UHF reception issue

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#2045143 28-Jun-2018 08:03

As a few others have said having the aerial at that hight might not be the correct hight, I have seen a large aerial on a 2.5m mast ( not los ) get nothing, drop down to 1m and had so much signal we could use a smaller aerial.

There were some changes in the transmitter mux's recently so the TVNZ mux might be in the fringe of the bandwidth of the aerial, without seeing the polar plots it is hard to know if that is the current suitable aerial for your area.

I would try a large phased array aerial like this http://www.freeviewshop.co.nz/large-phased-array-aerial-freeview-p-595.html and a new piece of coax as an experiment, move it up and down the pole ( standing height ) to see how it goes, if it works clamp it on and enjoy, if it does not work you will have to try something else.

I have helped with 30ft masts in the past and know the issue of dropping them and putting them back up.

Without a decent signal strength meter you are really just guessing.

If gain is the real issue something like this will help.

https://www.dtvs.co.nz/index.php?main_page=product_info&cPath=3&products_id=85

I have not had a look at the polar plot to see if this is suitable.

A masthead amplifier will possibly create more issue, they are like wifi extenders, most people dont know how to install them and use them properly. if you have a crap signal going in, you are going to get a larger crap signal coming out.

Best of luck.

John

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#2045171 28-Jun-2018 09:40

Apsattv:

Can you check the BER (Bit error rate) in the tuning menus somewhere?

I will look into that. I remember you said something about it being available on the Sony but I don't remember seeing anything. I'm also not sure what is available, if anything, on my current device. In typical Chinese fashion it comes with almost no useful information and I have to work things out by trial and error. Basic info is just 'S'(ignal) and 'Q'(uality) but I'm not sure what that measures. As I recall the Sony is about the same. It is a bit of a hassle changing the antenna feed but I will see what I can find out.

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#2045175 28-Jun-2018 09:44

Bung: When you say LOS blocked by low hills, how high are they? Mt Erin is apparently 490m.

In my location I'm about 60km from the transmitter. When I replaced the aerial I went with the same high gain type but going on signal level reported by set I possibly could have used a smaller aerial. If the long aerial twists I lose the highest frequency mux while the others hang on.

There is a low range of hills starting from across the road sufficient to block LOS but they are not especially high. I don't know exactly how high they reach but I'm fairly certain we could see Mt Erin without them in the way.

I have wondered if the frequency of the TVNZ mux could be an issue with the poorer reception, but it is between other muxes that work fine so not sure how that would work.

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#2045236 28-Jun-2018 09:58

SATTV:

As a few others have said having the aerial at that hight might not be the correct hight, I have seen a large aerial on a 2.5m mast ( not los ) get nothing, drop down to 1m and had so much signal we could use a smaller aerial.

There were some changes in the transmitter mux's recently so the TVNZ mux might be in the fringe of the bandwidth of the aerial, without seeing the polar plots it is hard to know if that is the current suitable aerial for your area.

I would try a large phased array aerial like this http://www.freeviewshop.co.nz/large-phased-array-aerial-freeview-p-595.html and a new piece of coax as an experiment, move it up and down the pole ( standing height ) to see how it goes, if it works clamp it on and enjoy, if it does not work you will have to try something else.

I have helped with 30ft masts in the past and know the issue of dropping them and putting them back up.

Without a decent signal strength meter you are really just guessing.

If gain is the real issue something like this will help.

https://www.dtvs.co.nz/index.php?main_page=product_info&cPath=3&products_id=85

I have not had a look at the polar plot to see if this is suitable.

A masthead amplifier will possibly create more issue, they are like wifi extenders, most people dont know how to install them and use them properly. if you have a crap signal going in, you are going to get a larger crap signal coming out.

Best of luck.

John

Thanks for the info. I like the parabolic antenna and I'm sure it would do the trick but it's probably overkill for our situation.

I can't bring our antenna down myself so have to organise it, which is why I am looking at other solutions first. My memory has become unreliable but I'm pretty sure we tried different heights when we did the original installation. In our case higher seemed better. I am not keen to experiment with that because it would mean repeatedly putting the antenna up and down and just doing it once is already hard enough. Each time I'm afraid we will lose it, as we did once and almost have other times. It is not a fun thing to do.

I am interested in your comment about changes to the muxes. Could this be why our reception has changed? Can you provide any details?

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#2045240 28-Jun-2018 10:01

I'm also confused by your outstanding 100/100 results in the Mediaworks mux, with such weak results on the TVNZ mux. I have always got more or less the same signal strength and SNR on every mux. I could understand if you were getting 70/100 on Mediaworks and 60/80 on TVNZ, but that difference is huge. I have direct unobstructed line of sight about 7km from the Sky Tower and I get 98/99 signal strength, not 100. Possibly this is down to the device doing the measuring - not sure how much standardisation there is between different TV/Freeview receiver models.

