Method for testing physical layer transmission characteristics of an avionics high-speed bus

Abstract

The present application belongs to the field of aviation high-speed bus, and particularly relates to a kind of aviation high-speed bus physical layer transmission characteristic test method. Including: step 1: in turn build the high-speed bus system to be tested, first test function module, second test function module, test module device;Step 2: use first test function module, second test function module, test module device complete the test and extraction of physical layer transmission characteristic scattering parameter;Step 3: the transmission characteristic scattering parameter extracted is handled, and the high-speed bus model close to actual transmission is obtained;Step 4: using the high-speed bus model close to actual transmission to test and determine the test result. The transmission characteristic test of high-speed signal can be completed efficiently at low cost.

Description

Technical Field

[0001] This invention belongs to the field of aviation high-speed bus, and specifically relates to a method for testing the physical layer transmission characteristics of aviation high-speed bus. Background Technology

[0002] With the continuous improvement of transmission speeds, high-speed buses play a crucial role in modern electronic systems. During the design process of high-speed buses, to ensure signal integrity and avoid problems during transmission, it is necessary to test the transmission characteristics of the designed product. Typically, to clearly locate problems in the transmission link, components in the link are removed, and after eliminating the influence of components, the link transmission parameters are measured. While this approach achieves the purpose of link testing, it has poor operability and increases cost and time during component removal and reassembly. Summary of the Invention

[0003] Purpose of the invention: To provide a method for testing the physical layer transmission characteristics of a high-speed aviation bus, which can complete the transmission characteristic test of high-speed signals at low cost and high efficiency.

[0004] Technical solution:

[0005] A method for testing the physical layer transmission characteristics of an aviation high-speed bus includes:

[0006] Step 1: Construct the high-speed bus system under test, the first test function module, the second test function module, and the test module device in sequence;

[0007] Step 2: Use the first test function module, the second test function module, and the test module device to complete the testing and extraction of the scattering parameters of the physical layer transmission characteristics;

[0008] Step 3: Process the extracted transmission characteristic scattering parameters to obtain a high-speed bus model that approximates actual transmission.

[0009] Step 4: Use a high-speed bus model that closely approximates actual transmission to conduct tests and determine the test results.

[0010] Preferably, in step 1, the high-speed bus system under test is built, specifically as follows:

[0011] The high-speed bus system consists of a backplane and two function boards. The two function boards are placed in parallel and connected to the backplane vertically via connector 1 and connector 2, respectively. The signal rate of the high-speed bus system under test is 25Gbps. The transmitting end of the communication link is the driver chip located on function board 1, and the receiving end of the communication link is the receiver chip located on function board 2. The link under test goes from the driver chip through vias and traces on function board 1, through connector 1 to the backplane, through vias and traces on the backplane, through connector 2 to function board 2, and finally through vias and traces on function board 2 to the receiver chip.

[0012] Preferably, in step 1, building the first test function module specifically involves:

[0013] The physical structure and physical structure attributes of the first test function module are consistent with the test link of the high-speed bus system under test. The physical structure attributes include the number of PCB trace layers, trace width, trace spacing and trace length of the first test function module. The difference from the high-speed bus system under test is that the transmitting end and receiving end of the first test function module are high-speed RF adapters. The link starts from the high-speed RF adapter on function board 1 and finally reaches the high-speed RF adapter on function board 2.

[0014] Preferably, in step 1, the establishment of the second test function module specifically includes:

[0015] The second test module consists of two sets of PCB traces with the same physical structure properties, namely the test group and the control group. The number of PCB trace layers, trace width, trace spacing and trace length should be the same for the test group and the control group. The difference is that the test group consists of high-speed RF adapters at both ends in the second test module, while the control group consists of a high-speed RF adapter at one end and a pad test point at the other end.

[0016] Preferably, in step 1, establishing the test module device specifically involves:

[0017] The test module includes: one adjustable-spacing high-speed signal probe; one 4-port vector network analyzer; and four high-speed cables for connecting the high-speed signal probe and the vector network analyzer. The high-speed cables are then connected and assembled with the adjustable-spacing high-speed signal probe and the 4-port vector network analyzer according to the test requirements.

