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DARWIN DAB+ TRIAL REPORT

JULY 2013

V0.1

Commercial Radio Australia Ltd

ACN 059 731 467 ABN 52 059 731 467

Level 5, 88 Foveaux Street

Surry Hills NSW 2010

T 02 9281 6577

F 02 9281 6599

E mail@commercialradio.com.au

www.commercialradio.com.au

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CONTENTS

BROADCASTER ACTIVITIES/CONTENT ........................................................................................................................... 3

INNOVATION – DARWIN TRIALS – COVERAGE AND SIGNAL .................................................................................... 3

INNOVATION –DARWIN TRIALS – CONTENT AND DEVICES ..................................................................................... 4

CHIP AND RECEIVER DEVELOPMENT AND TESTING................................................................................................ 6

TECHNICAL ISSUES ....................................................................................................................................................... 6

ONGOING ACTIVITIES – DARWIN ..................................................................................................................................... 7

PROGRESS ON FIELD MONITOR EQUIPMENT SETUP AND LOGGING ................................................................ 7

PROGRESS ON COVERAGE MODELLING .............................................................................................................. 12

SITE SURVEY OF DARWIN LICENCE AREA ........................................................................................................... 13

ISSUES WITH TRANSMITTER SITING ..................................................................................................................... 13

ISSUES WITH POWERING REPEATER SITES ........................................................................................................ 14

MULTIPLEX OPTIONS ............................................................................................................................................... 15

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A meeting was held with the Darwin trial broadcaster to discuss progress on activities. Further discussions with Grant Broadcasters have initiated a further project in Darwin with ongoing work detailed in the report with Emergency management agencies on how information from the emergency services RSS feeds can be integrated into DAB+ scrolling text and slideshow images.

BROADCASTER ACTIVITIES/CONTENT

Broadcasters’ services currently seem very stable, no audible dropouts on air which have been an issue during

the early part of the trial

All stations are considering the need to update their content storage and digital workflows.

o NT Broadcasters have been trialing a new pop up format to support the Cold Chisel tour launch and now have 5 services on air

(1) Hot 100 (2) Mix 104.9 (3) Classic Rock (4) Top Country Digital (5) Radio TAB

Transmission power (1) ACMA License = 5KW (2) Transmitter power = 1KW (3) Antenna gain = 7.7dBb = 9.8dBi dB. (4) Filter loss 1dB (5) Feeder losses = 1.2 dB (1 dB per 100m) (6) Combiner loss = 1 dB. (7) Transmission system gain (antenna - feeder - filter) 5.5dBb = 7.6dBi (8) Output 3548W ERP 5754 EIRP

INNOVATION – DARWIN TRIALS – COVERAGE AND SIGNAL

Forward Error Correction trials – field trials have been undertaken to assess both the accuracy of current

coverage prediction tools vs measured field strengths and the impact of using different FEC code rates to that

used in the Metro areas. Please see the technical report ‘Darwin Field Trials for FEC Code Rate Assessment’

for full details.

In Darwin propagation loss experiments have been done to measure rain fades during tropical storms and

severe rain events. Findings from these experiments are detailed in the Technical issues section below.

Advice on use of various code rates to trade off capacity and cost in an SFN configuration will also be part of

ongoing trial activity in the Canberra trial and the information will be used for modeling Darwin coverage.

Figure 1 shows proposed SFN transmission sites for the Darwin LAP.

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Figure 1 Darwin Licence area and potential repeater sites

Review the use of frequency re-use distances. Current distances are based on 1% interference predictions.

Propagation studies are planned to assess whether the current method is appropriate for DAB+. This

investigation may include the impact of different FEC code rates. This item was a joint suggestion from ACMA

and CRA for future trial activities.

The assignment of vertical polarisation for VHF DTV in regional areas will erode the protection between DAB+

and DTV in both directions, that is adjacent channel interference from DAB+ into DTV and DTV into DAB+. This

investigation will determine the impact of vertically polarised DTV on DAB+ planning. This has particular impact

on DAB+ transmission/repeater sites which are not co-located with VHF DTV transmitters. This investigation is

pending with regard to its potential impact on Darwin.

