Australian Digital Testing's
HDTV Reception Troubleshooting Guide
After a scan, no channels, or only some channels, are found

Your TV antenna may need to be replaced

Television antennas are exposed to varying weather conditions and are often used as a convenient perch for birds.  In coastal areas they are especially affected by salt air.

If visible from the ground, assess the condition of the antenna.  Check that all elements are still in place (not bent or missing).  Check that the antenna has clearance from the roof and is pointing in the direction of the TV transmission towers.

If your neighbours tell you they have good digital TV reception, compare the design and condition of your antenna with theirs.

You may need to arrange for a competent antenna installer to assess your antenna installation with a view to improving your reception. Make sure he/she is equiped with a digital TV signal strength meter.

Your TV antenna may not be properly connected to your HD digital receiver

Look for any connection diagrams in the installation manual. This will provide you with the optimum connection advice for your free to air TV viewing.

Check power connection and ensure a good quality flylead connection from the wallplate to the first device.

Check all antenna connections are securely in place. Especially at at wall plug and where cables connect with the antenna socket on your HDTV or HD set top box. And while you are at it check where cables connect to other devices such as DVD recorders/players and games consoles etc).

If possible, the HDTV or HD set top box must be the first component in the receiving equipment connected to the antenna outlet.

Some HD Digital TV services may not have not yet commenced in your area

Although digital TV is now available to over 90% of Australia's population, not all towns and regions in Australia can yet receive digital television transmissions. In some towns and regions only some broadcasters have commenced their HDTV services.

Infill transmitters are also deployed in many regional areas - use ACMA's listing of digital TV channels to check their applicability to your situation.

Download a listing of Logical Channel Numbers for digital TV services.

The signal received may be too poor to allow the digital receiver to find available channels

Cables, connectors, outlets and splitters might need replacement with high quality components, eg, Quad Shield coaxial cable and 'F' connectors.

You may be outside the transmission area for digital TV, experiencing some form of interference.

Your antenna is not providing the optimum signal strength to the digital television receiver. Older masthead amplifiers might produce unacceptable levels of interference (a carrier to noise ratio that is too high) - replace with an amplifier with interstage gain control and the correct maximum gain required for good reception.

You may need to arrange for a competent antenna installer to assess your antenna installation with a view to improving your reception. Make sure he/she is equiped with a digital TV signal strength meter.

Your old antenna may not be designed to receive all available channels

Using the ACMA's listing of channels - check the channels (VHF and/or UHF channels) upon which digital broadcasting is taking place in your area. Your antenna must be able to receive digital television services broadcast on all those channels.

If your masthead amplifier has not been designed to work on channels now used in your area for digital television, it may need to be replaced.

Picture regularly breaks up

The signal received may be too weak or too strong to allow the HDTV to generate a stable picture.

The signals present at the antenna input of a receiver should conform to the following:

1.  The signal strength should be between 50 dBµV and 85 dBµV. Signals below 50 dBµV may be too low to allow the receiver to receive the signal. Signals above 85 dBµV may overload the input of the receiver also causing it not to receive the signal properly.

2. The minimum Modulation Error Ratio (MER) should be greater than 25 dB. MER is a measure of the quality of the signal MERs of below 25 dB may too low for the receiver to decode the received signal.

Measurement of these parameters should be done at the antenna wall plate and at the digital TV (not just on the roof at the antenna) with a professional digital TV field strength meter (all good installers now carry these meters).

If signal levels are not OK, you are unlikely to have good reception unless signal strength can be improved - antenna relocation or changes to your amplifiers (masthead or distribution) may be indicated.

But remember amplifiers should only be used by your installer to provide the minimum necessary boost to signal strength - those with interstage gain control are recommended - see below.

Interference from impulse noise may be causing pictures to break up and audio to drop out momentarily

Check for domestic sources of impulse noise (eg, the use of light switches, fridges, hair dryers, air conditioners etc.).

Ensure a good quality quad-shielded flylead is connecting the wallplate to the set-top box or HDTV.

If present, arrange for all cables, connectors, outlets and splitters linking the roof-top antenna and set top box or the HDTV to be upgraded in accordance with antenna systems for homes handbook.

The Australian Digital Testing strongly recommends the use of quad shielded coaxial cable and F type connectors (hex crimp or compression type) at all times.

A masthead amplifier may have boosted the signal outside the receiver's "operating window", making reception impossible

The masthead amplifier (appears as a small box on the antenna pole within about a metre of the antenna arms) may be able to be turned down - if your antenna is on your roof you should arrange for an antenna installer to perform this task.

