Another TV antenna question

Analog6 (Odille) · #1 25-03-2010, 06:00 AM

This post is inspired by Doug's (I have a very peculiar problem). I have asked on Whirlpool bu tthe answers are so convoluted and technical that I gave up there.

I was going to buy a new antenna (but we live in a rental and I will have to pay for it myself) but the answers in Doug's thread, particularly John's (Scorpius 51) make me wonder if it will make any difference.

Our current aerial is just mounted on the gutter on the north side of the house, and is not properly wired into the house, that connection fell off and someone hooked up another one and had it coming in through the window (tenant before us, 8 years ago) and I drilled a hole through the bricks to pass into the house. When it rains the TV reception is awful until things warm up, I reckon moisture somehow comes in along the aerial.

I have a TV with HD digital receiver built in, and a set top box. We currently only use the HD one as an expensive device to watch DVDs! Reception on both it and the set top box is dreadfully patchy, with the picture breaking up all the time and several channels (there are lots of duplicates, it seems) have sound (perfect) and no picture at all.

Cable/dish is NOT an option at this time, we don't watch a lot of TV and I just cannot see the value.

We face north at a 100m elevation, about 3km inland from the ocean. Behind us are tall hills, big trees and a school. To the front the ground drops away and faces an inlet and then the Gold Coast Airport (2-3km away). The flight path, however, is off over the ocean, only small planes and helis pass overhead.

So what type of aerial is recommended? Any advice recommended.

Below are a wide and closer overhead view from Google earth, and one of the house (very poor quality, sorry) showing the aerial.

Barrykgerdes · #2 25-03-2010, 07:15 AM

If you want to see digital TV you will need a good outside aerial orientated towards the TV station aerial and preferably line of sight and probably a mast head amplifier.

If you are not an electronics expert you will need to get one of the TV aerial installers to fit you out with a suitable aerial. It will probably be expensive and as you are in a rental property it will probably be all your own expense unless you can convince the landlord.

When Analogue TV ends in three years the old indoor aerial on top of the TV set will no longer be sufficient. Digital TV is encoded and needs a good signal/noise ratio with no severe interference. If the decoder loses too many "bits" the decoder will loose sync and the dreaded "blue screen" will appear. Even so even a good signal may not be enough to stop the decoder losing sync in electrical storms.

I am an electronic engineer and I have had Digital TV since it started. Even a simple outside aerial was not enough. I needed a mast on the roof and a masthead amplifier to receive the digital signals. I am 25 km from the TV stations but it is Line of sight. The Digital TV is great for viewing but I still can't watch TV during a storm.

Barry

supernova1965 (Warren) · #3 25-03-2010, 07:23 AM

Firstly you need to find out exactly where your TV towers are and ensure that you have you antenna pointing directly at it. Their are Digital Antenna available that are meant for Digital TV. So I am trying to get your situation if I have it wrong please correct me you are not using your digital HD tv for reception and are using the Set top box for your tv reception. The duplicates are like place holders for the various channels so they can justify having the channels to the government so if in future they want to add more content they have the channel to do so. Is the STB a HD one as well because if it is SD it will only have the sound for the HD channels and not be able to display the HD picture. If you have picture going blocky with small cube shaped distortions and crackly sound this is the digital equivalent of the static in analogue meaning you don't have a good reception area. Some how you need to determine the direction of the TV broardcast stations to ensure you have your antenna pointed the correct direction. Hope some of this is useful to you

mithrandir (Andrew) · #4 25-03-2010, 08:31 AM

Quote:

Originally Posted by Barrykgerdes

I am an electronic engineer and I have had Digital TV since it started. Even a simple outside aerial was not enough. I needed a mast on the roof and a masthead amplifier to receive the digital signals. I am 25 km from the TV stations but it is Line of sight. The Digital TV is great for viewing but I still can't watch TV during a storm.

We've also had digital from the beginning and have had one antenna upgrade since then.

