Multi-channel audio switching test circuit for rail transit vehicle-mounted radio station and implementation method of multi-channel audio switching test circuit

Abstract

The invention discloses a multi-channel audio switching test circuit for a rail transit vehicle-mounted radio station and an implementation method, and is applied to the field of production test and fault maintenance of rail transit vehicle-mounted radio station equipment. Comprising a power supply circuit, an analog switch switching circuit, an audio channel switching circuit, an indicating lamp circuit, a tested equipment interface and an audio comprehensive tester interface. The audio channel switching circuit is respectively connected with the analog switch switching circuit, the tested equipment interface and the audio comprehensive tester interface; the power supply circuit is respectively connected with the indicator lamp circuit, the analog switch switching circuit and the audio channel switching circuit; the audio channel switching circuit comprises an audio switching circuit I, an audio switching circuit II, an audio switching circuit III, an audio switching circuit IV and an audio switching circuit V; according to the invention, the indexes of all audio channels of the tested equipment can be tested only through one-time equipment connection, and a tester does not need to carry out frequent line plugging and unplugging on each channel, so that the testing efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to a multi-channel audio switching test circuit for a rail transit vehicle-mounted radio station and an implementation method thereof, and is applied in the field of production testing and fault repair of rail transit vehicle-mounted radio station equipment. Background Art

[0002] Modern subway wireless communications widely use private network communications based on TETRA or LTE networks, which can realize voice calls and data communication functions between mobile devices and the ground. The on-board radio needs to test whether the indicators of each audio channel meet the design requirements when it leaves the factory or fails, which requires testers to test each device. The original method is that testers use test fixtures to test the indicators of each audio channel separately, so each test requires multiple connections between the instrument and the different interfaces of the device under test, which greatly affects the test efficiency. Summary of the invention

[0003] In view of the shortcomings of the prior art of audio path index test of rail transit vehicle radio, such as cumbersome connection and low efficiency, the present invention provides a multi-channel audio switching test circuit and implementation method for rail transit vehicle radio. By using the multi-channel audio switching test circuit, it is only necessary to connect the instrument and the device under test once, and then switch different test paths through a switch combination to complete the test of all indicators, thereby realizing a circuit for efficiently and conveniently testing the multi-channel audio indicators of the equipment.

[0004] The technical solution adopted by the present invention is a multi-channel audio switching test circuit for a rail transit vehicle radio, comprising a power supply circuit, an analog switch switching circuit, an audio path switching circuit, an indicator light circuit, a device under test interface and an audio comprehensive tester interface; the audio path switching circuit is respectively connected to the analog switch switching circuit, the device under test interface and the audio comprehensive tester interface, and the power supply circuit is respectively connected to the indicator light circuit, the analog switch switching circuit and the audio path switching circuit; The audio path switching circuit includes an audio switching circuit I, an audio switching circuit II, an audio switching circuit III, an audio switching circuit IV, and an audio switching circuit V; The analog switch switching circuit is used to control the switching of the audio path and the indicator light state according to the switch input state; the audio path switching circuit is used to switch different audio paths connected to the audio comprehensive tester interface; the indicator light circuit is used to indicate which audio test is currently being performed; the device under test interface is used to connect the power supply and the measured signal from the device under test to this multi-channel audio switching test circuit; the audio comprehensive tester interface is used to connect the audio path to be tested to the audio comprehensive tester so as to test specific indicators on the instrument; the audio switching circuit I is used to switch the connection state between the input end of the audio comprehensive tester interface and the audio input of the control box and the common end of the relay III according to the 12-pin output of N5 in the analog switch switching circuit; the audio switch The switching circuit II is used for switching the connection state between the output terminal of the audio comprehensive test instrument interface and the passenger intercom audio output and the common terminal of the relay IV according to the output of the 15th pin of N5 in the analog switch switching circuit; the audio switching circuit III is used for switching the connection state between the common terminal of the relay III and the audio output of the channel machine and the audio input of the passenger intercom according to the output of the 1st pin of N5 in the analog switch switching circuit; the audio switching circuit IV is used for switching the connection state between the common terminal of the relay IV and the broadcast audio output and the common terminal of the relay V according to the output of the 14th pin of N5 in the analog switch switching circuit; the audio switching circuit V is used for switching the connection state between the common terminal of the relay V and the output of the control box and the audio input of the channel machine according to the output of the 1st and 12th pins of N5 in the analog switch switching circuit.

[0005] A method for realizing a multi-channel audio switching test circuit for a rail transit vehicle-mounted radio station comprises the following steps: connecting an audio integrated tester with an audio comprehensive tester interface, connecting a device under test with a device under test interface, switching the input level of an analog switch switching circuit according to different audio channels to be tested so as to obtain different output control signals to be given to an indicator light circuit and an audio channel switching circuit; the indicator light circuit controls lighting of different LED indicator lights to display a channel selection state according to the output control signal of the analog switch switching circuit; the audio channel switching circuit switches the connection state between the audio channel of the device under test and the audio input and output of the audio comprehensive tester according to the output control signal of the analog switch switching circuit, thereby being able to read the measured indicators of different audio channels through the audio comprehensive tester, and then comparing the actual indicators read with the indicators required in the debugging instructions to determine whether they are normal.

[0006] The indicator light circuit controls the lighting of different LED indicator lights to display the channel selection status according to the output control signal of the analog switch switching circuit. The method for the audio channel switching circuit to switch the audio channel of the device under test according to the output control signal of the analog switch switching circuit is as follows: the device under test has three audio inputs, namely, channel machine audio input, control box audio input and passenger intercom audio input, and four audio outputs, namely, channel machine audio output, control box audio output, broadcast audio output and passenger intercom audio output, wherein the indicators of the channel machine audio input and the channel machine audio output are fixed values. To test the indicators of the control box audio input and the passenger intercom audio input, it is necessary to simulate the control box audio input and the passenger intercom audio input output by the audio comprehensive tester, connect the audio to the input end of the audio comprehensive tester after passing through the audio channel of the device under test, and measure whether the channel machine output indicator requirements can be met; to test the indicators of the control box audio output, broadcast audio output and passenger intercom audio output, it is necessary to connect the audio to the input end of the audio comprehensive tester to measure the indicators. The output audio analog channel machine audio input is connected to the input end of the audio comprehensive test instrument after passing through the audio path of the device under test to measure the indicators, and measure whether the output indicators of the device under test meet the requirements of the control box, broadcasting equipment and passenger intercom equipment; through the analog switch switching circuit interface XS2, interface XS3, interface XS4, the input levels of the 10, 11, 12 pins of the control chip N5, namely S0, S1, S2, the chip N5 outputs different control signals according to different input levels, the control signal output by the chip N5 is transmitted to the indicator light circuit and the audio path switching circuit at the same time, the indicator light circuit realizes the lighting of the corresponding indicator light according to the control signal, and the audio path switching circuit controls the relays I, II, III, IV and V of the audio switching circuit I, the audio switching circuit II, the audio switching circuit III, the audio switching circuit IV and the audio switching circuit V respectively according to the control signal, and realizes the path switching of different audio tests by switching the normally open and normally closed states of the relays.

