1,

[0148] a2、b 00 、c2.

[0149] Step 712: The common coefficients b0, a1, d1, a2, b 00 , c2 pseudo-parameters are substituted into the segmented phase expression of the difference frequency signal of formula (11): The expression of the phase increment of the difference frequency signal of formula (12) is

[0150] Step 713: According to the segmented phase expression of the difference frequency signal The expression of phase increment is The phase value of each segment is calculated by the phase calculation method of the difference frequency signal of each segment

[0151] Step 72: according to the value of the k accumulator and the phase value of each segment The phase of the difference frequency signal at the current time k is selected by the four-to-one selector Among them, the phase of the difference frequency signal The bit width is

[0152] Step 73: The truncation quantization module performs phase quantization on the difference frequency signal. Perform bit truncation quantization to obtain a bit width of B Φ(k) The target phase Φ(k) is

[0153] Step 74, according to the target phase Φ(k), search the cosine lookup table to obtain the target difference frequency signal cos(Φ(k)).

[0154] In the embodiment of the present invention, starting from k=0, the above steps are executed cyclically.

[0155] Furthermore, the bit width is B Φ(k) The phase result Φ(k) is suitable for digital system implementation.

[0156] Step 13, obtaining the target beat frequency signal according to the output of the triangle wave frequency modulation fuse beat frequency signal simulation model.

[0157] In the embodiment of the present invention, the time domain and frequency domain comparison results of the target difference frequency signal and the actual difference frequency signal are as follows: Figure 8 , Fig. 9 As shown, from Figure 8 and Fig. 9 It can be seen that the triangular wave FM fuze difference frequency signal simulation model of the present invention can accurately simulate the difference frequency signal of the triangular wave FM fuze, and the time domain and frequency domain characteristics of the simulated difference frequency signal are extremely close to the time domain and frequency domain characteristics of the actual difference frequency signal.

[0158] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for simulating a difference frequency signal of a triangular wave frequency modulation fuze, characterized in that: include: Acquire the simulation parameters of the difference frequency signal to be simulated, the simulation parameters include the carrier frequency f c , frequency deviation ΔF, frequency modulation period T m , sampling frequency f s , the initial projectile-target distance R0 and the projectile-target relative motion speed v; The carrier frequency f c , frequency deviation ΔF, frequency modulation period T m , sampling frequency f s , the initial missile-target distance R0 and the missile-target relative motion speed v are input into a triangular wave frequency modulation fuze difference frequency signal simulation model, wherein the triangular wave frequency modulation fuze difference frequency signal simulation model includes a time domain phase formula of the difference frequency signal, an expression of a common coefficient of the time domain phase formula, an expression of a phase increment of the difference frequency signal and a phase calculation method of the difference frequency signal; Obtaining a target beat frequency signal according to the output of the triangle wave frequency modulation fuze beat frequency signal simulation model; The step of generating the triangular wave frequency modulation fuse difference frequency signal simulation model comprises: Determine the time domain expression of the transmission signal of the triangular wave frequency modulation fuze according to the law of the signal frequency of the triangular wave frequency modulation fuze changing with time; Determine the time domain expression of the echo signal of the triangular wave frequency modulation fuze by using the time delay between the transmission signal and the echo signal of the triangular wave frequency modulation fuze; Mixing the transmission signal and the echo signal to obtain a time domain expression of a difference frequency signal of the triangular wave frequency modulation fuse; The time domain expression of the difference frequency signal is organized into a time polynomial. For the coefficients of each term in the time polynomial, the common coefficients are extracted for a primary simplification process. The common coefficients of the first simplified polynomials in different regular areas are subjected to a secondary simplification process. The time of the secondary simplified polynomial is represented by a sampling period, and the time domain formula of the difference frequency signal is obtained: In the above formula, U b represents the amplitude of the difference frequency signal; b0 = (1 / 2) β; β is the slope of the triangular wave frequency modulation, k is the serial number of the sampling point, which is a non-negative integer; n is a natural number; Represents a frequency modulation period T m The number of sampling points within Indicates the number of sampling points in the irregular area within the nth frequency modulation cycle; T s is the sampling period; a1=(f c -ΔF / 2)*2v / c, c is the speed of light; d1=β*2R0 / c; a2=4ΔFv / c; b 00 =β*2v / c; c2=4ΔFR0 / c; τ(t) is the time delay. When the FM fuze and the target are relatively stationary, τ(t)=2R / c is a constant, and R is the distance between the projectile and the target. When the FM fuze and the target are in relative motion, τ(t)=2R0 / c-2vt / c, R0 is the initial distance between the projectile and the target, and v is the relative motion speed between the projectile and the target. When the projectile and the target are close, v is positive, and when the projectile and the target are far away, v is negative. The time domain phase formula of the difference frequency signal is extracted from the time domain formula of the difference frequency signal, and the segmented phase Express: The phase increment of the difference frequency signal is calculated, and the time domain phase formula of the difference frequency signal is calculated by the accumulation method. The phase calculation method of the difference frequency signal is used to determine the change law of the difference frequency signal, and the simulation model of the triangle wave frequency modulation fuse difference frequency signal is obtained.

