Restack Discussion

[GoForMoe]

One concern that I have about the digital restack is that the decisions seem to be getting made without regard to what should happen with digital radio in both suburban community radio in large markets such as Sydney/Melbourne AND nearby markets eg. Gosford/Geelong.

The issue is more one of DAB+'s lack of suitability as a digital radio broadcast technology in the Australian situation than it is of digital television. Indeed the issue with bitrates is the opposite - there's too much for the small markets.

To look at Melbourne, there are a dozen or so stations that are low power community broadcasters, each with an exclusive coverage area including only their station - but the way DAB+ works is that it has to have the same 1.5MHz block of spectrum to broadcast one station to one area as it does to broadcast 20. The simplest solution would be a high powered community multiplex carrying all of them across the city, but that would put a station like WYN FM with a tiny target audience around Werribee on the same footing as the community stations covering the whole city - potentially lessening their focus on their local area in favour of targeting listeners across the city because they can. That's less of an issue with Joy of course, but still the basis of planning.

An earlier proposal about the inner city community stations was to basically group them into sub-metro areas and put them together, but even that would require a huge amount of additional bandwidth. Otherwise planning has more or less ignored them, simply because it isn't in the broadcaster's interest. Commercial Radio works on there being a scarcity of spectrum, because otherwise anyone could start up a radio station and ruin their business - it's only because there isn't enough to go around that the broadcasters can have a monopoly or near to it - which works in their interest, which is why they've pushed the government for the spectrum reservation they got and deferred the difficult questions on smaller stations for later.

There are two sources of additional DAB+ bandwidth - 'Channel 13' which is currently used by the Department of Defence for communications (which would double the amount of DAB+ spectrum), and the 'L-Band' which is used for some point to point links, is unsuitable for wide range broadcasting and not supported by all radios on the market. Both of these are more likely than cutting bandwidth from television, or moving more to UHF.

The other path is to use a different type of digital radio - DRM/DRM+ are being broadly considered for Australian usage and work on a smaller spectrum block than DAB+ does, which creates more flexibility in where the transmitters can be and would make digital broadcasting possible for the small stations. The downside here is that there are very few receivers on the market.

The more likely scenario is that they simply never go digital and either fade away through the lack of funds for operating costs, or move online. Or just keep going on FM where all the listeners are.

[dkint3]

but what say in the Sydney market for instance.. you have 17 low power community radio services in suburbs that are currently also covered by high power FM/DAB+ services from Artmaron

If you only have 4 channels in 8A, B, C, D available for use, do you:

(1) create four multiplexes in major hubs like Parramatta, Penrith, City and one other and put 4 to 5 services on each and create overspill

or

(2) re-use eg. Channel 8A in 4 or 5 different suburbs and hope no signal jamming occurs in each other's market?

(it obviously couldn't be an SFN type arrangement as they would each be carrying different services).

These scenarios also assume DRM is going to be used for adjacent markets like Gosford and Wollongong.

Edited January 7, 2013 by dkint3

[GoForMoe]

The rollout will start from the largest markets and work down - so places like Gosford and Wollongong would get DAB+ multiplexes, and once those were covered they'd start looking at what they could cover with the spectrum remaining.

I can't see there being anything left in Sydney itself, especially not enough to cover all the areas with stations. Perhaps in inner Sydney they could reuse a frequency used by Newcastle at very low power, but there's a lot of interference potential.

Even if we had the spectrum assigned to DAB, it is still very inefficient usage of it - they would be very expensive broadcasts for only a few stations - going digital just won't be worth it.

[nbound]

They wont be carried on DAB, at this stage DAB is to complement FM, not replace it.

The only services on the DAB multiplex are those licensed to cover the entire Sydney radio license area.

These other stations are only licensed to certain districts instead (eg. Parramatta, Campbelltown, and so on). Which is also why they are low power services.

Sydney-wide Services would be as-is 9A+9B (Commercial/Community) and 9C (ABC/SBS)

Localised community stations continue as-is on FM.

