Step 1: check the location settings and equipment
Check the location settings
Type in the address of your customer at mySwitch to check for:
- the TV transmission tower which provides the best signal coverage for this address
- predicted level of coverage
- channel frequencies
- antenna set-up information
mySwitch will also tell you if the predicted signal coverage comes from a distant TV tower that is not planned to cover this particular area. This is known as fortuitous reception and the unreliable nature of these weaker, distant signals are far more susceptible to interference. We do not investigate interference issues due to fortuitous reception.
If mySwitch indicates that the predicted level of coverage is poor, fortuitous or there is no coverage, your customer may need to get free-to-air TV by using the VAST service.
Check the antenna and equipment
Measure the level and quality of signal through the:
- antenna
- amplifiers
- splitters
- leads
- connectors
If the antenna and equipment are damaged, incorrectly installed or old you may need to install a new system.
Measure signal level
For good TV reception signal levels at wall plates should be around 54 dBµV.
Signal levels below 45 dBµV and above 80 dBµV are not suitable for TV reception.
Measure signal quality
CBER, VBER and MER give an indication of the quality of the signal provided to the receiver.
CBER
A TV receiver is able to identify and correct certain amounts of error in the transmission channel. In the TV receiver, error correction takes place in two distinct stages called Viterbi (inner) and Reed Solomon (outer) correction.
CBER indicates errors present before any correction has taken place in the TV, set-top box or test instrument.
CBER should be better than 2E-2 (2 errors in every 100 bits of data) for good quality TV reception.
VBER
The bit error rate after the Viterbi correction is known as VBER or post Viterbi. It should be better than 2E-4 (2 errors in every 10 000 bits of data).
MER
Modulation Error Ratio (MER) is a measure of the signal quality taking into account the sum of all interference effects occurring on the transmission channel. For good quality TV reception preferred MER is at least 25 dB.
Step 2: investigate interference
- Location settings
- Antenna
- Equipment
You have checked the location settings, the antenna and the equipment. These are correct and appropriate for this location.
The problems may be caused by other signals interfering with good TV reception. This is called interference and can be internal or external to the house.
A signal with good levels but poor quality can mean interference.
Check the interference is internal or external. The interference is internal if interfering signals are coming from a source inside the property and interfering with the TV reception. The interference is external if the interference source is not on the viewer’s premises, or beyond the viewer’s ability to control. If the interference is external you may report it to us.
Step 3: report interference
We will not investigate interference coming from inside the house or from power lines.
You can report other types of external interference to us.
Complete Digital TV interference online form on behalf of your customer. Make sure you provide the signal levels, CBER, VBER and MER for all channels measured at the wall outlet.
We may contact you to discuss. We may also ask you to be onsite with your customer.
We may conduct a field investigation, and will let you know the outcome.
We will protect your privacy and all others involved in the investigation.
We seek to resolve issues first through education and awareness. If necessary we may take formal steps to enforce the provisions of the Radiocommunications Act 1992.