TV Reception in Thanet Report on June 2014 Household Visits and Measurements
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TV Reception in Thanet Report on June 2014 Household Visits and Measurements Publication date: 2 December 2014 TV Reception in Thanet About this document Some viewers in the Thanet area have reported reception problems with digital terrestrial television (Freeview) services since the digital TV switchover in the Meridian region in mid- 2012. Ofcom and BBC staff visited a selection of them during June, 2014. Viewers were given the opportunity to discuss their experiences and signal measurements were taken from each household’s aerial system. Signal measurements were also made using survey vehicles at a number of locations in the Thanet area, by both Ofcom and BBC engineers. This report summarises the findings of the survey, provides an overview of the problems being experienced by viewers and outlines possible steps viewers can take to improve their reception. TV Reception in Thanet Contents Section Page 1 Executive summary 1 2 Why we carried out this work 2 3 What we did 3 4 Findings 6 5 Surveyed locations and signal coverage predictions 13 6 Background to TV signal and coverage planning 18 7 Next steps 20 Appendix Page 1 Measurements 21 2 Predicted coverage quality and summary of home visit discussions 28 3 Options for viewers who are experiencing problems 36 4 Channels carried on relays and main transmitters 41 5 Sources of further information 42 TV Reception in Thanet Section 1 1 Executive summary A study of reception conditions and viewer experiences of digital terrestrial TV (DTT, or Freeview) reception quality in the Thanet area was carried out during the summer of 2013. This was the most comprehensive such survey undertaken jointly by OFCOM and the BBC to date. BBC and Ofcom made a total of 37 home visits to households who had complained to local Members of Parliament that they had reception issues. From these we collected 34 sets of signal measurements (measurements were not taken at three locations due to factors such as viewers who were using satellite exclusively, or where the measuring equipment did not operate correctly) The BBC also carried out additional measurements using its specialist survey vehicle at 20 locations in the areas where viewers had reported reception problems. The objective of measuring with a survey vehicle was to measure the signal strength in potential problem areas using calibrated equipment with known technical performance. In addition, Ofcom had also undertaken measurements in a further 53 houses in Thanet, yielding 49 complete sets of measurement data, as part of a separate campaign investigating a new type of wireless device technology. These tests also provided valuable information on domestic aerial installations in those homes, and information on the installations is presented here to inform the study. The combined analysis is therefore based on measurements at 103 locations. Of these locations, only one household was found to be using the Margate TV relay transmitter and one other was found to be using the main Bluebell Hill transmitter. The remainder of households were using the main Dover transmitter. Analysis of the data shows that: • 38 of the households would benefit from realignment of their aerials to the Margate relay • 29 of the households already had good coverage for all three local ‘public service’ multiplexes • One household was completely outside the coverage areas of any digital transmitter. • The remaining 35 households could receive services from the main Sudbury transmitter; however Sudbury does not provide the correct regional news services for Kent. • In all cases, free-to-view satellite services could provide reliable reception of many of the most popular digital TV channels, and would include appropriate regional news programmes for the area. 1 TV Reception in Thanet Section 2 2 Why we carried out this work 2.1 The BBC and Ofcom have received reports of poor digital terrestrial (Freeview) TV reception from some parts of the Isle of Thanet. Most viewers that have complained describe fairly frequent and/or prolonged losses of reception. This makes watching TV difficult, or even impossible. 2.2 In the past we helped people who reported problems with bespoke advice and information leaflets. We also confirmed that the transmitters serving the area were operating normally and to their design specification. Nevertheless, we have continued to receive reports of poor reception. 2.3 Ofcom and BBC engineers visited Thanet during June 2014 to carry out a wide ranging investigation into signal and reception conditions in the area. This included visits to some viewers’ homes and measurements of their TV signals. We also took measurements of TV signals outside viewers’ homes using special survey vehicles. 2.4 We have analysed the information we gathered to look further into the likely causes of viewers’ problems and possible solutions. This document summarises our findings. 