A processing method for improving the transmission security performance of the friend-or-foe identification system channel

Abstract

The present invention relates to a processing method for improving the transmission security performance of a friend-or-foe (IFF) identification system channel, and belongs to the field of communication data processing technology. This method enables an interrogator or transponder to determine whether a received signal is a forwarded or reflected signal during operation, thereby eliminating interference from false interrogation signals or false response signals. The application of this method eliminates the defects that make traditional friend-or-foe (IFF) identification systems susceptible to interference during operation, and improves the anti-interference performance of the IFF identification system. The security and confidentiality of the channel are improved. In this method, the synchronization headers of the interrogation signal waveform frame or the response signal waveform frame are randomly perturbed. This random perturbation introduces time data, and a specific random sequence is used to generate the final offset value of the synchronization header. It is difficult for the enemy to decipher or spy on the changing pattern of the synchronization header position, and it is impossible to further extract the data bits immediately following the synchronization header, resulting in higher security and confidentiality.

Description

Technical Field

[0001] The present invention belongs to the technical field of communication data processing, and in particular relates to a processing method for improving the transmission security performance of a friend-or-foe identification system channel. Background Art

[0002] IFF technology originated in the 1940s, and IFF equipment developed based on this technology entered widespread military use in the 1960s. After undergoing numerous trials and tribulations in local wars, IFF equipment has become an indispensable component of the active combat systems of major military powers. IFF equipment includes interrogators, transponders, cipher machines, and a key management subsystem (including a key generation and management center, a key distribution management terminal, and a key loader), forming a comprehensive IFF system. Interrogators and transponders are deployed on various combat platforms and work in conjunction with cipher machines. The key management subsystem provides the keys necessary for the cipher machines to encrypt or decrypt data. On the battlefield, when a combat platform attacks a target, the interrogator on that platform generates an encrypted interrogation signal. The transponder on the target platform receives the interrogation signal, decrypts it, and generates a corresponding encrypted reply signal. The interrogator then decrypts the reply signal and verifies its identity based on the decrypted plaintext. This collaborative operation of the interrogator and transponder provides instantaneous identification of friend or foe, significantly reducing the probability of friendly targets being accidentally hit. However, with the rapid development of battlefield electronic countermeasure technology, the security performance of early traditional friend-or-foe identification systems has become increasingly fragile, exposing many shortcomings in modern warfare and is far from meeting the needs of modern warfare.

[0003] In traditional friend-or-foe (IFF) systems, when interrogators and transponders operate in tandem, signals are subject to multiple reflections and travel multiple paths to reach each other, often due to the geographical environment. These reflected signals are identical to the original signals, making them indistinguishable from the original signals and requiring processing by the IFF equipment. For the interrogator, processing the response reflections can lead to incorrect target location and range calculations. For the transponder, receiving and processing an excessive number of interrogation reflections can overwhelm its ability to process legitimate interrogation signals, resulting in a significant decrease in transponder performance.

[0004] In the traditional friend-or-foe identification system, the waveform frames of the interrogation signal generated by the interrogator and the response signal generated by the transponder are fixed, and their security only comes from the encrypted data part in the waveform frame, which provides the possibility for the enemy to interfere with our friend-or-foe identification equipment. First, on the battlefield, the enemy cannot decipher the ciphertext data by relying solely on a small number of intercepted electromagnetic wave signals. By repeatedly forwarding friendly interrogation signals, the enemy can deceive the transponders equipped on friendly combat platforms into producing several responses. This will allow the enemy to obtain enough samples. By traversing and analyzing these massive amounts of sample data, the enemy can obtain the inherent laws of friendly data encryption, providing the enemy with the possibility of deciphering the ciphertext data. Second, if the enemy forwards interrogation signals continuously and frequently in a short period of time, it will induce the transponder to continuously generate response signals, leaving it unable to respond to normal friendly interrogation signals. Through this saturation attack, the friendly transponder will not be able to operate normally, and its working efficiency will drop sharply. Finally, on the battlefield, after intercepting the friendly reply signal, the enemy can forward it again to the friendly interrogator, causing the friendly to mistakenly identify the enemy target as a friendly one, providing the enemy with the possibility of breaking through its air defense zone. This deception method brings great risks to combat, and its consequences are unpredictable and immeasurable.

[0005] The interrogation signal generated by a traditional IFF interrogator consists of four synchronization pulses and 32 position pulses. The positions of the leading edges (rising edges) of the pulses are fixed. The first four synchronization pulses are spaced identically, with the spacing between adjacent pulse leading edges being 2µs. These first four synchronization pulses are followed by 32 position pulses, with the leading edges of the first position pulse and the first synchronization pulse being 10µs apart. The 32 position pulses are spaced identically, with the spacing between adjacent pulse leading edges being 2µs. With such a fixed waveform frame, the interrogation signal after multiple reflections or the signal forwarded by the enemy is identical to the original signal, making it impossible to extract characteristic parameters that distinguish the two, thus failing to achieve the goal of suppressing reflected or forwarded signals. The reply signal waveform generated by a traditional IFF transponder consists of three pulses that only distinguish friend or foe. The spacing between adjacent pulse leading edges (rising edges) is fixed at 1.75µs. With such a fixed waveform frame, the signal after multiple reflections or the signal forwarded by the enemy is identical to the original signal, making it impossible to extract characteristic parameters that distinguish the two, thus failing to achieve the goal of suppressing reflected or forwarded signals.

[0006] Therefore, at this stage, it is necessary to design a processing method to improve the channel transmission security performance of the friend-or-foe identification system to solve the above problems. Summary of the Invention

[0007] The purpose of the present invention is to provide a processing method for improving the channel transmission security performance of the friend-or-foe identification system, so as to solve the technical problems existing in the above-mentioned prior art.

[0008] To achieve the above object, the technical solution of the present invention is:

[0009] A method for improving the transmission security performance of a friend-or-foe identification system channel comprises the following steps:

[0010] Step 1: The key management subsystem generates relative reference time data and distributes it to the key loader, which then loads the reference time data into the cipher machines located on the interrogator and transponder.

[0011] Step 2: The cipher machine uses the reference time data to generate the time reference factor T R , and use the time base factor T R As the initial value, the perturbation factor S for the query signal is generated using a pseudo-random generation sequence. I , the disturbance factor S used for the identification response signal F , the disturbance factor S used for the intelligence data reply signal R ; and transmit to the interrogator or transponder;

[0012] Step 3: The interrogator receives the time reference factor T from its own matching cipher machine R and the interrogation signal disturbance factor S I , generating an interrogation signal with a waveform frame change;

[0013] Step 4: The answering machine receives the time reference factor T from the cipher machine that matches it. R and the interrogation signal disturbance factor S I , calculate the disturbance value of the corresponding synchronization head, calculate the expected position of the synchronization head, and compare it with the synchronization head position value of the received inquiry signal to determine its validity. If it is invalid, no response signal is generated to shield the interfering false inquiry signal; if it is valid, subsequent processing is carried out;

[0014] Step 5: If the interrogation signal is valid and legal, the transponder receives the time reference factor T from the cipher machine according to the interrogation signal type. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S used to provide the intelligence data reply signal R , generates a response signal with a waveform frame change. If identity recognition is required, the identity recognition response signal disturbance factor S is used. F Generate a response signal with a waveform frame change. If you want to obtain intelligence information, you need to use the time base factor T R and the intelligence data response signal disturbance factor S R Generates a response signal of waveform frame change;

[0015] Step 6: For both types of response signals, the interrogator receives the time reference factor T from its own matching cipher machine. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S of the reply signal used to provide intelligence data R , calculate the disturbance value of the corresponding synchronization header and compare it with the received response signal synchronization header disturbance value to determine its validity. If it is invalid, no response signal is generated and the interfering false response signal is shielded; if it is valid, subsequent processing is performed.

