First, a big thank you to all the informed commentators on the forum. I think we'll need you a long time after the roll-out because not everyone is going to be delighted when analogue is put to sleep.

I live just out of LOS in SW Sydney, about 65K from Gore Hill and about the same to Knights Hill. Its a typical 3 bed BV on a quarter acre corner block, facing a little west of north in a small village. The street out the front carries light density traffic, (RTA says), the side street on our west services about thirty similar houses tucked in behind us. If I walk east half a k up the front street I get to the top of a rise and I can see Sydney. We might be about 20 metres below that crest. There are a couple of large gum trees in the blocks across the road and up the street, and 240v power lines on the other side of the road and down our western nature strip. Can't tell you too much about Wollongong, but depending on what happens when digital goes to full power, it may end up being a better choice for me.
The house originally had a Hills VHF LP pointing at Sydney and a Hills UHF yagi for Wollongong, all blue booms and orange plastic, on a 6 meter water pipe bolted to the barge board at the back of the house. The bottom of the pipe was in bare earth. The antennas went to a Kingray, but the previous owner took the injector with them. A friend gave me a Hills Q amp, I tidied up the cable connections and we got a pretty good analogue result.

Early 2006 relatives in the Gold Coast hinterland tossed their FTA digital setup because of electrical interference from high voltage transmission lines about a kilometer from where they lived, and behind them relative to their TV services. On analogue, bands of horizontal streaks would grow and intensify until it really wasn't worth watching the program. On digital, their Panasonic TU-SZT105A progesssively degraded, displaying loss of quality and strength on its indicators until loss of signal occured. I believe their serviceman put in a lot of time at no cost to them, but in the end they went to satellite. Anyway I scored their STB and started reading this forum.

I started with a Hills DY14 for Sydney and a TMX34WB for Wollongong, on the existing mast, through the Q Amp. Set the gains at about 20dB to start. Replaced all cabling with quadshield and crimped connectors, and fed it to one outlet below and to the right of the MHA. The cable is about ten meters long. Till I get things sorted out, the TV is a 19" GE CRT.

Problem. There is an ASKO washing machine about 10M away in the laundry below and to the left of where the mast is. Its about three years old, and it gets normal use for a two person household. No motor noise, but massive pixillation any time it switches anything.
Problem. There is a 2 year old Westinghouse fridge in the kitchen, maybe 15 meters away. Pixillates the picture when the door is opened, pixillates and screeches through the STB when the compressor starts. I never realised how often that motor comes on.
Problem. Ilve canopy rangehood a little further away in the kitchen. Like the Asko, no motor noise, but switching the exhaust fan on, or changing speeds? Forget it.
Problem. Almost any light in the house, CFD, conventional or halogen.
Problem. Any motor mower within 200 meters ( all five ).
Problem. At 3.30 any school day afternoon, the kids next door get home, go to the fridge, switch on the stove, exhaust fan, and/orget out the vitamiser or the blender ... their kitchen is about 30 meters away from the antenna, but, the antenna points right over it, so obviously its never going to work where it is.

Was wary about cranking the MHA up because of warnings about the digital cliff etc. Also aware that the amp is wide band, so I might not be getting away from the problem if this noise was coming from band 1. A FL3BPMH went in ahead of the MHA. It certainly cleared out the residual Ch 2 visible on analogue, but it didn't make a huge difference as far as the impulse noise was concerned.

Relocated the mast, its now on the western side of the house well away from next door's sources. Also bought a Spectramax 24+ (tossed up against a Fracarro 345, supposed to get more UHF gain out of the Hills). Discarded the DY14 and the Trumatch for now to concentrate on getting Sydney right. Set Q amp to max on both bands and wired it directly back to the outlet in the family room. It took most of a 30 meter roll of quadshield, but its point to point.

