7 replies to this topic

[razor_burn]

Hi All,
Hoping someone may be able to assist me. I am in the Rooty Hill/Plumpton NSW area and having some DTV reception issues. House is about 10yrs old, I have been there for 8yrs, never changed the antenna myself so I assume the original owners didn't either in the 2yrs they were there. I have 3 aerial points in the house (only 1 in use currently), they aren't screw type F connector plates/wall sockets, so that needs to be rectified first thing I guess. Not sure of brand or type of antenna or the quality of the co-axial/RF cable that was used, I would assume an installer would know if it's RG6 quad shield or not. The antenna is pointing the same way as the other houses nearby, but there is a little bit of vacant land with large trees next to my place so not sure if that's an issue, only about 5 or 6 big trees though.

I used to run a CRT with a twin HD tuner PVR (Sony SVRHD700- I know, I know, it's a good pic when it's working steady though ) in the lounge room. Got an LCD approx 12 months ago in the bedroom and the signal was poor in the bedroom, Ch 7 and 9 would constantly drop out but the PVR in the lounge was fine.  
I went into the roof several months ago and replaced the passive splitter with a digital 4 way passive one to see it it helped, the frequency range on the new one was bigger and said on the pack it was digital compatible so I thought it might help. Doesn't seem to though. Found it a Bunnings so that may have been a mistake

The LCD in the bedroom would also cut out when I switched the bedside light on too, since discovered that it's probably impulse noise interference by reading on this forum, but I haven't resolved that just yet.

The CRT in the lounge went belly up a few weeks back so I moved the CRT out and got the LCD from the bedroom and connected it up in the lounge room and ran the cables through the PVR too. I am not running the RF through the VCR, just from wall to RF in on the PVR, then RF out to TV, with a little RF connecting the twin tuners together on the back of the PVR.
Things went downhill from there.

I completely lost Ch7 and 9 is not much better, it breaks up constantly on both the PVR and the TV. Ch 10, ABC, SBS are about 80-90% on the TV and the PVR and TVS is 100% and rock solid on both. Might be because the transmitter is close by in St Mary's I hear?
I have tried re-tuning, different cables etc, no luck. I have not changed the wall plates to F screw connectors, the plate in the lounge feels like someone superglued it on and I can't get it off unfortunately.

I don't quite understand it but there are a bunch of numbers that appear on the screen when I check signal strength on the TV, I was told that the "Post Viterbi" number should be "0" and the "COFDM AGC" should be ~-300.
Well on all channels they aren't.
The Post Viterbi ranges from 1.14 to 9.00 and the "COFDM AGC" ranges from -337 to 430 depending on channel. No way to test Ch 7 of course, still can't tune it in on either PVR or TV.

Based off what I read on these forums I tried contacting JustService communications, he told me he was too busy before I got 5 words out of my mouth and then I tried another guy, erect antenna's, asked some questions via e-mail re digital metre and qualifications etc and have had no response to e-mail or to follow up phone call VM I left.

Sorry for the long post, total newbie here so please go easy on me!

If anyone can help or point me in the right direction at least it would be greatly appreciated.
Cheers

[mtv]

razor_burn, on Jun 25 2010, 07:33 PM, said:

Hi All,
Hoping someone may be able to assist me.

razor_burn,

I've replied to your PM.

There's too many variables to determine what you may need without some accurate signal measurements (site test) as digital reception in your area can be both difficult and varies greatly, depending on individual location.

[charlesc]

razor_burn, on Jun 25 2010, 07:33 PM, said:

...and TVS is 100% and rock solid on both. Might be because the transmitter is close by in St Mary's I hear?

From TVS website.
Tune in - Digital Channel 44 (logival channel 44) or Analogue UHF 31.  Digital UHF 29 (see below)
TVS is now broadcasting free-to-air in both digital and analogue from our transmitter located at Gore Hill in Sydney. You will almost certainly need to re-scan your television or set-top box to receive our digital signal.