[0016] Furthermore, step 1 includes:

[0017] Step 11: The key generation and management center generates relative reference time data containing year, month, day, hour, minute, and second;

[0018] Step 12: The key generation and management center distributes the generated reference clock data and key data together to the key distribution management terminal of the theater or combat unit via a wired network or encrypted storage medium;

[0019] Step 13: The key loader obtains the reference clock data and key data from the key distribution management terminal and loads them into the cipher machine located on the interrogator or transponder. The cipher machine uses the reference clock data to generate a 14-bit binary sequence of time reference factor T. R , and use the time base factor to generate the disturbance factor S.

[0020] Furthermore, step 2 includes:

[0021] Step 21: The cipher machine uses the reference time data to calibrate its own time, keeping the cipher machine time synchronized with the current key management subsystem time;

[0022] Step 23: The cipher machine generates a reference time factor T using the currently received time data R ;

[0023] Step 24: Generate a 7-bit binary pseudo-random sequence of the interrogation signal using a pseudo-random generation method, and use the reference time factor T R Limit the timing of extracting the 7-bit binary pseudo-random sequence, and the final sequence obtained is the disturbance factor S I ;

[0024] Step 25: Generate a 4-bit binary pseudo-random sequence for the identity recognition response signal using a pseudo-random generation method, and use the reference time factor T R The timing of extracting the 4-bit binary pseudo-random sequence is limited. The final sequence obtained is the 4-bit binary perturbation factor S used to identify the enemy attribute response signal. F ;

[0025] Step 26: Generate a 7-bit binary pseudo-random sequence for providing a response signal for obtaining intelligence data using a pseudo-random sequence, and use the reference time factor T R The timing of extracting the 7-bit binary pseudo-random sequence is limited. The final sequence obtained is the disturbance factor S of the 7-bit binary sequence used for situational awareness or obtaining intelligence data. R .

[0026] Furthermore, step 3 includes:

[0027] Step 31: Using the current time base factor T R and the interrogation signal disturbance factor S I The disturbance value S that generates the first synchronization header IP1 , its disturbance value S IP1 The specific algorithm process for obtaining is:

[0028] If T R mod 3=0, then S IP1 =(int(S I / 16))mod 8;

[0029] If T R mod 3=1, then S IP1 =(int(S I / 16))mod 8+8;

[0030] If T R mod 3=2, then S IP1 =(int(S I / 16))mod 8+16;

[0031] Finally, the disturbance value is used to generate the time domain position of the first synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is:

[0032] Natural position + disturbance position = 40.375us + S IP1 ×2×0.0625us;

[0033] Step 32: Using the current time base factor T R and the interrogation signal disturbance factor S I Generate the disturbance value S of the second synchronization header IP2 , its disturbance value S IP2 The specific algorithm process for obtaining is:

[0034] If T R mod 3=0, then S IP2 =(int(S I / 4))mod 4+16;

[0035] If TR mod 3=1, then S IP2 =(int(S I / 4))mod 4;

[0036] If T R mod 3=2, then S IP2 =(int(S I / 4))mod 4+20;

[0037] Finally, the disturbance value is used to generate the time domain position of the second synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is:

[0038] Natural position + disturbance position = 23us + S IP2 ×2×0.0625us;

[0039] Step 33: Using the current time base factor T R and the interrogation signal disturbance factor S I Generate the disturbance value S of the third synchronization header IP3 , its disturbance value S P3 The specific algorithm process for obtaining is:

[0040] If T R mod 3=0, then S IP3 =S I mod 4+8;

[0041] If T R mod 3=1, then S IP3 =S I mod 4+4;

[0042] If T R mod 3=2, then S IP3 =S I mod 4;

[0043] Finally, the disturbance value is used to generate the time domain position of the third synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is:

[0044] Natural position + disturbance position = 13us + S IP3 ×2×0.0625us.

[0045] Furthermore, step 4 includes:

[0046] Step 41: The answering machine receives the time reference factor T from its corresponding cipher machine. R and the interrogation signal disturbance factor S I , and save from the current T RThe data of three consecutive times up to now, namely T R 、T R -1, T R -2 and the corresponding S I 、S I1 、S I2 ;

[0047] Step 42: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The data is processed using the algorithm in step 31 to calculate the expected position of the first synchronization header pulse, and then compared with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, the data is processed; if the error exceeds ±15.625ns, the data is not received.

[0048] Step 43: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The data is then processed using the algorithm in step 32 to calculate the expected position of the second synchronization header pulse. This position is then compared with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, the data is processed. If the error exceeds ±15.625ns, the data is not received.

[0049] Step 44: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The algorithm in step 33 is used to calculate the expected position of the third synchronization head pulse, and then compare it with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, subsequent processing is carried out; if the error exceeds ±15.625ns, it is not received.

[0050] Furthermore, step 5 includes:

[0051] Step 51: If obtaining intelligence information, the current time reference factor T is required R and the intelligence data response signal disturbance factor S R Generate the disturbance value S of the first synchronization header in the intelligence response data RP1 , its disturbance value S RP1The specific algorithm process for obtaining is:

[0052] If T R mod 3=0, then S RP1 =(int(S R / 16))mod 8;

[0053] If T R mod 3=1, then S RP1 =(int(S R / 16))mod 8+8;

[0054] If T R mod 3=2, then S RP1 =(int(S R / 16))mod 8+16;

[0055] Finally, the disturbance value is used to generate the time domain position of the first synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is:

[0056] Natural position + disturbance position = 26.625us + S RP1 ×2×0.0625us;

[0057] Step 52: If obtaining intelligence information, the current time reference factor T is required R and the intelligence data response signal disturbance factor S R Generate the disturbance value S of the second synchronization header in the intelligence response data RP2 , its disturbance value S RP2 The specific algorithm process for obtaining is:

[0058] If T R mod 3=0, then S RP2 =(int(S R / 4))mod 4+16;

[0059] If T R mod 3=1, then S RP2 =(int(S R / 4))mod 4;

[0060] If T R mod 3=2, then S RP2 =(int(S R / 4))mod 4+20;

[0061] Finally, the disturbance value is used to generate the time domain position of the second synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is:

[0062] Natural position + disturbance position = 17.25us + S RP2 ×2×0.0625us;

[0063] Step 53: If obtaining intelligence information, the current time reference factor T is required R and the intelligence data response signal disturbance factor S R Generate the disturbance value S of the third synchronization header in the intelligence response data RP3 , its disturbance value S RP3 The specific algorithm process for obtaining is:

[0064] If T R mod 3=0, then S RP3 =S R mod 4+8;

[0065] If T R mod 3=1, then S RP3 =S R mod 4+4;

[0066] If T R mod 3=2, then S RP3 =S R mod 4;

[0067] Finally, the disturbance value is used to generate the time domain position of the third synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is:

[0068] Natural position + disturbance position = 5.0us + S RP3 ×2×0.0625us;

[0069] Step 54: If identity recognition is required, the disturbance value S of the first synchronization header in the identity recognition response signal FP1 and the identity recognition response signal disturbance factor S F The same; use the disturbance value to generate the time domain position of the first synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the second pulse is:

[0070] Natural position + disturbance position = 3.0us + S F ×2×0.0625us.