[0007] The technical effect of the present invention is that the present invention can test the indicators of all audio channels of the device under test by only one device connection, and the test personnel do not need to frequently plug and unplug the lines for each channel, thus realizing a circuit for efficiently and conveniently testing the multi-channel audio indicators of the device, greatly improving the convenience of production testing and fault repair. According to statistics, the use of this multi-channel audio switching test circuit can improve the work efficiency by 50% compared with the traditional test method, and the number of tests completed per day can be increased by several hundred compared with before. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A circuit connection block diagram for implementing the present invention; Figure 2 This is a schematic diagram of the power supply circuit of the present invention; Figure 3This is a schematic diagram of the analog switch switching circuit of the present invention; Figure 4 This is a schematic diagram of the indicator light circuit of the present invention; Figure 5 is a circuit schematic diagram of the audio switching circuit I of the present invention; Figure 6 It is a circuit principle diagram of the audio switching circuit II of the present invention; Figure 7 is a circuit schematic diagram of the audio switching circuit III of the present invention; Figure 8 is a circuit schematic diagram of the audio switching circuit IV of the present invention; Fig. 9 is a circuit schematic diagram of the audio switching circuit V of the present invention; Fig.10 Schematic diagram of the device under test interface XS1 of the present invention; Fig.11 A schematic diagram of the device under test interface XS5 of the present invention; Fig.12 A schematic diagram of the audio comprehensive tester interface XS6 of the present invention; Fig.13 A schematic diagram of the audio comprehensive tester interface XS7 of the present invention; Fig.14 A schematic diagram of the test equipment connection of the embodiment; Fig.15 It is a schematic diagram of all test indicators of the tested device in the embodiment. DETAILED DESCRIPTION

[0009] The present invention will be further described below in conjunction with the accompanying drawings; Figure 1 As shown, a multi-channel audio switching test circuit for rail transit vehicle radio includes a power supply circuit, an analog switch switching circuit, an audio path switching circuit, an indicator light circuit, a device under test interface and an audio comprehensive tester interface.

[0010] The audio path switching circuit includes an audio switching circuit I, an audio switching circuit II, an audio switching circuit III, an audio switching circuit IV, and an audio switching circuit V.

[0011] like Figure 2As shown, the specific circuit of the power supply circuit is: pin 1 and pin 2 of connector XS1 are connected to one end of capacitor C3, capacitor C4 and pin 1 of linear regulator ⅠN1, pin 3 of linear regulator ⅠN1 is connected to one end of capacitor C1, capacitor C2, capacitor C6, capacitor C7 and pin 3 of linear regulator ⅡN2, pin 2 of linear regulator ⅡN2 is connected to capacitor C5, capacitor C8, one end of resistor R1, and connected to 3V3 and test point TP1, the other end of resistor R1 is connected to GND through diode VD1, capacitor C3, capacitor C4, capacitor C1, capacitor C2, capacitor C6, capacitor C7, capacitor C5, capacitor C8, pin 2 of linear regulator ⅠN1 and pin 1 of linear regulator ⅡN2 are connected to GND respectively; the model of linear regulator ⅠN1 is 7805, and the model of linear regulator ⅡN2 is SPX1117-33.

[0012] like Figure 3 As shown, the specific circuit of the analog switch switching circuit is: the 3rd pin of chip N5 is connected to 3V3, the 9th pin of chip N5 is connected to the 3rd pin of interface XS4, the 1st pin of interface XS4 is connected to 5V through resistor R9, the 10th pin of chip N5 is connected to the 3rd pin of interface XS3, the 1st pin of interface XS3 is connected to 5V through resistor R7, the 11th pin of chip N5 is connected to the 3rd pin of interface XS2, the 1st pin of interface XS2 is connected to 5V through resistor R6, the 13th pin of chip N5 is connected to the positive electrode of diode VD2 of indicator light circuit, the 14th pin of chip N5 is connected to the positive electrode of diode VD3 of indicator light circuit and one end of resistor R18 in audio switching circuit IV, the 15th pin of chip N5 is connected to the positive electrode of diode VD4 of indicator light circuit and One end of the resistor R20 in the audio switching circuit II, the 12th pin of the chip N5 is connected to the positive electrode of the indicator circuit diode VD5, one end of the resistor R23 in the audio switching circuit I, and one end of the resistor R21 in the audio switching circuit V, the 1st pin of the chip N5 is connected to the positive electrode of the indicator circuit diode VD6, one end of the resistor R26 in the audio switching circuit III, and one end of the resistor R25 in the audio switching circuit V, the 16th pin of the chip N5 is connected to the capacitor C11, one end of the capacitor C12 and 5V, the 2nd pin of the interface XS4, the 2nd pin of the interface XS3, the 2nd pin of the interface XS2, the 6th pin of the chip N5, the 7th pin of the chip N5, and the 8th pin of the chip N5 are connected to GND respectively, and the chip N5 model is 74HTC4051PW.

[0013] like Figure 4As shown, the specific circuit of the indicator light circuit is: the cathodes of diodes VD2, VD3, VD4, VD5 and VD6 are connected to GND through resistors R14, R17, R19, R22 and R24 respectively, the anode of diode VD2 is connected to pin 13 of the analog switch switching circuit chip N5, the anode of diode VD3 is connected to pin 14 of the analog switch switching circuit chip N5, the anode of diode VD4 is connected to pin 15 of the analog switch switching circuit chip N5, the anode of diode VD5 is connected to pin 12 of the analog switch switching circuit chip N5, and the anode of diode VD6 is connected to pin 1 of the analog switch switching circuit chip N5.

[0014] like Figure 5 As shown, the specific circuit of audio switching circuit I is: pin 1 of relay ⅠN4 is connected to one end of capacitor C10 and 5V, and the other end of capacitor C10 is connected to GND, pin 2 of relay ⅠN4 is connected to pin 3 of relay Ⅲ N7, pin 7 of relay ⅠN4 is connected to pin 6 of relay Ⅲ N7, pin 4 of relay ⅠN4 is connected to pin 2 of audio isolation transformer T1, pin 9 of audio isolation transformer T1 is connected to pin 14 of interface XS1 of device under test, pin 5 of relay ⅠN4 is connected to pin 4 of audio isolation transformer T1, pin 7 of audio isolation transformer T1 is connected to pin 13 of interface XS1 of device under test, pin 6 of relay ⅠN4 is connected to pin 1 of audio comprehensive tester interface XS6, pin 3 of relay ⅠN4 is connected to pin 2 of audio comprehensive tester interface XS6, and relay ⅠN4 is connected to pin 1 of audio comprehensive tester interface XS6. Pin 8 is connected to the positive electrode of diode D2 and the collector of transistor Q2, the negative electrode of diode D2 is connected to 5V, the base of transistor Q2 is connected to resistor R3 and one end of resistor R5, the other end of resistor R5 is connected to the emitter of transistor Q2 and GND, the other end of resistor R3 is connected to the negative electrode of diode D10, and the positive electrode of diode D10 is connected to pin 12 of audio switching circuit Ⅰ chip N5 through resistor R23; the model of audio isolation transformer T1 is VT-36003, and the model of relay ⅠN4 is G6K-2F.