Wollongong/Newcastle/etc. would then use different DAB channels for commercial/community, and probably operate ABC/SBS in an SFN with 9C in Sydney.

In small enough markets assuming DAB is chosen over DRM, all regionwide commercial/community services could potentially be grouped into a signal multiplex. (eg. Darwin DAB Trial)

If a statewide ABC/SBS SFN is used, ABC Local Radio would need to be moved onto the (whats currently the) commercial/community multiplex to provide local content.

Edited January 7, 2013 by nbound

[nbound]

A highly speculative Illawarra DAB channel plan may look a little like this:

First multiplex-

2WIN - i98FM - Commercial (WIN Corporation)

--- Digital only stations---

2UUL - Wave FM - Commercial (Grant Broadcasters)

--- More digital only stations---

2RPH - Radio Print Handicapped - Community

2LIV - Pulse 94.1 - Community

2VOX - Vox FM - Community

2ILA - ABC Illawarra (Local Radio) - Public

Second multiplex-

Statewide ABC/SBS services

Nowra licensed stations would remain on FM (ie 2ST and Power FM). Nowra is covered by the Wollongong RA2 FM license area though, and would likely receive hypothetical Illawarra DAB broadcasts just fine. This is in addition to the Sydney DAB broadcasts that would be available around the Illawarra depending on location.

Edited January 7, 2013 by nbound

[dkint3]

They wont be carried on DAB, at this stage DAB is to complement FM, not replace it

....

A highly speculative Illawarra DAB channel plan may look a little like this:

Thanks for your replies, nbound and GoForMoe.

Now I always thought digital radio (be it DAB+ and/or a DRM format) would replace FM radio, albeit in 20 years time or so.

So community radio is going to have to be accommodated somewhere, sooner or later.

If they do decide to use both 9 and 9A for metro wide services only, I would hope existing multi-channel services (eg. MIX and sub-channels 80s, 90s) are 'spread out' across 9 and 9A so that higher bit rates can be used.

48 kbps sounds downright horrible for music.

.......

As for the Illawarra plan, where would you put it? On Channels 8A and 8B?

[nbound]

Could be anywhere that isnt used by neighbouring sites, there was a speculative channel map image floating around for a while, but i beleive it used a different scheme then what mine is based on.

Theoretically it may be possible to have services (such as those in Nowra) on a low power DAB channel as well, as GFM suggests. Though I dont think there is enough space for that.

DAB may replace FM in a few decades, but by then it will be a few generations old and have a larger data bandwidth, and spectrum space wont be an issue.

[GoForMoe]

Well in theory it could replace FM at some point in the future, but the benefits just aren't there - the sound quality point being the main one. If it got to the point of commercial viability, the existing AM/FM commercial stations could choose to turn off their analogue signals, and then community stations could move to better analogue frequencies to improve coverage.

No additional channels will be assigned to Sydney's main stations - basically they got 128kbps per AM/FM licence on digital - then community stations shared 256kbps per commercial multiplex (so 512kbps in Sydney) - so apart from a sale of the slight excess of capacity after that was done, there's nothing more to give. Mix's solution is simple - 32kbps music stations, so they can add even more stations in the capacity they have.

The good thing will be that the regional multiplexes will be less congested, so if you're within receiving range of their transmissions (which you likely will be in most parts of Sydney for at least one regional area) you might get some good quality stuff from the local stations, including regional community stations, just the sub-metro ones and smaller regional markets close to big cities will find it very difficult.

At least in theory the decision on regional digital radio hasn't been made - but I'd put money on DAB being chosen nationwide without any thought of the issues rightly raised about small community stations.

[dkint3]

I think you're right.... That DAB+ will be used wherever possible.... Wherever there is a DVB-T service, I think there'll be DAB+ radio in VHF Band III.

I think DRM will probably only be used for shortwave/national ABC radio services and possibly regional ABC services like 2CR Orange and 3WV Horsham that have a large footprint.