[0071] Furthermore, step 6 includes:

[0072] Step 61: The interrogator receives the time reference factor T from its own matching cipher machine. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S of the reply signal used to provide intelligence data R , and save from the current TR The data of three consecutive times up to now, namely T R 、T R -1, T R -2 and the corresponding S F 、S F1 、S F2 With S R 、S R1 、S R2 ;

[0073] Step 62: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 The data is received, and the algorithm in step 51 is used to calculate the expected position of the first synchronization header pulse, and then the position is compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, the data is processed; if the error exceeds ±15.625ns, the data is not received.

[0074] Step 63: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 The data is received, and the algorithm in step 52 is used to calculate the expected position of the second synchronization header pulse. This position is then compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, further processing is performed; if the error exceeds ±15.625ns, the signal is not received.

[0075] Step 64: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 The data is received, and the algorithm in step 53 is used to calculate the expected position of the third synchronization header pulse, and then the position is compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, the data is processed; if the error exceeds ±15.625ns, the data is not received.

[0076] Step 64: After the interrogator receives the response signal, if it is identity recognition response data, it uses the stored TR 、T R -1, T R -2 and corresponding S F 、S F1 、S F2 The data is processed by the algorithm in step 54 to calculate the expected position of the first synchronization header pulse, and then compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, subsequent processing is performed; if the error exceeds ±15.625ns, it is not received.

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] The present invention proposes a processing method for improving the channel transmission security performance of the IFF system, which enables an interrogator or transponder to determine whether a received signal is a forwarded or reflected signal during operation, thereby eliminating interference from false interrogation signals or false response signals. The application of this method eliminates the defect that makes traditional IFF systems susceptible to interference during operation, and improves the anti-interference performance of the IFF system.

[0079] The present invention proposes a processing method for improving the channel transmission security performance of an identification friend or foe system, thereby improving the security and confidentiality of the channel. In this method, the synchronization header of an inquiry signal waveform frame or a response signal waveform frame is randomly perturbed. This random perturbation introduces time data and uses a specific random sequence to generate the final offset value of the synchronization header. It is difficult for the enemy to decipher or spy on the changing pattern of the synchronization header position, and it is impossible to further extract the data bits immediately following the synchronization header, thereby improving security and confidentiality.

[0080] The proposed method for improving the channel transmission security of an IFF system, when used in conjunction with other anti-interference methods within the system, further enhances the system's anti-interference capabilities. The proposed method and other anti-interference methods have been implemented in IFF equipment, and their favorable performance has been further verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is a flow chart for controlling the generation of time data for generating a time reference factor and a disturbance factor in a friend-or-foe identification system in the present invention.

[0082] Figure 2 Schematic diagram of the inquiry-response signal synchronization pulse before and after the improvement in the present invention.

[0083] Figure 3 is the reference time factor T in the present invention R Generate an algorithm implementation flowchart.

[0084] Figure 4is the interrogation signal disturbance factor S in the present invention I Generate an algorithm implementation flowchart.

[0085] Figure 5 is the identity recognition response signal disturbance factor S in the present invention F Generate an algorithm implementation flowchart.

[0086] Figure 6 is the disturbance factor S of the state intelligence response signal in the present invention R Generate an algorithm implementation flowchart.

[0087] Figure 7 This is a flowchart of the algorithm for generating the first synchronization head position of the inquiry signal in step 1401 of the present invention.

[0088] Figure 8 This is a flowchart of the algorithm for generating the second synchronization head position of the inquiry signal in step 1402 of the present invention.

[0089] Figure 9 This is a flowchart of the algorithm for generating the third synchronization head position of the inquiry signal in step 1403 of the present invention.

[0090] Figure 10 This is a flowchart of the algorithm for generating the first synchronization head position of the intelligence response signal in step 1501 of the present invention.

[0091] Figure 11 This is a flowchart of the algorithm for generating the second synchronization head position of the intelligence response signal in step 1502 of the present invention.

[0092] Figure 12 This is a flowchart of the algorithm for generating the third synchronization head position of the intelligence response signal in step 1503 of the present invention.

[0093] Figure 13 This is a flowchart of the algorithm for generating the first synchronization head position of the identity recognition response signal in step 1601 of the present invention.

[0094] Figure 14 This is a flow chart for determining the validity of the synchronization header of the inquiry signal in the present invention.

[0095] Figure 15 This is a flow chart for determining the validity of the synchronization header of the intelligence response signal in the present invention.

[0096] Figure 16 This is a flow chart for determining the validity of the synchronization header of the identity recognition response signal in the present invention. DETAILED DESCRIPTION

[0097] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for the purpose of explaining the present invention and are not intended to limit the present invention. That is, the embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in various different configurations.

[0098] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative work shall fall within the scope of protection of the present invention. It should be noted that relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0099] Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0100] A method for improving the transmission security of the IFF system channel is proposed. The following specific steps are required to implement it:

[0101] Step 1: The key management subsystem generates relative reference time data and distributes it to the key loader, which loads the data into the cipher machine located on the interrogator and transponder.

[0102] Step 2: The cipher machine uses the reference time data to generate the time reference factor T R , and use the time base factor T R As the initial value, the perturbation factor S for the query signal is generated using a pseudo-random generation sequence. I , the disturbance factor S used for the identity recognition (including friend-or-foe attributes) response signal F , the disturbance factor S used for the intelligence data (situational awareness) response signal R and transmitted to the interrogator or transponder.

[0103] Step 3: The interrogator receives the time reference factor T from its own matching cipher machine R and the interrogation signal disturbance factor S I , generating an interrogation signal with a waveform frame change.

[0104] Step 4: The answering machine receives the time reference factor T from the cipher machine that matches it. R and the interrogation signal disturbance factor S I , calculate the disturbance value of the corresponding synchronization head, further calculate the expected position of the synchronization head, and compare it with the synchronization head position value of the received inquiry signal to determine its validity. If it is invalid, no response signal is generated, and the interfering false inquiry signal is shielded; if it is valid, subsequent processing is performed.