[0018] Preferably, step 2 includes:

[0019] Step 21: Use the test module device to test the transmission characteristic scattering parameters of the second test function module at multiple frequency points. The test group measures the transmission characteristic scattering parameter matrix S1 at any frequency point, and the control group measures the transmission characteristic scattering parameter matrix S2 at any frequency point.

[0020] Step 22: Use the test module device to test the transmission characteristic scattering parameters of the first test function module at multiple frequency points to obtain any transmission characteristic scattering parameter matrix S3.

[0021] Preferably, in step 1, establishing a test module device specifically includes: when the control group in the second test function module of the test module device is used, two high-speed cables are used, one end of which is connected to the port of a 4-port vector network analyzer and the other end is connected to the tail of an adjustable-spacing high-speed signal probe; another two high-speed cables are used, one end of which is connected to the port of the 4-port vector network analyzer and the other end is connected to a high-speed RF adapter on the function board.

[0022] Preferably, step 1, the establishment of the test module device, specifically includes: when the test group in the second test function module is used, four high-speed cables are used, one end of which is connected to the port of the four-port vector network analyzer, and the other end is connected to the high-speed RF adapter on the function board.

[0023] Preferably, step 1, the establishment of the test module device, specifically includes:

[0024] When the test module is used to test the first function module, four high-speed cables are used. One end is connected to the port of the 4-port vector network analyzer, and the other end is connected to the high-speed RF adapter on the function board.

[0025] Preferably, step 3 specifically includes:

[0026] Step 31: Based on the transmission characteristic scattering parameter matrix S1 obtained from the measurement test group and the transmission characteristic scattering parameter matrix S2 obtained from the measurement control group, calculate S', where S' is the scattering parameter matrix of the high-speed RF adapter that needs to be calculated.

[0027] Specifically, based on the cascade relationship of the three matrices at a single frequency point, S1 = S'·S2, the scattering parameter matrix S' of the high-speed RF adapter is calculated, where S' = S1·S2. -1 ;

[0028] Step 32: Based on the measured scattering parameter matrix S3 of the transmission characteristics, determine the scattering parameter matrix S" of the system model under test. Specifically,

[0029] Based on the cascade relationship of the links, S3 = S'·S"·S', determine the scattering parameter matrix S" of the system model under test, where S" = S' -1 ·S3·S' -1 , where S" is the scattering parameter matrix of the system model under test at a frequency point;

[0030] Step 33: Interpolate the scattering parameter matrix S" of the system under test model at all frequency points to obtain a scattering parameter model at a continuous frequency as a high-speed bus model that approximates actual transmission.

[0031] Beneficial effects:

[0032] 1. This transmission characteristic testing method can avoid the cost risks associated with removing components from the original link;

[0033] 2. No component disassembly or assembly is required when testing the high-speed bus system under test, making it simple and easy to operate;

[0034] 3. Impact on the performance of high-speed signal transmission links;

[0035] 4. The method of the present invention has universal applicability and can be used for characteristic parameters related to signal transmission, including but not limited to scattering parameters and dielectric constant.

[0036] 5. The method of the present invention uses a set of testing equipment to test the transmission characteristics of the high-speed bus system under test and the test module, and obtains the transmission characteristic scattering parameters through calculation, which can avoid the equipment error introduced by different testing equipment directly testing the same high-speed bus system under test. Attached Figure Description

[0037] Figure 1 A flowchart of a method for testing the physical layer transmission characteristics of an aviation high-speed bus provided in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the high-speed bus system under test and the test module provided in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of a test module device provided in an embodiment of the present invention. Detailed Implementation

[0040] The present invention provides a method for testing the physical layer transmission characteristics of an aviation high-speed bus, comprising:

[0041] Step 1: Construct the high-speed bus system under test, the first test function module, the second test function module, and the test module device in sequence;

[0042] Step 2: Use the first test function module, the second test function module, and the test module device to complete the testing and extraction of the scattering parameters of the physical layer transmission characteristics;

[0043] Step 3: Process the extracted transmission characteristic scattering parameters to obtain a high-speed bus model that approximates actual transmission.

[0044] Step 4: Use a high-speed bus model that closely approximates actual transmission to conduct tests and determine the test results.

