What factors affect the transmission distance of HDMI (optical fiber) cables?

The transmission distance of HDMI fiber optic cable is mainly affected by the following factors:

• Fiber material and quality:

① Material purity: The high-purity glass fiber has less impurities, the light signal is transmitted in it, the scattering and absorption loss is small, and the long-distance transmission can be achieved. For example, some HDMI fiber optic

    cables using high-quality quartz glass fiber can still maintain good signal quality over distances of 100 meters or more. Although the cost of plastic fiber is low, the light loss is relatively large, and the transmission distance is usually short.

② Manufacturing process: The production of sophisticated optical fiber, its internal structure is uniform, can reduce the mode dispersion and attenuation of optical signal transmission process. For example, optical fibers manufactured by 

    advanced processes can make the optical signal more concentrated in transmission, thereby extending the transmission distance.

• Photoelectric conversion chip performance:

① Conversion efficiency: Efficient photoelectric conversion chip can accurately and quickly convert electrical signals into optical signals, and restore optical signals to electrical signals in high quality at the receiving end. The high conversion 

   efficiency means that the signal has little distortion and low loss, which helps to extend the transmission distance. If the chip conversion efficiency is low, it may cause the signal to lose part of the information during the conversion process, so 

   that the transmission distance is limited.

② Signal processing capability: A chip with strong signal processing capability can optimize and enhance the input HDMI signal to compensate for signal attenuation during transmission. For example, some high-end chips can adapt to the 

   frequency, amplitude and other characteristics of the signal to ensure that the signal can maintain a high quality after long distance transmission.

• Transmission environment:

① Temperature: Too high or too low temperature will affect the optical fiber and photoelectric conversion chip. The high temperature may change the refractive index of the fiber material and increase the transmission loss of the optical signal. 

  At the same time, it will also affect the performance of the photoelectric conversion chip, making its work unstable. The temperature is too low, the fiber may become brittle, prone to fracture and other problems, affecting signal transmission. In

  general, HDMI fiber optic cables can maintain good transmission performance in an environment of 0 ° C to 70 ° C.

②Electromagnetic interference: Although the optical fiber itself has a strong ability to resist electromagnetic interference, if the connected part of the photoelectric conversion chip or cable is subjected to strong electromagnetic interference,

 it may affect the conversion andransmission of the signal. For example, in places near strong electromagnetic sources such as large motors and transformers, there may be certain interference with the transmission of HDMI fiber optic cables,

 but this effect is usually small.

• Resolution and frame rate:

① Data volume: High resolution and high frame rate video signal data volume is huge, requiring higher transmission bandwidth. For example, the data volume of the video signal at 8K@120Hz is much larger than that of the video signal at 4K@60Hz.

 When transmitting high resolution, high frame rate signals, in order to ensure signal quality, the transmission distance may be limited under the same optical fiber cable and equipment conditions. Because with the increase of the amount of data, the 

 signal is more susceptible to the influence of various factors in the transmission process and the attenuation and distortion.

② Encoding mode: Different video encoding modes have different requirements for transmission bandwidth. For example, H.265 encoding compared to H.264 encoding, at the same resolution and frame rate, can achieve similar video quality at a lower bit rate, so the

transmission bandwidth requirements are relatively low. Signals with efficient encoding may travel longer distances on HDMI fiber optic cables.

• Connector quality:

①Contact stability: High-quality connectors can be tightly connected with the HDMI interface of the device to ensure the stability of signal transmission. If the connector contact is poor, it will lead to signal reflection, attenuation and other problems, affecting the transmission

distance. For example, some connectors using the gold plating process have better electrical conductivity and corrosion resistance, which can reduce contact resistance and improve signal transmission quality.

②Signal transmission performance: The internal structure and material of the connector also affect signal transmission. For example, the use of high-quality insulation materials and reasonable shielding design of the connector, can reduce the crosstalk

and external interference between the signal, to ensure the efficient transmission of optical signals between the fiber and the device.