Avionics terminal time integrity error injection method

Abstract

The invention discloses an avionics terminal time integrity error injection method, which comprises the following steps of: establishing a test environment by a tested terminal, an accompanying test management end and an accompanying test terminal, and recording the measured network time delay as TDelay2; an error injection device is connected between the tested terminal and the test accompanying terminal, and the measured network time delay is recorded as TDelay2; the accompanying test terminal normally sends a message frame, and the error injection device modifies a timestamp of the message frame by using a timestamp deviation value X = TDdelay + Tmin / 2-TDdelay 2; and after the tested terminal receives the message frame, performing time integrity verification, if the verification fails, adding an error count, and verifying the time integrity verification function by checking whether the error count is increased or not. According to the invention, a more effective test means is provided for the integrity verification of the avionics terminal, so that the real-time security of message transmission of the avionics system is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of terminal time integrity testing of avionics systems, and particularly relates to a method for injecting time integrity errors into avionics terminals. Background Art

[0002] The avionics system is an important part of an aircraft and consists of many avionics terminals. Different terminals are responsible for performing different functions, and the data interaction between terminals enables the major functions of the aircraft to operate safely and normally. To ensure the timely and accurate transmission of data messages of airborne critical systems, the receiving terminal needs to verify the message integrity. Therefore, the time management mechanism of the avionics system has designed verification rules for sequential integrity and time integrity.

[0003] To solve the clock synchronization problem between different terminals, the terminals are divided into a management end and an agent end, and time management messages are transmitted between them. This message contains the timestamp information of each terminal, and the management end uses this timestamp information to calculate the clock deviation between terminals. When communicating between different terminals, to ensure the real-time nature of the message, the receiving end will use the clock information and the clock deviation information to calculate the transmission time of the message in the network, so as to judge whether the message transmission is timely. This transmission time is denoted as T transmit .

[0004] However, this series of complex integrity verification mechanisms has brought difficulties to the verification and testing work. The processing of time management messages and the verification of time integrity are carried out inside the terminal. During system-level testing, relevant information cannot be obtained, so it is difficult to construct an error scenario.

[0005] 1) First, the clock deviation value obtained from the time management message is an inaccurate value. After different terminals obtain this value from the management end, they will correct this value in combination with their own product characteristics to obtain a more reliable clock deviation value;

[0006] 2) Second, only the timestamp when the sending end sends can be known by monitoring the data frame, but the timestamp when the receiving end receives cannot be known, so it is difficult to estimate the T transmit value;

[0007] To implement the test of the error scenario, a special method for injecting time integrity errors needs to be designed. Summary of the Invention

[0008] The object of the present invention is to provide a method for injecting time integrity errors into avionics terminals, which realizes the construction of an error scenario for the time integrity verification of avionics terminals, thereby providing a more effective test means for the integrity verification of avionics terminals, and further ensuring the real-time nature and safety of message transmission in the avionics system.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] A method for injecting time integrity errors in an avionics terminal, comprising the following steps:

[0011] Step 1: Build a test environment with the terminal under test, the co-test management terminal, and the co-test terminal, and measure the network delay, denoted as T Delay ; Connect an error injection device between the terminal under test and the co-test terminal, and measure the network delay, denoted as T Delay2 ;

[0012] Step 2: Calculate the value range of the timestamp deviation value X as T Delay -T Delay2 <X<T Delay +T min -T Delay2 , T min is the minimum theoretical threshold for transmission time consumption;

[0013] Step 3: The co-test terminal normally sends a message frame, and the error injection device modifies the timestamp of the message frame using the timestamp deviation value X;

[0014] Step 4: After receiving the message frame, the terminal under test performs time integrity verification. If it fails, the error count is incremented, and the time integrity verification function is verified by checking whether the error count increases.

[0015] Preferably, in Step 2, the timestamp deviation value takes the intermediate value X = T Delay +T min / 2 - T Delay2

[0016] The beneficial effects of the present invention are as follows:

[0017] The method for injecting time integrity errors in an avionics terminal provided by the present invention has clear logic and reasonable design. This method uses the delay values in two scenarios of direct connection of the terminal and insertion of an error injection device, as well as the T transmit theoretical threshold, so as to approximately calculate the deviation value required for timestamp error injection. The present invention takes into account both the theoretical analysis value T transmit threshold and the actual network situation, i.e., the network delay. It solves the problem that the clock deviation value of time management and the received timestamp at the message receiving end are unknown, provides a practical test solution, realizes the construction of error scenarios for time integrity testing of avionics terminals, and further ensures the integrity of avionics network message transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flowchart of a method for injecting time integrity errors in an avionics terminal provided by an embodiment of the present invention;

[0019] Figure 2 Schematic diagram for building the test environment of the mis-injection scenario. Specific implementation manners

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0021] See Figure 1 As shown, a method for injecting time integrity errors of an avionics terminal in this embodiment includes the following steps:

[0022] Step 1. Build the test environment and measure the time delay:

[0023] Step 101: Build the test environment with the terminal under test, the co-test management terminal and the co-test terminal, and record the measured network time delay as T Delay2 .