[0015] like Figure 6As shown, the specific circuit of audio switching circuit II is: Pin 1 of relay II N3 is connected to one end of capacitor C9 and 5V, the other end of capacitor C9 is connected to GND, pin 2 of relay II N3 is connected to pin 3 of relay IV N6, and pin 7 of relay II N3 is connected to relay IV Pin 6 of N6 and pin 4 of relay Ⅱ N3 are connected to pin 10 of the interface XS5 of the device under test, pin 5 of relay Ⅱ N3 is connected to pin 9 of the interface XS5 of the device under test, pin 6 of relay Ⅱ N3 is connected to pin 1 of the audio comprehensive tester interface XS7, pin 3 of relay Ⅱ N3 is connected to pin 2 of the audio comprehensive tester interface XS7, pin 8 of relay Ⅱ N3 is connected to the positive electrode of diode D1 and the collector of transistor Q1, the negative electrode of diode D1 is connected to 5V, the base of transistor Q1 is connected to resistor R2 and one end of resistor R4, the other end of resistor R4 is connected to the emitter of transistor Q1 and GND, the other end of resistor R2 is connected to the negative electrode of diode D7, and the positive electrode of diode D7 is connected to pin 15 of audio switching circuit Ⅰ chip N5 through resistor R20; the model of relay Ⅰ N3 is G6K-2F.

[0016] like Figure 7 As shown, the specific circuit of the audio switching circuit III is: the 1st pin of relay III N7 is connected to one end of capacitor C14 and 5V, and the other end of capacitor C14 is connected to GND, the 2nd pin of relay III N7 is connected to the 2nd pin of audio isolation transformer T2, the 9th pin of audio isolation transformer T2 is connected to the 14th pin of the interface XS5 of the device under test, the 7th pin of relay III N7 is connected to the 4th pin of audio isolation transformer T2, the 7th pin of audio isolation transformer T2 is connected to the 13th pin of the interface XS5 of the device under test, the 4th pin of relay III N7 is connected to the 2nd pin of audio isolation transformer T3, the 9th pin of audio isolation transformer T3 is connected to the 8th pin of the interface XS5 of the device under test, the 5th pin of relay III N7 is connected to the 4th pin of audio isolation transformer T3, the 7th pin of audio isolation transformer T3 is connected to the 7th pin of the interface XS5 of the device under test, the 6th pin of relay III N7 is connected to the 7th pin of relay I N4, the 3rd pin of relay III N7 is connected to the 2nd pin of relay I N4, and the 4th pin of relay III N7 is connected to the 8th pin of audio isolation transformer T3. Pin 8 of N7 is connected to the positive electrode of diode D4 and the collector of transistor Q4, the negative electrode of diode D4 is connected to 5V, the base of transistor Q4 is connected to resistor R10 and one end of resistor R12, the other end of resistor R12 is connected to the emitter of transistor Q4 and GND, the other end of resistor R10 is connected to the negative electrode of diode D11, and the positive electrode of diode D11 is connected to pin 1 of audio switching circuit Ⅰ chip N5 through resistor R26; the models of audio isolation transformers T2 and T3 are VT-36003, and the model of relay ⅠN4 is G6K-2F.

[0017] like Figure 8As shown, the specific circuit of the audio switching circuit IV is: the 1st pin of relay IV N6 is connected to one end of capacitor C13 and 5V, the other end of capacitor C13 is connected to GND, the 2nd pin of relay IV N6 is connected to the 3rd pin of relay V N8, the 7th pin of relay IV N6 is connected to the 6th pin of relay V N8, the 4th pin of relay IV N6 is connected to the 18th pin of the interface XS1 of the device under test, the 5th pin of relay IV N6 is connected to the 17th pin of the interface XS1 of the device under test, the 6th pin of relay IV N6 is connected to the 7th pin of relay II N3, the 3rd pin of relay IV N6 is connected to the 2nd pin of relay II N3, the relay IV Pin 8 of N6 is connected to the anode of diode D3 and the collector of transistor Q3, the cathode of diode D3 is connected to 5V, the base of transistor Q3 is connected to resistor R8 and one end of resistor R11, the other end of resistor R11 is connected to the emitter of transistor Q3 and GND, the other end of resistor R8 is connected to the cathode of diode D6, and the anode of diode D6 is connected to pin 14 of audio switching circuit Ⅰ chip N5 through resistor R18; the model of relay ⅠN6 is G6K-2F.

[0018] like Fig. 9 As shown, the specific circuit of the audio switching circuit V is: pin 1 of relay V N8 is connected to one end of capacitor C15 and 5V, and the other end of capacitor C15 is connected to GND, pin 2 of relay V N8 is connected to pin 2 of audio isolation transformer T4, pin 9 of audio isolation transformer T4 is connected to one end of resistor R16 and pin 16 of device under test interface XS1, pin 7 of relay V N8 is connected to pin 4 of audio isolation transformer T4, pin 7 of audio isolation transformer T4 is connected to the other end of resistor R16 and pin 15 of device under test interface XS1, pin 4 of relay V N8 is connected to pin 16 of device under test interface XS5, pin 5 of relay V N8 is connected to pin 15 of device under test interface XS5, pin 6 of relay V N8 is connected to pin 7 of relay IV N6, pin 3 of relay V N8 is connected to pin 2 of relay IV N6, and relay V Pin 8 of N8 is connected to the positive electrode of diode D5 and the collector of transistor Q5, the negative electrode of diode D5 is connected to 5V, the base of transistor Q5 is connected to resistor R13 and one end of resistor R15, the other end of resistor R15 is connected to the emitter of transistor Q5 and GND, the other end of resistor R3 is connected to diode D8 and the negative electrode of diode D10, the positive electrode of diode D8 is connected to pin 12 of audio switching circuit Ⅰ chip N5 through resistor R21, and the positive electrode of diode D10 is connected to pin 1 of audio switching circuit Ⅰ chip N5 through resistor R25; the model of relay Ⅰ N8 is G6K-2F, and the model of audio isolation transformer T4 is VT-36003.