INNOVATION –DARWIN TRIALS – CONTENT AND DEVICES

Grant broadcasters are currently conducting experiments to determine the potential to improve access to feeds

from the Bureau of Meteorology and the NT Emergency Management agency.

Meetings with these agencies have helped to understand the feeds available for broadcast. Following this

investigation it is apparent that some issues need to be worked through to get useable formats for broadcast.

This is similar to the findings in the Canberra trial where broadcasters and ACT agencies are working together to

develop broadcaster specific feeds.

Broadcasting emergency information to the public makes radio part of the NT’s critical infrastructure and is

essential when emergencies occur as radio is considered by the Federal Trusted Information Sharing Network

(TISN) of Government and industry emergency management and business continuity experts as the “last man

standing” during extreme events.

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Battery powered radio is often used in the NT during cyclones, when the power is out, especially if the internet is

congested or down and the phone batteries are expended. It is radio that helps keep the public informed and

helps them to take the best course of action. NT Broadcasters have operated 24/7 from their Darwin studios

during the most extreme events.

Digital radio is a broadcast medium that allows not only audible information to be communicated in an

emergency situation, but also can provide text and visual representation.

From investigating the Northern Territory agencies’ sources for emergency information, CRA and the

broadcasters have found multiple websites which provide different essential information but do not use a

standard format for feeds and have no common approach to the escalation of events. Below is the list of

websites that can be used to get information in the NT.

Bureau of Meteorology – Weather/Fire Warnings – RSS feeds

Northern Territory Police, Fire and Emergency Services Tri-service home. – Media Releases RSS

secureNT – Northern Territory Government – Twitter and Facebook pages

Road Report – No Feeds.

Having multiple sources and different formats for information is not an efficient way to communicate the latest

emergency information to the media for broadcast. More work needs to be done with the local agencies to

formalise the process on the format in which information should be given to broadcasters in a digital age, to help

support the public during critical events. It may take liaison with the Bureau of Meteorology at the Federal level

as the investigations so far show that there is no potential at the NT level to make anything other than generic

feeds available.

Grant Broadcasters will develop some suggestions to input into ongoing discussions with the emergency

agencies as part of the forthcoming trial activities.

For recent weather activity in Darwin the broadcasters have manually updated the track maps from the BOM

website every 4 hours and put them to air as single images viewed on the Sensia. The manual processing of

cyclone track maps and BOM radar images is not viable in the midst of a major weather event and the process

will need to be automated. Discussions between Darwin BOM and NT broadcasters show that the BOM are

unwilling to develop any particular streams for an individual entity so more work will need to be done by CRA to

encourage the BOM, through the Federal Government’s Communications Sector Group to highlight any missing

feeds that would aid radio broadcasters’ ability to provide public safety messages using BOM information.

CRA has been developing animated PNGs of the Radar otherwise described as slideshow Animation of the

PNGs – 10 frames per second max. This is compliant with the DAB+ legislation as it is not video which has

frame rates of over 25 frames a second.

The animation process takes PNG images from the BOM radar and combines them in a PNG editor. This is a

manual way for radio broadcasters to show the direction of a storm front and the density and location of

expected rain. The file size of the APNGs depends on the density of the weather data they include so the more

rain in the radar image, the larger each PNG file is. The maximum file size would be around 50kB. CRA are

investigating ways to reduce the file size without compromising the content.

Frontier Silicon’s Venice 8 modules support APNGs so CRA can render these on a Frontier “development kit”

which has been upgraded to Venice 8.1 software. To be able to view more advanced APNG images which

contain typically 5 or 6 sequential radar images a suitable receiver is required such as the Revo Axis which is not

yet available in Australia.

The animation study document will consider implementation options for platforms, such as use of the NPAD or

XPAD streams and weather broadcasters are using a third party PAD server such as AIM, or simply using the

Digidia directory to show a carousel of images with no synchronisation. The following activities are underway:

NT broadcasters to investigate whether it is possible to prioritise the radar images using the Emux SLS carousel.

