Problem with Mediaworks Terrestrial Channels in Wellington

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JimmyH

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Topic # 29300 2-Jan-2009 10:50

I have finally finished the upgrade of my system, and now have a TV with an integrated Freeview tuner (Samsung L40A650) which I really like. I can pick up all the TVNZ HD channels fialry much flawlessly, as well as the others (Maori, Chinese, Preview etc). However, I cannot get either of the mediaworks channels (TV3, TV4) at all - they simply don't show up in channel scans. Is anyone else having this issue, and does anyone who is a bit more technically adept than me have any suggestions (manual tuning to frequencies, aerial amplifier etc) that might resolve the issue.

In case it helps, details are:
- external UHF aerial
- pointed (I think) at Mt Kaukau, but not quite line of sight as I am down is a "wee dip" in the road
- aerial connected direct to TV - I have taken VCR, DVR etc out of the loop
- TVNZ channel reception is pretty solid (does not break down into artifacts etc at all) which indicates to me that the aerial and telly are working fine?
- The quality of my Prime TV reception (on UHF) is, however, not all that great

Would love to fix this, as VHF analogue reception of TV3 & 4 is not brilliant - ghosting etc. Fallback is to watch through the Sky set top box - but impractical when I am simultaneously recording a film etc.

Interested in your suggestions & thoughts on this one

Cheers

cyril7

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Reply # 186984 2-Jan-2009 11:01

Hi, When last I checked when installing an antenna a few days ago (on leave currrently) all three muxs were fine and no other reports of them being down, all three are from the same Tx sites using the same gear all lined up on the same racking feeding the same antennas. I suggest you need to locate your antenna in a location where all three muxs can be successfully recieved, once you leave line of sight this is not always obvious and requires a field strength meter (appropriate to DTT) to examine your reception issues.

Approx where are you.

Cyril

sbiddle

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Reply # 186988 2-Jan-2009 11:33

WHat signal levels are you getting off the other channels? TV can tell you this in one of the menus (sorry can't remember off the top of my head, think it's in the main menu then information).

Where are you located? I'd be 99% certain it's just an aerial issue. Does your UHF & VHF aerial run through a diplexer and then a single cable to your TV?

JimmyH

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Reply # 187058 2-Jan-2009 19:52

Thanks for those comments. Further info is:
- I am in Khandallah
- I am just off line of sight to Kaukau - it is line of sight from the top of my drive but not the house
- I can't get to the antenna, it is on top of a pitched roof on the second story and needs a long extension ladder to get to it (which I don't have)
- I think it goes through a diplexer - only one cable going in for UHF and VHF - but as per above I can't get to the aerial to look
- Signal strength (TV one) seems to range between 65 and 75 according to the TV

mruane

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Reply # 187292 4-Jan-2009 12:19

Hi Jimmy

I have a similar problem. Interestingly, I was involved in setting up a Media Portal installation using the Mt Kaukau transmitter yesterday and we had similar results - but for us, the TVNZ and MediaWorks muxes were fine. The mux we could not recieve was the Kordia mux! In our case, the signal strength and quality of the two good transmissions was nearly full strength on the MP meter, but Kordia were just not at home.

It seems to me, that if you can get one mux you should be able to get all three unless they are very well spread apart. In the case of Kaukau, the transmissions are between 714000 and 762000 MHZ - not that far apart I would have thought.

Cyril7: I know that moving an antenna to a new position just a wave length away produces a significant difference. However this antenna has received all three muxes in the past (i.e. a couple of months ago). Any idea what could cause this after such a short time?

Cheers Mike

sbiddle

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Reply # 187295 4-Jan-2009 12:36

JimmyH: Thanks for those comments. Further info is:
- I am in Khandallah
- I am just off line of sight to Kaukau - it is line of sight from the top of my drive but not the house
- I can't get to the antenna, it is on top of a pitched roof on the second story and needs a long extension ladder to get to it (which I don't have)
- I think it goes through a diplexer - only one cable going in for UHF and VHF - but as per above I can't get to the aerial to look
- Signal strength (TV one) seems to range between 65 and 75 according to the TV

After playing with a couple of Samsung's I believe that 65-75 is too low to give you a good picture. Based upon your location you should be getting around 90% - 100%and it appears from my brief time playing that at least 80% is needed to give a good stable picture.

cyril7

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Reply # 187463 5-Jan-2009 11:19

Hi, with my Feild Strength meter I can select all three muxs to show in a bar graph type fashion at the sametime (11 selected DTT carriers if desired), this allows me to move the antenna about and find a location where all optimise very quickly. Obviously in some locations where there is hilly terrain or buildings you get some very dynamic results. Living in close proximity of a major transmitter and especially when off the side of the main lobe (or under it as you are in Khandalla) you get some pretty dynamic changes aswell, hence if you dont find a good location where all three muxs are sitting pretty stable then its not unexpected that you dont get some minor change in local topography and its all over rover.

Cheers
Cyril

mruane

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Reply # 187470 5-Jan-2009 11:51

Thanks Cyril7. I guess both the OP and I need to get an antenna guy round with the right gear to really solve the problems!

Cheers Mike

JimmyH

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Reply # 192023 25-Jan-2009 21:21

That's the conclusion I have now come to as well - signal strength is even weaker on some of the other Freeview channels. Alternatively, after some more reading around, it could be the cable instead of the aerial (its fairly old).

It sounds like I need to get an antenna guy with a few clues to look at it - not some drone who only has one solution - "sell me a Gizmo". Does anyone have any recommendations on a good antenna guy (or gal) in the Wellington area?

Jaxson

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Reply # 192075 26-Jan-2009 09:41

Sounds like you guys have this sorted. Was just going to through in that a friend of my had similar issues, he was in the hutt, and turned out his ET box was grabbing channels/mux's from different transmitters for whatever reason. It did not necessarily opt for the strongest signals either.
In the end he had to manually enter the frequencies he wanted to receive to ensure they came from the sources he wanted and it all worked fine from there. (That and getting a bigger UHF aerial + decent coax cable too).