[0019] The working principle is as follows: Fig.15The tested equipment shown has three audio inputs and four audio outputs. The three audio inputs are channel machine audio input, control box audio input, and passenger intercom audio input; the four audio outputs are channel machine audio output, control box audio output, broadcast audio output, and passenger intercom audio output. Among them, the indicators of channel machine audio input and channel machine audio output are fixed values, and the control box audio input, passenger intercom audio input and control box audio output, broadcast audio output, and passenger intercom audio output need to be measured to see if they meet the requirements. To test input indicators such as the control box audio input and the passenger intercom audio input, the audio output of the audio comprehensive tester needs to simulate the control box audio input and the passenger intercom audio input, and then connect them to the input end of the audio comprehensive tester after passing through the audio path of the device under test to measure the indicators and see whether the requirements of the channel machine output indicators can be met; to test output indicators such as the control box audio output, broadcast audio output, and passenger intercom audio output, the audio output of the audio comprehensive tester needs to simulate the channel machine audio input, and then connect them to the input end of the audio comprehensive tester after passing through the audio path of the device under test to measure the indicators and see whether the output indicators of the device under test meet the requirements of the control box, broadcasting equipment and passenger intercom equipment.

[0020] according to Fig.14 As shown, the device under test, the multi-channel audio switching test circuit and the audio comprehensive tester are connected. The analog switch switching circuit interface XS2, interface XS3, and interface XS4 are used to control the input levels of the 10, 11, and 12 pins of the 74HTC4051PW chip N5, namely, S0, S1, and S2. The high level state connected to 5V is 1, and the low level state connected to ground is 0. The internal connection of the analog switch is switched to control the switching of the subsequent G6K-2F relay to realize the switching of the audio path and the lighting of the corresponding indicator light, so as to achieve the effect of switching different audio paths to connect to the audio comprehensive test instrument for testing. Therefore, only one device connection is required to test the indicators of all audio paths of the device under test, and the test personnel do not need to frequently plug and unplug the lines for each path, which greatly improves the test efficiency.

[0021] Embodiment 1, as Figures 10 to 15 As shown in the figure, the implementation method of the multi-channel audio switching test circuit for rail transit vehicle radio, the specific switching logic combination and test method are as follows: First, connect the output of the audio comprehensive tester to the XS6 socket of this multi-channel audio switching test circuit, then connect the input of the audio comprehensive tester to the XS7 socket of this multi-channel audio switching test circuit, and then connect the device under test to the device under test interfaces XS1 and XS5 of this multi-channel audio switching test circuit to complete the connection of the test equipment. This test circuit can be used to test the control box audio output index, broadcast audio output index, passenger intercom audio output index, control box audio input index and passenger intercom audio input index, that is, Fig.15 The measured indicators in Fig.15 The input and output indicators of the channel machine in the system are fixed values ​​and are known. The other two inputs and three outputs need to be measured to see if they meet the requirements. Therefore, it is necessary to use known indicators to test the indicators to be tested.

[0022] (I) To test the audio output index of the control box from the host device under test to the control box, it is necessary to switch the audio comprehensive tester input to the channel machine audio input, and switch the audio comprehensive tester output to the control box audio output. At this time, the input index of the audio comprehensive tester can be adjusted to simulate the channel machine audio input, and the audio output value of the control box can be measured by the audio comprehensive tester to see if it meets the index requirements. The specific operation is: turn the interfaces XS2, XS3, and XS4 to the GND connection state, then the 11, 10, and 9 pins of the chip N5 in the analog switch switching circuit are all in a low level state, and according to the switching logic of the chip N5, the 3rd and 13th pins of the chip N5 are turned on. At this time, the level of the 13th pin of the chip N5 is 3.3V, and the light-emitting diode VD2 connected to it is turned on and emits light. And because the 1, 12, 15, and 14 pins of the chip N5 are all in a floating state at this time, the three-pole in the audio switching circuit I cannot be turned on. The transistor Q2, the transistor Q1 in the audio switching circuit II, the transistor Q4 in the audio switching circuit III, the transistor Q3 in the audio switching circuit IV and the transistor Q5 in the audio switching circuit V are turned on, so the 8 pins of relays I, II, III, IV and V are pulled up by 5V and diodes D2, D1, D4, D3 and D5 respectively, making the five relays in the normally closed state, that is, the 3rd pin (audio integrated tester IN+) and the 2nd pin (relay III) of relay I N4 are connected to the 5V pin. Pin 3 of N7) is connected, pin 6 (audio integrated tester IN+) is connected to pin 7 (pin 6 of relay III N7), pin 3 of relay III N7 is connected to pin 2 and then connected to the channel machine audio input positive EADS_SPK+ through pin 2 and pin 9 of the isolated audio transformer T2, pin 6 of relay III N7 is connected to pin 7 and then connected to the channel machine audio input negative EADS_SPK- through pin 4 and pin 7 of the isolated audio transformer T2, thereby realizing the connection between the input of the audio integrated tester and the audio input of the channel machine; similarly, pin 3 of relay II N3 (audio integrated tester output OUT+) is connected to pin 2 (pin 3 of relay IV N6), then connected to pin 3 of relay V N8, and finally connected to pin 2 and pin 9 of the isolated audio transformer T4 through pin 2 of relay V N8, connected to the control box audio output SP1+, pin 6 of relay II N3 (audio integrated tester output OUT-) is connected to pin 7 (pin 6 of relay IV N6), and then connected to relay V Pin 6 of N8 is connected to the isolation audio transformer T4 through relay V. Pin 7 of N8 is finally connected to the control box audio output SP1-, thus finally realizing the connection between the output of the audio comprehensive tester and the audio output of the control box. At this time, the audio output index of the control box can be obtained by reading the index of the audio comprehensive tester, and then the read index is compared with the index required in the debugging instructions to determine whether it is qualified.

