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alanh

ABC now promoting DAB+

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The ABC management has been kicked by the politicians and others because they switched off all receivable radio to most of the NT and surrounding areas. The money is to be used instead to pay for DAB+ transmitters in Darwin, Gold Coast, Canberra and Hobart. It has been pointed out that the reason they think that there was no listeners for NT short wave was that they do not promote it or even acknowledge its existence except for a few lines on their Reception line site. Only a few know it existed. Their location information recommends AM and FM transmitters thousands of km away!

Similarly they are constantly advertising listen on the phone via the app, which costs the listener to listen, where as with DAB+ it is free after you buy a receiver. I pointed out to the parliamentary enquiry that they don't advertise DAB+ limiting the number of listeners. The reason they are doing this is because in the 1990s the ABC in the Eastern States were converted to high powered FM except for the capital cities because they were scared of loosing listeners. If they had bitten the bullet, now mobile phones' FM tuner would work on their programs as it is now, no phone receives AM so they want you to use an app instead.

http://www.abc.net.au/radio/perth/dab+-radio-upgrade/8622144

They also have been playing an "advertisement" for DAB+ in the breakfast program weekdays.

Alanh

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Hi Alan.  Haven't you heard the ABC say "On the radio, on mobile and on digital"? or "On the radio, online and on digital?" or similar?

 

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All a bit pointless promoting it when DAB coverage is still quite flakey and the ABC's digital coverage is the worst.

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My issue with ABC advertising is that often their information is wrong.

They promote a radio program, without pointing out that it is only available in State Capitals.

They also promote a radio program as available on "digital radio" when it is not available on DAB+.

To their credit, they remove incorrect information from their websites, when I send them an e-mail. However, they never reply to my e-mails.

 

 

 

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And they have gone back to their old habits in Perth of continuing after the breakfast program with their Saturday morning Sports Talk program on the local ABC Perth digital service instead of breaking away as they should to the nation wide alternate program. They only do this in the non daylight saving period.
The sport program is also broadcast on the Grandstand digital service as well as the normal statewide AM and FM local radio stations so there is absolutely no need for it to be on the local Perth ABC radio digital service too. I had correspondence with the station manager two years ago when they started to do it and was told that it was to get more coverage via the digital service. (Edit: It was also suggested that I could listen to a rebroadcast of Glynns' program "It's Just Not Cricket" on Sunday morning at 4:00 am or some such ridiculous time!!! Or I could listen on line - but I didn't get a digital radio to be reliant on being tied to the computer) I did go on to point out that there was already the coverage on digital through the Grandstand channel. However a few weeks later as I recall it did change, but in hindsight I think that was because daylight saving started again. Last year they got it right but as I said they have got it wrong again this year ever since daylight saving finished.

Hey Alan, maybe with your alleged connections you can get it sorted. After all, you have said that Glynn Greensmith's program is worth listening to, so surely you too are not happy about their nonbroadcasting of the first hour here in Perth? And Glynn often promotes the alternate program availability on digital of his and other programs when sport is on, so for Perth to NOT broadcast it is surely incorrect by the programmers.

Edited by hrh

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Ron,

In the ABC's terms digital means on line either via the internet or by phone not by DAB+ transmitters.

Liz,

Where I am the coverage areas compared to the commercials is identical and I am talking of the edge of the coverage area where both ABC and commercial signals break up.

DAB+ repeaters are still required on TV translator sites which do not have substitutes such as Bilgola replaces Bouddi where there is to be no coverage in the adjacent licence areas.

After all the DAB+ transmitter power is the same as the TV power from the main transmitter sites and the channels used surround the DAB+ channel giving similar coverage areas.

What are you using for a receiver and what is the antenna. If it is inside, is there a metal roof or a unit above you? Have you tried listening to DAB+ in one of the new cars so equipped?

Hrh, I am a big fan of Glen's program but he is a contractor who has another job during the week outside of the ABC.

The ABC seems to be unaware that all telcos sell 1 GB of prepaid data for $10 per month. Their programs are sent to the phone at 64 kbit/s.

