Best Practice & General Tips

Hints, tips and considerations for HDMI over Cat 5/5e/6 (CATX) applications:

Tools for the job

• RJ45 connector plugs (preferably shielded but not essential)
• RJ45 crimping tool
• Unshielded Cat 5/5e/6 raw cable (Unshielded [UTP] preferable over shielded [STP] due to attenuation issues)
• Electrician’s tape (having various colour options is helpful)
• LAN cable tester
• Permanent marker

DO NOT: hot-plug the CATX cabling or any HDMI cables whilst your equipment is powered on or in standby mode – this can cause serious damage to the electronics in those devices.

DO: always ensure that all devices are completely powered off when connecting to each other. When powering equipment back on do it one device at a time.

DO NOT: use wall plates, faceplates, patch panels, joiners, couplers or adapters of any kind anywhere in the CATX cable run from the TX to the RX. Even the most perfectly terminated connections will cause bottleneck or weak point in the flow of data transmission where bandwidth becomes severely reduced - something that is just not acceptable for a HDMI video transmission. This drop in bandwidth results in a much reduced resolution capability from the extenders or no picture at all. This is so important for HDMI over Twisted Pair extender devices as they send uncompressed data (not compressed packet data like an IT network). Uncompressed data is pure video data that requires pretty much all the bandwidth that the CATX cable can provide. HDMI over Twisted Pair devices are design to work in a point-to-point fashion with no breaks in the CATX cable.

DO: use brush plates instead.

DO: keep the CATX cabling at least 15cm of any power cabling and at right angles if possible.

DO NOT: Use crossover CATX cabling.

DO: Make sure your CATX cables are wired ‘straight’ through (i.e. the same both ends). A great guide that we always use can be found at this web address.

DO NOT: Pull or stretch the cable, Staple or dent the cable nor over-tighten with cable ties. Treat all cable in a gentle way - don’t pinch, knot, kink, couple, untwist, staple, splice, dent or stretch the CATX wire.

DO: If you are running 2x CATX cables ensure that they are the same length, as exact as possible.

DO: use a cable tester to check all CATX terminations are good. Terminate the twisted pairs to exactly the same length. A good termination can be the deciding factor in whether your solution works or not. Make sure you are 100% certain that your Cat cables are terminated perfectly by testing them with a LAN cable tester!

DO NOT: connect HDMI cables longer than 5m to either the TX or RX units.

DO: use a cable tester to check all CATX terminations are good.

In general:

Be careful and cautious, take your time a get things right! Sending HDMI, particularly with HDCP, involves a lot of different things happening at very high speed. Transmission or wiring errors often will result in no picture at all. In component video, you can have problems and still get a picture ranging from pretty good to bad. With HDMI, problems often mean no picture at all.

Error or losses in the signal chain accumulate. If that last statement is not scary enough, losses may be tolerated on some content material more than others. The bottom line is that you can’t cut corners. Some past wiring practices will get you into trouble. Be wary of jobs where someone else ran the wiring and pay close attention to the advice given on this page.

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HDMI over Cat 5/6/7 (CATX) Extender SKUs: YKCAT3GB, GRCAT01GB, ASCAT60GB

FAQs

What is the recommended type of CATX network cabling that I should be using?

For the HDCable.co.uk HDMI over Twisted Pair extender product range we recommend using a minimum CATX spec of solid core CAT-5e cable rated at 350MHz and terminated in T568a or T568b fashion. For 1080p resolution over challenging distances (30m+) we strongly recommend that you to use shielded ‘Shielded Twisted Pair’ (STP) CAT-6 or CAT-7 cabling to ensure the best possible data transmission

Is there any picture quality loss using the extenders?

No. The picture will be 100% the same as if you were using a direct connection with a HDMI cable.

What is the maximum distance that can be achieved?