Are you on the west side of one of the hills Barry? We are on the west side of the Old Northern Rd ridge and the Sydney UHF masts are out of sight, even from the top of our mast and amp. We got a separate UHF antenna pointed at the Illawarra transmitters.

We notice that pixellation does not usually happen when we get hit by rain or wind gusts. It seems to be when the rain/wind affects something between us and the transmitter. Sydney VHF can be affected and Illawarra UHF be fine, and vice versa.

bojan · #5 25-03-2010, 08:47 AM

Quote:

Originally Posted by Analog6

. When it rains the TV reception is awful until things warm up, I reckon moisture somehow comes in along the aerial.

Possibly the water is getting into the cable.
I suggest you replace it with new one.

Also, water on surrounding trees does affect signal propagation/reflections, especially if you do not have clear line of sight towards transmitters.. Antenna on higher mast may help here.

As for your other questions, they are already answered more or less

Barrykgerdes · #6 25-03-2010, 09:23 AM

Quote:

Originally Posted by mithrandir

We've also had digital from the beginning and have had one antenna upgrade since then.

Are you on the west side of one of the hills Barry? We are on the west side of the Old Northern Rd ridge and the Sydney UHF masts are out of sight, even from the top of our mast and amp. We got a separate UHF antenna pointed at the Illawarra transmitters.

We notice that pixellation does not usually happen when we get hit by rain or wind gusts. It seems to be when the rain/wind affects something between us and the transmitter. Sydney VHF can be affected and Illawarra UHF be fine, and vice versa.

Hi Andrew
Yes we are on the West side of Castle Hills. It is probably not strictly LOS but it is near enough considering the height of the TV aerials. There are some trees and of course houses if your antenna is not above the roof line.

I get the Illawarra TV off an antenna side lobe so I have never bothered with a separate aerial. My aerial now suffers from bird collisions etc on the VHF section. I have not measured the field strength but having spent many years with UHF/microwave transmitters/receivers and RF propogation I just stuck my aerial in the most convenient spot on the ridge cap with the amplifier/distrbutor just under the tiles and pointed it to where I knew the TV stations were.

I played around with analogue TV (and colour) years before colour was released in Australia using a VSB transmitter I built that had about 1 watt pep. We needed very good antennas in those days to get any results but did manage to get signals (a bit noisy but watchable) over 60 mile paths. My best was from Hornsby to Oberon.

Aerial selection is important for UHF TV now. The Yagi aerials do have a limited bandwidth and produce some very odd directivity problems and side lobes when operated away from their designed centre frequency. Different antennas are required for different areas depending on the the frequency dispersion of your local service.

Barry

Analog6 (Odille) · #7 25-03-2010, 03:37 PM

Barry, thanks for the answer, at last one I can understand! I doubt we'd find anyone willing to get up on our roof, it is effectively 3 stories and the tiles really need to be re-anchored and generally 'done over'. But the house is owned by a developer (he has the whole 22 acres, old banana farm with 2 houses, all leased separately) and it is eventually going to be knocked down for little boxes. The chances of them spending major money on it are nil. We haven't had an oven since 2005! However, I might get a quote from an aerial guy, just to see.

supernova, thanks for asking. No we don't use the set top box at all, it would never pick up the ABC and the reception was all spotty. We have the aerial into the DVD recorder hooked up to the TV (analogue type). The STB is an expensive dustcatcher at the moment!

Nice to finally get an answer I can understand.

Barrykgerdes · #8 25-03-2010, 06:11 PM

Hi Odille

It sounds like you may be in trouble when the analogue ends. You and thousands of others. I expect an almighty fuss when all the viewers suddenly find they don't have a free to air TV service and are expected to outlay thousands for aerial systems or get satellite TV.

I get the foxtel people calling every couple of weeks trying to sell their service but for over $1000 dollars a year just to watch sport, no way. I can buy a lot of old TV series on DVD for that and watch them when I want.

Barry