[Digital Penetration]

I think DAB+'s main use is in replicating/replacing interference prone AM services in areas of high population concentration. There's no reason to use it to replicate FM services atm.

[RF Burns]

I think DAB+'s main use is in replicating/replacing interference prone AM services in areas of high population concentration. There's no reason to use it to replicate FM services atm.

I agree, & this is going off topic for the DTV re-stack but, if AM services were given a fighting chance, it wouldn't be needed for to replace AM either.

AM radio in Australia & the USA alike, haven't had an AM transmitter power increase (except for a few who have gone day/night switching), for over 30 years, but the background noise floor, from non-broadcasting equipment has risen quite significantly, which is why AM radios are suffering interference.

Many broadcast engineers in the US are wanting AM power increases, with broadcast engineers & listeners as well, now coming to the idea/conclusion, that it would be much better to turn off IBOC HD radio, & increase the analogue AM TX powers.

This is a brief of a petition sent to the US FCC, outlining just that (more or less). http://www.radio-bro...rence-power.htm

I have actually read a very detailed paper written by some radio broadcast engineers, about how modern electrical equipment has increased in use, & created much higher levels of interference to AM radio. Why they want AM radio power increases & the positive effect it will have on reception, quality & coverage, along with more listener satisfaction & efficient use of the AM broadcast band spectrum. Unfortunately I can find it, but will post a link if I do. This goes further into the story, but isn't the detailed paper I read. http://arstechnica.c...0x-power-boost/

[alanh]

Dink3

All DAB+ channel allocations in Australia will be in 195 - 205 MHz range which is TV channels 9 and 9A or labelled as DAB+ channels 8A, 8B, 8C,8D, 9A, 9B,.9C and 9D. Remember that tranmitters on the same channel must be atleast 320 km apart. So this leaves Sydney, Illawarra, Canberra, Central Coast, Hunter Region (Newcastle) and Central Tablelands to fight it out. For example Canberra and Hunter Valley may be able to share transmitter frequencies. Sydney being in the centre cannot share wth anyone.

GlennP

AM version of HD radio is virtually unused at night time in the USA due to interference at existing power levels. This can only get worse if power levels increase. Increasing power levels will be a trade between interference and noise.It does not fix the appauling receiver design which limits the high frequencies to voice quality.

AM has been around about 112 years so not only has the electronic noise level increased but so as technology. So why to we have to persist with a poor system when there is much better ones around.

Alanh

[Theres Always Radio]

AM has been around about 112 years so not only has the electronic noise level increased but so as technology. So why to we have to persist with a poor system when there is much better ones around.

Alanh

Dear reader (AlanH excluded as this has been previously noted)

The emergency services broadcaster knows that in the event of requiring communications for an extended period to isolated people in a natural disaster, AM radio is the only technology capable of fulfilling this role due to coverage capability and power consumption efficency.

James

[newtaste]

This is a speculative digital radio spectrum reuse allocation from ACMA for the surrounding areas of Sydney.

From: https://docs.google....WCsLxZPw2NEQuug

[GoForMoe]

It's worth noting the notes from that slide (Google Docs doesn't show it for some reason), which is what was spoken with the slide - a lot of it reiterating points made by others here.

•The current legislation envisages that two DAB+ multiplexes – one for the nationals, the other for commercial and community broadcasting – would be offered in each commercial radio licence area, right across the country.

•As each DAB+ channel is a little over 1.5MHz wide, 14MHz – two ordinary television channels – only fits up to 8 (eight) DAB+ multiplexes.

•If you were to plan these multiplexes like ordinary, high power FM radio services, with a single transmitter serving something like the current FM coverage area, you would ideally need to have about 300km distance between co-channelled transmitters to avoid mutual interference.

•So let’s stick with Sydney and consider its surrounds.

