261 replies to this topic

[GlennP]

M, on 18 May 2013 - 06:58 PM, said:

Your amplifier will only be needed to cover losses in the system.

I may not be reading that statement correctly, however, speaking as an installer, if i have around 40dBµV of good quality signal coming from an antenna (not uncommon with some of my installs), after adding an amplifier, I would not be leaving the property with only 40dBµV of signal available from the outlet plate.

You're probably not.
I'm an installer to, been doing it for years.

You're right with 40dBuV. I'm yet to find a long term successful installation with only 40dB at the antenna, even if I was to instal an amp & boost it to 57dBuV at the outlet, I wouldn't be guaranteeing long term reliable solid reception. 40dBuV is way too close to the cliff edge.

Absolute minimum I look for out of the antenna is 48dBuV, having at least 9dBuV margin above the general cliff edge. With getting a quality signal with a power of around 54-57dBuV at the outlet. I wouldn't boost the signal though just to get that level at the outlet.

You should well know the standard recommended minimum signal level is 45dBuV at the outlet, but having 40dBuV at the antenna & amplifying it to 45dBuV won't cut it. You should also know an amplifier won't improve a digital signal & 40dBuV is too low for long term robust signal quality, just because you have a good MER at a low signal strength, doesn't mean it'll stay good, if the TX goes to low power, weather conditions change & general system degradation, causing the signal strength to drop very close or over the cliff edge. You should also know that not only does an amp, amplify the good, it also amplifies the bad & can make a borderline signal, terminal. An amp should always be turned to minimum & adjusted upwards till you get what you need. Minimal amplification for max. gain. That's even part of the recommended digital installation standards & has been since day one.

We're not there, & don't have accurate measurements, so can't say, but I stand by my recommendation to wind it back to minimum & see what you can get away with/need, obviously if it's too low, turn it up.
The most commonly available amp is a Kingray, MHU24F or MHU24FS, especially if he's getting it from an Electrical Wholesaler, where he got the antenna. I honestly don't think he's going to want that much (24dBuV) or more amplification.

Edited by GlennP, 19 May 2013 - 09:33 AM.

[SFC]

Thanks so much for all the replies and help for my questions and application, there really is more to this than pointing an antenna in the right direction.

I've realigned the antenna by about 1 degree to point strait at the Bald Knob tower and removed the old amplifier, a Hills A3PU band 3 + VHF.

I have all the channels I did before and all have a 'good' signal quality, 10 on a scale of 0-10 as measured by a Panasonic HDD twin tuner. All apart from channel 44, 31 digital which is at 9 on the 0-10 scale.  The main difference now is that some of the channels have a reduced signal strength, 7, 8 and 9 on the 0-10 scale, but still in the good range.  Without any real measurements there is no way of knowing how close the signal strength is to the digital cliff.  For now I will leave it as is and wait to see if we get any dropouts.

A couple of tips for the average mug like me;
1. If your going to buy new equipment that needs specialised tools get the equipment and tools from the same place.  I bought a compression tool from one place and the compression f-connectors from another, the F-connectors didn't fit in the compression tool.

2. Figure out what the problem is before you go buying new equipment.  A mates second TV had no reception and they where sold a masthead amp to fix the problem.  After I installed the amp the TV still had no reception because the fly lead was plugged into the TV and not the set top box. Dooh.  

Steve.

Edited by SFC, 21 May 2013 - 05:23 PM.

[Malich]

SFC, on 21 May 2013 - 04:58 PM, said:

All apart from channel 44, 31 digital which is at 9 on the 0-10 scale.

If you're getting Briz31, you're getting it from Brisbane - AFAIK it's not broadcast from Bald Knob (or anywhere other than Mt. Coot-tha) , unless that's started quite recently.

(Good to hear that Briz31's 15kW ERP QPSK signal is reaching as far as - or further than - SBS Brisbane's 200kW ERP QAM64 signal. That should settle an old argument or two - or maybe start a new one )

Edited by Malich, 21 May 2013 - 05:45 PM.

[SFC]

Malich, on 21 May 2013 - 05:42 PM, said:

If you're getting Briz31, you're getting it from Brisbane - AFAIK it's not broadcast from Bald Knob (or anywhere other than Mt. Coot-tha) , unless that's started quite recently.

(Good to hear that Briz31's 15kW ERP QPSK signal is reaching as far as - or further than - SBS Brisbane's 200kW ERP QAM64 signal. That should settle an old argument or two - or maybe start a new one )

Thanks for that,

we don't really watch Briz31, but I kind of thought we were getting it from Brisbane as a bonus.  I have no idea what the technical jargon is and unashamedly really don't wan't too as long as I have a clear picture.