[0045] In step 1, the high-speed bus system under test is set up, specifically as follows:

[0046] The high-speed bus system consists of a backplane and two function boards. The two function boards are placed in parallel and connected to the backplane vertically via connector 1 and connector 2, respectively. The signal rate of the high-speed bus system under test is 25Gbps. The transmitting end of the communication link is the driver chip located on function board 1, and the receiving end of the communication link is the receiver chip located on function board 2. The link under test goes from the driver chip through vias and traces on function board 1, through connector 1 to the backplane, through vias and traces on the backplane, through connector 2 to function board 2, and finally through vias and traces on function board 2 to the receiver chip.

[0047] In step 1, the first test function module is built, specifically as follows:

[0048] The physical structure and attributes of the first test functional module are consistent with those of the test link of the high-speed bus system under test. The physical structure attributes include the number of PCB trace layers, trace width, trace spacing, and trace length of the first test functional module. The difference between the first test functional module and the high-speed bus system under test is that the transmitting and receiving ends of the first test functional module are high-speed RF adapters. The link starts from the high-speed RF adapter on functional board 1 and ends at the high-speed RF adapter on functional board 2.

[0049] In step 1, the second test function module is established, specifically as follows:

[0050] The second testing module consists of two sets of PCB traces with identical physical structure properties: a test group and a control group. The number of PCB trace layers, trace width, trace spacing, and trace length should be identical for both the test and control groups. The difference lies in the ends: in the second testing module, the test group consists of high-speed RF adapters at both ends, while the control group consists of a high-speed RF adapter at one end and pad test points at the other.

[0051] In step 1, the establishment of the test module device specifically includes: the test module device comprises:

[0052] One high-speed signal probe with adjustable spacing; one 4-port vector network analyzer; four high-speed cables for connecting the high-speed signal probe and the vector network analyzer;

[0053] Based on subsequent testing requirements, the high-speed cable was connected and assembled with the adjustable-spacing high-speed signal probe and the 4-port vector network analyzer.

[0054] Step 2 includes:

[0055] Step 21: Use the test module device to test the transmission characteristic scattering parameters of the second test function module at multiple frequency points. The test group measures the transmission characteristic scattering parameter matrix S1 at any frequency point, and the control group measures the transmission characteristic scattering parameter matrix S2 at any frequency point.

[0056] Step 22: Use the test module device to test the transmission characteristic scattering parameters of the first test function module at multiple frequency points to obtain any transmission characteristic scattering parameter matrix S3.

[0057] Step 1, the establishment of the test module device specifically includes: when the control group in the second test function module of the test module device is used, two high-speed cables are used, one end of which is connected to the port of the 4-port vector network analyzer and the other end is connected to the tail of the adjustable-spacing high-speed signal probe; another two high-speed cables are used, one end of which is connected to the port of the 4-port vector network analyzer and the other end is connected to the high-speed RF adapter on the function board.

[0058] Step 1, the establishment of the test module device specifically includes: when the test group in the second test function module is used, four high-speed cables are used, one end of which is connected to the port of the four-port vector network analyzer, and the other end is connected to the high-speed RF adapter on the function board.

[0059] Step 1, the establishment of the test module device, specifically includes: when the test module device is testing the first functional module, using 4 high-speed cables, one end of which is connected to the port of the 4-port vector network analyzer, and the other end is connected to the high-speed RF adapter on the function board.

[0060] Step 3 specifically includes:

[0061] Step 31: Based on the transmission characteristic scattering parameter matrix S1 obtained from the measurement test group and the transmission characteristic scattering parameter matrix S2 obtained from the measurement control group, calculate S', where S' is the scattering parameter matrix of the high-speed RF adapter that needs to be calculated.

[0062] Specifically, based on the cascade relationship of the three matrices at a single frequency point, S1 = S'·S2, the scattering parameter matrix S' of the high-speed RF adapter is calculated, where S' = S1·S2. -1 .

[0063] Step 32: Based on the measured scattering parameter matrix S3 of the transmission characteristics, determine the scattering parameter matrix S" of the system model under test. Specifically,

[0064] Based on the cascade relationship of the links, S3 = S'·S"·S', determine the scattering parameter matrix S" of the system model under test, where S" = S' -1 ·S3·S' -1 , where S" is the scattering parameter matrix of the system model under test at a frequency point;

[0065] Step 33: Interpolate the scattering parameter matrix S" of the system under test model at all frequency points to obtain a scattering parameter model at a continuous frequency as a high-speed bus model that approximates actual transmission.

