Why HDMI cables are not optimal for longer distances

The general assumption regarding HDMI cables is that they are immensely superior to their component connection counterparts, regardless of any other factors involved. However, this assumption fails to take into account several other aspects, which, in practice, will render the HDMI cable a sub-optimal choice. In essence, the reason why most people consider HDMI better is the fact that the uncompressed digital method of signal transmission is more accurate and free of errors. This is false, there is, in fact, data loss that can occur for reasons independent of the type of cable lost and that are more or less proprietary to the transmission source.

Moreover, the signal loss becomes quite a bit more palpable over longer distances for those who use HDMI cables. Granted, the HDBaseT technology is an effective means of ensuring that the signal stays strong throughout, up to 800 meters. On the other hand, the component video can perform equally well without the help of signal boosters of any type. It is important to note that the impedance for long cables needs to be controlled with pinpoint accuracy. This means that when it fluctuates for more than plus/minus 1.75 ohms, you can expect ghost signals or other type of data inaccuracies.

In order to understand why HDMI cables are not ideal for long lengths, you will need to understand that they are built from two balanced cables twisted in a pair. It is not yet clear why the manufacturers have decided to avoid the coaxial cable approach that they had first settled on when the SDI standard was ratified. Nevertheless, the twisted-pair cables approach can provide a very limited control over the impedance, meaning that it is somewhere in the plus/minus 10% range. Whilst this may not be excessively visible over short distances, it will definitely make itself noticed once you hit a certain cable length.
This is often referred to as the “digital cliff” effect. To put it simple, over short distances the bit streams are reconstructed via the bi-way connection that reflects the signal. Consequentially, even though a certain part of the signal is lost along the way, the corrections based on the feedback it receives from the output will enable it to reconstruct it fairly easily, and therefore, the loss will not be noticed. On the other hand, once you hit a certain distance, the signal reflection becomes increasingly difficult and hence, the reconstruction of the bit streams can no longer occur with the same efficiency.

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