•Three of your eight multiplexes are already in use – for the channel 9A services. The semicircle represents the 300km re-use distance, and as you can see, there are far too many commercial radio licence areas within the semi-circle, if it is wished to have two multiplexes, on their own separate frequencies, in every one of those markets.

•In fact, if we wanted to plan DAB+ the way we have planned FM in the past, you would need practically the whole of VHF Band III to do it – in places like the Sydney hinterland, it would take up the equivalent of seven out of the eight TV channels in the band.

•As television needs most of those channels, other ways will need to be found.

•We could throw up our hands at this point and say, well there isn’t enough VHF spectrum for DAB+ digital radio. And there are other options. These might include, for example, use of 1.5GHz spectrum known as the L-Band – a second range of frequencies internationally identified for digital sound broadcasting (though not widely used). Or we could restrict further use of DAB+ to a few larger centres, such as Canberra and Newcastle, and introduce a second technology for the smaller markets. [DRM+, a rival European digital radio standard from the Digital Radio Mondiale family of standards, is commonly mentioned at this point. DRM30, its lower-frequency sister-standard, might also have a role in replacing wide-coverage AM radio. The DRM standards family could make use of parts of the spectrum not used internationally for DAB+.]

•But the L-Band option has to date attracted little support from within the radio industry. And whatever the eventual role for the DRM family of standards, the interest here and now is in planning innovatively, to make best possible use of DAB+ in the VHF spectrum that has actually been set aside for it. The attitude is ‘let’s make this work,’ meaning, let’s as far as possible try to bring VHF DAB+ digital radio to all regional markets.

•So can it be done?

•Ultimately, when and how the radio industry makes use of the 14MHz will be a question for the Government – whether for the Minister, who has the key role of determining commencement dates for digital radio in regional markets, or – if it is wished to vary aspects of the current legislative scheme – for Parliament itself. (And let’s not forget that someone will have to want it enough to actually pay for it.)

•But in terms of accommodating a regional DAB+ roll-out using only the present 14MHz, at least two directions of technical planning research would appear to hold out some promise.

•One idea is the use of very wide coverage single frequency networks, allowing re-use of the same channel within the 300km radius. Potentially, the DAB+ technology would allow regional national services to be co-channelled across all the regional markets shown in this example.

•Another – which has already been canvassed publicly by Commercial Radio Australia - would entail use of only a single DAB+ multiplex in smaller regional markets, which typically have only small numbers of existing radio services.

•Both these potential lines of inquiry immediately throw up further issues and challenges. But our engineers believe they represent promising lines of inquiry. While the choices they throw up are ultimately matters of policy for Government, the ACMA’s Digital Transition Division is mindful of its role as a key source of technical advice on planning issues. We are interested in talking with the radio industry and anyone else with light to shed on future technical options for digital radio.

•So if that’s you, by all means please treat this as an invitation.

I did a dartboard of spectrum allocation around Sydney with a ABC/SBS SFN assumption a while back. You could probably reprioritise if you ignored some of the smaller markets like Katoomba and Campbelltown - assuming no other changes, dropping Campbelltown and using 8D would be more suitable than 8A at the Central Coast, and dropping Katoomba and using 8B at Wollongong. But what you've just done in doing that is more or less deny two commercial radio stations on the edges of Sydney a chance to go digital, probably very long term.

One of my assumptions in the map that I would suggest has merit is that 9D be used in Newcastle (and the Gold Coast and Geelong) for DAB+, as it becomes available much sooner than 8A-8D - and these secondary cities seem like the places with the strongest likelihood of being the first regional sites for DAB.

Edited January 9, 2013 by GoForMoe

[nbound]

I wonder if we'll see a radio aggregation/amalgamation of some markets to ease the planning burden.

[nbound]

Remember that tranmitters on the same channel must be atleast 320 km apart.

Im not sure this is exactly true. Else we would already have problems.

ABC9A (dig) in Canberra is less than 320km from DAB9A,9B,9C in Sydney; DAB10B in Canberra is also in turn less than 320km from TEN10 (analog) in Sydney. (Distance is roughly 250km as the crow flies).

