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

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 connections.

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.

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.

Two main factors limit the range of signal levels that should be present at the input to a HDTV (called the "operating window of the receiver"):

  1. The minimum level of the digital signal, which must not fall below the threshold (typically 35-40dBµV, but in some cases higher)
  2. The maximum level of signal should not exceed 77dBµV, otherwise the receiver overloads and shuts off the signal completely.

Measurement of this 'operating window' 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). The installer should ensure that normal signal levels are at least 6dB above threshold by attenuating the signal and checking that the receiver still works on all channels.

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.).

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 installation guidelines.

The Australian Digital Testing strongly recommends the use of quad shielded coaxial cable and F connectors 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 'Operating Window of the Receiver' above.

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

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.

Home unit dwellers cannot display signal

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