58 replies to this topic

[The Baja]

alanh, on 19 June 2012 - 07:12 PM, said:

The Baja,
The ABC's site is so up to date, they still have analog TV transmitters in regional Victoria which closed down in the first half of last year.

Alanh

I use that to find the coverage map. it can be used thru the  "ozdigitaltv" site. But that would be no good to you"AlanH" as you don't currently actively work in the Trade . It's All just "Armchair Opinion" from you.
If you have a problem with that link, then i suggest that you use one of the other links that i have posted on this thread.


Cheer's



The Baja

[alanh]

The Baja,
The ABC maps are produced with a few reception tests. The ACMA has been comprehensively testing field strengths in each area of Australia to ensure that digital reception is at least as good as analog. These tests have been used to validate the digital ready maps.

The http://ozdigitaltv.com/ does not show coverage areas and is out of date. For example 3 high powered commercial DTV transmitters came on air in August last year. GWN (Prime WA), WIN, TenWest. This is shown on the digital ready website when it works and also includes planned startups. This is not the case for the ACMA transmitter list.

AlanH

[DrP]

Despite the apparent application of Infallibility status to the ACMA transmitter list by some here, it has been demonstrated quite succinctly in days past that the ACMA list is anything but.

<insert waffle reponse here>

Edited by DrP, 21 June 2012 - 06:54 AM.

[alanh]

DrP
Go and commiserate with your other identities

[MLXXX]

Alanh, the fact that so many members repeatedly express disagreement with you should not explained away as arising from the use of multiple identities.

In particular, I am aware of no evidence to suggest DrP posts under any other name than DrP. Both he and you have unmistakeable, distinctive, posting styles.

[DrP]

At one stage or another everyone that doesn't agree with the waffle that alanh posts has, at least according to alanh, been me including you, MLXXX.  His belief is, of course, bizarrely wrong but this is a quite familiar theme when it comes to alanh.

alanh is quite welcome to keep claiming that other forum members are me, it only goes to further demonstrate his disconnect from reality.

Edited by DrP, 22 June 2012 - 06:29 AM.

[muiredachau]

DrP, on 10 June 2012 - 01:35 PM, said:

Oh dear.  Rather than accept the mistake, here we see alanh feverishly trying to rewrite history.  A question for you alanh:  If you understood at the time that you were referring to the 'headcasting' feature why did it require me to pull you up and tell you precisely what you were referring to and how MPEG-4 AVC works; and why did you then go on to insist that your view was how MPEG-4 worked and why did you suddenly fall silent when the very document you claimed said that 'this is how MPEG-4 worked' in fact said something totally different; and then why did you restate your flawed view of how things worked in two separate threads later on?

I think we know the answer to that one, eh?  

Sydney is the same as Perth?  Hmm.  Might be a spot of trouble there.  I'm sure Sydney-siders and Perth-ites know that there's a difference between the two.  Perhaps you are referring to cable carried services?  alanh, its OK.  You just pretend that no one in Perth is watching Foxtel via cable and no one in Perth is using Bigpond internet via cable.  Everyone else will just snicker behind your back.


The afternoon thought: To change the play frame rate of a BD, simply spin it slower or faster.

not everyone in Sydney watches Foxtel via cable anyway

[clipper]

The 'myswitch' coverage maps can be pretty scratchy, esp in the bush. I usually check the 'myswitch' coverage when I'm going out to a job in a tricky area and it is often wrong. "Good coverage' can mean no coverage and vica versa, Often the 'other' transmitter I'm interested in comparing is not listed in the alternative transmitter page. I have to drag the red bubble thingy around the map till it 'locks on' to the second translator.

[alanh]

Clipper,
There is a link to additional transmitters which lists the surrounding transmitters. You can then select the one you want and get it to regenerate the map.
This link shows planned transmitters and their predicted coverage areas as well.

AlanH

[alanh]

Has the Myswitch website stopped working for you?