This depends greatly on the quality and type of the CATX cabling being used. Greater distances are achievable with Cat6 cabling compared to Cat5e for example. As a rough rule of thumb, 1080p can be sent up to around 50m and 1080i 100m. HDCable.co.uk recommends Cat6 cabling be used for optimum performance.

Can I use the extenders as part of my home network?

No. The extenders are not IP based devices - they do not convert it into traditional network traffic data packets. For HDMI over IP products click here.

Can I use the extenders with my Ethernet powerline adapters?

No. The extenders need a physical piece of CATX cable to work. The extenders use the physical properties of the twisted pairs within the CATX cabling to send the HDMI data transmission; they do not convert it into traditional network traffic data packets.

Can the extenders be used with HDMI switches, splitters and matrixes?

Yes. All HDCable.co.uk products are fully compatible with one another. You can use the extenders in exactly the same way as if it were a normal short HDMI cable and expect exactly the same performance.

Troubleshooting

I’m getting no video at all on the display, what should I check?

Firstly, if you are using a DUAL Cat5/6/7 extender make sure that both CATX cables are connected correctly to the corresponding video and DDC ports (video-to-video & DDC-to-DDC).

Now follow this power on procedure.

1. Power down the display, extender and source device at the mains.
2. Power on the display device and select the correct HDMI channel.
3. Power on the extender.
4. Finally, power on the source device.
5. Now the handshake process should complete successfully and video should appear on the screen.

If this does not resolve the problem, check the cable run ensuring that the CATX cabling does not run within 15cm of any power cabling. Interference from the power cabling will seriously affect the performance of the extenders, possibly resulting in bad picture break-up or no picture at all.

If the problem persists, test the extender using shorter length cables to help diagnose whether it is an issue with the CATX cabling. If it is, re-terminate the longer length cables and test again. If the problem still persists, upgraded CATX cabling is required.

Occasionally the picture blanks out, how do I fix this?

Flickering or blinking images are often caused by a loss of sync between the display and the source. This can be caused by a number of external influences.

NB. In some circumstances after the HDMI signal becomes active and extender initializes, it can take up to ten minutes for the signal equalization processing within the unit to adjust and stabilize video playback so that it is completely glitch free.

The HDMI transmission running along the Ethernet cabling is particularly susceptible to electro magnetic interference (EMI). This can be caused by being in close proximity to power cabling, fluorescent lighting or by spikes on the circuit generally caused by electrical motors such as those found in washing machines, fridges and dishwashers.

Firstly, try lowering the source resolution to see if that helps, if it does, the CAT cabling being used are unable to handle the required bandwidth or the termination is at fault. Firstly, re-terminate and test again. If the problem still persists, upgraded Ethernet cabling is required. Try upgrading the CAT cabling to shielded CAT-5 or CAT-6 cable on the video line to reduce interference.

There is a green or pink tint to my picture?

A tint of green or pink in the picture is a result of incorrect colour space being transmitted. This can be resolved by recycling the devices to re-sync by powering off and on the source equipment. If this does not help, the DDC data containing the colour space is not being transmitted correctly due to loss in the CAT cable on the DDC side, Firstly, re-terminate and test again. If the problem still persists, upgraded Ethernet cabling is required. Try upgrading the CAT cabling to shielded CAT-5 or CAT-6 cable on the DDC line.

When I turn on a light switch or a power socket, the picture drops out momentarily?

This is caused by a power arc/spike in the circuit that is caused when you flick the switch. If the Ethernet cabling runs close or across any power cabling at any point in the cable run, the momentary jump in power will cause a burst of electromagnetic interference (EMI) to occur. This affects the HDMI signal transmission over the extender. However, this is only for a fraction of a second and the connection is quickly re-established. Unfortunately there is no an easy fix for this problem other than re-routing the Ethernet cabling a sufficient distance away from the power cabling.

This issue can also be caused by an ‘earth leak’ somewhere on the electrical circuit. A qualified electrician should be able to locate and repair the fault.

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CAT 6 Cable Reel (305m - 1000ft) SKU: CECAT6R

FAQs

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