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Australian Digital Testing's
HDTV Reception Troubleshooting Guide

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 - click here.

 

 



 

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.

 
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