Can you believe it’s nearly two decades since HDMI cables came to rescue us from the mess that was multiple wires and jack pins behind our TV walls?
Yes, HDMI has evolved to be the most standardized way to transmit uncompressed audio and visual signals from source devices like projectors, computers, home theatres, among others, to output devices like TV screens.
This is not to say it has been all so rosy since HDMI came to make our lives simpler. No!
HDMI cords have their limitations and challenges.
Today, we will attempt to answer some of the most pressing questions we have come across regarding HDMI signal interference.
Keep reading to learn.
Does power interfere with HDMI?
No, a power cable run next to HDMI has no impact on its performance. HDMI is hardly susceptible to any form of induced interference as long as it is shielded thickly.
However, it is good practice not to run your power and HDMI too close from a safety standpoint. If possible, keep them in separate trucking. Slightly more work, but it’s completely worth it.
A vast majority of cable installers recommend that when compartmentalizing trucking, bundle up the high voltage cables together like the power cable and similarly bundle up the low voltage together.
This will minimize any chance of the highs energizing the lows, therefore no interference.
What can interfere with HDMI?
Interference is unwanted electrical signals that interfere with the original signals. The interference can either be constant or transient.
Since HDMI cables transmit electrical signals, they are bound to experience signal interference now and then.
In some cases, the cords cause the interference, and in others, they are the ones picking up the interference.
Interference can either be in the form of degradation or disruption of signal transmissions or data.
Cable interference, especially electromagnetic interference, radiofrequency, and electrostatic induction, are almost becoming a nuisance in the cabling industry.
This is because of the increased distance that signals have to travel and the number of signals required. These two are the major causes of HDMI and other cable interference.
Sources of HDMI signal interference
There are different sources of signal interference like magnetic noise, static noise, crosstalk, and common-mode noise.
Let’s look at the main sources of HDMI cord interference.
Electromagnetic interference: EMI can be due to power circuit switches, circuit breaks, automotive ignitions, and sometimes electromagnetic discharges from humans and equipment.
Because of the sporadic nature of the interferences, EMI can degrade your cable and affect its ability to transmit signals. It can also affect the devices connected to the cable and cause your equipment to burn down in a worst-case scenario.
Electrostatic noise: Occurs when electrical fields distort signals. This often happens between wires in an individual cable.
Crosstalk: Occurs when nearby cables and wires within a bundle bleed signals into each other. Crosstalk interference often occurs between two unshielded cables.
What happens is, the electronic signals moving in the adjacent wires create a magnetic field that results in “disturbance.” The disturbance slowly causes degradation of signals and data delivered to the destination.
Common mode noise: caused by current flowing between different grounds within the same system but from different points.
Do HDMI cables carry voltage?
Even though HDMI cables are conductors, they are not designed to supply power. They are low voltage cables that carry only 5 volts.
As you can tell, this is a significantly low voltage that cannot be felt by hand. Well, don’t go touching your plugged cable to confirm this!
How to avoid power interfering with HDMI?
The first step to avoiding the power interfering with the HDMI or any cable for that matter is buying a premium quality HDMI. This means an HDMI cord with thick shielding.
Proper shielding protects the HDMI cable from signal degradation and disruptions. This is particularly true when transmitting signals over long distances.
Another way to avoid power interference is to use an RF-Shielded HDMI. This particular shielding features ferrite nodules at both ends of the cable that look more like flattened cylinders.
The primary function of the ferrite nodules is to eliminate any possible RF interference.
To avoid power interference also, avoid using extremely long HDMI cables when not necessary. Reason being that the longer the cable, the weaker the network performance, and of course, the higher likelihood that it will pick up unwanted frequencies.
The most suitable HDMI cable length for optimal transmission signal is between 5 to 10 meters. Well, you can stretch it to 25 meters, but that’s the max you can go. In fact, you will hardly come across an HDMI cable that is longer than 25 meters in a store.
If your setup needs to use a longer cable, then you may need to use a power repeater or equalizer to regenerate the signal to distances of hundreds of meters.
HDMI-over-cat extenders allow transmission of signals over distances of up to 80 meters. However, it depends on the CAT cable you are using. The kit uses CAT 5e, 6, or 7 cables.
HDBaseT, on the other hand, transmits multiple AV signals for distances of up to 100 meters over CAT 5e or CAT 6 cables.
HBase Technology is perhaps the most standard extender for commercial and domestic signal transmission and can handle up to 5 different signal sources.
These include the Ultra-HD (up to 4K), Ethernet, USB, Power over Cable (PoC), and High-quality audio.
In addition to all the above, you can also employ the following measures to protect your HDMI from other sources of interference:
- Installing a proper and carefully engineered grounding system.
- Ensuring that all the nearby cables and wires are individually shielded.
- Continually using foil shields.
- Separating the HDMI from the source of the interference.
- Ensuring that cables cross at 90 degrees if at all they must cross. Maintaining even a slight separation helps to combat interference.
- When bundling up your HDMI cables with other cables or wires, make sure that there are no exposed wires, or at least they are twisted all the way to the connection ends.
Cable signal inference is a pretty common interference that also affects HDMI cables. This should, however, not scare you from bundling up your HDMI with other cables. Ensure the cables are shielded and insulated to minimize any chances of interference.
As for the power cable being adjacent to the HDMI cord, there is no cause for alarm. It’s safe to bundle them up. However, it’s best to keep the high voltage cables separate from low voltage cables.