[0105] Step 5: If the interrogation signal is valid and legal (the present invention does not involve the determination and processing method of legality), the transponder receives the time reference factor T from the cipher machine matched with it according to the type of interrogation signal. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S used to provide the intelligence data reply signal R , generates a response signal with a waveform frame change. If identity recognition is required, the identity recognition response signal disturbance factor S is used. F Generate a response signal with a waveform frame change (including enemy and friend attributes). If you want to obtain intelligence information, you need to use the time base factor T R and the intelligence data response signal disturbance factor S R Generates a response signal with a changing waveform frame (combat platform code, longitude, latitude, altitude, etc.).

[0106] Step 6: For both types of response signals, the interrogator receives the time reference factor T from its own matching cipher machine. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S of the reply signal used to provide intelligence data R , calculate the disturbance value of the corresponding synchronization header and compare it with the received response signal synchronization header disturbance value to determine its validity. If it is invalid, no response signal is generated, shielding the interfering false response signal; if it is valid, subsequent processing is performed.

[0107] Furthermore, the step 1 specifically includes:

[0108] Step 11: The key generation and management center generates relative reference time data containing year, month, day, hour, minute, and second (accurate to 0.01 second). This time can be used to extract the absolute time of the system, or it can be manually set according to operational requirements. The manually set reference time has stronger confidentiality and security.

[0109] Step 12: The key generation and management center distributes the generated reference clock data and key data together to the key distribution management terminal of the war zone or combat unit through a wired network or encrypted storage medium.

[0110] Step 13: The key loader obtains the reference clock data and key data from the key distribution management terminal and loads them into the cipher machine located on the interrogator or transponder. In order to achieve the system's anti-interference and forwarding interference function, the cipher machine needs to use the reference clock data to generate a 14-bit binary sequence of time reference factor T R , and use the time base factor to generate the disturbance factor S.

[0111] Furthermore, the step 2 specifically includes:

[0112] Step 21: The cipher machine uses the reference time data to correct its own time and keep the time of the cipher machine synchronized with the time of the current key management subsystem.

[0113] Step 23: The cipher machine generates a reference time factor T using the currently received time data. R The principle is to convert 24 hours / day into seconds, that is: 24×60×60=86400 seconds, with 8 seconds (the setting of this value needs to take into account the time it takes for the cipher machine to transmit data to the interrogator or transponder, the time it takes for the interrogator to generate an interrogation signal, the time it takes for the transponder to receive and process the interrogation signal, the time it takes for the transponder to generate a response signal, the time it takes for the interrogator to receive and process the response signal, the propagation time of the 1030MHz carrier interrogation signal between the interrogator and the transponder, and the propagation time of the 1090MHz carrier response signal between the transponder and the interrogator) as a time period. 86400 seconds can be divided into 10800 time periods. The cipher machine uses the received time data as the reference for timing. If the current time is an integer multiple of 8 seconds, its value is converted to T R For example, if the current time is 15:14:16, then 15×60×60+14×60+16=54856 seconds, T R =54856÷8+1=6858. Then every 8 seconds, T is output. R In short, the benchmark time factor T R It is calculated from the reference time data, and the reference time data can be set by yourself, so the reference time factor T R Has a certain degree of randomness.

[0114] Step 24: Generate a 7-bit binary pseudo-random sequence of the interrogation signal using a pseudo-random generation method, and use the reference time factor T R Limit the timing of extracting the 7-bit binary pseudo-random sequence, and the final sequence obtained is the disturbance factor S I(The corresponding maximum decimal value is 127.) Since the balance, run distribution, and autocorrelation characteristics of the M sequence are very similar to those of the random sequence, and the number of sequences included is larger, the pseudo-random sequence generation algorithm uses the characteristic polynomial x 7 +x 3 The specific generation process of the M sequence of +1 is as follows: the initial value of the 7-bit M sequence generator is set to a6a5a4a3a2a1a0=1001000 (the user can set different initial values, and the initial values of the cipher machine running the algorithm equipped with any platform interrogator or transponder must be exactly the same); the operation of the nonlinear feedback shift register is completed under the triggering of the clock signal or periodic signal, that is, the assignment operation a' is performed. 0＝ a1、a' 1＝ a2、a' 2＝ a3、a' 3＝ a4、”'

[0115] a 4＝ a5、a 5＝ a6、a Completion time factor T R When the same number of shift operations are performed (in order to improve its randomness, the reference time factor T calculated by using time data such as year, month, day, minute, second, etc. or several of them can also be used R To control the number of shift operations), the value of a'6a'5a'4a'3a'2a'1a'0 is the perturbation factor S of the 7-bit binary sequence. I . Due to S I T R Control, while T R The output cycle is 8 seconds, so S I The value output cycle is 8 seconds.

[0116] Step 25: Generate a 4-bit binary pseudo-random sequence for the identity recognition response signal using a pseudo-random generation method, and use the reference time factor T R The timing of extracting the 4-bit binary pseudo-random sequence is limited. The final sequence obtained is the 4-bit binary perturbation factor S used to identify the enemy attribute response signal. F Since the balance, run distribution, and autocorrelation characteristics of the M sequence are very similar to those of the random sequence, and the number of sequences included is larger, the pseudo-random sequence generation algorithm uses the characteristic polynomial x 4The specific generation process of the M sequence of +x+1 is as follows: the initial value of the 4-bit M sequence generator is set to a3a2a1a0=1001 (the user can set different initial values, and the initial values of the cipher machine running the algorithm equipped with any platform interrogator or transponder must be exactly the same); the operation of the nonlinear feedback shift register is completed under the triggering of the clock signal or periodic signal, that is, the assignment operation a' is performed. 0＝ a1、a' 1＝ a2、a' 2＝ a3. Completion time factor T R When the same number of shift operations are performed (in order to improve its randomness, the reference time factor T calculated by using time data such as year, month, day, minute, second, etc. or several of them can also be used R To control the number of shift operations), the value of a'3a'2a'1a'0 is the perturbation factor S of the 4-bit binary sequence. F Although S F T R Control, generate S F The value period is also 8 seconds, but S F It is used to identify the target in combat. In order to improve the security of this important data, S F It is sent to the host each time the cipher machine interacts with the host in plaintext and ciphertext.

[0117] Step 26: Generate a 7-bit binary pseudo-random sequence for providing a response signal for obtaining intelligence data using a pseudo-random sequence, and use the reference time factor T R The timing of extracting the 7-bit binary pseudo-random sequence is limited. The final sequence obtained is the disturbance factor S of the 7-bit binary sequence used for situational awareness or obtaining intelligence data. R Since the balance, run distribution, and autocorrelation characteristics of the M sequence are very similar to those of the random sequence, and the number of sequences included is larger, the pseudo-random sequence generation algorithm uses the characteristic polynomial x 7 +x 3 The specific generation process of the M sequence is as follows: the initial value of the 7-bit M sequence generator is set to a6a5a4a3a2a1a0=0010001 (the user can set different initial values, and the initial values of the cipher machine running the algorithm equipped with any platform interrogator or transponder must be exactly the same); the operation of the nonlinear feedback shift register is completed under the triggering of the clock signal or periodic signal, that is, the assignment operation a' is performed. 0＝ a1、a' 1＝ a2、a' 2＝ a3、a' 3＝ a4、a' 4＝ a5、a' 5＝ a6、a' Completion time factor T R When the same number of shift operations are performed (in order to improve its randomness, the reference time factor T calculated by using time data such as year, month, day, minute, second, etc. or several of them can also be used R To control the number of shift operations), the value of a'6a'5a'4a'3a'2a'1a'0 is the perturbation factor S of the 7-bit binary sequence. R . Due to S R T R Control, while T R The output cycle is 8 seconds, so S R The value output cycle is 8 seconds.