CRA to talk to Revo regarding their distribution in Australia and the product features that they will support and form factors of the receiver device.

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CRA to invite AIM rapid to jointly investigate how difficult it would be to automate the process to take relevant images from the BOM and reduce the image file sizes, put them into an APNG editor automatically and then send them to the data mux for broadcast.

Initial discussions with AIM and other middleware providers to allow broadcast of BOM Radar images during floods and severe weather events have been held. CRA has also been investigating the use of APNG images to automate the display of the BOM weather radar image sequence, but the file size needs to be reduced for this to be viable for the PAD data channel on DAB+.

CHIP AND RECEIVER DEVELOPMENT AND TESTING

Contact has been made with Frontier Silicon who supplies many of the leading consumer brands with DAB+

chips and modules. The first generation chips were developed in 1997 and there has been significant changes

made to the silicon and software to improve performance in later generations. They are currently up to the fourth

generation.

Frontier are investigating their current support for DL+ which would allow embedded links to be broadcast in text

and to be stored so that listeners can use an embedded URL in the transmitted text and click on it to drill down

on a connected device via a back channel. There are currently several connected portable devices, but it will

become more important when DAB+ is available in mobile phone handsets.

Most radios will support pause and rewind in the next 12-18 months and this will allow listeners to pause or

repeat announcements which will be useful to help them check their understanding of emergency broadcasts,

breaking news and so on.

Frontier is also supporting Radio Tag in the coming chips which will allow listeners to tag content for future

investigation.

Request have been made of a number of chip/module makers to understand the more modern receiver

sensitivity as this will impact the planning for coverage and use of SFNs in regional Australia. The information

has not been forthcoming so far and CRA is considering the options to determine the performance of a range of

receiver modules on the bench.

TECHNICAL ISSUES

There has been ongoing technical work on infrastructure issues, software updates, remote control data inputs,

links and hardware siting and improvements

Grant Broadcasters have been using 3G ADSL to get their content out to the data mux which is located at the

transmission site at Deloraine Road. Telstra cannot provide a fixed IP address which means that the track

playing data is unstable and is not always rendered properly at the site or on air.

Investigation of use of the NBN, which goes past the Deloraine Road site in Darwin has resulted in advice that

only Defence have access to it in Darwin at the current time. So the broadcasters can find no cost effective

alternative path. They would be interested in a briefing from NBN Co as to when and how they can access the

NBN in the future as the current roll out map does not show the NBN running near Deloraine Road.

Currently the most cost effective and technically robust service is the 850MHz link which is in place between the

city based studio and the transmission site. Grant Broadcasters recently had to lift the link antennas 10m

because they were losing line of site due to new high rise development and the ridge of hills between the city

and Deloraine Road.

Investigations of what other broadcasters are doing for their digital feeds reveals that the ABC feed is satellite

based and subject to rain fade in wet season. Other service use ISDN connections.

If the NBN is not the solution and the 850MHz frequencies are replanned by the ACMA, then the only robust

technical platform would be a dedicated fibre optic cable for use by broadcast. This would be one path where the

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DTV broadcasters, ABC, SBS and Grant Broadcasters radio services as well as Radio Larikia could be sure of a

reliable path which would be resilient to the severe lightning and weather impacts in the area.

Both CRA and Grant Broadcasters have had ongoing reviews of the Project Plan activities to adjust resourcing

and more detailed timings as we work around limited field testing equipment, vast distances and staff resources.

ONGOING ACTIVITIES – DARWIN

PROGRESS ON FIELD MONITOR EQUIPMENT SETUP AND LOGGING

The setup of the CRA field monitor (FMON) in Darwin since January to test rain fade has gone well and interesting

results were found during the March period when there was increased rainfall. A remote connection to the logger

was also setup so it could be easily accessed by CRA staff and the technicians in Darwin.

