59 replies to this topic

[M'bozo]

webbiegareth, on Oct 19 2010, 12:52 PM, said:

he's convinced it's an electrical fault (probably a grounding issue he said) and that I needed to get an electrician in to take a look and he'll come in after that if needed, possibly to ground the splitter he said if the electrician couldn't fix it.

It's the first thing I do if I strike a funny, but don't think it will fix your problem.

I read back on your posts and saw you are in a new house, so I didn't think bad connections or corroded switch contacts would be a problem., apart from the washing machine.

As I see it, (based on empirical testing I have done), house wiring can act as a loop antenna which conducts/radiates interference from arcing switch contacts (and other sources, washing machines etc). If this interference field impinges on the antenna, and the incoming wanted signal level is overcome by the interference, picture breakup occurs.

A tiled roof, such as you have, may allow more of this interference to escape and affect the incoming wanted signal compared to, say, a colorbond roof.

In any case, the solution, (if there is one), involves getting a signal at the antenna that is less affected by the interference, if this is possible.

This would usually involve the attending technician using a selection of antennas at different heights & locations on your property to effect the best countermeasure.

It also requires the use of instrumentation that can give a similar indication to your Sony's UEC, to assist with finding the best antenna location. A couple of hand-held transceivers are also useful, so you don't have to yell commands at each other when testing.

Even so, it may only be possible to reduce the problem, and not eliminate it entirely.

As an aside, I listen to 774 ABC Melbourne a lot. A couple of weeks ago, the morning announcer was talking about his woes with a new PVR that had been installed, and was having IIRC, glitching issues. Apart from laughing at the suggestions sent in by listeners, it struck me that people served by VHF digital transmissions have a lot of trouble such as you are experiencing, whether due to poor installation or poor signal issues.

I'm so glad all transmissions here that I get  to work with are on UHF.  

[bellotv]

M'bozo, on Oct 19 2010, 05:07 PM, said:

it struck me that people served by VHF digital transmissions have a lot of trouble such as you are experiencing, whether due to poor installation or poor signal issues.

I'm so glad all transmissions here that I get  to work with are on UHF.  

Me too !

Recon the government would be better reallocation all VHF digital services to UHF  ( hey and why not make MPEG4 at the same time ) and selling off all the VHF spectrum .

[webbiegareth]

Hi again everyone,

Great to see people getting involved.... any advice is always welcomed!

To confirm.... when I came home I put the TV on both analogue & digital modes, and flicked the light switch on and off over and over. In analogue, on ABC (which gives bad reception due to the antenna type) - every time I flick the light switch, I get lots of white lines and dots on the screen. For channels 7 / 9 / 10 etc, I have to flick the switch a few times to see a few dots. It doesn't appear visibly every time I flick the switch.

When it comes to digital, I found I have to flick the light switch 10 times or more to get a glitch on 7 / 9 / 10 .... for SBS, I didn't get it to glitch, though I know I've seen it randomly glitch when watching dodgy martial arts movies late at night. For channel 31, I couldn't get anything.... and strangely enough, the Sony TV reported both pre-viterbi and post-viterbi of "0" on that channel. All other channels report something for the pre-viterbi (somethingx10-6 to somethingx10-5).

So it definitely looks like UHF isn't being effected as much... but to fix this interference is going to be very hard from the looks of it!

EDIT - Next step, get the electrician to see if there is a fault, and if not, get a REAL antenna professional (from here hopefully) and not a local backyard jockey from Melton to do a proper site survey, and do whatever is needed to improve the signal received at the antenna.

Edited by webbiegareth, 19 October 2010 - 07:49 PM.

[webbiegareth]

I've just remembered something... and hopefully this makes sense and is correct! When the Jim's Antenna guy was working, I'm pretty sure he said he had a 60db signal up on the roof, and he added a 5db gain with the masthead amplifier so that it'd still be around 60db at the wallplate (using the amp to cover losses between the antenna and wallplate).

He thought it was great and more than adequate.... perhaps it really isn't good enough, at least to overcome the impulse noise?