[0118] Furthermore, the step 3 specifically includes:

[0119] Step 31: Using the current time base factor T R and the interrogation signal disturbance factor S I The disturbance value S that generates the first synchronization header IP1 , its disturbance value S IP1 The specific algorithm process for obtaining is: If T R mod 3=0, then S IP1 =(int(S I / 16))mod8;if T R mod 3=1, then S IP1 =(int(S I / 16))mod 8+8; if T R mod 3=2, then S IP1 =(int(S I / 16))mod 8+16. Finally, the disturbance value is used to generate the time domain position of the first synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: inherent position + disturbance position = 40.375us + S IP1 ×2×0.0625us (because each synchronization header is composed of 16 chips and uses a 16MHz transmission rate, 0.0625 is the time domain width of each chip). R and the interrogation signal disturbance factor S I All of them change randomly, and the corresponding random algorithm is used to generate the disturbance value S IP1 ,Therefore, the position of the first synchronization head will also change randomly.

[0120] Step 32: Using the current time base factor T R and the interrogation signal disturbance factor S I Generate the disturbance value S of the second synchronization header IP2 , its disturbance value SIP2 The specific algorithm process for obtaining is: If T R mod 3=0, then S IP2 =(int(S I / 4))mod 4+16; if T R mod 3=1, then S IP2 =(int(S I / 4))mod 4; if T R mod 3=2, then S IP2 =(int(S I / 4))mod 4+20. Finally, the disturbance value is used to generate the time domain position of the second synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: inherent position + disturbance position = 23us + S IP2 ×2×0.0625us, due to the time base factor T R and the interrogation signal disturbance factor S I All of them change randomly, and the corresponding random algorithm is used to generate the disturbance value S IP2 ,Therefore, the position of the second synchronization head will also change randomly.

[0121] Step 33: Using the current time base factor T R and the interrogation signal disturbance factor S I Generate the disturbance value S of the third synchronization header IP3 , its disturbance value S P3 The specific algorithm process for obtaining is: If T R mod 3=0, then S IP3 =S I mod 4+8; if T R mod 3=1, then S IP3 =S I mod 4+4; if T R mod 3=2, then S IP3 =S I Mod 4. Finally, the disturbance value is used to generate the time domain position of the third synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: inherent position + disturbance position = 13us + S IP3 ×2×0.0625us, due to the time base factor T R and the interrogation signal disturbance factor S I All of them change randomly, and the corresponding random algorithm is used to generate the disturbance value S IP3 ,Therefore, the position of the third synchronization head will also change randomly.

[0122] Furthermore, the step 4 specifically includes:

[0123] Step 41: The answering machine receives the time reference factor T from its corresponding cipher machine. R and the interrogation signal disturbance factor S I , and save from the current T R The data of three consecutive times up to now, namely T R 、T R -1, T R -2 and the corresponding S I 、S I1 、S I2 .

[0124] Step 42: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 Data, use the algorithm in step 31 to calculate the expected position of the first synchronization header pulse, and then compare it with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, subsequent processing is performed; if the error exceeds ±15.625ns (1 / 4 code chip width), it is not received.

[0125] Step 43: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The algorithm in step 32 is used to calculate the expected position of the second synchronization header pulse, and then compare it with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, subsequent processing is performed; if the error exceeds ±15.625ns, it is not received.

[0126] Step 44: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The algorithm in step 33 is used to calculate the expected position of the third synchronization head pulse, and then compare it with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, subsequent processing is carried out; if the error exceeds ±15.625ns, it is not received.

[0127] Furthermore, the step 5 specifically includes:

[0128] Step 51: If obtaining intelligence information, the current time reference factor T is required R and the intelligence data response signal disturbance factor S R Generate the disturbance value S of the first synchronization header in the intelligence response data RP1 , its disturbance value S RP1 The specific algorithm process for obtaining is: If T R mod 3=0, then S RP1 =(int(S R / 16))mod 8; if T R mod 3=1, then S RP1 =(int(S R / 16))mod 8+8; if T R mod 3=2, then S RP1 =(int(S R / 16))mod 8+16. Finally, the disturbance value is used to generate the time domain position of the first synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: inherent position + disturbance position = 26.625us + S RP1 ×2×0.0625us. Time base factor T R and the response signal disturbance factor S R All of them change randomly, and the corresponding random algorithm is used to generate the disturbance value S RP1 ,Therefore, the position of the first synchronization head will also change randomly.

[0129] Step 52: If obtaining intelligence information, the current time reference factor T is required R and intelligence data (situational awareness) response signal disturbance factor S R Generate the disturbance value S of the second synchronization header in the intelligence response data RP2 , its disturbance value S RP2 The specific algorithm process for obtaining is: If T R mod 3=0, then S RP2 =(int(S R / 4))mod 4+16; if T R mod3=1, then S RP2 =(int(S R / 4))mod 4; if T R mod 3=2, then S RP2 =(int(S R / 4))mod 4+20. Finally, the disturbance value is used to generate the time domain position of the second synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: inherent position + disturbance position = 17.25us + S RP2×2×0.0625us, due to the time base factor T R and the response signal disturbance factor S R All of them change randomly, and the corresponding random algorithm is used to generate the disturbance value S RP2 ,Therefore, the position of the second synchronization head will also change randomly.

[0130] Step 53: If obtaining intelligence information, the current time reference factor T is required R and intelligence data (situational awareness) response signal disturbance factor S R Generate the disturbance value S of the third synchronization header in the intelligence response data RP3 , its disturbance value S RP3 The specific algorithm process for obtaining is: If T R mod 3=0, then S RP3 =S R mod 4+8; if T R mod 3=1, then S RP3 =S R mod 4+4; if T R mod 3=2, then S RP3 =S R Mod 4. Finally, the disturbance value is used to generate the time domain position of the third synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: inherent position + disturbance position = 5.0us + S RP3 ×2×0.0625us, due to the time base factor T R and the response signal disturbance factor S R All of them change randomly, and the corresponding random algorithm is used to generate the disturbance value S RP3 ,Therefore, the position of the third synchronization head will also change randomly.

[0131] Step 54: If identity recognition is required, the disturbance value S of the first synchronization header in the identity recognition response signal FP1 and the identity recognition response signal disturbance factor S F The disturbance value is used to generate the time domain position of the first synchronization head. The time interval between the falling edge of the synchronization head pulse and the falling edge of the second pulse is: inherent position + disturbance position = 3.0us + S F ×2×0.0625us, due to the disturbance factor S of each identification response signal F The position of the first sync header will also change randomly.