When digital broadcasting services begin operating in an area some masthead amplifiers (boosters) operating at maximum output or maximum gain may need to be turned down to avoid signal overload for the set top box or HDTVs. This matter should be determined by a competent antenna installer, who will be able to adjust the amplifier for you.

Please note that performing this operation may affect any existing analog signals, so you may need to find a medium point between adequate analog reception and good digital reception.

Some channels display no signal
Received signal may have deteriorated

Check all cables are still in good condition and connections are firmly in place. Check that your antenna arms have not been damaged by weather or birds.

If you have split the antenna input you may now not be receiving enough signal to display all the channels - so disconnect those antenna inputs not in use.

Received signal may be marginal

You will need to contact an antenna installer with a view to upgrading your antenna installation to improve your reception.

See the Digital Switchover Taskforce Antenna Systems for Homes Handbook.

The set top box or HDTV needs to be "re-booted" & re-scanned

If channels had previously been received with no difficulties, but now the set top box or HDTV is reporting 'no signal', re-boot the HDTV by switching off the HDTV at the power button then unplug at the main power point.

Leave for 15 seconds then plug back in and switch back on again. Re-scan all channels, if necessary.

In some circumstances it may also be necessary to reset the set top box or TV to factory default settings before commencing the rescan.

Home unit dwellers cannot display signal
Talk to your neigbours in the building

You need to ascertain whether the reception problem in your unit is due to a local problem or a building wide problem.  If your neighbours say they have good digital TV reception, your reception problems could be due to a faulty or cheap TV fly lead (from wallplate to TV), a faulty or loose wall plate or a cabling fault within your unit.  If your neighbours have similar problems, read on.

Are you and your neighbours having reception problems with some or all channels?

If you and your neigbours in the building are receiving most digital TV channels without interruption, the reception problem may be limited to the antenna, the headend or cabling.  If you and your neighbours are not receiving any of the digital TV channels, it could require a major refit of the Master Antenna System.  With those overriders in mind, read on...

Problem receiving some digital TV channels? Start with the antenna.

If the antenna is able to deliver enough signal to the Master Antenna TV (MATV) system, it may be able to overcome other deficiencies within the system. The antenna is probably the least expensive part of an MATV system to replace so it is the best place to start if you have HDTV reception problems throughout the building.

If the reception problem relates to a UHF channel (say SBS in metro areas), it could mean that the UHF element needs to be replaced.  If the reception problem relates to a VHF channel (say Ten Digital or ABC in metro areas), it could mean the VHF antenna is not optimised for VHF digital TV reception.

Problem receiving some digital TV channels? Check the headend equipment is working properly.

The headend equipment is the part of the MATV system takes the digital signal from the antenna and then amplifies and, for larger buildings, processes that signal before distributing through the cabling system.  Checking the headend is a relatively straight forward job for an experienced MATV installer.  Replacing the headend is relatively inexpensive for smaller 3 storey walk-ups but becomes more expensive with larger buildings where channel processing is required.

Problem receiving some digital TV channels? Check the cabling

If the antenna and the headend equipment are working well, then the building may have a number of cabling faults that will need to be fixed.  An experienced installer will be able to isolate these faults and, if the cabling is otherwise in good condition, fix those faults. 

The installer may also be able to rebalance the amplifiers in the cabling system to ensure a more consistent signal is distributed throughout the building.

However if cable is generally in a poor condition or is not properly insulated for digital TV reception, it may need to be replaced.  This is relatively costly especially if access to the cable risers and conduits is restricted.  If replacing the cable, it would also make sense to replace all the wallplates at the same time with screw in F-connector type.

Problem receiving all or most digital TV channels? The Master Antenna TV (MATV) system may have been originally designed only for analog PAL TV, and may need substantial upgrade or replacement

Your body corporate or owners corporation will need expert advice about the scope and cost of rectification work. Remedies may include:

  1. the upgrade or replacement of the master antenna
  2. the removal of channel blocking devices
  3. discarding systems that decode and remodulate channels
  4. discarding frequency shifting techniques
  5. the upgrade or replacement of distribution amplifiers
  6. single channel amplifiers used for analog services will need to be extended to include digital channels
  7. cabling, splitters, taps and outlets may need replacementFor more information on digital television reception in home units

Still haven't fixed the problem?

HD Tick Licensed Suppliers Customer Care Numbers

A listing of HD Tick Licensed Suppliers Customer Care numbers is available at www.hdtick.com.au/products.htm.

Australia's DTV Forum

Other people in your area may be experiencing the same problems - check out the Geographical Listing on the DTV Forum.

Use the search function to see if your question has already been asked by someone else.

If you register as a member of the forum, you can post a question for digital TV enthusiasts to help you.

© Australian Digital Testing Pty Limited - www.digitaltesting.com.au