[0066] The following is a detailed explanation with reference to the accompanying drawings.

[0067] Figure 2 This is a schematic diagram of the high-speed bus system under test and the test module. Component A is the signal driver, and component B is the signal receiver. The first test module consists of PCB traces with high-speed RF adapters at both ends, C and D. The second test module consists of a group of PCB traces with identical physical properties. The number of PCB trace layers, trace width, trace spacing, and trace length are the same in the second test module. The difference is that in the second test module, the test group ends E and F are composed of high-speed RF adapters, the control group end G is composed of high-speed RF adapters, and the control group end H is composed of pad test points.

[0068] Figure 3 This is a schematic diagram of the test module device. In the diagram, the vector network analyzer is connected to the system under test and the test function module through high-speed cables and high-speed probes.

[0069] Example 1:

[0070] A method for testing the physical layer transmission characteristics of an aviation high-speed bus includes:

[0071] Step 1: Construct the high-speed bus system under test, the first test function module, the second test function module, and the test module device in sequence;

[0072] In step 1, the high-speed bus system under test is set up, specifically as follows:

[0073] The high-speed bus system consists of a backplane and two function boards. The two function boards are placed in parallel and connected to the backplane vertically via connector 1 and connector 2, respectively. The signal rate of the high-speed bus system under test is 25Gbps. The transmitting end of the communication link is the driver chip located on function board 1, and the receiving end of the communication link is the receiver chip located on function board 2. The link under test goes from the driver chip through vias and traces on function board 1, through connector 1 to the backplane, through vias and traces on the backplane, through connector 2 to function board 2, and finally through vias and traces on function board 2 to the receiver chip.

[0074] The first test function module is set up as follows:

[0075] The physical structure and attributes of the first test functional module are consistent with those of the test link of the high-speed bus system under test. The physical structure attributes include the number of PCB trace layers, trace width, trace spacing, and trace length of the first test functional module. The difference between the first test functional module and the high-speed bus system under test is that the transmitting and receiving ends of the first test functional module are high-speed RF adapters. The link starts from the high-speed RF adapter on functional board 1 and ends at the high-speed RF adapter on functional board 2.

[0076] In step 1, the second test function module is established, specifically as follows:

[0077] The second test module consists of two sets of PCB traces with the same physical structure properties, namely the test group and the control group. The number of PCB trace layers, trace width, trace spacing and trace length should be the same for the test group and the control group. The difference is that the test group consists of high-speed RF adapters at both ends in the second test module, while the control group consists of a high-speed RF adapter at one end and a pad test point at the other end.

[0078] The device for establishing the test module is specifically as follows:

[0079] The test module includes: one adjustable-spacing high-speed signal probe; one 4-port vector network analyzer; and four high-speed cables for connecting the high-speed signal probe and the vector network analyzer. The high-speed cables are then connected and assembled with the adjustable-spacing high-speed signal probe and the 4-port vector network analyzer according to the test requirements.

[0080] Step 2: Use the first test function module, the second test function module, and the test module device to complete the testing and extraction of the scattering parameters of the physical layer transmission characteristics;

[0081] Step 3: Process the extracted transmission characteristic scattering parameters to obtain a high-speed bus model that approximates actual transmission.

[0082] Step 4: Use a high-speed bus model that closely approximates actual transmission to conduct tests and determine the test results.

[0083] Example 2:

[0084] Figure 1 This is a flowchart of the physical layer transmission characteristic test method for aviation high-speed bus, including:

[0085] S401 is used to build a high-speed bus system under test, ensuring that the bus link is completely routed on the PCB from the driver end to the receiver end.

[0086] S402, establish the first test function module, ensuring that the physical structure attributes of the first test function module are consistent with the high-speed bus system under test. Specifically, this is manifested in:

[0087] (1) The number of PCB trace layers is consistent.

[0088] (2) PCB trace width and spacing.

[0089] (3) The PCB trace lengths should be kept consistent.