[0132] Furthermore, the step 6 specifically includes:

[0133] Step 61: The interrogator receives the time reference factor T from its own matching cipher machine.R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S of the reply signal used to provide intelligence data R , and save from the current T R The data of three consecutive times up to now, namely T R 、T R -1, T R -2 and the corresponding S F 、S F1 、S F2 With S R 、S R1 、S R2 .

[0134] Step 62: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 Data, use the algorithm in step 51 to calculate the expected position of the first synchronization header pulse, and then compare it with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, subsequent processing is carried out; if the error exceeds ±15.625ns, it is not received.

[0135] Step 63: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 The data is processed by the algorithm in step 52 to calculate the expected position of the second synchronization head pulse, and then compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, subsequent processing is performed; if the error exceeds ±15.625ns, it is not received.

[0136] Step 64: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2The data is processed by the algorithm in step 53 to calculate the expected position of the third synchronization header pulse, and then compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, subsequent processing is performed; if the error exceeds ±15.625ns, it is not received.

[0137] Step 64: After the interrogator receives the response signal, if it is identity recognition response data, it uses the stored T R 、T R -1, T R -2 and corresponding S F 、S F1 、S F2 The data is processed by the algorithm in step 54 to calculate the expected position of the first synchronization header pulse, and then compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, subsequent processing is performed; if the error exceeds ±15.625ns, it is not received.

[0138] Example description:

[0139] Figure 1 This is a flowchart for controlling the time data for generating the reference time factor and the disturbance factor when the friend-or-foe identification system is operating. The key generation and management center is the source of the time data. This time can use the system time, or, for confidentiality and security, a manually set time. Once the time is determined, all equipment in the friend-or-foe identification system will operate collaboratively based on this time. In this figure, the key generation and management center is generally located in the national military command and control center, and the key distribution management center is generally located in the military district or service combat command center. When the key generation and management center transmits data to the key distribution management terminal, it can use a highly confidential wired or wireless method, or manually transmit using a highly confidential storage medium. The key loader obtains the time data from the key distribution management terminal and loads it into the cipher machine of each combat platform. The cipher machine generates the time reference factor T based on the reference time data. R , and use pseudo-random algorithm to generate disturbance factor S I、 S F 、S R The key machine must be used in conjunction with the interrogator, transponder, and interrogator-responder on each combat platform. Each host uses the time reference factor T generated by the received cipher machine. R and the disturbance factor S I、 S F 、S R , using algorithms to generate signals (interrogation or response) and process the received signals to suppress interference signals. Interrogators or integrated interrogator-responder machines are generally equipped on combat platforms with active attack capabilities.

[0140] Figure 2 The following diagrams show the waveforms of the interrogation and reply signals before and after the improvements. The improved reply signals are of two types, both with synchronization headers. One type is used to determine the target's identity at the moment of attack. Therefore, this signal waveform has a shorter duration, minimizing identification time and improving the real-time performance of the IFF system. The other type is used to provide the intelligence reply signal needed for pre-combat deployment and situational awareness during combat. Therefore, this type of reply signal must include data such as the combat platform code, longitude, latitude, and altitude, and its waveform duration is longer.

[0141] Figure 3 The cipher machine uses the received reference time data to generate the reference time factor T R The processing flow is to obtain T R The time is calculated in 8-second intervals. The time required for the interrogator and transponder to work together is taken into account when setting this value. This time includes the time it takes for the cipher machine to transmit data to the interrogator or transponder, the time it takes for the interrogator to generate the interrogation signal, the time it takes for the transponder to receive and process the interrogation signal, the time it takes for the transponder to generate the response signal, the time it takes for the interrogator to receive and process the response signal, the propagation time of the 1030MHz carrier interrogation signal between the interrogator and transponder, and the propagation time of the 1090MHz carrier response signal between the transponder and interrogator. During the processing process, when the reference time reaches an integer multiple of 8 seconds, T is calculated once. R , and output T R , that is, T R Output is performed in 8-second cycles.

[0142] Figure 4 It is the disturbance factor S that generates the synchronization header of the interrogation signal in the cipher machine. I The implementation process uses the M pseudo-random sequence generation algorithm. When the time base factor T is first received R When using T R Control the number of shifts of the shift register to increase the disturbance factor S I To ensure the randomness, other pseudo-random sequence generation algorithms can be used, or time data such as year, month, day, minute, second, etc. or a reference time factor T calculated from several of these time data can be introduced. R To control the number of shift operations. During the algorithm implementation, it is necessary to assign an initial value to the a6a5a4a3a2a1a0 sequence. In this example, a6a5a4a3a2a1a0 = 1001000. Users can also set different initial values. However, the initial values of the cipher machine running the algorithm must be exactly the same when it is used in any platform interrogator or transponder. Considering the large number of shifts, in order to improve the real-time performance of the algorithm, it is necessary to shorten the shift processing time of the shift register. Therefore, in the FPGA, the first time a T is received, the cipher machine is initialized.R and subsequently receive T R The two cases are handled separately. In addition, the control clock of the shift register needs to be multiplied to above 100MHz. R Control, therefore, S I Output is performed in 8-second cycles.

[0143] Figure 5 It is the synchronization head disturbance factor S that generates the identity recognition response signal in the cipher machine. F The implementation process adopts the M pseudo-random sequence generation algorithm and uses the time base factor T R Control the number of shifts of the shift register to increase the disturbance factor S I To ensure the randomness, other pseudo-random sequence generation algorithms can be used, or time data such as year, month, day, minute, second, etc. or a reference time factor T calculated from several of these time data can be introduced. R To control the number of shift operations. During the algorithm implementation, it is necessary to assign an initial value to the a3a2a1a0 sequence. In this example, a3a2a1a0 = 1001. Users can also set different initial values. However, the initial values of the cipher machine running the algorithm must be exactly the same when it is used in any platform interrogator or transponder. Considering the large number of shifts, in order to improve the real-time performance of the algorithm, it is necessary to shorten the shift processing time of the shift register. Therefore, in the FPGA, the first time a T is received, the cipher machine is initialized. R and subsequently receive T R The two cases are handled separately. In addition, the control clock of the shift register needs to be multiplied to above 100MHz. R Control, but S F It is used to identify the target in combat. In order to improve the security of this important data, S F It is sent to the host each time the cipher machine interacts with the host in plaintext and ciphertext.

[0144] Figure 6 It is the synchronization head disturbance factor S that generates the intelligence response signal in the cipher machine. R The implementation process adopts the M pseudo-random sequence generation algorithm and uses the time base factor T R Control the number of shifts of the shift register to increase the disturbance factor S I To ensure the randomness, other pseudo-random sequence generation algorithms can be used, or time data such as year, month, day, minute, second, etc. or a reference time factor T calculated from several of these time data can be introduced. RTo control the number of shift operations. During the algorithm implementation, it is necessary to assign an initial value to the a6a5a4a3a2a1a0 sequence. In this example, a6a5a4a3a2a1a0 = 0010001. Users can also set different initial values. However, the initial values of the cipher machine running the algorithm must be exactly the same when it is used in any platform interrogator or transponder. Considering the large number of shifts, in order to improve the real-time performance of the algorithm, it is necessary to shorten the shift processing time of the shift register. Therefore, in the FPGA, the first time a T is received, the cipher machine is initialized. R and subsequently receive T R The two cases are handled separately. In addition, the control clock of the shift register needs to be multiplied to above 100MHz. R Control, therefore, S R Output is performed in 8-second cycles.