When I use it, I insert an address the screen then shows a map of Australia and will not go any further.
The DBCDE has recognised there is a problem. Please use their contact us form using the website selection to complain.

AlanH

[nbound]

clipper, on 04 July 2012 - 12:55 AM, said:

The 'myswitch' coverage maps can be pretty scratchy, esp in the bush. I usually check the 'myswitch' coverage when I'm going out to a job in a tricky area and it is often wrong. "Good coverage' can mean no coverage and vica versa, Often the 'other' transmitter I'm interested in comparing is not listed in the alternative transmitter page. I have to drag the red bubble thingy around the map till it 'locks on' to the second translator.

They are only a guide, doesnt take into account forestation, urbanisation, minor terrain variations, and probably a few other things i cant think of. And is generated for a certain (and unknown) height above ground level. But yeah Ive done several installs where the is no reception, not even from alternate transmitters, I go out and walk the rooftop and tada, works fine. Sometimes the predicted sweet spot at a long distance is there but its not in the actual location. Other times, "good" locations are quite poor. Nothing beats an aerial survey.

Edited by nbound, 04 July 2012 - 12:35 PM.

[digital doctor spock]

laceys.tv, on 04 June 2012 - 02:45 AM, said:

Based on Australian Communications and Media Authority data.

http://tinyurl.com/aus-dtv-map

Hopefully it helps finding your best DTV transmitter.

Notwithstanding that this data contains quite a few errors it is still a good guide as to the location of the digital transmitters. A really good iPhone app is Antenna Mate which uses the same data and thus the same errors but useful nonetheless. However from this it is hard to determine signal strength and quality whereas the digital ready web site ( as a previous contributor mentioned) provides a coverage map which can be quite handy.  I would encourage viewers to pay particular attention to polarisation as in many cases there is antennas with the wrong orientation

[CWulf]

Hi Digital Doctor Spock

If you know of errors maybe you could post them here or some more appropriate place in  this forum?  Has the ACMA been told of the errors so they can correct their data or are they not interested?

[alanh]

The predicted signal strengths are for antennas 10 m above the ground. This has been done to identify which areas which will need VAST coverage instead.

AlanH

[CWulf]

alanh, on 04 July 2012 - 09:19 PM, said:

The predicted signal strengths are for antennas 10 m above the ground. This has been done to identify which areas which will need VAST coverage instead.

AlanH

Alan, while field strengths are predicted for, and measured at 10m, the MySwitch good coverage predictions will be based on what the ACMA refer to as suburban and urban signal levels which have allowances for height gain and assume viewers have roof height antennas, say 5m.

10m antenna heights should only be discussed as the extreme of viewer reception installations - not what would be typically installed.

[digital doctor spock]

I think AlanH could have worded his statement as "All field strength testing to validate transmit antenna performance is conducted with a calibrated antenna where measurements are recorded at 10 metres above ground"
This is standard practice to conduct field strength measurements . Obviously antennas are mounted where it best suits the home occupier.

[nbound]

alanh, on 04 July 2012 - 09:19 PM, said:

The predicted signal strengths are for antennas 10 m above the ground. This has been done to identify which areas which will need VAST coverage instead.

AlanH

Perhaps, but unless theres a source, we dont know for sure.

As others have said they also use Urban. Suburban, and Rural areas and signal levels. Usually signal is usable below those levels anyway. So what may be a variable area @ 10m, may be crap by 8m, and unusable by 5m. Or may be variable at 10m and almost as good at 5m. Hence why you cant trust digitalready.

This is why James T et al were having a go at you in the thread relating to Bald Hill on the Sunshine Coast. Despite being blocked by a large stand of trees, being predicted for an unknown height (which you state is 10m now anyway), and despite local installer experience, you were suggesting Bald Hill over Mt Cootha, which had a single hill and less obstructions. Perhaps you were right and there is good signal at 10m AGL. But thats hardly an easy option is it.