SBS9A (dig) for Manning River is also less than 320km from DAB9A,9B,9C in Sydney Sydney. (Distance is roughly 280km) [NEN9 (dig) also exists at this site]

All transmisions mentioned above are Vertical (excluding TEN10) and are high powered (except DAB10B [Canberra]).

There are also low powered 9A sites at Bathurst (V - 160km from SYD - also a service on CH9), and Batemans Bay (H - 250km from SYD). Im going to assume you meant high powered sites at that distance so these can be ignored if you like.

Even ignoring the sites that are cross-polarised in relation, there doesnt appear to be much interference going on at this stage.

TCN9 in conjunction with NEN9 (Manning RIver), and to an extent SBS9 (Bathurst), rule out DAB8A-D services for much of the area surrouding Sydney.

ABC9A, SBS9A, and to an extent CTC9A (Bathurst) and ABC9A (Batemans Bay), rule out DAB9A-D services again for much of the area surrouding Sydney.

Further out, similar services exist on more distant transmitters.

If the comment was refering to what was said in the PDF that newtaste linked to above (with the DAB allocation picture):

Due to interference protection requirements, no VHF channels are available for digital radio within approximately 300 km radius around metropolitan areas until analog TV switch off.

I beleive that this is refering to the lack of spectrum due to the DAB channels already being in use by TV until post switchoff/restack [as demonstrated above]. Not due to any magic barrier at 300/320km. The terrain considerations for most sites over the dividing range would make the 300/320km figure seem even less likely.

Edited January 10, 2013 by nbound

[alanh]

You cannot believe all you read without analysis;

In the Illawarra, which areallocated to TV in the Sydney TLAP. Were Channel 10 in Sydney to start broadcasting at high power, it would make digital radio reception very unreliable in the Northern Illawarra. The ACMA is constantly saying that DAB+ radio is on TV channels 9, 9A which equals DAB+ channels 8A - 8D and 9A - 9D.

The 320 km separation is for a pair of 50 kWerp omnidirectional transmitters. For Canberra and the SW Sydney, it can be closer because SW Sydney won't be as powerfull and for Canberra the radiation pattern will have a reduction of power in the NE direction.

There is no evidence of the use of SFN for the ABC/SBS in the above map. For this to be true all areas would have one channel allocation which is identical, and this is not the case.

AlanH

[nbound]

In the Illawarra, which areallocated to TV in the Sydney TLAP. Were Channel 10 in Sydney to start broadcasting at high power, it would make digital radio reception very unreliable in the Northern Illawarra.

What on earth are you going on about. Structure and add context to your sentences please!

Regardless, last i checked CH10 Sydney was high power!? (200kW analog)

The ACMA is constantly saying that DAB+ radio is on TV channels 9, 9A which equals DAB+ channels 8A - 8D and 9A - 9D.

This has been repeated multiple times on this page already, including my post directly above.

The 320 km separation is for a pair of 50 kWerp omnidirectional transmitters. For Canberra and the SW Sydney, it can be closer because SW Sydney won't be as powerfull and for Canberra the radiation pattern will have a reduction of power in the NE direction.

Where are we pulling SW Sydney from?

I said the Canberra DTV ABC9A (50kW, V, Omni), and the Sydney DAB9A,9B,9C transmitters (50kW, V, Omni) are only 250km from each other!

Manning River SBS9A (80kW, V, directional*) and the Sydney DAB9A,9B,9C transmitters (50kW, V, Omni) are only 280km from each other!

*Sydney is not at the centre of any of the 80kw allowable headings so i will concede it wont be blasting the full 80kW at Sydneys angle. It is a full 20 degrees within one of the 80kW regions from the nearest edge though, so is likely still blasting a significant amount of Signal in Sydney's general direction.

There is no evidence of the use of SFN for the ABC/SBS in the above map. For this to be true all areas would have one channel allocation which is identical, and this is not the case.