[0023] (ii) To test the broadcast audio output index of the host device under test to the broadcasting equipment, it is necessary to switch the audio comprehensive tester input to the channel machine audio input, and switch the audio comprehensive tester output to the broadcast audio output. At this time, the input index of the audio comprehensive tester can be adjusted to simulate the channel machine audio input, and the broadcast audio output value is measured by the audio comprehensive tester to see if it meets the index requirements. The specific operation is: turn the interface XS2 to the 5V pull-up state, and turn the interfaces XS3 and XS4 to the GND state. Then, the 11th pin of the chip N5 in the analog switch switching circuit is in the high level state, and the 10th and 9th pins are in the low level state. According to the switching logic of the chip N5, the 3rd and 14th pins of the chip N5 are turned on. At this time, the level of the 14th pin of the chip N5 is 3.3V, and the light-emitting diode VD3 connected to it is turned on and emits light, and because at this time the 1st, 12th, 15th, and 13th pins of the chip N5 All of them are in the suspended state, and the transistor Q2 in the audio switching circuit Ⅰ, the transistor Q1 in the audio switching circuit Ⅱ, the transistor Q4 in the audio switching circuit Ⅲ, and the transistor Q5 in the audio switching circuit Ⅴ cannot be turned on. Therefore, the 8 pins of relay Ⅰ, relay Ⅱ, relay Ⅲ, and relay Ⅴ are pulled up by 5V and diodes D2, D1, D4, and D5 respectively, making the four relays in the normally closed state, that is, the 3rd pin (audio integrated tester IN+) and the 2nd pin (relay Ⅲ) of relay ⅠN4 are connected to the 5V pin. Pin 3 of N7) is connected, pin 6 (audio integrated tester IN+) is connected to pin 7 (pin 3 of relay III N7), pin 3 of relay III N7 is connected to pin 2 and then connected to the positive audio input EADS_SPK+ of the channel machine through pin 2 and pin 9 of the isolated audio transformer T2, pin 6 is connected to pin 7 and then connected to the negative audio input EADS_SPK- of the channel machine through pin 4 and pin 7 of the isolated audio transformer T2, thereby realizing the connection between the input of the audio integrated tester and the audio input of the channel machine; similarly, pin 3 of relay II N3 (audio integrated tester output OUT+) is connected to pin 2 (pin 3 of relay IV N6), pin 6 of relay II N3 (audio integrated tester output OUT-) is connected to pin 7 (pin 6 of relay IV N6), and because pin 14 of chip N5 is a high level of 3.3V, the transistor Q3 of the audio switching circuit IV is turned on, thereby pulling down pin 8 of relay IV N6 to control relay IV N6 is connected from the common end to the normally open end, that is, pin 3 is connected to pin 4 (broadcast audio output BRD_AF+), and pin 6 is connected to pin 5 (broadcast audio output BRD_AF+). Finally, the output of the audio comprehensive tester is connected to the broadcast audio output. At this time, the broadcast audio output index can be obtained by reading the index of the audio comprehensive tester, and then the read index is compared with the index required in the debugging instructions to determine whether it is qualified.

[0024] (III) To test the passenger intercom audio output index of the host device under test to the passenger intercom device, it is necessary to switch the audio comprehensive tester input to the channel machine audio input, and switch the audio comprehensive tester output to the passenger intercom audio output. At this time, the input index of the audio comprehensive tester can be adjusted to simulate the channel machine audio input, and the passenger intercom audio output value is measured by the audio comprehensive tester to see if it meets the index requirements. The specific operation is: turn the interface XS3 to the 5V pull-up state, and turn the interfaces XS2 and XS4 to the GND state. Then, the 10th pin of the chip N5 in the analog switch switching circuit is in the high level state, and the 11th and 9th pins are in the low level state. According to the switching logic of the chip N5, the 3rd and 15th pins of the chip N5 are turned on. At this time, the level of the 15th pin of the chip N5 is 3.3V, and the light-emitting diode VD4 connected to it is turned on and emits light, and because at this time the 1, 12, 13, and 14th pins of the chip N5 All of them are in the suspended state, and the transistor Q2 in the audio switching circuit Ⅰ, the transistor Q4 in the audio switching circuit Ⅲ, the transistor Q3 in the audio switching circuit Ⅳ, and the transistor Q5 in the audio switching circuit Ⅴ cannot be turned on. Therefore, the 8 pins of relay Ⅰ, relay Ⅲ, relay Ⅳ, and relay Ⅴ are pulled up by 5V and diodes D2, D4, D3, and D5 respectively, making the four relays in the normally closed state, that is, the 3rd pin (audio integrated tester IN+) and the 2nd pin (relay Ⅲ) of relay ⅠN4 are connected to the 5V pin. Pin 3 of N7) is connected, pin 6 (audio integrated tester IN+) is connected to pin 7 (pin 6 of relay III N7), pin 3 of relay III N7 is connected to pin 2 and then connected to the positive audio input EADS_SPK+ of the channel machine through pin 2 and pin 9 of the isolated audio transformer T2, pin 6 is connected to pin 7 and then connected to the negative audio input EADS_SPK- of the channel machine through pin 4 and pin 7 of the isolated audio transformer T2, thereby realizing the connection between the input of the audio integrated tester and the audio input of the channel machine; and because pin 15 of chip N5 is a 3.3V high level, the transistor Q1 of the audio switching circuit II is turned on, thereby pulling down pin 8 of relay II N3 to control relay II N3 from the common end to the normally open end, that is, pin 3 is connected to pin 4 (passenger intercom audio output EMER_SPK+), and pin 6 is connected to pin 5 (passenger intercom audio output EMER_SPK-). Finally, the output of the audio comprehensive tester is connected with the passenger intercom audio output. At this time, the passenger intercom audio output indicators can be obtained by reading the indicators of the audio comprehensive tester, and then the read indicators are compared with the indicators required in the debugging instructions to determine whether they are qualified.

[0025] (IV) To test the control box audio input index received by the host device under test, it is necessary to switch the audio comprehensive tester input to the control box audio input, and switch the audio comprehensive tester output to the channel machine audio output. At this time, the input index of the audio comprehensive tester can be adjusted to simulate the control box audio input, and the audio output value of the channel machine can be measured by the audio comprehensive tester to determine whether the control box audio input index meets the fixed value of the channel machine's output index. The specific operation is: turn the interfaces XS2 and XS3 to the 5V pull-up state, and turn the interface XS4 to the GND state. Then the 10th and 11th pins of the chip N5 in the analog switch switching circuit are in the high level state, and the 9th pin is in the low level state. According to the switching logic of the chip N5, the 3rd and 12th pins of the chip N5 are turned on. At this time, the level of the 12th pin of the chip N5 is 3.3V, and the light-emitting diode VD5 connected to it is turned on and emits light. Because the 1st, 13th, 14th, and 15th pins of the chip N5 are all suspended at this time, the transistor Q1 in the audio switching circuit II, the transistor Q4 in the audio switching circuit III, and the transistor Q3 in the audio switching circuit IV cannot be made to work. Therefore, the 8th pins of the relay II, relay III, and relay IV are pulled up by 5V and diodes D1, D4, and D3 respectively, so that the three relays are in the normally closed state, that is, the 3rd pin of relay II N3 (audio integrated tester OUT+) is connected to the 2nd pin (the 3rd pin of relay IV N6) and connected to the relay V Pin 3 of N8 is connected, pin 6 of relay II N3 (audio integrated tester OUT-) is connected to pin 7 (pin 6 of relay IV N6) and connected to pin 6 of relay V N8. Because pin 12 of chip N5 is 3.3V high level, transistor Q5 of audio switching circuit V is turned on, thereby pulling pin 8 of relay V N8 down to control relay V N8 from the common end to the normally open end, that is, pin 3 of relay V N8 (audio integrated tester OUT+) is connected to pin 4 (channel machine audio output EADS_MIC+), and pin 6 of relay V N8 (audio integrated tester IN+) is connected to pin 5 (channel machine audio output EADS_MIC-), thereby realizing the connection between the output of the audio integrated tester and the audio output of the channel machine; and because pin 12 of chip N5 is 3.3V high level, transistor Q2 of audio switching circuit I is turned on, thereby pulling pin 8 of relay I N4 down to control relay I N4 is connected from the common end to the normally open end, that is, pin 3 is connected to pin 4 and then connected to (control box audio input MIC+) through pin 2 and pin 9 of the isolation audio transformer T1, and pin 6 is connected to pin 5 and then connected to (control box audio input MIC-) through pin 4 and pin 7 of the isolation audio transformer T1, finally realizing the connection between the input of the audio comprehensive tester and the audio input of the control box. At this time, the channel machine audio input index can be obtained by reading the index of the audio comprehensive tester, and the control box input index can be judged whether it is qualified according to the fixed value of the channel machine input index.