I wrote to the producer of the Drive program who keeps recommending that listeners use their phone between 5:30 - 6pm on Fridays and some Thursdays when the footie is on. I pointed out to her that if a listener listens to her program every weekday for a month and a half the listener would have paid for a DAB+ radio from a chain store.

Remember that the ABC rejected an offer in the 1990s for metro local radio stations to go FM. They thought they would loose listeners. The high powered FM local radio network was rolled out down the eastern seaboard an is on air today.

 

Alanh

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El Saif,

The ABC can and does split their networks between capital cities and country areas. For example the advertising I mentioned in my initial post was in the breakfast program is local. For example Dan Bourchier does breakfast, Genevieve Jacobs mornings and Adam Shirley Drive where as their Sydney equivalents are Robbie Buck, Wendy Harmer and Richard Glover.

The only DAB+ promos I have heard have been in the local breakfast program.

Alanh

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11 hours ago, alanh said:

Hrh, I am a big fan of Glen's program but he is a contractor who has another job during the week outside of the ABC

And that has what to do with them not broadcasting the first hour of his program in Perth as well as the two programs preceding it after the breakfast program which is available to rest of the DAB+ audiences in the other cities? By the same thinking then, they may as well not be broadcasting part of Tracey Vo's programs!!!

As per usual you are telling me what I already know, (not that I have said so as such) that being I am fully aware that Glynn has a job at one of the tertiary institutions, because he is who I first corresponded with regard to the non-broadcasting of his program two years ago.

Edited by hrh

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Alan, I'm using the DAB radio in my 2016 Camary Atara as a reference point. In home dab reception west of Blacktown is very hit and miss and has been ever since DAB+ launched. Mobile reception via a car radio is too patchy to be useful. Large trucks moving by me on the highway is enough to see the audio disappear for a minute or two usually during the most interesting part of an interview. So even though I've got a DAB equipped car we use AM/FM only because it reliably covers the Sydney area something DAB is a long way from yet.

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1 hour ago, lizclinton said:

So even though I've got a DAB equipped car we use AM/FM only because it reliably covers the Sydney area something DAB is a long way from yet.

Yeah,roll out and acceptance is very slow,probably a decade or more before its a feasible alternate to FM.

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Liz,

When DTV started there were quite a few posts about unreliable reception in Penrith and surrounding areas. There was a few causes for this, one is the level of interference due to industrial activities including high voltage power lines, the distance from Artarmon and the terrain.

When television started in 1956 there was only a very small population in Western Sydney and with the deep valleys along the coastline, it was decided to put the TV transmitters in Gore Hill, Willoughby and later Artarmon. If this decision was to be made today I suspect that another high point further west would have been used. Since all fixed outdoor antennas are directional it is unlikely that the main Sydney transmitter site will change. The solution has been to create a network of UHF translators to fill in the shadow areas. Considering that on the main transmitter sites DAB+ transmissions are between TV channel "9" and TV channel "10" and all transmitters including digital radio are at the same power. 

The coverage area for TV is defined as reliable reception from antennas up to 10 m above the ground. This is unlikely to be the case for DAB+ for headphone portable, tabletop and car radios.

The current TV translators in the Sydney licence area on the left and the DAB+ repeaters are in italics

far Northern Beaches (Bouddi)  Sydney Northern Beaches (Bilgola)

Sydney North West (Kurrajong Heights). Penrith (Hawkesbury)

Manly/Mosman, Collaroy Plateau (Collaroy) which should reach Manly

Kings Cross for Sydney City, Neutral Bay and the Eastern coastal suburbs  Sydney City 100 Market St for Sydney City, Neutral Bay and possibly Mosman

Sydney South (Redfern)

Sydney South West (Razorback), Campbelltown (Gregory Hills)

Picton,

Woronora

What is needed is to produce a second http://myswitch.digitalready.gov.au using the same program but inserting an antenna height of 1 metre instead of 10 m and the height of the DAB+ antenna on the Artarmon transmitter and the sensitivity of DAB+ receivers. A new colour should be added to indicate indoor reception to include and allowance typical absorption of building materials. and also including the repeater sites. Hopefully it will discover the areas of insufficient signal strength in your area and other.

How reliable Is the FM radio reception (does the stereo indicator stay on) where the DAB+ disappears?