Noone said their was, most of the discussion surrounding this has been hypothetical. It would only be statewide [or even timezone wide] services on any potential ABC/SBS SFN anyway (ie. ABC Local Radio would have to be moved to the commercial/community multiplex). Even without going as far as the statewide, regional ABC/SBS SFNs could still be implemented (and then carry several ABC Local Radio stations for each of its constituent sub-regions - though given the current multiplex usage this would require a drop in station bitrates).

Edited January 10, 2013 by nbound

[CWulf]

Re TV chans for DAB+. Chs 9 and 9A will be made available for DAB+ in metro and regional licence areas but will continue to be used for digital TV in some remote licence area markets.

So, if (and that's a big if) DAB+ was to roll out in those areas it would be on channels other than 9 or 9A unless the radio broadcasters were able to get the TV broadcasters to change channels.

Look at the discussion in the discussion paper and engineering report for the ACMA DCP variation for RCEA. (Sorry no links as having enough trouble typing this in the iPhone browser )

[nbound]

Re TV chans for DAB+. Chs 9 and 9A will be made available for DAB+ in metro and regional licence areas but will continue to be used for digital TV in some remote licence area markets.

So, if (and that's a big if) DAB+ was to roll out in those areas it would be on channels other than 9 or 9A unless the radio broadcasters were able to get the TV broadcasters to change channels.

Look at the discussion in the discussion paper and engineering report for the ACMA DCP variation for RCEA. (Sorry no links as having enough trouble typing this in the iPhone browser )

For sites where one DTV channel exists in 9/9A i assume they would just use DAB channels from the other channel.

For sites where two DTV channel exists in 9/9A i assume they would just use DAB channels from other within the other empty VHF channels* (it would only become a problem if manufacturers create device firmwares which only scan 8 & 9 A,B,C,D for the Australian market.)

Of course, I agree that its a very big if, and probably a long way into the future for many of these sites.

*Not the UA placeholder DTV allocation, but from either of the completely unallocated channels that would exist.

Edited January 11, 2013 by nbound

[nbound]

As we currently seem to be focusing on VHF, heres a pretty table which is a good reference for TV channel to DAB allocation comparisons, as well as international allocations.

http://upload.wikime...c/VHF_Usage.svg

Edited January 11, 2013 by nbound

[alanh]

Cwulf,

If you think that Wollongong is a remote area then Brisbane must be a regional area.

[CWulf]

Cwulf,

If you think that Wollongong is a remote area then Brisbane must be a regional area.

Sorry Alan - no idea what your referring to (as usual). My comment was in response to your claim that "The ACMA is constantly saying that DAB+ radio is on TV channels 9, 9A ..." which as I was trying to point out is (also as usual) a misrepresentation of the ACMA position in that this is only the intent for regional (ie Wollongong) and metro (ie Brisbane) areas but won't necessarily apply to ALL of Australia.

As Nbound (and probably many others realise) the danger of saying that Australia will only have DAB+ on TV channels 9 and 9A is that manufacturers may produce receivers that only operate on those frequencies and such receivers would therefore not operate in areas which used frequencies outside channels 9 and 9A.

[alanh]

CWulf

There is no chance that manufacturers will only make receivers for DAB+ channels 8A - 9D. The international DAB/DAB+ specification is for receivers to receive all channels from DAB+ channel 5A (174.928 MHZ) to DAB+ channel 13F (239.344 MHz), even though we don't use 230 - 240 MHz for TV. The Australian Defence Force will not release these frequencies for civilian use.

If you read the TV restack plan it shows that TV channels 9, 9A (DAB+ channels 8A - 9D) are allocated to digital radio. It is only some TV transmitters in remote areas which will be allowed to stay on channels 9 and or 9A. But note that the digital radio standard for regional and remote Australia is yet to be chosen. DAB+ has a much smaller coverage area than DRM particularly at low power.

AlanH