[0026] (V) To test the passenger intercom audio input index of the passenger intercom device received by the host device under test, it is necessary to switch the input of the audio comprehensive tester to the passenger intercom audio input, and switch the output of the audio comprehensive tester to the channel machine audio output. At this time, the input index of the audio comprehensive tester can be adjusted to simulate the passenger intercom audio input, and the audio output value of the channel machine can be measured by the audio comprehensive tester to determine whether the passenger intercom audio input index meets the fixed value of the channel machine's output index.The specific operation is: turn the interface XS4 to the 5V pull-up state, and turn the interfaces XS2 and XS3 to the GND state. Then, pin 9 of the chip N5 in the analog switch switching circuit is in a high level state, and pins 10 and 11 are in a low level state. According to the switching logic of chip N5, pins 3 and 1 of chip N5 are turned on. At this time, the level of pin 1 of chip N5 is 3.3V, and the light-emitting diode VD6 connected to it is turned on and emits light. Because pins 12, 13, 14, and 15 of N5 are all suspended at this time, it is impossible to make the transistor Q2 in the audio switching circuit Ⅰ, the transistor Q1 in the audio switching circuit Ⅱ, and the transistor Q3 in the audio switching circuit Ⅳ. Therefore, the 8 pins of relay Ⅰ, relay Ⅱ, and relay Ⅳ are pulled up by 5V and diodes D2, D1, and D3 respectively, so that these three relays are in a normally closed state, that is, pin 3 of relay Ⅱ N3 (audio integrated tester OUT+) is connected to pin 2 (pin 3 of relay Ⅳ N6) and connected to relay Ⅴ Pin 3 of N8 is connected, pin 6 of relay II N3 (audio comprehensive tester OUT-) is connected to pin 7 (pin 6 of relay IV N6) and connected to pin 6 of relay V N8. Because pin 1 of chip N5 is 3.3V high level, transistor Q5 of audio switching circuit V is turned on, thereby pulling pin 8 of relay V N8 down to control relay V N8 from the common end to the normally open end, that is, pin 3 of relay V N8 (audio comprehensive tester OUT+) is connected to pin 4 (channel machine audio output EADS_MIC+), pin 6 of relay V N8 (audio comprehensive tester IN+) is connected to pin 5 (channel machine audio output EADS_MIC-), thereby realizing the connection between the output of the audio comprehensive tester and the audio output of the channel machine; relay I is in the normally closed state, that is, pin 3 of relay I N4 (audio comprehensive tester IN+) is connected to pin 2 (pin 3 of relay III N7), and pin 6 of relay I N4 (audio comprehensive tester IN-) is connected to pin 7 (relay III The 6th pin of N7 is connected to the 6th pin of N7, and because the 1st pin of the chip N5 is 3.3V high level, the transistor Q4 of the audio switching circuit III is turned on, so that the 8th pin of the relay III N7 is pulled down to control the relay III N7 from the common end to the normally open end, that is, the 3rd pin is connected to the 4th pin and then connected to the (passenger intercom audio input EMER_MIC+) through the 2nd and 9th pins of the isolation audio transformer T3, and the 6th pin is connected to the 5th pin and then connected to the (passenger intercom audio input EMER_MIC-) through the 4th and 7th pins of the isolation audio transformer T3, finally realizing the connection between the input of the audio comprehensive tester and the passenger intercom audio input. At this time, the indicators of the audio comprehensive tester can be read to obtain the channel machine audio output indicators. According to the fixed value of the channel machine output indicators, it is judged whether the passenger intercom input indicators are qualified.

Claims

1. A multi-channel audio switching test circuit for rail transit vehicle radio, characterized in that: It includes a power supply circuit, an analog switch switching circuit, an audio path switching circuit, an indicator light circuit, a device under test interface and an audio comprehensive tester interface; the audio path switching circuit is respectively connected to the analog switch switching circuit, the device under test interface and the audio comprehensive tester interface, and the power supply circuit is respectively connected to the indicator light circuit, the analog switch switching circuit and the audio path switching circuit; The audio path switching circuit includes an audio switching circuit I, an audio switching circuit II, an audio switching circuit III, an audio switching circuit IV, and an audio switching circuit V; The analog switch switching circuit is used to control the switching of the audio path and the indicator light state according to the switch input state; The audio path switching circuit is used to switch different audio paths connected to the interface of the audio integrated tester; The indicator light circuit is used to indicate which audio test is currently being performed; The device under test interface is used to connect the power supply and the signal under test from the device under test to the multi-channel audio switching test circuit; The audio comprehensive tester interface is used to connect the audio path to be tested to the audio comprehensive tester so as to test specific indicators on the instrument; The audio switching circuit I is used to switch the connection state between the audio comprehensive test instrument interface input terminal and the control box audio input and the common terminal of the relay III according to the 12-pin output of N5 in the analog switch switching circuit; The audio switching circuit II is used to switch the connection state between the output terminal of the audio comprehensive test instrument interface and the passenger intercom audio output and the common terminal of the relay IV according to the output of the 15th pin of N5 in the analog switch switching circuit; The audio switching circuit III is used to switch the connection state between the common end of relay III and the audio output of the channel machine and the audio input of the passenger intercom according to the output of pin 1 of N5 in the analog switch switching circuit; The audio switching circuit IV is used to switch the connection state between the common end of relay IV and the common end of the broadcast audio output and relay V according to the 14-pin output of N5 in the analog switch switching circuit; The audio switching circuit V is used to switch the connection state between the common end of relay V and the control box output and the channel machine audio input according to the output of pin 1 and pin 12 of N5 in the analog switch switching circuit.

2. A multi-channel audio switching test circuit for a rail transit vehicle radio according to claim 1, characterized in that: The specific circuit of the power supply circuit is as follows: Pin 1 and Pin 2 of connector XS1 are connected to one end of capacitor C3, capacitor C4 and pin 1 of linear regulator ⅠN1, Pin 3 of linear regulator ⅠN1 is connected to one end of capacitor C1, capacitor C2, capacitor C6, capacitor C7 and pin 3 of linear regulator ⅡN2, Pin 2 of linear regulator ⅡN2 is connected to capacitor C5, capacitor C8 and one end of resistor R1, and connected to 3V3 and test point TP1, the other end of resistor R1 is connected to GND through diode VD1, capacitor C3, capacitor C4, capacitor C1, capacitor C2, capacitor C6, capacitor C7, capacitor C5, capacitor C8, pin 2 of linear regulator ⅠN1 and pin 1 of linear regulator ⅡN2 are connected to GND respectively; the model of linear regulator ⅠN1 is 7805, and the model of linear regulator ⅡN2 is SPX1117-33.