Steve

[alanh]

James is the poster who recommended to receive a signal from Brisbane over 70 km away when the viewer was 7 km from this site. There was no terrain to block signals. Go back to page 9 and check http://myswitch.digitalready.gov.au/ and type in 1 Myrtle St Melany. The default transmitter used is at Bald knob (see down arrow on right side of the map). This signal strength is in the strongest category over nearly all of the town. When the signal strength from Mt Coot-tha is selected, the signal strength of all of the town is much lower. So keep recommending more expensive antennas for unsuspecting posters James.

He cannot calculate any dBs which any half decent technician needs to do when working on transmitters was demonstrated here previously. dBs are also used when measuring signals in receiving signals as well.

He can't describe the exact reasons why one type of receiving antenna is better than another. Which one is best for each type of situation

Who cares if there is a pair of towers next to each other. Receiving antennas are not that directional anyway.

SPC fixed his own problem anyway.

James hates me because I have sprung his lack of knowledge previously and GlennP has this fixation that DAB+ receivers are not selling regardless of the fact that he is not an area covered by DAB+ signals. Even if chain stores in Newcastle sell digital radios, they will only receive FM signals there and none of the AM signals. I bet they just sit on the shelves.

It can be seen in the large number of posts in this strand I have given valuable advice over many years..

So no I will expect another load of insulting posts

Alanh

[Malich]

alanh, on 23 May 2013 - 01:25 AM, said:

James is the poster who recommended to receive a signal from Brisbane over 70 km away when the viewer was 7 km from this site.

James is also the poster who read and understood that particular OP's question - specifically the bit where the OP quite clearly said he wanted to receive the Brisbane stations, not the SC ones - and answered the question asked with technically sound and useful information based on local knowledge and experience.

Unlike one so-called 'senior poster' (an appelation automatically decided by the forum software based purely on the number of posts and - quite obviously - not related to any level of technical skill or knowledge, quality of posts, or even length of membership) who, on the other hand, ignored the question that was asked, answered the question he had in his head instead, and continued to insist that his answer was the only correct one even after the OP explained to him exactly why his answer wasn't satisfactory. All while sitting on the other side of the country and copying his 'information' from websites.

The fact you keep bringing it up as an example of a failure on James' part and a success on yours speaks volumes...

alanh, on 23 May 2013 - 01:25 AM, said:

It can be seen in the large number of posts in this strand I have given valuable advice over many years..

Unfortunately they were mostly long ago, and have been overwhelmed in more recent years by the even larger number of posts where you've given poor advice and/or shown a complete misunderstanding of technical subjects, particularly those relating to digital transmissions.

And never forget - don't confuse 'quantity' with 'quality'...

alanh, on 23 May 2013 - 01:25 AM, said:

So no I will expect another load of insulting posts

What a disappointment it must be to you to get this calm, considered, and accurate reply instead...

Edited by Malich, Yesterday, 04:27 AM.

[SFC]

I find it interesting that I'm getting a channel from Brisbane whilst setup to receive from Bald Knob.  Just before Malich pointed that out I was playing on the Matchmaster site and their antenna selection guide has Mnt Coot-tha as the recommended transmitter for my location at the southern end of the Sunshine Coast. When the preferred transmitter is changed to Bald Knob the antenna of choice is changed to a phased array.  They recommend a masthead amp for both applications but from experience it appears that I don't need one for Bald Knob but I can't really say that for sure without properly checking our received signal.

For what it's worth hears the statistics from the Matchmaster antenna selection guide for Kawana Island, Parrearra 4575.  

Recommended Transmitter - TXA T-Site Tower 445 Sir Samuel Griffith Drive MOUNT COOT-THA
Avg Signal: 64 dBuV, Digital Channels: 12 36 38 11 6 8
Distance: 85.2km, Bearing: 192 deg.
Recommended Antenna - 01MM-DC21A
Antenna VHF/UHF(6-12)(28-40) 21 Element
Polarity Horizontal: VHF Gain 7dBuV,UHF Gain 11dBuV - Masthead Amplifier Required


TV Translator Site BALD KNOB
Avg Signal: 59 dBuV, Digital Channels: 36 47 53 56 59 62 65 68
Distance: 22.4km, Bearing: 247.4 deg.
Recommended Antenna - 02MM-EE06-1
Antenna UHF(21-69) Phased Array 'F' Type
Polarity Horizontal: UHF Gain 13dBuV - Masthead Amplifier Required

Steve.

[GlennP]

alanh, on 23 May 2013 - 01:25 AM, said:

GlennP has this fixation that DAB+ receivers are not selling regardless of the fact that he is not an area covered by DAB+ signals. Even if chain stores in Newcastle sell digital radios, they will only receive FM signals there and none of the AM signals. I bet they just sit on the shelves.