I ask this question because the main FM transmitters are 160 kW and commercial 150 kW but the DAB+ is 50 kW.

If stations use the alternate frequency system where on DAB+ and FM RDS a table of alternative sources of the same program will cause the receiver to automatically switch to the best signal. This is up to the broadcasters to transmit it, I don't know how many DAB+ receivers will respond and lastly there is a delay in encoding and decoding DAB+ signals which can cause either part of the program to be repeated or be lost on the switch.

 

Lastly I blame some car manufacturers for poor DAB+ reception because of the sharkfin antenna. is nowhere near 1/4 wavelength long (370 mm) https://aerpro.com/ct27uv57 as a better example. The sharfin are more designed for the frequencies used for GPS.

 

Alanh

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Alan, I'm not sure what all the DTV references have to do with DAB but yes we do have a bit of multi path interference around the area on FM but some flutter is easy to live with when compared to all audio vanishing at the most inconvenient moment like DAB does. Most of my listening is to 702 ABC Sydney and it's on good old reliable AM so coverage is excellent everywhere I go but I must say it sounds fantastic on DAB when I'm east of Blacktown. If only DAB coverage wasn't so poor and I find it totally irresponsible of the ABC to promote DAB as an "upgrade" to its AM broadcast when many will find themselves outside of its coverage area.

Edited by lizclinton

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Liz,

The DTV is relevant because the transmitted power is the same as DAB+ as is the transmission frequency is very similar and their transmitting antennas are on the same towers.  Some FM transmitters are on the same towers but their power is higher and their frequency is roughly half meaning that it will go round obstructions better. DTV use the same modulation system as DAB+.

The effect of multipath reception is distortion on FM if the DAB+ is subjected to the same multipath reception will cause errors. If the errors are sufficient then cannot be corrected and the receiver will mute.

High levels of reflections occur in the CBDs because of the tall buildings which also block the original signal at ground level. This is why the first DAB+ repeater was installed in Collins St Melbourne CBD. Now there is repeaters in Sydney and Perth CBD for this reason. Parramatta has tall buildings so there may be a case for another repeater on the top of one of those buildings.

You should put a complaint into http://www.abc.net.au/reception/contact/ and let us know their reply.

This is what the ABC claims to be the coverage area https://www.google.com/maps/d/viewer?ll=-33.79740899999998%2C150.99609399999997&spn=0.798849%2C0.961304&hl=en&msa=0&z=9&source=embed&ie=UTF8&mid=1kNyJ8aqkP_HS4-IuHhTgrnl2JeA

and the Commercials version of the coverage area

http://www.digitalradioplus.com.au/DigitalRadioPlus/media/DRP_Media/Coverage-Maps_Sydney.pdf

Neither of these maps have the repeater coverage and the level of detail used by the 3D computed coverage area maps on www.myswitch.digitalready.gov.au for DTV.

What is your reception like at home?

I particularly like the high frequencies and the stereo sound. It is a pity they don't use stereo sound during interviewing a guest.

Alanh

 

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While I understand that DAB operates on similar frequencies to DTV and here in Sydney the main transmitters are co located with the DTV services. As a non technical person I would have thought a 50Kw 1.5Mhz wide channel would propagate differently to a 50Kw 7Mhz wide channel radiated from the same antenna not to mention I'd expect the error correction to be far more robust on the DAB signal when compared to DTV. Looking at the coverage maps the ABC one looks exactly right from my experience and the commercial one is incredibly optimistic or just completely incorrect. We have DAB in home coverage but it's only in certain spots through the house and nothing like what anyone would call acceptable for a home well inside the licence area. How broadcasters have been allowed to have no coverage in some parts of their licence area is quite odd. I was always of the opinion that if a broadcaster chose not to serve parts of their licence area those parts were permanently surrendered from the licence area but obviously that's just not the case.

Edited by lizclinton

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Liz,

4 DAB+ channels fit into a TV channel. The total power of the channel is being measured so one would expect that the total power of the 1.5 MHz of the DAB+ channel would be 4 times higher than for a 1.5 MHz portion of a TV channel. This is an increase of 6 dB. However this increase is drop in the ocean when compared to the losses introduced by buildings, blocking terrain etc.

