Copper Cable Limitations
Signal Losses in Copper Cables Increase as the Data Rate Increases
For a copper cable of a given length and wire thickness, signal losses increase dramatically as the data rate increases. At a certain data rate there is actually no usable signal coming out of the end of the cable! This can be mitigated to some extent by using pre-emphasis and equalization techniques which are for example built into the HDMI, DisplayPort and USB3 standards. However as the data rate increases these techniques become ineffective. The only solution is then to increase the thickness (AWG) of the copper wires used inside the cable to compensate for the signal loss. This results in the copper cable becoming much thicker, heavier and less flexible as well as increasing the cost of the cable. As an example a copper cable operating at 10 Gbps or 12 Gbps can easily be up to 8mm in diameter for a cable length of only 2m or less.
Active Copper Cables also have their Limitations
Active copper technology has been developed to address the limitations of passive copper cables at high data rates. This technology consists of adding semiconductors inside the cable to further boost and equalize the signal. This results in slightly longer and thinner cables but also has its limitations. These type of cables are power hungry and only extend the copper cable length a short distance. They also do not work at higher data rates.
Wireless Doesn’t Work Either
Several wireless standards (Wireless HD, Ultragig etc) have been developed in an attempt to remove the need for copper cables altogether. However they all suffer the same limitations. Their maximum total data rate is around 7 to 10 Gbps which is sufficient only for the old 1080p HD resolution, not for today’s 4K UHD and certainly not for 8K. In addition they have a very high latency which rules them out for game playing. They are costly and power hungry as well as needing a line of sight (so don’t walk between the wireless transmitter and your TV otherwise there will be a picture drop out!). So wireless technology does not work for these new high speed consumer interfaces.
The Answer – Thin, Light and Long Active Optical Cables
Active Optical Cables suffer from none of the issues of passive or active copper cables or indeed wireless technologies. There is no data rate dependent signal loss. They can be used for data rates up to 25 Gbps per channel (over 100 Gbps in total) and lengths from 1m to 100m or longer. They remain the same thickness no matter what the data rate and in general this is around 3mm compared with up to 8mm for passive copper cables for 10 Gbps or 12 Gbps.