[M'bozo]

Minimum gain for a MHW24FE is 12-14dB at VHF (sloped), 14dB for UHF. To reduce the gain to 5dB doesn't sound feasible without the use of an attenuator, I couldn't see one in your pictures.+
Also the MHW24FE is a wideband 44-820MHz amplifier, I'm wondering why this is being used, even though I have been told this is SOP for the big cities. I use MHW24F's with combo antennas, at least the VHF & UHF inputs are band limited and the respective gains are independently adjustable.



I also have a different approach to what seems conventional wisdom when it comes to the use of masthead amplifiers, since I use so many.

If the need arises and a masthead amplifier is used, I aim for 75dBµV at the wall plates (consistent with not causing overload in the system). That should reduce the effect of induction of impulse noise from electrical cables, if it is indeed an issue.

Having said that, a good signal is still required at the antenna before amplification is used.




There's an interesting report here discussing shielding effectiveness of coaxial cable distribution systems, for those interested.

[webbiegareth]

M'bozo, on Oct 20 2010, 09:35 AM, said:

Minimum gain for a MHW24FE is 12-14dB at VHF (sloped), 14dB for UHF. To reduce the gain to 5dB doesn't sound feasible without the use of an attenuator, I couldn't see one in your pictures.+
Also the MHW24FE is a wideband 44-820MHz amplifier, I'm wondering why this is being used, even though I have been told this is SOP for the big cities. I use MHW24F's with combo antennas, at least the VHF & UHF inputs are band limited and the respective gains are independently adjustable.

The Jim's Antenna guy didn't originally put the masthead amplifier on, it was the original "backyard amateur" guy from my local paper who fitted it... the Jim's guy just said he may as well reuse it since it's already there, but he'll just not crank up the gain much (just enough to counter any losses in the cable).

So it really does sound like I need someone over to perhaps replace the masthead amp with a more suitable model, and to adjust the gain a bit? (and maybe relocate / raise the antenna higher etc).

Is it a good idea if I buy the MHW24F (approx $59 delivered), and reuse my existing F-type power injector.... and then get someone to swap it over?

http://cgi.ebay.com....=item2eb080ea9d

Or the MHW34F model:

http://cgi.ebay.com....=item2eb0219522

Or heck, the fully-shielded MHW24FS model?

http://cgi.ebay.com....=item2eb04e8017


(As an aside, in regards to grounding the splitter.... I recently got one of those DSE powerboards, which has F-type coax protection.... I put the coax into that before it reaches the splitter to see if that improved anything. I was curious, so I opened it up, and it appears that the powerboard actually grounds the outer part of the connector, so I think grounding the splitter as well would be redundant?)

EDIT - I read the link, it was actually very good reading. I'm curious though, as there was a major difference in quality between the "consumer" splitters and the "professional" splitters..... but where do you find these professional splitters? If I can go to bunnings and buy a 2-way splitter for $8... from where do I buy the professional ones, and for how much? I'm 99% sure this is the splitter I have:

http://cgi.ebay.com....=item2eb08ba178

Apart from the electrician to check the earth of my house, I guess the next step is to get someone in to swap over the masthead amp (with whichever model you guys recommend), and do whatever else is needed (hopefully reusing my current newer antenna - maybe relocating it or putting it on a taller mast?).... even swap some coax over as the guy for some reason connected some short lengths of quad-coax in the roof together with F-joiners... and of course start off with a decent site test first!

Edited by webbiegareth, 20 October 2010 - 12:29 PM.

[debruis]

webbiegareth, on Oct 20 2010, 07:52 AM, said:

I've just remembered something... and hopefully this makes sense and is correct! When the Jim's Antenna guy was working, I'm pretty sure he said he had a 60db signal up on the roof, and he added a 5db gain with the masthead amplifier so that it'd still be around 60db at the wallplate (using the amp to cover losses between the antenna and wallplate).

He thought it was great and more than adequate.... perhaps it really isn't good enough, at least to overcome the impulse noise?

Hi

If your are getting 60dbuv, good Signal to Noise ratio on the roof at the antenna and the cabling from antenna to the wallplate is RG6. You do not need m/h amplifier for a single outlet. If the outlet is under 25mt you may lose 1-2db. 2 outlets or you may require some amplification. Even then it will depend on SNR at the outlet after splitting.
I would try with no m/h amplifier straight to one outlet.

