Shoalhaven reception and interference issues | ACMA

Interference

07 October, 2014 11:24 AM

Interference

Shoalhaven reception and interference issues

By Editor

Reception difficulties post-retune

Following the retune of the Knights Hill (Illawarra) broadcasting station on 10 June and the Cambewarra lookout (Nowra North) broadcasting station on the 28 July, some viewers around Kiama and Nowra in the Shoalhaven area reported reception difficulties for some or all television services.

The ACMA investigated and found that some viewers who used ‘auto scan’ to tune their television receivers may not be receiving their television services from the broadcasting station that provides the best terrestrial digital television coverage. 

Digital television coverage in the Shoalhaven area is provided by several broadcasting stations including Knights Hill (Illawarra), Cambewarra Lookout (Nowra North), Brokers Nose (Wollongong), and Little Forest Trig (Ulladulla). Viewers in the Shoalhaven area who have been experiencing reception difficulties following the retune may want to consider performing a manual tune on their television receivers, as this is the only way to guarantee that they are receiving services from the broadcasting station that provides them the best digital television reception. If you’re experiencing problems, contact the Digital Ready information line on 1800 20 10 13 (8 am to 10 pm AEST, 7 days a week) to get help with performing a manual tune. More information about the retune can be found from the Retune website.

Viewers in marginal digital television coverage areas, or viewers with inadequate antenna receiving systems, are more likely to experience reception difficulties after the retune. This is because their antenna receiving systems are vulnerable to any environmental change, including the retune-related channel changes. These affected viewers may still experience reception difficulties for some or all television services, even if they have correctly manually tuned their television receivers.

If you continue to have reception difficulties after performing a manual tune, you may want to consider contacting an experienced antenna installer to check if your antenna and cabling systems are in good working condition, and that you have the best setup to receive digital television.

'Ducting' interference from Newcastle

In early 2014, the ACMA investigated reception issues in the Shoalhaven area following a number of complaints from viewers. The investigation indicated that many of these reception difficulties were caused by an anomalous form of radio wave propagation known as ‘seasonal ducting’. This phenomenon can cause distant television transmissions operating on the same channels (in this case, Newcastle services) to propagate further than they normally would and cause interference to reception of services from Knights Hill.

Ducting is seasonal in nature. It is more common during summer but can happen occasionally during the other seasons on warmer days. It occurs in many parts of Australia—predominately coastal regions—and is not unique to the Shoalhaven area.

Viewers watching Knights Hill services in marginal coverage areas who have an inadequate antenna system or are located in an elevated position with clear views in the northerly direction are more likely to be affected by ducting. If this is the case, you are encouraged to contact an antenna installer to get advice about whether your receiving system can be improved to reduce the impact of interference from the Newcastle services.

Seasonal ducting could also potentially affect the Cambewarra Lookout broadcasting station, which uses Knights Hill services as programming input, causing reception difficulties to viewers watching the Cambewarra Lookout services. Local viewers and antenna installers have reported that services from the Cambewarra Lookout site have also been affected by ducting. Broadcasters are considering options for improving the programming input to the Cambewarra Lookout broadcasting station to provide more reliable reception of the services from this site.

Viewers should consider visiting the MySwitch website to get location specific information about their digital television coverage—in particular, whether they can get alternate coverage from the Little Forest Trig (Ulladulla) broadcasting station or the Brokers Nose (Wollongong) broadcasting station, as these stations should not be affected by ducting. An antenna installer can also advise if there is a suitable alternate station. Sometimes the alternate station may provide weaker signals, but they may be more reliable if they are from a broadcasting station not affected by ducting.

Alternative options for viewers with reception difficulties

If you still experience ongoing reception difficulties after you have correctly tuned your television receivers, and have had an antenna installer confirm that your antenna system is working well, you may be affected by some localised interference. The antenna installer should be able to identify if you are being impacted by localised interference, and help you to fill out a request for interference investigation form (R202).

The webpage Interference to TV reception has further information about potential sources of interference.

Viewers who don’t have adequate terrestrial reception of all digital services may be eligible to access digital TV from the Australian Government-funded Viewer Access Satellite Television (VAST) service. The government’s VAST service is intended to provide digital television services for individual households who are unable to get adequate reception from existing terrestrial broadcasting stations. To apply for access to VAST, viewers can go to the mySwitch website and type in their address. Once the coverage information appears, there is an option on the left hand side, shaded in dark grey called ‘Satellite Summary’ which allows application for access to VAST. Viewers who are eligible for VAST access will need to meet the costs of having VAST equipment installed (a set top box, cabling and a satellite dish).

An experienced antenna installer would also be able to advise if you are in an area that is expected to receive reliable terrestrial digital television (based on measurements at your location) and should be able to provide information about VAST if required.