3. The multi-channel audio switching test circuit for rail transit vehicle radio according to claim 1 is characterized in that: The specific circuit of the analog switch switching circuit is as follows: pin 3 of chip N5 is connected to 3V3, pin 9 of chip N5 is connected to pin 3 of interface XS4, pin 1 of interface XS4 is connected to 5V through resistor R9, pin 10 of chip N5 is connected to pin 3 of interface XS3, pin 1 of interface XS3 is connected to 5V through resistor R7, pin 11 of chip N5 is connected to pin 3 of interface XS2, pin 1 of interface XS2 is connected to 5V through resistor R6, pin 13 of chip N5 is connected to the positive electrode of diode VD2 of indicator light circuit, pin 14 of chip N5 is connected to the positive electrode of diode VD3 of indicator light circuit and one end of resistor R18 in audio switching circuit IV, pin 15 of chip N5 is connected to the positive electrode of diode VD4 of indicator light circuit and audio One end of the resistor R20 in the audio switching circuit II, the 12th pin of the chip N5 is connected to the positive electrode of the diode VD5 of the indicator circuit, one end of the resistor R23 in the audio switching circuit I and one end of the resistor R21 in the audio switching circuit V, the 1st pin of the chip N5 is connected to the positive electrode of the diode VD6 of the indicator circuit, one end of the resistor R26 in the audio switching circuit III and one end of the resistor R25 in the audio switching circuit V, the 16th pin of the chip N5 is connected to the capacitor C11, one end of the capacitor C12 and 5V, the 2nd pin of the interface XS4, the 2nd pin of the interface XS3, the 2nd pin of the interface XS2, the 6th pin of the chip N5, the 7th pin of the chip N5, and the 8th pin of the chip N5 are connected to GND respectively, and the chip N5 model is 74HTC4051PW; The specific circuit of the indicator light circuit is: the cathodes of diodes VD2, VD3, VD4, VD5 and VD6 are connected to GND through resistors R14, R17, R19, R22 and R24 respectively; the anode of diode VD2 is connected to pin 13 of the analog switch switching circuit chip N5; the anode of diode VD3 is connected to pin 14 of the analog switch switching circuit chip N5; the anode of diode VD4 is connected to pin 15 of the analog switch switching circuit chip N5; the anode of diode VD5 is connected to pin 12 of the analog switch switching circuit chip N5; and the anode of diode VD6 is connected to pin 1 of the analog switch switching circuit chip N5.

4. The multi-channel audio switching test circuit for rail transit vehicle radio according to claim 1 is characterized in that: The specific circuit of the audio switching circuit I is as follows: pin 1 of relay ⅠN4 is connected to one end of capacitor C10 and 5V, the other end of capacitor C10 is connected to GND, pin 2 of relay ⅠN4 is connected to pin 3 of relay Ⅲ N7, pin 7 of relay ⅠN4 is connected to pin 6 of relay Ⅲ N7, pin 4 of relay ⅠN4 is connected to pin 2 of audio isolation transformer T1, pin 9 of audio isolation transformer T1 is connected to pin 14 of tested device interface XS1, pin 5 of relay ⅠN4 is connected to pin 4 of audio isolation transformer T1, pin 7 of audio isolation transformer T1 is connected to pin 13 of tested device interface XS1, pin 6 of relay ⅠN4 is connected to pin 1 of audio comprehensive tester interface XS6, pin 3 of relay ⅠN4 is connected to pin 2 of audio comprehensive tester interface XS6, and relay ⅠN4 is connected to pin 1 of audio comprehensive tester interface XS6. Pin 8 is connected to the positive electrode of diode D2 and the collector of transistor Q2, the negative electrode of diode D2 is connected to 5V, the base of transistor Q2 is connected to resistor R3 and one end of resistor R5, the other end of resistor R5 is connected to the emitter of transistor Q2 and GND, the other end of resistor R3 is connected to the negative electrode of diode D10, and the positive electrode of diode D10 is connected to pin 12 of audio switching circuit Ⅰ chip N5 through resistor R23; the model of audio isolation transformer T1 is VT-36003, and the model of relay ⅠN4 is G6K-2F.

5. The multi-channel audio switching test circuit for rail transit vehicle radio according to claim 1 is characterized in that: The specific circuit of the audio switching circuit II is as follows: the 1st pin of the relay II N3 is connected to one end of the capacitor C9 and 5V, the other end of the capacitor C9 is connected to GND, and the 2nd pin of the relay II N3 is connected to the relay IV Pin 3 of N6, pin 7 of relay Ⅱ N3 is connected to pin 6 of relay Ⅳ N6, pin 4 of relay Ⅱ N3 is connected to pin 10 of the interface XS5 of the device under test, pin 5 of relay Ⅱ N3 is connected to pin 9 of the interface XS5 of the device under test, pin 6 of relay Ⅱ N3 is connected to pin 1 of the audio comprehensive tester interface XS7, pin 3 of relay Ⅱ N3 is connected to pin 2 of the audio comprehensive tester interface XS7, pin 8 of relay Ⅱ N3 is connected to the positive electrode of diode D1 and the collector of transistor Q1, the negative electrode of diode D1 is connected to 5V, the base of transistor Q1 is connected to resistor R2 and one end of resistor R4, the other end of resistor R4 is connected to the emitter of transistor Q1 and GND, the other end of resistor R2 is connected to the negative electrode of diode D7, and the positive electrode of diode D7 is connected to pin 15 of audio switching circuit Ⅰ chip N5 through resistor R20; the model of relay Ⅰ N3 is G6K-2F.