The question about the maps is why are they different? The pair of commercial transmitters and the repeaters are identical to the ABC/SBS transmitters and repeaters. The operating frequencies are very similar so the maps should be identical, however how were they produced?

Was it driving selected routes measuring the signal strength, which means lots of areas are unmeasured.

The myswitch website map is likely to be the most accurate because it is computed using a 3D map of the earth and well researched formulas which calculate the path losses.  It does however assume the antenna is outside and up to 10 m above the ground.  The map has no details about buildings and vegetation blocking paths. At 10 m above the ground it is less of a problem than 1 m above the ground as is the situation in cars.

Are you using the telescopic antenna fully extended and vertical? What is the roof made of? I ask this because my next door neighbour used to have a concrete tile roof and her mobile phone was fine. The roof was replaced with a steel roof. Now she has to use the phone outside. Radio waves do not travel through metal. The reason why the AM radio has a wavelength around 300 m compared to DAB+ which is around 1.4 m.

Metal blockages which are a wavelength or longer in size it will drastically reduce the signal strength. This is why you are having less problem with AM. In addition the path that your AM signal is from Prestons which is different to the one from Artarmon.

http://www.acma.gov.au/licplan/defmaps/documents/maps/la_542.pdf is the licence area for commercial/community radio stations. The Licence area is to keep other competitors out.

Please complain to the ABC reception site.

Alanh

 

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11 hours ago, lizclinton said:

While I understand that DAB operates on similar frequencies to DTV and here in Sydney the main transmitters are co located with the DTV services. As a non technical person I would have thought a 50Kw 1.5Mhz wide channel would propagate differently to a 50Kw 7Mhz wide channel radiated from the same antenna not to mention I'd expect the error correction to be far more robust on the DAB signal when compared to DTV. Looking at the coverage maps the ABC one looks exactly right from my experience and the commercial one is incredibly optimistic or just completely incorrect. We have DAB in home coverage but it's only in certain spots through the house and nothing like what anyone would call acceptable for a home well inside the licence area. How broadcasters have been allowed to have no coverage in some parts of their licence area is quite odd. I was always of the opinion that if a broadcaster chose not to serve parts of their licence area those parts were permanently surrendered from the licence area but obviously that's just not the case.

Hello Liz

Although you state you are a non technical person you are in fact much closer to the mark than those responding have chosen to acknowledge.

"As a non technical person I would have thought a 50Kw 1.5Mhz wide channel would propagate differently to a 50Kw 7Mhz wide channel radiated from the same antenna not to mention I'd expect the error correction to be far more robust on the DAB signal when compared to DTV." You are so spot on, others noting the same 50kW ERP for both DTV and DAB is an utter irrelevance as compared to the error correction capability afforded DAB+ due the adopted modulation method as you correctly note.

Responses such as this are inept and seriously flawed " 4 DAB+ channels fit into a TV channel. The total power of the channel is being measured so one would expect that the total power of the 1.5 MHz of the DAB+ channel would be 4 times higher than for a 1.5 MHz portion of a TV channel." This is an increase of 6 dB."  Possible differences in horizontal radiation pattern ie antenna system gain and differences in licensed ERP leave no doubt this is a ridiculous statement to make.

Going back to your "robust" comment, here's some technical stuff. What DAB+ does is use a different modulation scheme to DVB-T, DAB+ uses DQPSK whereas DVB-T presently uses 64QAM. (Slower data rate permits weaker signals to be recovered) In essence the difference between how much the received DVB-T signal needs to be above the noise floor over how much is needed for DAB+ is around 12dB, ie DAB+ can operate from a much weaker signal.

All three DAB+ ensembles are  being transmitted from Artarmon tonight and once you get to Blacktown, Artarmon reception is terrain dependent and the on channel repeater at Hawkesbury Heights becomes line of sight for you, again transmitting all three DAB+ ensembles.  This may the issue you are facing, your DAB+ receivers with no directional antenna are struggling with multiple sources combined with terrain reflections. If your television at home from Artarmon is stable and reliable, this would tend to support this theory.  Contacting the Commercial and National Broadcaster with some details of your reception issues could prompt an investigation.

James

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