Solution. Cant see the Asko any more.
Solution. Cant see next doors kitchen any more
Solution. Cant see the fridge any more.
Solution. Perfect picture on TVS analogue - couldn't even see it it was worth bothering with before.
Solution. Range hood noise reduced substantially but we can live with it.
Solution. House lights occasionally pixillate, but not the problem they were.
Problem. Cant watch when anyone in earshot is using a motor mower or leaf blower. Picture degrades to loss of signal accompanied by clicks, clocks, squarks and screeches.
Problem. Now seeing the occasional car and motor bike going past the front of the house. Can interrupt the program for up to five seconds.
Problem. At various times of the day for no apparent reason, the picture will pixillate, the audio will do its thing and quality will degrade but stop short of loss of signal. I can hear no motors running outside and no other activity that would account for it. Can actually power down everything electrical in the house and still see it. Switching to analogue, though, there is electrical interference consistent with power lines dotting the display. I suspect that in moving the antenna, its closer to the power lines that run along the front and side of the block. We've probably run into the legendary Western Suburbs electrical distribution problems, like the audio tones I was getting through recording equipment power supplies I was using in Blaxland when I was a kid.

Took the Q amp out and substituted a Kingray MDA20H to see if I got better Band 1-2 suppression. Immediately noticed the loss of gain, and not a lot of difference in the interference. In fact that rangehood came back quite suprisingly. The next step will be restore the Q amp and the filter and take about 3 meters of mast up on the ridgecap.

Those of you who are still with me, this isn't a gripe, its a series of observations about whats ahead for some of us. The professionals among you will have seen things like this already. I think you will see more.
To guys like Alan and Col, thanks for your interest and perseverance. Reputable installers can be hard to find, and solutions to problems like this can come at a cost, whether you are dealing with a good guy or a rogue, the difference being the good guy will get you the proper result eventually. A forum like this allow some of us to minimise the costs of chasing the solution, and we're thankful for it.

Any comments will be gratefully received.

VanyA

Not always.

VanyaA,
Thanks for the complements.
I do not know why you removed the DY10 for Sydney

A phased array for Sydney would be better however it is a huge step, because this is a physically tall & large antenna.

What model of Q amplifier are you using? I would replace it with 34 dB amplifier

An MDA20H is a distribution amplifier and I would mount it in the roof, prior to splitting the signals.
Check with Kingray that you can power the masthead amplifier through the MDA20H

AlanH

If there's a choice, I would be pursuing a UHF reception option first every time.

+1

Same problems here (using an indoor antenna though, but only 10km from the transmitter).

I suspect that the extreme vulnerability of VHF DVB-T to impulse noise could have something to do with the fact that the system was originally specified to operate at UHF in Europe when it was first developed (the Standard mainly references UHF) but was later adapted for VHF, hence the error correction is not really optimised for the somewhat noisier VHF environment. Fingers crossed DVB-T2 remedies this somewhat...
(Not a great deal of comfort for those that have already forked out $$$ on DVB-T hardware though... )
I could also hope that one day all DTV transmissions will move to UHF, but...somehow I don't think that's going to happen...

VanyaA,

Your post highlights the need for correct antenna/amp/cabling selection and more importantly, mounting location of the antenna to obtain the highest possible digital channel power and MER and lowest possible BER.

DVB-T in most cases works fine on VHF, when the correct antenna is installed in the optimum-signal mounting location, but yes, I'd agree UHF is less-prone to impulse noise interference.

It was probably because the channel spacing on UHF there is 8MHz compared to 7MHz for VHF, so a potentially higher data rate was achievable.



+1

(Although I wonder if LTE will ever have an effect on the higher Band V channels)

...sigh...
There goes some of the best DTV spectrum...

Hi Alan.

That was actually a DY14 and was sidelined mainly to calm she who does the shopping. On the pole at the side of the house it looks like it covers most of the roof. Its almost as confronting as a phased array might be, even if not as high. Going up, with extra guying it will need for its weight, I will leave till I've explored alternatives. It wasn't so visible at the back of the house, but you'll understand why I see that as a poor location. But it did have the gain I was looking for.