The diagram below shows the locations where the field monitor was set up. The logger was setup at Test Point One

in Berry Spring between January and March. The logger was then relocated to Test Point 2 in Palmerston after

March for further testing.

Figure 2 Darwin Rain fading log sites

Darwin has not had a severe wet season between January and May as shown in the table and charts below. However,

interesting results were found during the recording period between the dates of 13th -15

th March 2012 at Point 1 in Berry

Springs.

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Figure 3 Darwin Rainfall Comparison

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOW DEC TOTAL

2010/ 630.2 428.8 198.4 136.6 66.2 0.0 0.2 0.0 40.4 157.8 208.2 390.4 2257.2

2011/ 627.2 1110.2 231.6 193.0 0.6 0.0 0.0 0.0 3.2 141.0 152.0 227.2 2686.0

2012/ 459.2 250.2 572.4 70.2 51.4

The results recorded in that March period were plotted in MATLAB shown in Figure 4. During this recording period, it

can be seen that the signal strength increased and peaked on the 14th March 2012 21:25UTC at -71.54dBm and 15

th

March 01:45 UTC at -71.03dBm as shown in the graph. At these points in time moderate to heavy rainfall fell in Darwin

in between the path from the transmitter and the logging site. This is a strange result as rain is expected to have a rain

fade effect which decreases the signal strength. What was observed was that the signal strength gradually increased

and then decreased.

Figure 4 Signal Strength Measurements between 13th - 15th March 2012

0

200

400

600

800

1000

1200

JAN FEB MAR APR MAY

Darwin Rainfall Comparison 2010-2011

2010/

2011/

2012/

14/03/2012 21:25UTC -71.54dBm

15/03/2012 01:45UTC -71.03dBm

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The results show that during these heavy rain periods the signal strength increased by 2-3dB from the norm of -74dBm

to -75dBm. It is a very interesting result and requires further investigation to determine how signals will be affect during

the cyclone season in tropical areas.

The BOM radar images that were captured during this period can be seen in the tables below. Closely correlating the graph and the BOM radar images, it can be seen as the front of the storm passes the path between transmitter site and Berry Springs (the red line) the signal strength increased from the norm. As the rain front moved away, the signal gradually returned back to the norm of approximately -74dBm to -75dBm.

BOM RADAR IMAGES BETWEEN 14/03/12 20:55UTC - 14/03/12 21:45UTC

14/03/12 20:55UTC

14/03/12 21:05UTC

14/03/12 21:15UTC

14/03/12 21:25UTC

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14/03/12 21:35UTC

14/03/12 21:45UTC

BOM RADAR IMAGES BETWEEN 14/03/12 20:55UTC - 14/03/12 21:45UTC\

15/03/12 01:25UTC

15/03/12 01:35UTC

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15/03/12 01:45UTC

15/03/12 01:55UTC

15/03/12 02:05UTC

15/03/12 02:15UTC

.

The area around Darwin, as with many other areas in the tropical north of Australia, has high iron content soils. The photos above show the red soils around Darwin which typically have high iron content. During the wet season it is not

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uncommon for the ground to become supersaturated; this will no doubt change the conductivity of the surface relative to the dry season. While it is generally accepted that the ground conductivity does not play a major role in Band III VHF transmission performance perhaps extreme conditions will affect performance. The results above indicate that after a severe rain storm the transmission became more efficient. Also, while rain fading does not usually affect transmissions at VHF there is a possibility that extreme rainfall as experienced during cyclonic weather may impact transmission efficiency. Both of these aspects deserve further investigation to determine the impact of heavy rainfall and extreme weather on DAB+ transmissions. The proposed investigations will target the following questions relating to VHF Band III transmissions:

How does extreme rainfall impact transmission efficiency? o What is the impact of changes in ground conductivity? o Will transmission performance be reduced by propagation path attenuation due to extreme rain rates

Impact on coverage area

Impact on the ability of receivers to operate in emergency situations such as cyclones

Figure 5 Radioscape Test receiver screen shot

Observing the trial stability and content – Sensia receiver is being used to monitor off air. Grant Broadcasters

arranged for CRA to have remote access to the audio to be available remotely from FMON. They have installed

UltraVNC which is working fine for screen observation, control and file transfer but does not provide audio from the

remote unit. Radmin may be used for this.