[0090] The difference between this and the high-speed bus system under test is that the first test function module consists of high-speed RF adapters at both ends.

[0091] The purpose of setting up the first test function module is to construct a link transmission environment identical to that of the high-speed bus system under test, avoiding the need to remove circuit components in traditional testing. Furthermore, adding high-speed RF adapters at both ends of the first test function module facilitates the acquisition of parameters other than the transmission characteristic scattering parameter model, expanding the applicability of this method.

[0092] S403, establish a second test function module. The physical structure of the second test function module is set as two groups of PCB traces with the same physical structure properties, namely the test group and the control group. Specifically, it is implemented as follows:

[0093] (1) The number of PCB trace layers, trace width, trace spacing and trace length should be the same for the test group and the control group.

[0094] (2) The test group consists of high-speed radio frequency adapters at both ends, while the control group consists of a high-speed radio frequency adapter at one end and a pad at the other end.

[0095] The purpose of setting up functional module 2 is to obtain the scattering parameter model by measuring the transmission characteristics of the second test functional module, and to obtain the scattering parameters of the high-speed RF adapter by calculating the model.

[0096] S404. Perform transmission characteristic scattering parameter testing on the second test function module. Connect the test group traces in the second test function module to the vector network analyzer using a high-speed cable to obtain the scattering parameter model of the test group. Connect the high-speed probe to the vector network analyzer using a high-speed cable. Use the high-speed probe to test the pad end, and connect the other end with a high-speed cable to obtain the scattering parameter model of the control group.

[0097] S405, perform transmission characteristic scattering parameter testing on the first test function module, and use a high-speed cable to connect the wiring in the first test function module to the vector network analyzer to obtain the scattering parameter model.

[0098] S406, the parameters obtained from the second test function module are model extracted to obtain the scattering parameter models of the test group and control group of the second test function module, and the scattering parameter model of the high-speed RF adapter is calculated.

[0099] S407, The parameters obtained from the first test function module are extracted to obtain the scattering parameter model of the first test function module.

[0100] S408 uses the high-speed RF adapter scattering model obtained from S406 and inputs it into the scattering parameter model of the first test function module to calculate the PCB transmission line model after removing the adapter.

[0101] S409 provides test results based on the transmission characteristics requirements of the device under test, and replaces the model of the system under test to complete the transmission characteristics.

[0102] The present invention provides a method for testing the physical layer transmission characteristics of a high-speed aviation bus, which can complete the transmission characteristic test of high-speed signals at low cost and high efficiency.

[0103] The present invention has the following significant advantages:

[0104] 1. This transmission characteristic testing method can avoid the cost risks associated with removing components from the original link;

[0105] 2. No component disassembly or assembly is required when testing the high-speed bus system under test, making it simple and easy to operate;

[0106] 3. Impact on the performance of high-speed signal transmission links;

[0107] 4. The method of the present invention has universal applicability and can be used for characteristic parameters related to signal transmission, including but not limited to scattering parameters and dielectric constant.

[0108] 5. The method of the present invention uses a set of testing equipment to test the transmission characteristics of the high-speed bus system under test and the test module, and obtains the transmission characteristic scattering parameters through calculation, which can avoid the equipment error introduced by different testing equipment directly testing the same high-speed bus system under test.

Claims

1. A method for testing the physical layer transmission characteristics of an aviation high-speed bus, characterized in that, include: Step 1: Construct the high-speed bus system under test, the first test function module, the second test function module, and the test module device in sequence; Step 2: Use the first test function module, the second test function module, and the test module device to complete the testing and extraction of the scattering parameters of the physical layer transmission characteristics; Step 3: Process the extracted transmission characteristic scattering parameters to obtain a high-speed bus model that approximates actual transmission. Step 4: Use a high-speed bus model that closely approximates actual transmission to perform tests and determine the test results.

2. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 1, characterized in that, In step 1, the high-speed bus system under test is set up, specifically as follows: The high-speed bus system consists of a backplane and two function boards. The two function boards are placed in parallel and connected to the backplane vertically via connector 1 and connector 2, respectively. The signal rate of the high-speed bus system under test is 25Gbps. The transmitting end of the communication link is the driver chip located on function board 1, and the receiving end of the communication link is the receiver chip located on function board 2. The link under test goes from the driver chip through vias and traces on function board 1, through connector 1 to the backplane, through vias and traces on the backplane, through connector 2 to function board 2, and finally through vias and traces on function board 2 to the receiver chip.

3. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 2, characterized in that, In step 1, the first test function module is built, specifically as follows: The physical structure and physical structure attributes of the first test function module are consistent with the test link of the high-speed bus system under test; the physical structure attributes include the number of PCB trace layers, trace width and spacing, and trace length of the first test function module. The difference between this system and the high-speed bus system under test is that the transmitting and receiving ends of the first test function module are high-speed RF adapters. The link starts from the high-speed RF adapter on function board 1 and ends at the high-speed RF adapter on function board 2.

4. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 3, characterized in that, In step 1, the second test function module is established, specifically as follows: The second test module consists of two sets of PCB traces with the same physical structure properties, namely the test group and the control group. The number of PCB trace layers, trace width, trace spacing and trace length should be the same for the test group and the control group. The difference is that the test group consists of high-speed RF adapters at both ends in the second test module, while the control group consists of a high-speed RF adapter at one end and a pad test point at the other end.

5. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 4, characterized in that, In step 1, the test module device is established, specifically as follows: The test module includes: one adjustable-spacing high-speed signal probe; one 4-port vector network analyzer; and four high-speed cables for connecting the high-speed signal probe and the vector network analyzer. The high-speed cables are then connected and assembled with the adjustable-spacing high-speed signal probe and the 4-port vector network analyzer according to the test requirements.

6. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 1, characterized in that, Step 2 includes: Step 21: Use the test module device to test the transmission characteristic scattering parameters of the second test function module at multiple frequency points. The test group measures the transmission characteristic scattering parameter matrix S1 at any frequency point, and the control group measures the transmission characteristic scattering parameter matrix S2 at any frequency point. Step 22: Use the test module device to test the transmission characteristic scattering parameters of the first test function module at multiple frequency points to obtain any transmission characteristic scattering parameter matrix S3.

7. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 5, characterized in that, In step 1, the test module device is set up, specifically including: when the control group in the second test function module of the test module device is used, two high-speed cables are used, one end of which is connected to the port of the 4-port vector network analyzer and the other end is connected to the tail of the adjustable-spacing high-speed signal probe. Two other high-speed cables are used, one end of which is connected to the port of the 4-port vector network analyzer and the other end is connected to the high-speed RF adapter on the function board.

8. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 5, characterized in that, Step 1, the establishment of the test module device specifically includes: when the test group in the second test function module is used, four high-speed cables are used, one end of which is connected to the port of the four-port vector network analyzer, and the other end is connected to the high-speed RF adapter on the function board.

9. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 5, characterized in that, Step 1, the establishment of the test module device specifically includes: When the test module is used to test the first function module, four high-speed cables are used. One end is connected to the port of the 4-port vector network analyzer, and the other end is connected to the high-speed RF adapter on the function board.

10. The method for testing the physical layer transmission characteristics of an aviation high-speed bus according to claim 1, characterized in that, Step 3 specifically includes: Step 31: Based on the transmission characteristic scattering parameter matrix S1 obtained from the measurement test group and the transmission characteristic scattering parameter matrix S2 obtained from the measurement control group, calculate S', where S' is the scattering parameter matrix of the high-speed RF adapter that needs to be calculated. Specifically, based on the cascade relationship of the three matrices at a single frequency point, S1 = S'·S2, the scattering parameter matrix S' of the high-speed RF adapter is calculated, where S' = S1·S2. -1 ; Step 32: Based on the measured scattering parameter matrix S3 of the transmission characteristics, determine the scattering parameter matrix S" of the system model under test. Specifically, Based on the cascade relationship of the links, S3 = S'·S"·S', determine the scattering parameter matrix S" of the system model under test, where S" = S' -1 ·S3·S' -1 , where S" is the scattering parameter matrix of the system model under test at a frequency point; Step 33: Interpolate the scattering parameter matrix S" of the system under test model at all frequency points to obtain a scattering parameter model at a continuous frequency as a high-speed bus model that approximates actual transmission.

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