[0145] Figure 7 This is a flowchart of an algorithm for generating the first synchronization head position of the inquiry signal in step 1401 in an embodiment of the present invention. Other algorithms may also be used to generate the first synchronization head position of the inquiry signal.

[0146] Figure 8 This is a flowchart of an algorithm for generating the second synchronization head position of the inquiry signal in step 1402 in an embodiment of the present invention. Other algorithms may also be used to generate the second synchronization head position of the inquiry signal.

[0147] Figure 9 This is a flowchart of an algorithm for generating the third synchronization head position of the inquiry signal in step 1403 in an embodiment of the present invention. Other algorithms may also be used to generate the third synchronization head position of the inquiry signal.

[0148] Figure 10 This is a flowchart of an algorithm for generating the first synchronization header position of the intelligence response signal in step 1501 in an embodiment of the present invention. Other algorithms may also be used to generate the first synchronization header position of the intelligence response signal.

[0149] Figure 11 This is a flowchart of an algorithm for generating the second synchronization head position of the intelligence response signal in step 1502 in an embodiment of the present invention. Other algorithms may also be used to generate the second synchronization head position of the intelligence response signal.

[0150] Figure 12 This is a flowchart of an algorithm for generating the third synchronization header position of the intelligence response signal in step 1503 in an embodiment of the present invention. Other algorithms may also be used to generate the third synchronization header position of the intelligence response signal.

[0151] Figure 13This is a flowchart of an algorithm for generating the first synchronization header position of the identity recognition response signal in step 1601 in an embodiment of the present invention. Other algorithms may also be used to generate the first synchronization header position of the identity recognition response signal.

[0152] Figure 14 This is a flowchart of the implementation of the answering machine to determine the validity of the interrogation signal synchronization header in an embodiment of the present invention, including steps 1401, 1402, and 1403. The corresponding processing flows are as follows: Figure 7 、 Figure 8 、 Figure 9 In the flowchart, when determining whether the synchronization header is valid, the difference between the preset position and the actual position is required to be within ±15.625ns, where 15.625ns = the length of one chip representing a data bit (62.5ns) × 1 / 4.

[0153] Figure 15 This is a flow chart of the interrogator determining the validity of the synchronization header of the intelligence response signal according to an embodiment of the present invention, including steps 1501, 1502, and 1503. The corresponding processing flows are as follows: Figure 10 、 Figure 11 、 Figure 12 In the flowchart, when determining whether the synchronization header is valid, the difference between the preset position and the actual position is required to be within ±15.625ns, where 15.625ns = the length of one chip representing a data bit (62.5ns) × 1 / 4.

[0154] Figure 16 The flowchart of the interrogator determining the validity of the synchronization header of the identity recognition response signal according to the embodiment of the present invention includes step 1601. The corresponding processing flow is as follows: Figure 13 In the flowchart, when determining whether the synchronization header is valid, the difference between the preset position and the actual position is required to be within ±15.625ns, where 15.625ns = the length of one chip representing a data bit (62.5ns) × 1 / 4.