PROGRESS ON COVERAGE MODELLING

Further field testing of a market which is using FEC code rate 1A to compare coverage and capacity against other rates,

especially 3A as used in the metro LAPs. CRA conducted the trials in Darwin and surrounds in mid April..

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SITE SURVEY OF DARWIN LICENCE AREA

A site survey around Darwin’s licence area has shown that the vegetation around Darwin is differentiated within areas of

the license area. It was found in areas around Humpty doo that the vegetation growth can reach around 10-15m and it

is quite dense as shown in the images below. While in areas around Berry Springs and Livingstone the vegetation

growth was not as dense or high as shown in the images below.

High and dense vegetation growth has a marked effect on radio signals. Trees and foliage can attenuate radio signals,

particularly when it is wet. Such factors will need to be taken into consideration when the DAB+ system is to be

designed to cover the whole of Darwin’s licence area and other regional areas. More field testing will need to done to

help tune any coverage predictions and plans in the future.

Humpty Doo Terrain

Humpty Doo Terrain

Livingstone Terrain

Livingstone Terrain

Figure 6 Site Survey for Humpty Doo and Livingstone Areas

ISSUES WITH TRANSMITTER SITING

A number of issues exist with the transmitter siting and flat terrain in Darwin.

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1. lack of cost effective data communications paths

2. active positive lightning strikes during wet season rendering copper pairs useless

3. lack of a clear line of sight from Darwin to Deloraine Road

4. lack of elevation (Deloraine Road is only 34 m above sea level, Darwin is 19 m above sea level)

It is understood that DAB+ transmission broadcast in Band III are optimised by being located at the highest point possible. Coverage maps showing the difference in height on the tower were included in the Canberra report. The Deloraine Road site is not located at the highest location in Darwin and is restricted by the need to protect nearby Defence assets and the airport which is used by both Defence and general aviation.

Deloraine Road is at 35m AGL and Darwin is 19m AGL. There is approximately a 40m ridge – between the main

transmission site and the population centre of Darwin which will impact reception.

Figure 7 Darwin Antenna site - Antenna Locations

ISSUES WITH POWERING REPEATER SITES

Figure 8

Powering of repeaters in some of the rural areas will be extremely difficult due to the lack of infrastructure from

power and water and telecommunications

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Figure 9

THE CHALLENGES IN TERMS OF REPLICATING FM (STEREO/MONO) COVERAGE.

The location of the current trial antenna at 77m as well as the section currently earmarked for DAB at xxxxm. Point

to the current FM location (transmitting at 30kW), which is higher than the location proposed for DAB (meaning

DAB+ will not get as far from the main site!)

Grant broadcasters originally broadcast from the Palmerston water tower in the prospect area which is higher than

the Deloraine Road site by 10 to 20m.

Investigation of the options for SFN repeaters to extend and improve DAB+ coverage have been underway and the

following sites identified by Grant broadcasters for repeaters

Experience from the fibre optic cable roll out from Darwin to Katherine shows that there was issues with vandalism

of the relay stations and generators. Equipment and cables were regularly removed or destroyed. DAB+ will need

to consider replacement funding by local councils if the integrity of the sites cannot be protected.

MULTIPLEX OPTIONS

Interoperability and time delay is being investigated in correspondence with suppliers and use of 3 of the 4 leading mux

equipment brands in trials and permanent services.. Confirmation that VDL and Radioscape encoder equipment are

compatible. Ongoing business developments may mean that the Factum systems will be compatible in the future.

Digidia have responded that they believe that their the FlexiDAB should accept EDI input from other brands of

equipment, however this needs software options for each "EDI input"

Interoperability tests (could be carried out on site and any issues resolved by sending Digidia EDI captures (network

captures using the "wireshark" tool) to check the Darwin trial mux is compatible with other EDI streams