2 TV Reception in Thanet Section 3 3 What we did Signal Measurements and Home Visits 3.1 There were three main aspects to the TV signal survey work in the Isle of Thanet, which allowed us to capture signal measurements at a total of 103 locations. These were: 3.2 Home Visits 3.2.1 Ofcom and the BBC offered to visit the homes of many viewers who had complained about their TV reception. In total, 37 householders accepted, and the visits were carried out between 16th and 20th June 2014. 3.2.2 During these visits, we discussed the individual householder’s experiences of TV reception, noted the type of TV aerial system they were using, and took basic measurements of the TV signals at the main aerial socket. Where possible, we offered advice to viewers on how they may be able to improve their TV reception. Of the 37 households visited, we collected 34 sets of useful measurement data. Of the remaining three locations, one householder was using satellite exclusively, at one location the measurement equipment did not operate correctly, and at one location the householder was using the same communal aerial system as a previous measurement point. 3.2.3 The reception complaints received were concentrated in relatively localised areas of Thanet where particular issues (such as obstructions caused by the local terrain) make reception - particularly of the Dover main transmitter - difficult. 3.3 New Wireless Device Technology Measurements 3.3.1 Completely separately, engineers from Ofcom have been carrying out technical tests in a number of areas of the UK looking at the possible future use of a new type of wireless device technology. 3.3.2 The Wireless Device Tests allowed us to measure TV signal strengths at a variety of locations in Thanet. These measurements provided further technical detail on the performance of typical household aerial installations. Wireless Device Tests were carried out at 53 locations, from which we obtained 49 complete sets of measurements. 3.3.3 The Wireless Device tests could only be carried out at certain properties because the test equipment included a tall aerial pole which needed to be specifically positioned in relation to the householder’s rooftop TV aerial. This meant we chose the majority of the Wireless Device test locations for their physical suitability rather than because there had been a reception complaint from the viewer. Nevertheless, measurements gave us extra data on signal conditions, across a wider area of Thanet. 3 TV Reception in Thanet 3.4 Survey Vehicle Measurements 3.4.1 A specialist BBC reception survey vehicle recorded detailed signal levels on some of the streets where viewers had reported reception problems. This gave us information on the strength and quality of signals from all the TV transmitters that could provide signals at each location – and not just the transmitters to which viewers’ aerials were pointing. The survey vehicle also recorded the absolute strength of the signals in each location, independently of the technical performance of individual household aerial systems). Vehicle survey measurements were carried out at 20 locations. Map of Visits and Measurements 3.5 The map below shows all the locations where we made measurements or visited homes. 4 TV Reception in Thanet Figure 1: All visit and measurement locations 5 TV Reception in Thanet Section 4 4 Findings 4.1 This section provides a brief summary of our findings. Full breakdowns of the results of our measurements are in Appendix 1. Some viewers in Thanet experience relatively frequent reception disruption 4.2 Many viewers who had previously complained about their reception told us that they were experiencing relatively frequent disruption or losses of reception on some, or all, Freeview channels. Problems were particularly common during the evenings when the weather was fine. A significant number of people reported experiencing problems on the main BBC services in particular, though some people reported problems on other (or all) channels. 4.3 The duration and frequency of the disruption did, however, vary significantly between households. This indicates that the problems are likely to be primarily due to effects such as variations in the strength of interference from other transmitters, or the quality of the aerial installation, rather than problems with the transmitted signal itself. Our survey vehicle measurements confirmed that the signals from the local transmitters themselves were free from transmission impairments. The vast majority of viewers in Thanet have aerials pointing towards the Dover transmitter, even in locations where its signals are poor 4.4 Historically, most viewers in Thanet have picked up their terrestrial TV signals from the large Dover (Hougham) transmitter mast. We found they are still doing this: 98% of the homes we tested or visited had aerials which were pointing towards Dover. 4.5 Reception of Dover has however always been difficult in parts of Thanet, and two smaller ‘relay’ transmitters were built in the early 1990s in order to improve TV reception in relatively small areas of Margate and Ramsgate.