Signal impedance matching wire harness

Abstract

The impedance matching wire harness comprises a front cover, a USB A interface, a PCB, a rear cover and a data signal line, the USB A interface is electrically connected with the PCB, and the PCB is electrically connected with the data signal line; the USB A interface is arranged in the front cover, and the PCB is arranged in the rear cover; the data signal line is electrically connected with a signal port of the vehicle-mounted host, and the USB A interface is electrically connected with multimedia equipment; and a vehicle-mounted data transmission impedance matching circuit is welded on the PCB and is used for matching data transmission impedance to a set value. The system has the advantages that a data storage port of a vehicle-mounted host or other vehicle-mounted multimedia equipment is connected to the human-computer interaction interface, a special vehicle-mounted data transmission impedance matching circuit is further designed for the wire harness and the USB interface, impedance is matched to 90 ohms and is used for optimizing eye pattern signals to a good state, and the system is convenient to use. Good eye pattern quality is obtained, and rapid response and efficient and rapid transmission of signals are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of data transmission of in-vehicle multimedia devices, and particularly relates to a signal impedance matching wire harness. Background Art

[0002] In vehicles, there are an increasing number of imaging information recording devices such as dash cams, T-BOXes, and cameras. The information recording data documents are also getting larger and larger, and the storage requirements are getting higher and higher. The impedance matching of common USB wire harnesses is not good, resulting in problems such as data packet loss and slow response speed. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a signal impedance matching wire harness.

[0004] This signal impedance matching wire harness includes: a front cover, a USB A interface, a PCB board, a rear cover, and data signal lines. The USB A interface is electrically connected to the PCB board, and the PCB board is electrically connected to the data signal lines; the USB A interface is disposed inside the front cover, and the PCB board is disposed inside the rear cover; the data signal lines are electrically connected to the signal ports of the in-vehicle host, and the data storage ports of the in-vehicle host or other in-vehicle multimedia devices are connected to the human-machine interaction interface, and the USB A interface is electrically connected to the multimedia device; a vehicle-mounted data transmission impedance matching circuit is welded on the PCB board, and the vehicle-mounted data transmission impedance matching circuit is used to match the data transmission impedance to a set value.

[0005] Preferably: in the vehicle-mounted data transmission impedance matching circuit, one end of the USB A connector (TYPE_A) is grounded, one end of the DP of the USB A connector is connected to the GREEN wire of the data line through a resistor R1, and the other end is grounded through a TVS; one end of the DM of the USB A connector is connected to the WHITE wire of the data line through a resistor R2, and the other end is grounded through a TVS tube; the VBUS of the USB A connector and the RED wire of the data line are connected through PCB traces, and the VBUS line is bypassed of miscellaneous signals through decoupling capacitors C 1 、C 2 grounding, and the GND wire of the USB A is connected to the GND of the data line through PCB traces, and the braid of the data line is welded to the GND of the PCBA.

[0006] Preferably: the multimedia devices include USB flash drives, mobile phones, and tablets.

[0007] Preferably: the vehicle-mounted data transmission impedance matching circuit welded on the PCB board is used to match the data transmission impedance to 90 ohms.

[0008] The beneficial effects of the present invention are as follows: The data storage port of the in-vehicle host or other in-vehicle multimedia devices is connected to the human-machine interface. The present invention also designs a dedicated in-vehicle data transmission impedance matching circuit in the wire harness and USB interface, matching the impedance to 90 ohms, which is used to optimize the eye diagram signal to a better state, obtain better eye diagram quality, achieve fast response of the signal, and realize efficient and fast transmission. Description of the Drawings

[0009] Figure 1 It is a schematic structural diagram of the signal impedance matching wire harness of the present invention;

[0010] Figure 2 It is a schematic circuit diagram of the in-vehicle data transmission impedance matching circuit of the present invention;

[0011] Figure 3 It is an eye diagram of a poor signal transmitted by a USB wire harness without an impedance matching circuit;

[0012] Figure 4 It is a signal diagram of a signal transmitted by a USB wire harness without an impedance matching circuit;

[0013] Figure 5 It is an eye diagram of a better signal transmitted by a USB wire harness with an impedance matching circuit set by the present invention;

[0014] Figure 6 It is a signal diagram of a signal transmitted by a USB wire harness with an impedance matching circuit set by the present invention.

