"Interference from Illawarra DTTB services into reception of Newcastle DTTB services in the " Free TV February 2013 1. Introduction. This report seeks to bring to the attention of the Australian Digital switch Over Task Force the ongoing problems being experienced by television viewers in the Hunter region of NSW of interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region. Since the householders in the region between Medowie, Lemon Tree Passage, Salt Ash and Soldiers Point have been focussing on DTTB reception arising from the switch off of analogue services this issue has caused an increasing number of complainants to the local broadcaster, NBN TV. This includes a large populated area stretching from Raymond Terrace to Medowie west of Nelson Bay. NBN TV seeks the DSO-TF’s recognition of this matter and action toward developing a strategy to establish - what is required in the current DTTB planning to minimize interference to DTTB reception in the area, and - what is required by householders to optimise reception of the Newcastle services 2. Background. NBN TV has been in discussion with the former Australian Broadcasting Authority and now the Australian Communications and Media Authority on the issue of interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region for many decades. Since February 2003 the Department has been investigating measures toward mitigation of interference from Illawarra services into the Hunter region which culminated in the then DCITA trial at Port Stephens of a TVBSP Alternative Technical Solution. While the establishment of a new set of services from a transmission facility on Gan Gan at Nelson Bay for the Port Stephens area the solution provided only a “localised” re transmission of the Newcastle services for a small coverage area within the region. The DTTB assignments from Mt Sugarloaf serving the Hunter region at present are: ABC SBS NEN NBN NRN Digital 37 38 53 36 51 Over the last 12 months and arising from the imminent switch off of analogue services for the region between Medowie, Lemon Tree Passage, Salt Ash and Soldiers Point there has been an increasing number of complainants to the local broadcaster, NBN TV, of DTTB reception issues of the Newcastle services. In addition to the large volume of complaints received by NBN, an interested local party has also collected a sizeable amount of complaints numbering in the hundreds. What is apparent is that in spite of some potential terrain restrictions on line of sight propagation of the Illawarra signals areas like Dungog have also been affected. It is therefore considered that “ducting” is apparent as a factor with the propagation of the Illawarra service signals up the central coast of NSW. "Interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region"

P.1546 Illawarra coverage pattern – 1% time

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"Interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region"

Terrain profile - Illawarra into Medowie

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"Interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region"

Terrain profile - Illawarra into Dungog

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"Interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region"

Within the ACMA Coverage Evaluation Program field measurement data indicates in the Medowie area there is one location near 1 Chestnut Close which has marginal DTTB reception. 3. Results of the ACMA Restack Planning Advisory Group studies on Underserved Areas in the Hunter Region Within the studies of the Restack Planning Advisory Group on suitable DTTB planning and potential effects of co-channel in the Hunter Region, the ACMA came to the following conclusion: There are clear cost and restack timing advantages for Option B. However, the argument about interference impact to viewers is less straightforward. • If it is assumed that interference to any service should be avoided, Option B is the preferred option because it is predicted to affect 5,000 or 10,000 fewer people. • However if the requirement was recast as the ability to receive 6 interference-free services Option A would be preferred (at least for interference minimisation) as it offers significantly fewer potentially affected viewers than Option B (2,800 fewer if Rec 1546-1 is assumed or 20,000 fewer if the CRC predict propagation model is assumed). If Option B was adopted there are predicted to be in the order of 3,200 or 17,700 people that would receive interference to their reception of Block C Newcastle services. Most of these viewers would be either in the Central Coast area or at the southern outskirts of the Newcastle coverage. In practice a percentage of these viewers may be resorting to alternative, “below standard”, terrestrial services but in the absence of alternative terrestrial services with adequate field strengths viewers in this category may need to be authorised to receive VAST services. Option B has been implemented with 3 gap fillers at Belmont North, Anna Bay and Warners Bay. The studies on Option B indicated that the Illawarra services were predicted to cause interference to about 2,000 / 19,000 people without these gap fillers. No study has been completed to date that indicates by how much the impact of the 3 gap fillers reduces the impact of interference into the Medowie, Lemon Tree Passage, Salt Ash and Soldiers Point areas. 4. Results of a Study of interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region. Recently NBN Ltd has undertaken a measurement study of the signals from the Illawarra services into the Dungog area from its Dungog translator sight. The characteristics of the DTTB receiving station are: Dungog Transmission Site: 32°23'42.71"S, 151°47'6.35"E Receive antenna: Scalar Y615TV 12.1dB Gain Antenna height: 2-3 Metres AGL. Cable type and length: 8m. LMR400. 3dB splitter in line with the cable. With reports of interference being reported on the evening of 9th December 2012 NBN TV took the unprecedented action of switching off the Mt Sugarloaf transmitter at this time to see if the interference was in fact coming from . On the output from the monitoring receiver at 2.30am at the Dungog site the receiver locked to the incoming signal from Wollongong showing an MER (in the final grab) of 31.8dB.

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"Interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region"

Given the impact of this interference at Dungog it is understood the interference at Medowie, Lemon Tree Passage, Salt Ash and Soldiers Point is likely to be comparable. 5. Recommendation. NBN TV seeks the assistance of the Digital Switch Over Task Force and the ACMA to recognise the presence of interference from Illawarra DTTB services into reception of Newcastle DTTB services in the Hunter Region and develop a strategy to establish what is required in the current DTTB planning to minimize interference to DTTB reception in the area and what is required by householders to optimise reception of the Newcastle services.

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