[0155] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions and effects do not exceed the scope of the technical solution of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A processing method for improving the transmission security performance of a friend-or-foe identification system channel, characterized in that: The following steps are involved: Step 1: The key management subsystem generates relative reference time data and distributes it to the key loader, which then loads the reference time data into the cipher machines located on the interrogator and transponder. Step 2: The cipher machine uses the reference time data to generate the time reference factor T R , and use the time base factor T R As the initial value, the perturbation factor S for the query signal is generated using a pseudo-random generation sequence. I , the disturbance factor S used for the identification response signal F , the disturbance factor S used for the intelligence data reply signal R ; and transmit to the interrogator or transponder; Step 3: The interrogator receives the time reference factor T from its own matching cipher machine R and the interrogation signal disturbance factor S I , generating an interrogation signal with a waveform frame change; Step 4: The answering machine receives the time reference factor T from the cipher machine that matches it. R and the interrogation signal disturbance factor S I , calculate the disturbance value of the corresponding synchronization head, calculate the expected position of the synchronization head, and compare it with the synchronization head position value of the received inquiry signal to determine its validity. If it is invalid, no response signal is generated to shield the interfering false inquiry signal; if it is valid, subsequent processing is carried out; Step 5: If the interrogation signal is valid and legal, the transponder receives the time reference factor T from the cipher machine according to the interrogation signal type. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S used to provide the intelligence data reply signal R , generates a response signal with a waveform frame change. If identity recognition is required, the identity recognition response signal disturbance factor S is used. F Generate a response signal with a waveform frame change. If you want to obtain intelligence information, you need to use the time base factor T R and the intelligence data response signal disturbance factor S R Generates a response signal of waveform frame change; Step 6: For both types of response signals, the interrogator receives the time reference factor T from its own matching cipher machine. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S of the reply signal used to provide intelligence data R , calculate the disturbance value of the corresponding synchronization header, and compare it with the received response signal synchronization header disturbance value to determine its validity. If it is invalid, no response signal is generated to shield the interfering false response signal; If effective, proceed with follow-up treatment; Step 2 includes: Step 21: The cipher machine uses the reference time data to calibrate its own time, keeping the cipher machine time synchronized with the current key management subsystem time; Step 23: The cipher machine generates a reference time factor T using the currently received time data. R ; Step 24: Generate a 7-bit binary pseudo-random sequence of the interrogation signal using a pseudo-random generation method, and use the reference time factor T R Limit the timing of extracting the 7-bit binary pseudo-random sequence, and the final sequence obtained is the disturbance factor S I ; Step 25: Generate a 4-bit binary pseudo-random sequence for the identity recognition response signal using a pseudo-random generation method, and use the reference time factor T R The timing of extracting the 4-bit binary pseudo-random sequence is limited. The final sequence obtained is the 4-bit binary perturbation factor S used to identify the enemy attribute response signal. F ; Step 26: Generate a 7-bit binary pseudo-random sequence for providing a response signal for obtaining intelligence data using a pseudo-random sequence, and use the reference time factor T R The timing of extracting the 7-bit binary pseudo-random sequence is limited. The final sequence obtained is the disturbance factor S of the 7-bit binary sequence used for situational awareness or obtaining intelligence data. R ; Step 3 includes: Step 31: Using the current time base factor T R and the interrogation signal disturbance factor S I The disturbance value S that generates the first synchronization header IP1 , its disturbance value S IP1 The specific algorithm process for obtaining is: If T R mod 3=0, then S IP1 =(int(S I / 16))mod 8; If T R mod 3=1, then S IP1 =(int(S I / 16))mod 8+8; If T R mod 3=2, then S IP1 =(int(S I / 16))mod 8+16; Finally, using the disturbance value S IP1 The time domain position where the first synchronization head is generated, the time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: Natural position + disturbance position = 40.375us + S IP1 ×2×0.0625us; Step 32: Using the current time base factor T R and the interrogation signal disturbance factor S I Generate the disturbance value S of the second synchronization header IP2 , its disturbance value S IP2 The specific algorithm process for obtaining is: If T R mod 3=0, then S IP2 =(int(S I / 4))mod 4+16; If T R mod 3=1, then S IP2 =(int(S I / 4))mod 4; If T R mod 3=2, then S IP2 =(int(S I / 4))mod 4+20; Finally, using the disturbance value S IP2 The time domain position of the second synchronization head is generated. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: Natural position + disturbance position = 23us + S IP2 ×2×0.0625us; Step 33: Using the current time base factor T R and the interrogation signal disturbance factor S I Generate the disturbance value S of the third synchronization header IP3 , its disturbance value S IP3 The specific algorithm process for obtaining is: If T R mod 3=0, then S IP3 =S I mod 4+8; If T R mod 3=1, then S IP3 =S I mod 4+4; If T R mod 3=2, then S IP3 =S I mod 4; Finally, using the disturbance value S IP3 The time domain position of the third synchronization head is generated. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: Natural position + disturbance position = 13us + S IP3 ×2×0.0625us; Step 4 includes: Step 41: The answering machine receives the time reference factor T from its corresponding cipher machine. R and the interrogation signal disturbance factor S I , and save from the current T R The data of three consecutive times up to now, namely T R 、T R -1, T R -2 and the corresponding S I 、S I1 、S I2 ; Step 42: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The data is processed using the algorithm in step 31 to calculate the expected position of the first synchronization header pulse, and then compared with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, the data is processed; if the error exceeds ±15.625ns, the data is not received. Step 43: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The data is then processed using the algorithm in step 32 to calculate the expected position of the second synchronization header pulse. This position is then compared with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, the data is processed. If the error exceeds ±15.625ns, the data is not received. Step 44: Utilize the stored T R 、T R -1, T R -2 and corresponding S I 、S I1 、S I2 The data is then processed using the algorithm in step 33 to calculate the expected position of the third synchronization header pulse. This position is then compared with the corresponding pulse position extracted from the received interrogation signal. If the error is within ±15.625ns, the data is processed. If the error exceeds ±15.625ns, the data is not received. Step 5 includes: Step 51: If obtaining intelligence information, the current time reference factor T is required R and the intelligence data response signal disturbance factor S R Generate the disturbance value S of the first synchronization header in the intelligence response data RP1 , its disturbance value S RP1 The specific algorithm process for obtaining is: If T R mod 3=0, then S RP1 =(int(S R / 16))mod 8; If T R mod 3=1, then S RP1 =(int(S R / 16))mod 8+8; If T R mod 3=2, then S RP1 =(int(S R / 16))mod 8+16; Finally, using the disturbance value S RP1 The time domain position where the first synchronization head is generated, the time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: Natural position + disturbance position = 26.625us + S RP1 ×2×0.0625us; Step 52: If obtaining intelligence information, the current time reference factor T is required R and the intelligence data response signal disturbance factor S R Generate the disturbance value S of the second synchronization header in the intelligence response data RP2 , its disturbance value S RP2 The specific algorithm process for obtaining is: If T R mod 3=0, then S RP2 =(int(S R / 4))mod 4+16; If T R mod 3=1, then S RP2 =(int(S R / 4))mod 4; If T R mod 3=2, then S RP2 =(int(S R / 4))mod 4+20; Finally, using the disturbance value S RP2 The time domain position of the second synchronization head is generated. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: Natural position + disturbance position = 17.25us + S RP2 ×2×0.0625us; Step 53: If obtaining intelligence information, the current time reference factor T is required R and the intelligence data response signal disturbance factor S R Generate the disturbance value S of the third synchronization header in the intelligence response data RP3 , its disturbance value S RP3 The specific algorithm process for obtaining is: If T R mod 3=0, then S RP3 =S R mod 4+8; If T R mod 3=1, then S RP3 =S R mod 4+4; If T R mod 3=2, then S RP3 =S R mod 4; Finally, using the disturbance value S RP3 The time domain position of the third synchronization head is generated. The time interval between the falling edge of the synchronization head pulse and the falling edge of the fourth pulse is: Natural position + disturbance position = 5.0us + S RP3 ×2×0.0625us; Step 54: If identity recognition is required, the disturbance value S of the first synchronization header in the identity recognition response signal FP1 and the identity recognition response signal disturbance factor S F Same; using the disturbance value S FP1 The time domain position where the first synchronization head is generated, the time interval between the falling edge of the synchronization head pulse and the falling edge of the second pulse is: Natural position + disturbance position = 3.0us + S F ×2×0.0625us; Step 6 includes: Step 61: The interrogator receives the time reference factor T from its own matching cipher machine. R , the disturbance factor S of the identity recognition response signal F and the disturbance factor S of the reply signal used to provide intelligence data R , and save from the current T R The data of three consecutive times up to now, namely T R 、T R -1, T R -2 and the corresponding S F 、S F1 、S F2 With S R 、S R1 、S R2 ; Step 62: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 The data is received, and the algorithm in step 51 is used to calculate the expected position of the first synchronization header pulse, and then the position is compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, the data is processed; if the error exceeds ±15.625ns, the data is not received. Step 63: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 The data is received, and the algorithm in step 52 is used to calculate the expected position of the second synchronization header pulse. This position is then compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, further processing is performed; if the error exceeds ±15.625ns, the signal is not received. Step 64: After receiving the response signal, if the interrogator obtains intelligence information, it uses the stored T R 、T R -1, T R -2 and corresponding S R 、S R1 、S R2 The data is received, and the algorithm in step 53 is used to calculate the expected position of the third synchronization header pulse, and then the position is compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, the data is processed; if the error exceeds ±15.625ns, the data is not received. Step 64: After the interrogator receives the response signal, if it is identity recognition response data, it uses the stored T R 、T R -1, T R -2 and corresponding S F 、S F1 、S F2 The data is processed by the algorithm in step 54 to calculate the expected position of the first synchronization header pulse, and then compared with the corresponding pulse position extracted from the received response signal. If the error is within ±15.625ns, subsequent processing is performed; if the error exceeds ±15.625ns, it is not received.

2. The method for improving the transmission security performance of a friend-or-foe identification system channel according to claim 1, characterized in that: Step 1 includes: Step 11: The key generation and management center generates relative reference time data containing year, month, day, hour, minute, and second; Step 12: The key generation and management center distributes the generated reference clock data and key data together to the key distribution management terminal of the theater or combat unit via a wired network or encrypted storage medium; Step 13: The key loader obtains the reference clock data and key data from the key distribution management terminal and loads them into the cipher machine located on the interrogator or transponder. The cipher machine uses the reference clock data to generate a 14-bit binary sequence of time reference factor T. R , and use the time base factor to generate the disturbance factor S.

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