[0015] Description of the reference numerals: Front cover 1, USB A interface 2, PCB board 3, Rear cover 4, Data signal line 5. Detailed Embodiments

[0016] The following further describes the present invention in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0017] As an embodiment, as Figure 1As shown in the figure, a signal impedance matching wire harness includes: a front cover 1, a USB A interface 2, a PCB board 3, a rear cover 4, and a data signal wire 5. The USB A interface 2 is electrically connected to the PCB board 3, and the PCB board 3 is electrically connected to the data signal wire 5. The USB A interface 2 is disposed inside the front cover 1, and the PCB board 3 is disposed inside the rear cover 4. The data signal wire 5 is electrically connected to the signal port of the vehicle-mounted host, and the data storage port of the vehicle-mounted host or other vehicle-mounted multimedia devices is connected to the human-machine interaction interface. The USB A interface 2 is electrically connected to a USB flash drive, a mobile phone, or a tablet. A vehicle-mounted data transmission impedance matching circuit is soldered on the PCB board 3, and the vehicle-mounted data transmission impedance matching circuit is used to match the data transmission impedance to 90 ohms.

[0018] As Figure 2 shown, in the vehicle-mounted data transmission impedance matching circuit, one end of the USB A connector (TYPE_A) is grounded. One end of the DP of the USB A connector is connected to the GREEN wire of the data line through a resistor R1, and the other end is grounded through a TVS. One end of the DM of the USB A connector is connected to the WHITE wire of the data line through a resistor R2, and the other end is grounded through a TVS tube. The VBUS of the USB A connector and the RED wire of the data line are connected through PCB traces. The VBUS wire is bypassed of miscellaneous signals through decoupling capacitors C 1 、C 2 grounded. The GND wire of the USB A is connected to the GND of the data line through PCB traces, and the braid of the data line is soldered to the GND of the PCBA.

[0019] In order to measure the performance of the USB wire harness transmission, in the laboratory, the method of observing the received signal waveform with an oscilloscope is usually used to analyze the influence of inter-symbol interference and noise on the system performance, which is the eye diagram analysis method. The eye diagram is a graph displayed by accumulating a series of digital signals on an oscilloscope. It contains rich information. The influence of inter-symbol interference and noise can be observed from the eye diagram, which reflects the overall characteristics of the digital signal, so as to estimate the quality of the system. Therefore, the eye diagram analysis is the core of the signal integrity analysis of high-speed interconnect systems. In the prior art, the eye diagram of the USB wire harness with poor signal transmission without an impedance matching circuit and the signal diagram of the USB wire harness transmission are as Figure 3 and Figure 4 shown, while the eye diagram of the USB wire harness with better signal transmission and the signal diagram of the USB wire harness transmission with the impedance matching circuit set in the present invention are as Figure 5 and Figure 6 shown; by comparison, it can be seen that the differential signal voltage of the poorly matched eye diagram is lower than 0.4V at 0 - 0.2uS and 0.8 - 1.0uS, and the differential signal voltage of this design is above 0.4V at 0 - 1.0uS, and the eye diagram voltage is relatively consistent.

Claims

1. A signal impedance matching wire harness, characterized in that, it includes: a front cover (1), a USB A interface (2), a PCB board (3), a rear cover (4) and a data signal wire (5). The USB A interface (2) is electrically connected to the PCB board (3), and the PCB board (3) is electrically connected to the data signal wire (5); the USB A interface (2) is arranged inside the front cover (1), and the PCB board (3) is arranged inside the rear cover (4); the data signal wire (5) is electrically connected to the signal port of the vehicle-mounted host; the USB A interface (2) is electrically connected to the multimedia device; a vehicle-mounted data transmission impedance matching circuit is welded on the PCB board (3), and the vehicle-mounted data transmission impedance matching circuit is used to match the data transmission impedance to a set value.

2. The signal impedance matching wire harness according to claim 1, characterized in that: In the in-vehicle data transmission impedance matching circuit, one end of the USB A connector is grounded. One end of the DP of the USB A connector is connected to the GREEN wire of the data line through the resistor R1, and the other end is grounded through the TVS. One end of the DM of the USB A connector is connected to the WHITE wire of the data line through the resistor R2, and the other end is grounded through the TVS tube. The VBUS of the USB A connector and the RED wire of the data line are connected through PCB traces. The VBUS wire bypasses the miscellaneous signals through the decoupling capacitors C 1 and C 2 ground. The GND wire of the USB A is connected to the GND of the data line through PCB traces, and the braid of the data line is welded to the GND of the PCBA.

3. The signal impedance matching wire harness according to claim 1, characterized in that: The multimedia device includes a USB flash drive, a mobile phone and a tablet.

4. The signal impedance matching wire harness according to claim 1, characterized in that: The vehicle-mounted data transmission impedance matching circuit welded on the PCB board (3) is used to match the data transmission impedance to 90 ohms.

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