These are the channels from the main transmitters on the North Shore.
ABC    VHF 12 Hor 226.5 MHz ABC Tower 221 Pacific Highway GORE HILL
SEVEN   VHF 6 Hor 177.5 MHz Ch7/10 Tower 192-196 Hampden Road ARTARMON
NINE    VHF 8 Hor 191.625 MHz TCN 9 Television Tower Artarmon Road WILLOUGHBY
TEN     VHF 11 Hor 219.5 MHz Ch7/10 Tower 192-196 Hampden Road ARTARMON
SBS     UHF 34 Hor 571.5 MHz ABC Tower 221 Pacific Highway GORE HILL
TVS     UHF 29 Hor 536.625 MHz ABC Tower 221 Pacific Highway GORE HILL
Dig44   UHF 35 Hor 578.5 MHz ABC Tower 221 Pacific Highway GORE HILL (closed 30 April, 2010)
3D Trial UHF 35 Hor 578.5 MHz ABC Tower 221 Pacific Highway GORE HILL  (June, July 2010)


razor_burn, I've replied to your PM.

[razor_burn]

Issues resolved now, thanks to Beachboy, CharlesC and MTV for replying to my PM's and phone calls and also for their advice and assistance. Thanks also to forum user plumgas for the advice rendered.

MTV ended up doing the work, did a fantastic job over the 2 days he was at my house.

In case anyone is interested in the results, details below.

I had a 10yr old antenna on the roof which I have kept purely for FM radio reception.
MTV did the site test and ended up reccomending and installing a Fraccro LP (sorry MTV, forgot the model number, 348 maybe?) which is mounted a few metres up on a mast, (the old antenna wasn't very high up) now the Fracarro is up high enough that the M7 noise barrieres aren't an issue anymore.

He also replaced the coaxial cable, there was air spaced installed throughout the house so MTV replaced the lot (to 3 points in the house) with RG6 Quad, put in and amp/splitter and replaced all connection points in the house with F connectors. Had some fly leads made up too, keep the sigal as pure as possible before it hits the TV.
(whilst he was at it I had CAT 6a data cable run through to multiple points in the house, hence the lenghty install time and thanks again to MTV's infinite patience with me!)

At first and straight after the work was complete, I had channel 9 drop out completley on the PVR and the TV, but about 10 seconds later everything righted itself. CH 9 is the weekest of them all and aside from that first night, the only other issue I have had was during the NRL Grand Final when Ch 9 dropped out completley through the TV's tuner and I had to watch through the PVR. No big deal though, the PVR is HD and about an hour after the final I got CH 9 back on the TV after a full re-scan. I have never had an issue with Ch 9 (or any other channel for that matter) since that day.

As for the impulse noise, not an issue in the lounge at all now, the air con or lights don't affect the signal on either the PVR's or the TV's tuner.

The other TV in the bedroom is still affected by impulse noise every now and again, however only from the bedside lamp and not the air con or the ceiling light. The interference from the lamp is minute, the picture breaks up for less than a second and rights itself, but that happens so rarely I am not fussed, I will probably get some ferrite to wrap around the cord or try other lamps to see if it makes a dfference.

Thanks again to MTV, everything is working beautifully.

Hope some of this info will be useful to other forum members.

razor_burn

[mtv]

Thanks for the update, razor_burn.

As expected, the TV rescan solved the Ch9 issue.
Sometimes there are transmission glitches... it's not always antenna/reception issues.

Have to admit, your job was a bit of a challenge, given the numerous issues encountered along the way, but we got there in the end.
The antenna selected was the Fracarro LP34F which gave the lowest BER figures, providing the highest signal quality.
Further proof how well these antennas perform in reasonable signal areas.

The air-spaced coax had been run through the same stud/nogging holes as mains power cables, creating most of the impulse noise problems.

A ferrite suppressor may help with the bedlamp, as it's quite a nasty little noise-generator as we discovered.

Your job was a good example of lots of things contributing to poor digital reception and that it's only as good as the weakest link in the signal chain and the importance of obtaining good signal quality at the antenna to begin with..

