Pixelation on TV NZ UHF

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Rikkitic

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#224283 10-Nov-2017 13:44

I have been doing a lot of work on Sky alternatives recently and I keep running into frustrating problems that shouldn't be happening. The latest is very bad pixelation and picture break-up on UHF reception of TV1 and TV2. Our UHF comes through a high-gain antenna on a very high mast from the Mt. Erin Freeview transmitter. We don't have line of sight as there is a hill in the way but until today picture quality has always been excellent and dependable. Today it is very windy and reception has gone to hell for the first time ever, but apparently only on the TV NZ channels. I checked Three and Prime and they seem fine.

I am left wondering if this is a problem at our end or not. If it is, it is going to be a real hassle. Is anyone else experiencing this? Could it be something with the transmitter or a feed? I can see our antenna moving around a little in the wind and the long coax cable also moving a bit (nothing major) but as stated, we only seem to be getting issues with TV1 and 2. I haven't checked the other TV NZ channels. Could it be frequency-related? We have had the antenna set-up for years though we haven't used it much in the past. This is the first time I have ever seen anything like this. How can I tell what is causing this?

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#1899219 11-Nov-2017 11:53

Yes it's possible the transmitter / transmitting aerials are developing a fault. You could use the signal quality and strength meters of your receiver to check TV NZ channels and compare to others.

Rest assured if it is a transmitter fault the appropriate people (Kordia perhaps) will attend to it asap. Have you had a look on the Kordia web site for any known issues?

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Goosey

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#1899230 11-Nov-2017 12:32

Is your aerial solid as, i.e. fixed well, nothing loose, nothing rusted and are all the cable connections solid.

Rikkitic

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#1899241 11-Nov-2017 13:22

Goosey:

Is your aerial solid as, i.e. fixed well, nothing loose, nothing rusted and are all the cable connections solid.

As far as I can tell it is. The mast is a DIY job, two solid pipes welded end to end. It is firmly anchored to an unused chimney. It moves back and forth a little in strong wind, but nothing major. The cable connections were solid when I made them. It has been a few years but I don't think they have deteriorated. I can't check them close up. The cable is anchored to the mast part-way down to avoid jiggling the connection and seems fine. I have never had issues before and as I said, other channels seem to be normal. This is why I wondered if it could be at the transmitter end.

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Rikkitic

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#1899264 11-Nov-2017 14:59

I took another look at this and am still having the same problem. Frequent but not continuous bad break-up and pixelation of channels on TV NZ mux only. Other muxes seem okay. May be wind-related but I can't establish a clear link. Nothing about this on Network status site so I have to assume it is at my end. The only problem is that the connection to the antenna is virtually unreachable and I'm not sure what I would do with it if I could reach it.

Question: We are in a poor reception area and should not be able to get a signal at all. We don't have line of sight and we could only get reception by elevating the antenna a long way above the roof. Even then, there is still a hill in the way. Our signal has always been strong and steady, but from reading I did at the time, I believe we were probably picking up a signal bounce of some kind. There is no way we can see the transmission mast. So could small movements of the antenna elements in the wind cause this kind of thing? Does it have to be a bad connection?

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Brunzy

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#1899272 11-Nov-2017 15:35

No it doesn't have to be a bad connection.
If you're in a poor reception area its common for this to happen.Check the quality levels on all muxes,TVNZ is probably the weakest, and the rest are maybe just above the threshold. A masthead amp is your best bet if there is no better spot on the roof.

Apsattv

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#1899584 12-Nov-2017 13:22

A photo or even better a video of the antenna swaying in the breeze? would be a help.

Rikkitic

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#1899586 12-Nov-2017 13:30

At the moment the breeze isn't blowing, but even when it is, there isn't a lot of movement. Enough to be visible, but only barely. I was just wondering if slight movement of the elements could be enough to affect the picture at this frequency. On reflection, I doubt that is the case but I don't really know. I think what the above poster says is probably more likely, a marginal signal that is tipping over the edge.

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Cozzyman

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#1925317 26-Dec-2017 13:37

Interesting to hear that other people have problems with this issue. It's been a very frustrating situation for several month now. I'm in Brooklyn, Wellington and only affects TV1 & 2, not Three or any other channel not associated with TVNZ. Yesterday (25/12) there was no reception from just after lunchtime till around 10pm when the service gradually returned. Initially I thought it was rain related, but with the downpour we had this morning, the service has continued. It's such an intermittent thing and never know when or when not this occurs. Would love to get to the bottom of this. If it was an aerial issue at my place, I would expect that all channels would be down?

Rikkitic

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#1925332 26-Dec-2017 14:15

Eventually we brought the aerial down, which is a major undertaking. The elements are aluminum but a screw was badly rusted that looked like it could be blocking the connection to one of the elements. I carefully cleaned and inspected everything and we put the aerial back up and it didn't make a blind bit of difference! We continued to get the same pixelation problem on TVNZ.

It is not unusual that one mux (channel group) has problems while others do not. Many things can affect this. As I said, we are in a marginal reception area, but something has changed from the past to the present. After observing for a time, I decided that wind wasn't altering our reception, but something else was. Then I heard about tropospheric ducting, a weather phenomenon that affects UHF frequencies a bit like ionospheric reflection affects short wave. Apparently when conditions are right, higher frequency signals can travel much further than normal, causing interference where they shouldn't. I have no idea if that is what I am getting, but it is an intriguing possibility. With digital TV, you won't see ghost images from another signal, but you might see pixelation as the signal quality drops. This also seems to happen more in the summer, which fits our pattern as well.

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Jase2985

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#1925348 26-Dec-2017 15:06

get a better aerial?

Rikkitic

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#1925356 26-Dec-2017 15:20

This one is supposed to be one of the best for fringe reception and it worked fine for years until it didn't.

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Jase2985

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#1925384 26-Dec-2017 16:54

water in the cabling? bad cable connection?

Rikkitic

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#1925389 26-Dec-2017 17:01

Don't think so. No sign of the former, the cable was nice and shiny when I unscrewed it.

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Basil12

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#1925518 26-Dec-2017 20:29

Is the pixellating effect across a number of TVs or only one? We occasionally have a similar issue on one TV (and always TVNZ only) which is invariably a loose aerial cable inside. The other TVs do not suffer the same issue for some reason.

Rikkitic

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#1925546 26-Dec-2017 21:59

I have had the same results with the TV and with a UHF box. The other TVs are not connected to the aerial but two devices that used to work well and now don't are a pretty good clue. Others will know more than I do, but I think the TVNZ mux is more sensitive to problems because it is at the highest frequency.

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