Just about any entertainment device you have seen in recent years has needed an HDMI cable. Even if you aren’t the most technically adept, there’s a very good chance that you have heard of HDMI cables.
Though you may know that they are part of these everyday entertainment items, you probably don’t really know how they work. This is how an HDMI cable works and how it became the standard we use today.
What is HDMI?
HDMI was created as the new standard by a group of electronics manufacturers. An HDMI cable has become the standard for high-bandwidth connections between a pair of digital devices. It can carry up to 1080p high-definition signals, supports up to eight channels of uncompressed audio, and can cut down substantially on the number of cables needed to connect everything, even cutting down on how many remotes you need.
The key is to ensure that all components are compatible with one another. HDMI is so advanced that there are even features that are not prominent for consumer use. The latest standard, HDMI 1.3, is thought to have rendered previous standards obsolete in just a few short years.
HDMI Connections and How They Work
In order to fully understand how HDMI cables work, we also need to know the various connection types. HDMI uses differential signalling technology, which uses minimal data transitioning, to move data or information from one place to the other. TDMS is used to keep information safe from degradation while it travels from one device to the other.
HDMI connections come in a number of adapters. Since older devices use component video, DVI, or even S-Video, having the appropriate connector makes it possible to use those old devices on new televisions that typically only have HDMI or USB connectors.
HDMI and DVI are similar in that they both use a grid of pins to transmit signals. HDMI uses roughly 10 fewer pins and doesn’t require pin support to provide stability. Mini HDMI also works for small devices like camcorders and digital cameras.
Encoding Signals
Perhaps the most common misconception when it comes to HDMI is that the digital signal is automatically better than any analogue signal. With no analogue-to-digital conversion, the signal is pure and undamaged when it gets to the device. The reality is that the signal transmission doesn’t require any encoding.
HDMI makes use of something known as transition minimized differential signalling (TDMS) to move information from one device to another. This is a way of encoding that signal in a way that protects it from any degradation as it travels down the cable. Here is what happens during that transmission:
The device in question, called the sending device (DVD player, gaming console, etc.) will encode the signal to ensure that the number of transitions is between zero (off) and one (on). Each transmission is basically a sharp drop-off where the signal begins to wear. By encoding it, the signal quality is protected because the number of potential degradations is reduced drastically.
One of the cables, which is part of a twisted pair, carries the signal. The other cable will carry the total inverse of that signal. The receiving device – a television, monitor, projector – then decodes that signal. The receiving device measures the differential, which is the difference between the signal and the aforementioned inverse. By using this information, it can compensate for any potential loss of signal throughout the transmission process.
While that all sounds quite complicated, HDMI has made it a nearly instant process. It is now standard to find televisions with nothing but HDMI connections to accommodate.