Alanh

Actually Alanh, I mightn't be in the licensed, or even expected DAB+ coverage area, but I can receive DAB+ from Sydney quite well at home, & am sitting listening to it right now whilst I post this, with a BER on the radio of 8-10, in cold windy, heavy rainy weather. OMG, yes I own a DAB+ radio, I know what's broadcast & I know what it sounds like first hand, all without leaving my house, 100km away from the Sydney DAB+ transmission site.

I also receive DTV from Sydney quite well from the Artarmon triangle transmitters, 100km away. In fact I very rarely watch any TV transmitted from Newcastle, SBS is the only channel, but that will change after re-stack when I can get it on VHF 7. Often during Summer when ducting from the Illawarra, knocks out my Newcastle reception, Sydney DTV is needed, otherwise I couldn't watch anything.

Yes DAB+ radios are selling in regional areas, but they're selling as FM radios, anyone with half a brain can comprehend that, & in no way can you or anyone associate the sales & success of DAB+ with the sales of a radio to be used on FM, despite having the ability to receive DAB+. Obviously most don't receive AM signals, big drawback under the current circumstances, but I can't help that. There is one DAB+ reciver that does do AM as well though, that's sold at BigW http://www.bigw.com....gital-dab-radio

As for the amount of DAB+ listeners in metro areas. I have it in printing from Joan Warner at CRA, that the reason digital radio figures aren't released publicly is, there's not enough listeners to create any accurate data figures. The truth finally came out earlier this month, that figures CRA release are only guesstimates, there's not enough data to be acuarate. You work it out statistically how small, levels of data are needed to make an accurate representation of metro area listeners.

[Malich]

Just to clarify, SFC - when I wrote "that particular OP's question" in my previous comment, I was referring to an earlier exchange between James T Kirk and AlanH over a question asked by someone up around Maleny who specifically wanted to receive the Mt Coot-tha transmissions.

Alan likes to hold this particular exchange up as an example of how James T Kirk doesn't know anything and his incorrect advice costs people money. Others like to interpret it as an example of how Alan doesn't read the question asked, ignores the asker's requirements, insists his answer is the only correct one, and never admits to making errors .

For the record, I believe James T Kirk is a technician working in the TV broadcasting field around SE Qld, while it's public knowledge that Alan is an ex-ABC trainer who retired prior to the advent of digital TV and lives in Perth. Make of that what you will.

---

Given your location (Kawana Island, correct?) I'm a little surprised that Brisbane would be recommended in any case - you're well into the fringe area for Mt Coot-tha and there are at least 2 better choices. I'm also bloody impressed that you're apparently receiving Briz31 with decent signal level at 45 degrees or so off-axis - that does support something of Alans earlier statement about the relative merits of yagis vs that type of phased array (i.e phased arrays are less directional in their orientated plane than an equivalent yagi, and so may suffer more from interference).

(It also supports my point - in a previous 'discussion' with AlanH, which is why I mentioned it earlier - that Bris31's modulation is robust enough to give it equivalent coverage to SBS Brisbane with much less power i.e. 15kW vs 200kW.)

I'm also a little surprised that the Matchmaster site suggests a masthead amp is needed for that phased array pointed at Bald Knob from where you are - although I admit that's without doing even rough calculations, let alone experience with signal levels in your area. It's more than likely they're generally correct and I'm over-guesstimating the signal level. But, ultimately, if it works, it works - and it seems to be working for you!

Edited by Malich, Yesterday, 11:37 AM.

[James T Kirk]

alanh, on 23 May 2013 - 01:25 AM, said:

James hates me because I have sprung his lack of knowledge previously.

Alanh

I don't hate anyone, or even AlanH, I just think he's a nutter.

James

[Ron12]

I was in Noosa this summer for a holiday, and the apartment building was able to receive Brisbane VHF channels from 140+ Km [EDIT: 119+ Km as the crow flies] away.  Perhaps they were in a high enough area to do so.  Analog TV was a bit snowy, but digital TV had a perfect picture, except for the occasional split second dropout on Ch7.  The signal strength was very good and the signal quality was also very good.  They also received the Sunshine Coast stations very well on UHF.

Edited by Ron12, Yesterday, 08:05 PM.

[Ron12]

Interesting the differences between the recommendations made by the Matchmaster Antenna Selection Guide and Myswitch websites.  For example, for the location in Noosa Heads in my previous post, MySwitch says that Noosa/Tewantin gives good reception and that an amplifier is not required, whereas reception from Brisbane is variable.  However, the Matchmaster website says that the recommended transmitter is Brisbane (the ones on Mt. Coot-Tha), and that if you choose the Tewantin transmitter, the signal strength is lower.  Matchmaster's website says that a masthead amplifier is required for both transmitters.