[0024] Step 102: Connect an error injection device between the terminal under test and the co-test terminal, and record the measured network time delay as T Delay2 .

[0025] The test environment of the error scenario built in this embodiment is as Figure 2 shown, which consists of three terminals, including the terminal under test ES_1, the co-test terminal ES_2, and the co-test management terminal ES_3. An error injection device is connected in series between ES_2 and ES_1. The co-test management terminal is used to send time management messages to the terminal under test and the co-test terminal, and send clock deviation value information to the error injection device. The co-test terminal is used to periodically send high-integrity message frames to the terminal under test. The error injection device is used to modify the timestamp value in the high-integrity message frame with the clock deviation value. The dotted line is the time management message, and the solid line is the high-integrity terminal message.

[0026] T Delay and T Delay2 are the sum of the two delays from the co-test terminal to the terminal under test and from the terminal under test to the co-test terminal.

[0027] Step 2. Calculate the timestamp deviation value X = T Delay + T min / 2 - T Delay2 .

[0028] In this embodiment, the value of X is derived through the following method:

[0029] Step 201: The theoretical range of X: The time taken for message transmission T transmit The calculation formula is T1 - T2 + ΔT 21 where T1 represents the clock time of the terminal under test ES_1 as the message receiving end, T2 represents the clock time of the co-test terminal ES_2 as the message sending end, and ΔT 21is the deviation value between the ES_2 clock and the ES_1 clock; in order to construct the error scenario of 0 < T transmit < T min the error scenario of, T min is the theoretical threshold of the minimum transmission time. Use the error injection device to modify the timestamp of the sending end by adding the deviation value X, that is, 0 < T1 - (T2 + X) + ΔT 21 < T min , it can be further deduced that T1 - T2 + ΔT 21 - T min < X < T1 - T2 + ΔT 21 , where T1 is the timestamp of the receiving end and cannot be directly obtained, and ΔT 21 cannot be directly obtained by internal calculation of the terminal;

[0030] Step 202: Approximate the theoretical range of X with the delay T Delay Since T1 and ΔT 21 cannot be directly known, the following approximation needs to be made to the calculation formula; T transmit essentially reflects the delay between the two moments from the start of sending at the sending end to receiving at the receiving end. Therefore, in the case of unchanged environmental factors, the T transmit = T1 - T2 + ΔT 21 should approach a fixed value, denoted as T transmit _1; T transmit _1 can be divided into two parts. One part is the delay on the network line, that is, the measured T Delay , and the other part is the delay of the receiving and sending processing processes inside the terminal, denoted as Δ. The formula can be simplified to T Delay + Δ - T min < X < T Delay + Δ;

[0031] Step 203: Take the middle value as the deviation value X for the experiment according to the range of the approximate deviation value X = T Delay + T min / 2 - T Delay2 ; T Delay2 is the network delay when no error is injected. Therefore, the delay Δ introduced by the terminal to process the message should satisfy 0 < Δ ≤ T transmit _1 - T Delay2 , and it can be further deduced that 0 < Δ ≤ T min - T Delay2 ; take Δ = T min - T Delay2 , and X takes the middle value X = T Delay + Δ - T min / 2 = T Delay + T min / 2 - T Delay2 .

[0032] Step 3. Error injection test:

[0033] Step 301: The co-testing terminal ES_2 normally sends a message frame to ES_1, and the error injection device modifies the timestamp of the message frame by using the timestamp deviation value X. The time management terminal ES_3 normally sends time management messages to ES_1 and ES_2.

[0034] Step 4. Result analysis:

[0035] Step 401: Analyze the test results through error counting. After modifying the timestamp with the deviation value, the message frames received by the terminal under test will be discarded due to the failure of the terminal time integrity check, and the error count inside the terminal under test increases. Therefore, the time integrity check function can be verified by checking whether the error count increases.

[0036] It can be understood that for those of ordinary skill in the art, equivalent substitutions or changes can be made according to the technical solution of the present invention and its inventive concept, and all such changes or substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for injecting time integrity errors in an avionics terminal, characterized in that It includes the following steps: Step 1: Build a test environment with the terminal under test, the companion test management terminal, and the companion test terminal, and record the measured network latency as T Delay ; Connect an error injection device between the terminal under test and the companion test terminal, and record the measured network latency as T Delay2 ; Step 2, calculate the value range T of the timestamp deviation value X Delay -T Delay2 <X<T Delay +T min -T Delay2 ,T min is the minimum theoretical threshold for transmission time consumption; Step 3: The co-testing terminal normally sends a message frame, and the error injection device modifies the timestamp of the message frame by using the timestamp deviation value X; Step 4: After receiving the message frame, the device under test performs a time integrity check. If the check fails, the error count is incremented, and the time integrity check function is verified by checking whether the error count has increased.

2. The method for injecting time integrity errors in an avionics terminal according to claim 1, characterized in that In step two, the time stamp deviation value takes the intermediate value X = T Delay + T min / 2 - T Delay2 .

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