2. The simulation method according to claim 1, characterized in that: The expression of the phase increment of the difference frequency signal in each of the segments is:

3. The simulation method according to claim 2, characterized in that: The difference frequency signal Segmentation, The segmented phase calculation method includes: For the difference frequency signal In segments, loop through the following steps: Determine the current phase at the current sampling period k and the current phase increment According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1 Using the current phase increment and stated Segmented second-order phase increment 4πb0 Ts 2 , calculate the phase increment at the next sampling period k+1 The phase of the next sampling period k+1 is As the current phase The phase increment at the next sampling period k+1 As the current phase increment or, For the difference frequency signal In segments, loop through the following steps: Determine the current phase at the current sampling period k and the current phase increment According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1 Using the current phase increment and stated Segmented second-order phase increment 4πb0 Ts 2 , calculate the phase increment at the next sampling period k+1 The phase of the next sampling period k+1 is As the current phase The phase increment at the next sampling period k+1 As the current phase increment 4. The simulation method according to claim 2, characterized in that: The difference frequency signal Segmentation, The segmented phase calculation method includes: For the difference frequency signal In segments, loop through the following steps: A1: The current sampling period k is the initial moment, that is, when k = 0, the phase Phase increment A2: According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1 A3: Take the next sampling period k+1 as the current sampling period k time k=k+1, and determine whether the current sampling period k time satisfies k=K T -1+nK T If yes, go to step A4; if no, go to step A7; A4: According to the phase of the current sampling period k and stated The current variable period increment of the current frequency modulation period of the segment Calculate the phase at the next sampling period k+1 A5: Using the current phase increment and stated The second-order phase increment of the segment is 2π[a2T s -2b 00 T s 2 ], calculate the phase increment at the next sampling period k+1 A6: By the current variable cycle increment and stated The second-order phase increment of the segment is 2π[a2T s K T +a2T s ], calculate the variable period increment of the next frequency modulation period Go to step A2; A7: Using the current phase increment and stated Segmented second-order phase increment -4πb 00 Ts 2 , calculate the phase increment at the next sampling period k+1 Go to step A2; or, For the difference frequency signal In segments, loop through the following steps: B1: The current sampling period k is the initial time, that is, when k = 0, the phase Phase increment B2: According to the current phase and the current phase increment Calculate the phase at the next sampling period k+1 B3: Take the next sampling period k+1 as the current sampling period k time k=k+1, and determine whether the current sampling period k time satisfies k=K T -1+nK T If yes, go to step B4; if no, go to step B7; B4: According to the phase of the current sampling period k and stated The current variable period increment of the current frequency modulation period of the segment Calculate the phase at the next sampling period k+1 B5: Using the current phase increment and stated The second-order phase increment of the segment is 2π[2b 00 Ts 2 -a2Ts], calculate the phase increment at the next sampling period k+1 B6: By the current variable cycle increment and stated The second-order phase increment of the segment is 2π[a2TsK T +a2Ts], calculate the variable period increment of the next frequency modulation period Go to step B2; B7: Using the current phase increment and stated Segmented second-order phase increment 4πb00Ts 2 , calculate the phase increment at the next sampling period k+1 Go to step B2.

5. A simulation system for a difference frequency signal of a triangular wave frequency modulation fuze applied to the simulation method for a difference frequency signal of a triangular wave frequency modulation fuze as claimed in claim 1, characterized in that: include: k accumulator, a segmented phase calculation module of the difference frequency signal, a four-to-one selector, a truncated quantization module and a cosine lookup table, wherein: In each sampling period, the segment phase calculation module of the difference frequency signal outputs the current phase value of each segment respectively. According to the value of the k accumulator and the phase value of each segment The phase of the difference frequency signal at the current time k is selected by the four-to-one selector Among them, the phase of the difference frequency signal The bit width is The truncation quantization module performs phase quantization on the difference frequency signal. Perform bit truncation quantization to obtain a bit width of B Φ(k) The target phase Φ(k); According to the target phase Φ(k), the cosine lookup table is searched to obtain the target difference frequency signal cos(Φ(k)).

6. The simulation system according to claim 5, characterized in that The segmented phase calculation module of the difference frequency signal outputs the current phase value of each segment respectively include: Using the simulation parameters, calculate the common coefficient b0=(1 / 2)β; β is the slope of the triangular wave frequency modulation, a1=(f c -ΔF / 2)*2v / c, c is the speed of light, d1=β*2R0 / c, a2=4ΔFv / c, b 00 =β*2v / c and c2=4ΔFR0 / c; The common coefficients b0, a1, d1, a2, b 00 , c2 is substituted into the segmented phase of the difference frequency signal The expression of the phase increment of the difference frequency signal Expression of According to the segmented phase of the difference frequency signal The expression and phase increment The phase value of each segment is calculated by the phase calculation method of the difference frequency signal of each segment. Among them, the expression of the phase increment of the difference frequency signal in each segment is:

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