No one locally has a phased array at all, even where you might expect to see them. I agree with your thought, though, and will keep it in the back pocket. The area looks like you might expect from a moderate "fringe" location. A small percentage of the village is on a ridge, with LOS. Most dewllings are however on the reverse slope of the ridge, and 4 and 6 meter masts on the roof ridges are common. There are a few DY10s and 3010s behind me, with UHF yagis looking at Wollongong. Digimatch is becoming pretty common and there are a surprising number of new Hills OMGs complete with Band 1. I guess this is "Digital Ready" marketing at work.

The MHA is Hills FC658205, 30dB band 1&3 and 34dB uhf. It was a gift, and I would probably have bought the MHW34F as its better sealed. Understand the MDA20H is a distribution amp, but GME publish that it can be used as I've done, and it even comes in the mast-mountable box. It does its work from 174Meg up and with the Spectramax there is no carrier from CH2. Previously the up to 30dB in the Hills amp overcame the -12dB set in the FL3PMH when the DY14 was up, so I really had to do more to knock out Band 1.

I've borrowed a newer STB and temporarily swapped out my STB , with similar to worse results. I haven't done anything with Wollongong because s.h.d.t.s. (see line 1) likes whats on 7TWO and Prime hasn't bought it yet. I agree that may be the ultimate solution though.

I dont believe I'm in a problem area. What is tolerable on analogue, however, can be a major irritation on digital. Here, when things are quiet, its brilliant. It even copes with the low level AC buzz off the power lines that is often present on a hot day. As is so often stressed in this forum, there is no substitute for a proper site analysis to see exactly where optimum locations are to mount the antenna and get the best result for the customer. I'm fortunate that I have access to information and opinion like this to make myself better informed.

The retailers are going to have to wait a bit longer before I get a flat panel, though.

Thanks

VanyaA

7TWO launched on Prime Wollongong December 23rd.

Link

Thanks, its all happening. Once the roof dries off & before we get the 40+ degrees back we'll see what that part of the spectrum looks like.

OK, hands up all those that knew the answer. I've tossed the VHF gear and am just running the TMX34 through the UHF amp in the MHA. Brilliant! Had some rain, and a bit of wind, and locals doing burnouts on New Years Eve, still brilliant. Even next doors motor mower has gone.

What I was struggling with is that I just have to walk maybe 200 meters up the street and around the corner and I can see right across the basin to Sydney, buildings, the bridge, everything. I'm not that far down the reverse side of the hill, and there are plenty of other VHF instals around me and not as high as I am. Proper measurements, as is stressed time and again here, and rightly so, may have picked up that the signal strength might not have been as high as one would have thought. MER and BER? As long as something somewhere wasn't being switched, and/or arcing, everything was fine.

This by the way is not to dismiss the work professional installers do. I wanted to find out for myself what the problem was and whether I could fix it, having had some training in a related industry.

So thanks contributors, I have a clean signal and can now ponder things like LEDs and LCDs, screen size, how many gig for the PVR, can I keep track of two programs while recording a third if the phone rings ..... the list goes on.

Seroiusly, Thanks cuys.

VanyaA

VanyaA, it's clear you've taken quite some time to put your post together, and to carry out the various tests you've made. I'm sure this will be very useful to others reading through, so thanks for that.

Can you please clarify a couple of things?


Your reception is now dedicated UHF, presumably sourced from Knights Hill (Illawarra)? You have removed any VHF Sydney reception.

Your first post gave problems/solutions for your reception situation, which at that point seems to have included VHF and UHF sources (Knights Hill and Sydney main transmitters). You commented that reception problems included video pixellation and screeches on sound as local interference occurred, but no distinction was made whether the problem channel was from Knights Hill or Sydney.
Did you originally see much problem with your UHF reception from Knights Hill?