Did you double check the frequencies you are tuning? The only time I got results like yours was when I accidentally tuned one mux to the frequency of the wrong transmitter. (Waiatarua). My aerial was pointing in the wrong direction entirely but still picked up enough of a signal to get a patchy picture. That said if there is only one transmitter that you are even remotely close to it's hard to imagine how this could be your issue.

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#2045257 28-Jun-2018 10:24

Could just be that TVNZ transmission antenna are mounted lowest on Mt Erin tower.

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#2045266 28-Jun-2018 10:33

Spyware:

Could just be that TVNZ transmission antenna are mounted lowest on Mt Erin tower.

This is probably it, in combination with unpredictable atmospheric effects.

You need to add another metre to your mounting pole!

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#2045289 28-Jun-2018 10:53

allio:

You need to add another metre to your mounting pole!

That might endanger passing aircraft!

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#2045294 28-Jun-2018 11:03

Satellite (dish and decoder) as a simple last resort?

trig42

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#2045299 28-Jun-2018 11:22

Rickles:

Satellite (dish and decoder) as a simple last resort?

Haha. If you have read any of the OP's posts, you will know he does nothing the 'simple' way.

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#2045306 28-Jun-2018 11:29

Rickles:

Satellite (dish and decoder) as a simple last resort?

We also have that but the quality is better on UHF. This whole thing started because it used to work perfectly, then it didn't, and I was trying to figure out what was causing the difference.

I finally got around to checking the frequency info. While doing so I also noticed that the signal is perfect on all muxes again. Sometimes this happens, then it drops off again. Right now I am getting 90% signal and 100% quality on TVNZ. Mediaworks is 92% and 100%. This gives perfect reception. Often the Signal drops to 86% on TVNZ and I get pixelation. I never have this with Mediaworks, where the signal is often 100%. I have checked this many times.

I don't recall offhand all the channels and muxes so I just checked a few that I know are different muxes. The values I can see include vpid, apid and ppid. Vpid and ppid are the same in every case. TV1 gives a frequency of 586000 and transponder 35, vpid 270, apid 421. For TV3 the values are 570000, 33, 450, 410. Prime is 602000, 37, 554, 604. Maori TV is 618000, 39, 360, 460. Choice is 602000, 37, 556, 606. This is everything I can find on the receiver I have.

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#2045307 28-Jun-2018 11:30

trig42:

Haha. If you have read any of the OP's posts, you will know he does nothing the 'simple' way.

:)

Now you have hurt my feelings.

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#2045365 28-Jun-2018 12:07

Not intended to hurt your feelings. I like that you have your way of doing things, and that (for the most part) it works for you.

I am a little the same - I probably choose the 'geeky' way of doing things, and sometimes it doesn't always work out. It is fun though, and I learn most of the time.

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#2045367 28-Jun-2018 12:16

trig42:

Not intended to hurt your feelings. I like that you have your way of doing things, and that (for the most part) it works for you.

I am a little the same - I probably choose the 'geeky' way of doing things, and sometimes it doesn't always work out. It is fun though, and I learn most of the time.

Just kidding. I have also noticed that I often seem to end up doing things the hard way, but I have never been able to figure out quite why. It just seems to happen that way.

I think a lot of it probably has to do with making false economies. I live on a budget and am always mindful of costs. At the time we put the antenna, it seemed like a good way to do it, and it was as long as there were no reception issues. But it is a real bugger if you have to diagnose anything. On that basis a proper tower with vertically extendable mast might have been better, but the cost difference was just too great. It is hard sometimes to resist the temptation of number 8 wire.

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#2045813 29-Jun-2018 02:43

Rikkitic:

Rickles:

Satellite (dish and decoder) as a simple last resort?

We also have that but the quality is better on UHF. This whole thing started because it used to work perfectly, then it didn't, and I was trying to figure out what was causing the difference.

I finally got around to checking the frequency info. While doing so I also noticed that the signal is perfect on all muxes again. Sometimes this happens, then it drops off again. Right now I am getting 90% signal and 100% quality on TVNZ. Mediaworks is 92% and 100%. This gives perfect reception. Often the Signal drops to 86% on TVNZ and I get pixelation. I never have this with Mediaworks, where the signal is often 100%. I have checked this many times.

I don't recall offhand all the channels and muxes so I just checked a few that I know are different muxes. The values I can see include vpid, apid and ppid. Vpid and ppid are the same in every case. TV1 gives a frequency of 586000 and transponder 35, vpid 270, apid 421. For TV3 the values are 570000, 33, 450, 410. Prime is 602000, 37, 554, 604. Maori TV is 618000, 39, 360, 460. Choice is 602000, 37, 556, 606. This is everything I can find on the receiver I have.

Well that post confirms at least you are on the right tower

Now you need to find the BER or some sort of reading in your tv or device that shows error rate. You can have high signal level but a crappy signal full of errors. Similar to the old days of a strong but ghosty analogue signal.

The fact that you have good strong signals, may also indicate that any disturbances may in fact be locally generated.

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