6. The multi-channel audio switching test circuit for rail transit vehicle radio according to claim 1 is characterized in that: The specific circuit of the audio switching circuit III is as follows: pin 1 of relay III N7 is connected to one end of capacitor C14 and 5V, and the other end of capacitor C14 is connected to GND, pin 2 of relay III N7 is connected to pin 2 of audio isolation transformer T2, pin 9 of audio isolation transformer T2 is connected to pin 14 of interface XS5 of device under test, pin 7 of relay III N7 is connected to pin 4 of audio isolation transformer T2, pin 7 of audio isolation transformer T2 is connected to pin 13 of interface XS5 of device under test, pin 4 of relay III N7 is connected to pin 2 of audio isolation transformer T3, pin 9 of audio isolation transformer T3 is connected to pin 8 of interface XS5 of device under test, pin 5 of relay III N7 is connected to pin 4 of audio isolation transformer T3, pin 7 of audio isolation transformer T3 is connected to pin 7 of interface XS5 of device under test, pin 6 of relay III N7 is connected to pin 7 of relay I N4, pin 3 of relay III N7 is connected to pin 2 of relay I N4, and pin 4 of relay III N7 is connected to pin 6 of audio isolation transformer T3. Pin 8 of N7 is connected to the positive electrode of diode D4 and the collector of transistor Q4, the negative electrode of diode D4 is connected to 5V, the base of transistor Q4 is connected to resistor R10 and one end of resistor R12, the other end of resistor R12 is connected to the emitter of transistor Q4 and GND, the other end of resistor R10 is connected to the negative electrode of diode D11, and the positive electrode of diode D11 is connected to pin 1 of audio switching circuit Ⅰ chip N5 through resistor R26; the models of audio isolation transformers T2 and T3 are VT-36003, and the model of relay ⅠN4 is G6K-2F.

7. The multi-channel audio switching test circuit for rail transit vehicle radio according to claim 1 is characterized in that: The specific circuit of the audio switching circuit IV is as follows: pin 1 of relay IV N6 is connected to one end of capacitor C13 and 5V, the other end of capacitor C13 is connected to GND, pin 2 of relay IV N6 is connected to pin 3 of relay V N8, pin 7 of relay IV N6 is connected to pin 6 of relay V N8, pin 4 of relay IV N6 is connected to pin 18 of the interface XS1 of the device under test, pin 5 of relay IV N6 is connected to pin 17 of the interface XS1 of the device under test, pin 6 of relay IV N6 is connected to pin 7 of relay II N3, pin 3 of relay IV N6 is connected to pin 2 of relay II N3, and relay IV Pin 8 of N6 is connected to the anode of diode D3 and the collector of transistor Q3, the cathode of diode D3 is connected to 5V, the base of transistor Q3 is connected to resistor R8 and one end of resistor R11, the other end of resistor R11 is connected to the emitter of transistor Q3 and GND, the other end of resistor R8 is connected to the cathode of diode D6, and the anode of diode D6 is connected to pin 14 of audio switching circuit Ⅰ chip N5 through resistor R18; the model of relay ⅠN6 is G6K-2F.

8. The multi-channel audio switching test circuit for rail transit vehicle radio according to claim 1 is characterized in that: The specific circuit of the audio switching circuit V is as follows: pin 1 of relay V N8 is connected to one end of capacitor C15 and 5V, the other end of capacitor C15 is connected to GND, pin 2 of relay V N8 is connected to pin 2 of audio isolation transformer T4, pin 9 of audio isolation transformer T4 is connected to one end of resistor R16 and pin 16 of device under test interface XS1, pin 7 of relay V N8 is connected to pin 4 of audio isolation transformer T4, pin 7 of audio isolation transformer T4 is connected to the other end of resistor R16 and pin 15 of device under test interface XS1, pin 4 of relay V N8 is connected to pin 16 of device under test interface XS5, pin 5 of relay V N8 is connected to pin 15 of device under test interface XS5, pin 6 of relay V N8 is connected to pin 7 of relay IV N6, pin 3 of relay V N8 is connected to pin 2 of relay IV N6, and relay V Pin 8 of N8 is connected to the positive electrode of diode D5 and the collector of transistor Q5, the negative electrode of diode D5 is connected to 5V, the base of transistor Q5 is connected to resistor R13 and one end of resistor R15, the other end of resistor R15 is connected to the emitter of transistor Q5 and GND, the other end of resistor R3 is connected to diode D8 and the negative electrode of diode D10, the positive electrode of diode D8 is connected to pin 12 of audio switching circuit Ⅰ chip N5 through resistor R21, and the positive electrode of diode D10 is connected to pin 1 of audio switching circuit Ⅰ chip N5 through resistor R25; the model of relay Ⅰ N8 is G6K-2F, and the model of audio isolation transformer T4 is VT-36003.

9. A method for implementing the multi-channel audio switching test circuit for rail transit vehicle radio stations according to claim 1, characterized in that: The steps are as follows: connect the audio integrated tester with the audio comprehensive tester interface, connect the device under test with the device under test interface, switch the input level of the analog switch switching circuit according to the different audio paths that need to be tested to obtain different output control signals to the indicator light circuit and the audio path switching circuit, the indicator light circuit controls the lighting of different LED indicator lights to display the path selection status according to the output control signal of the analog switch switching circuit, and the audio path switching circuit switches the connection status between the audio path of the device under test and the audio input and output of the audio comprehensive tester according to the output control signal of the analog switch switching circuit, so that the measured indicators of different audio paths can be read through the audio comprehensive tester, and then the actual indicators read out are compared with the indicators required in the debugging instructions to determine whether they are normal.

10. The method for implementing a multi-channel audio switching test circuit for a rail transit vehicle radio station according to claim 9, characterized in that: The indicator light circuit controls the lighting of different LED indicator lights to display the channel selection status according to the output control signal of the analog switch switching circuit. The method for the audio channel switching circuit to switch the audio channel of the device under test according to the output control signal of the analog switch switching circuit is as follows: the device under test has three audio inputs, namely, channel machine audio input, control box audio input and passenger intercom audio input, and four audio outputs, namely, channel machine audio output, control box audio output, broadcast audio output and passenger intercom audio output, wherein the indicators of the channel machine audio input and the channel machine audio output are fixed values. To test the indicators of the control box audio input and the passenger intercom audio input, it is necessary to simulate the control box audio input and the passenger intercom audio input output by the audio comprehensive tester, connect the audio to the input end of the audio comprehensive tester after passing through the audio channel of the device under test, and measure whether the channel machine output indicator requirements can be met; to test the indicators of the control box audio output, broadcast audio output and passenger intercom audio output, it is necessary to connect the audio to the input end of the audio comprehensive tester to measure the indicators. The output audio analog channel machine audio input is connected to the input end of the audio comprehensive test instrument after passing through the audio path of the device under test to measure the indicators, and measure whether the output indicators of the device under test meet the requirements of the control box, broadcasting equipment and passenger intercom equipment; through the analog switch switching circuit interface XS2, interface XS3, interface XS4, the input levels of the 10, 11, 12 pins of the control chip N5, namely S0, S1, S2, the chip N5 outputs different control signals according to different input levels, the control signal output by the chip N5 is transmitted to the indicator light circuit and the audio path switching circuit at the same time, the indicator light circuit realizes the lighting of the corresponding indicator light according to the control signal, and the audio path switching circuit controls the relays I, II, III, IV and V of the audio switching circuit I, the audio switching circuit II, the audio switching circuit III, the audio switching circuit IV and the audio switching circuit V respectively according to the control signal, and realizes the path switching of different audio tests by switching the normally open and normally closed states of the relays.

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