Hi Charles. I'm cash poor and time rich these days, plus I have some q&e in analogue VHF transmission & reception. As dtv is inevitable I decided to do some of the dog work myself. I accept that if I get a good result without proper measurements and antenna location some of the outcome will be as much good luck as science.

I've just deleted a chapter & verse rendition of what path I took to get to my final solution, as the answers to your questions got submerged and definitely not clarified. Answering you point by point:

Yes, its only UHF from Knights Hill. The antenna is a TMX 34 through a Hills Q amp using the UHF circuit only, the VHF section gains set to zero and a dummy load in the VHF input.

The impulse noise was not confined to one channel. In the original location at the back of the house, the interruptions I described were visible/audible across all bands, but decreasing in severity as one moved further into UHF, as you might expect. The DY14 was also getting transients from next door's kitchen electrical appliances. As the antenna was pointing straight over their kitchen, thats probably no surprise either.

We still saw the disruptions on UHF, but with less severity. We saw minor pixillations and split screens, and the squeaks were fewer, but still happening often enough to annoy.

I substituted a borrowed stb for comparison. The results were as near to the same as made no difference. I put an fl3bpmh in ahead of the Q amp to reduce anything coming from band 1. No discernable difference.

The house is an "L" shape, on a corner block, with 240 volt power lines on the right and underneath the "L". I moved the "mast" from the top of the "L" to the other end, then put up a Spectramax 24B4+ only, to iron out the Sydney signal. Please refer my earlier rant. The problem now seemed to be related to passing motor traffic, plus switching transients in the 240 volt power lines. We also got spectacular results when the street lighting went on at dusk. However, anything we were used to seeing from the fridge, rangehood, washing machine etc, was gone.

Its worth saying here that there is quite often a low level buzz from the street power lines, particularly on hot days. This is typically bands of small dots or streaks perhaps 50cm apart, seen on analogue. Both stbs I've used dont appear to be affected by this.

Persevering with VHF was a personal choice. Some information from Alan also showed me that the hill between us and the direct LOS was perhaps more of an obstacle that I thought, and I now believe that to pursue the VHF option we would need to get the TC870 and the Unaohm out and go for it. This, plus encouragement from M'bozo, and logic, sent me back on the roof with the TMX. In spite of my rave at last post, I still see one or two hiccups a day, but I'm happy to live with what I have now. Alan's information suggests I'm a lot closer to LOS than I originally thought, and for that input I'm very grateful.

In going to UHF, I need to say that on analogue, the results were never that great, and that influenced my thinking a lot. UHF used to drop to poor margins whenever rain was about, and there were a lot of multipaths and ghosting that didnt affect VHF. The Panasonic stb I'm using atm registers maxima of 90% for quality and strength. It now consistently shows 90% for quality but occasionally will drop to as low as 83% strength, at various times, for varying lengths of time, minutes to many minutes, and for no reason that I have been able to pinpoint. The picture and sound are unaffected when this happens.

I know these values are not "real", but they do indicate to me that perhaps there is some variation in signal strength, that I'm not going to resolve until I get a professional in.

So that's my story. I really have doubts about how many problems my neighbors are having or about to have. One I know has been told they don't need to switch to digital until analogue gets switched off. My next door neighbor has bought Foxtel.



Thanks for your interest,

VanyaA

ok hoping someone can help. I live in Bundamba, ipswich queensland on the side of a hill and the reception here is so bad on analogue you get nothing but snow so digital is our only option. Recently we had alot of storms and our set top box was fried.so we bit the bullet and bought a new tv, the picture is now that bad that it skips and screeches all the time, meanwhile in the bedroom reception on the old analogue tv with set top box is fine how do i fix this problem.

lorne 74,
Get the Best Reception, Brisbane and read the links
Please post any of your antenna problems in the Brisbane Viewers' forum as the answer depends on your location.

AlanH

removed