How many 10m antennas do you think go up these days anyway, I service the fringes of several transmitters, and I can tell you its not many at all (ie. big $$$$). Long gone are the days of high masts and massive guy systems.

Edited by nbound, 05 July 2012 - 01:28 PM.

[digital doctor spock]

nbound, on 05 July 2012 - 01:24 PM, said:

Perhaps, but unless theres a source, we dont know for sure.

As others have said they also use Urban. Suburban, and Rural areas and signal levels. Usually signal is usable below those levels anyway. So what may be a variable area @ 10m, may be crap by 8m, and unusable by 5m. Or may be variable at 10m and almost as good at 5m. Hence why you cant trust digitalready.

This is why James T et al were having a go at you in the thread relating to Bald Hill on the Sunshine Coast. Despite being blocked by a large stand of trees, being predicted for an unknown height (which you state is 10m now anyway), and despite local installer experience, you were suggesting Bald Hill over Mt Cootha, which had a single hill and less obstructions. Perhaps you were right and there is good signal at 10m AGL. But thats hardly an easy option is it.

How many 10m antennas do you think go up these days anyway, I service the fringes of several transmitters, and I can tell you its not many at all (ie. big $$$$). Long gone are the days of high masts and massive guy systems.

The primary purpose of field strength testing is simply to validate the performance of the transmit antenna and it has to be done at 10 metres to minimise the ground effect. Therefore the field strength plots can only be used as a guide in determining what the reception would in any given area. It wont provide certainty for a domestic house antenna installation.

[nbound]

digital doctor spock, on 05 July 2012 - 04:22 PM, said:

Therefore the field strength plots can only be used as a guide in determining what the reception would in any given area. It wont provide certainty for a domestic house antenna installation.

Which is what I and others have been saying all along.

Edited by nbound, 05 July 2012 - 05:22 PM.

[mtv]

I've been to many locations which are located within supposedly good signal areas, only to find terrain completely blocking terrestrial signals.

Yes, they are a guide only..... often far removed from reality.... something particular posters of this forum have in common.

There is no substitute for an experienced installer with the right equipment on site, to determine what works best.

[clipper]

done at 10 metres to minimise the ground effect.

Whatever the 'ground effect' is, it may help digital strength/quality. In the country without any LOS, I generally start my surveys on the ground to get a "base reading' then compare to up on the roof at varying heights/positions etc.Occasionally, the levels at ground are better, and I don't mean just because we are getting a better signal under  tree branches. BTW, a fair chunk of my jobs would qualify for VAST- the standard is very generous.

[nbound]

clipper, on 06 July 2012 - 08:35 AM, said:

BTW, a fair chunk of my jobs would qualify for VAST- the standard is very generous.

Agree there.
What is it? 44dBuV for UHF if I recall correctly... Im quite happy when Im getting that at roof height

[digital doctor spock]

One thing I did forget to mention and that is the difference between Field Strength and Signal Strength. Most coverage maps indicate Field Strength whereas measuring instruments measure signal strength.
Field Strength = Signal Strength + Antenna Factor where antenna factor is frequency and gain dependent.

[alanh]

yes digital Dr spock

the Antenna factor is usually called antenna gain which is controlled by the number of directors and whether there is a reflector and whether stacking is used. If it's phased array it is controlled by the number the bays. To put it in simple terms, the weaker the field strength the more money which has to be spent on the antenna and perhaps a masthead amplifier.

AlanH

[digital doctor spock]

Hi Alan, antenna factor and antenna gain are two quite separate parameters. For instance if you were to measure a VHF service and a UHF service of identical field strength with a VHF and a UHF receive antenna both of identical gain, the VHF antennas will record a higher signal strength reading than the UHF antenna. The difference between the VHF and UHF readings can be quite significant even with identical field strength and identical antenna gain.
The higher the frequency the higher the antenna factor (also referred to as K Factor) that has to be added to the signal strength reading.