Pleased to hear all is going well, mate.

[beeblebrox]

mtv, on Jan 2 2011, 01:12 PM, said:

A ferrite suppressor may help with the bedlamp, as it's quite a nasty little noise-generator as we discovered.

Speaking of nasty little noise generators , got a callback from a customer who was reporting picture breakup on every channel every couple of seconds, after a new install that had very good ber and dcp but needed an amp for the distribution system...  
imeadiate thought as dcp looked ok was the amp as the cber would go from 2or 3 x 5^10  to no lock..  have seen an amp do this before, changed the amp and pwrsup, same problem.  
Up the ladder on the chimney plugged into the antenna, same problem looked at the spectrum, was getting 40-50db of interference every 10 seconds at different spots across the spectrum (this wasn't here the other day)....  looked like a dodgey electric fence but not in the inner eastern suburbs of melbourne.


asked the customer if he had anything electrical running that he didn't have the other day, sure enough we turned off the christmas tree lights and magically it was all good again...   cheap chinese rubbish, I'm sure they don't meet any compliance standards and the best noise generator I've seen in a long time...   even beats my old drill I use for creating noise when testing new antennas. could not believe the 50 db of noise it was generating on VHFH

[reddahaydn]

hey guys,
I have a similar issue with channel 7 and 9.

I have a plasma on one side of a wall on a entertainment unit with a dvd player, modem (naked dsl) and phone. All plugged into the same power board. Was working fine then I installed a splitter and a wall mounted lcd on the opposite side of the wall. I replaced all my old arial cables with good ones but channel 7 and 9 still dont work on the plasma. i pulled apart the power cord and arial on the lcd and they work fine.

now the thing is, as soon as I turn the modem off, all is fine. the modem plug in the wall is next to (but with a steel stud in between) the arial outlets. The problem isn't in the wall because when I move the tv unit out about a foot channel 7 and 9 do work with the modem on. Note that the lcd on the wall has f plug and the plasma in the lounge has the other sort of plug.

Is there anything I can do to make them work with the modem on? it is annoying not to be able to use the internet while watching 7 and 9.

Cheers guys

Edited by reddahaydn, 06 January 2011 - 10:05 AM.

[mtv]

reddahaydn, on Jan 6 2011, 10:44 AM, said:

hey guys,
I have a similar issue with channel 7 and 9.

I have a plasma on one side of a wall on a entertainment unit with a dvd player, modem (naked dsl) and phone. All plugged into the same power board. Was working fine then I installed a splitter and a wall mounted lcd on the opposite side of the wall. I replaced all my old arial cables with good ones but channel 7 and 9 still dont work on the plasma and are really bad on the lcd.

now the thing is, as soon as I turn the modem off, all is fine. the modem plug in the wall is next to (but with a stud in between) the arial outlets. The problem isn't in the wall because when I move the tv unit out about a foot channel 7 and 9 do work with the modem on.

Is there anything I can do to make them work with the modem on? it is annoying not to be able to use the internet while watching 7 and 9.

Cheers guys

If all was working fine until you installed the splitter, it sounds like either there's a problem with how you've connected the splitter/cabling/outlets, or splitting the signal has caused levels to drop too low.

Is all your cabling RG6 Quadshield, splitter and connections F type?... If not, poorly-shielded cabling/splitters/connectors can allow interference in.

Are you using RG6 Quadshield flyleads? If not, cheap poorly-shielded flyleads are a very common problem with a tendency to pick up interference.

If it's a wireless modem on your ADSL, that can also create interference issues, but cabled modems can also do this.

Do you have a central ADSL filter/splitter installed?

I understand it's naked ADSL and that you don't have phones on the line, but without an ADSL central filter/splitter, sometimes the cabling acts as an antenna, picking up, or transmitting interference.

Just a few possibilities, but difficult to determine without being there and inspecting and testing the installation.

As I said, considering everything worked before you added the splitter, that's where I'd start looking.

Edited by mtv, 06 January 2011 - 10:18 AM.