[webbiegareth]

debruis, on Oct 20 2010, 03:00 PM, said:

Hi

If your are getting 60dbuv, good Signal to Noise ratio on the roof at the antenna and the cabling from antenna to the wallplate is RG6. You do not need m/h amplifier for a single outlet. If the outlet is under 25mt you may lose 1-2db. 2 outlets or you may require some amplification. Even then it will depend on SNR at the outlet after splitting.
I would try with no m/h amplifier straight to one outlet.

I have the cable going into the lounge room, into a two-way splitter. My HTPC has two dual HDTV tuners, I.e. four tuners all up

So, basically, it goes like this:

Antenna -> Masthead Amp -> Long run of coax into lounge room -> Power Injector -> 30cm coax -> DSE powerboard -> 30cm coax -> 2-way splitter -> Two lots of short 45cm coax to the two dual HDTV tuners.

I used the DSE powerboard as a test since it seems to ground the coax, but I've left it like that ever since. Also currently I've disabled one of those dual tuners, so from the splitter, one cable goes to one of the dual tuners, and the other cable goes to the back of the TV (so I can use Sony's diagnostic page to check for errors with the signal).

Quad shielded coax and F-connectors used everywhere, with those F-to-PAL adapters to connect to the tuners. Note in the roof there's two F-joiners where the cable has been cut, the builder didn't install enough coax cable to reach where the new antenna is located so it needed to be extended.

Edited by webbiegareth, 20 October 2010 - 02:58 PM.

[M'bozo]

As a cheap & cheerful test, connect the antenna direct to the Sony, bypassing all amplifiers, power injectors, splitters, dick smith power boards etc.

It sounds as if you may have enough F-F female connectors to implement this anyway.

See if you still get picture breakup and an UEC indication on the TV.

If yes, more than likely your antenna needs attention.

Changing masthead amplifiers of & by itself will give no benefit, unless you have an unimpaired signal to start with.

[debruis]

webbiegareth, on Oct 20 2010, 03:34 PM, said:

I have the cable going into the lounge room, into a two-way splitter. My HTPC has two dual HDTV tuners, I.e. four tuners all up

So, basically, it goes like this:

Antenna -> Masthead Amp -> Long run of coax into lounge room -> Power Injector -> 30cm coax -> DSE powerboard -> 30cm coax -> 2-way splitter -> Two lots of short 45cm coax to the two dual HDTV tuners.

I used the DSE powerboard as a test since it seems to ground the coax, but I've left it like that ever since. Also currently I've disabled one of those dual tuners, so from the splitter, one cable goes to one of the dual tuners, and the other cable goes to the back of the TV (so I can use Sony's diagnostic page to check for errors with the signal).

Quad shielded coax and F-connectors used everywhere, with those F-to-PAL adapters to connect to the tuners. Note in the roof there's two F-joiners where the cable has been cut, the builder didn't install enough coax cable to reach where the new antenna is located so it needed to be extended.

I would connect antenna without M/H amplifier & power supply directly to the TV and start switching lights on and off. 60dbuv at the antenna will be fine if the signal to noise ratio being received is good to run a test using the Sony.  This will be fine for internal TV tuner but I have found it a little low for PC tuners even if signal to noise ratio is good but you can cross that bridge when it comes.

[M'bozo]

Well, there you go.

At least 2 people think similarly.

[webbiegareth]

M'bozo, on Oct 20 2010, 04:20 PM, said:

As a cheap & cheerful test, connect the antenna direct to the Sony, bypassing all amplifiers, power injectors, splitters, dick smith power boards etc.

It sounds as if you may have enough F-F female connectors to implement this anyway.

See if you still get picture breakup and an UEC indication on the TV.

If yes, more than likely your antenna needs attention.

Changing masthead amplifiers of & by itself will give no benefit, unless you have an unimpaired signal to start with.

I like the idea, but actually doing this will be hard... as I have no idea in how to actually get onto the roof to bypass the amplifier in the first place. I just have a standard ladder, not something tall enough to get me safely on the roof Either I need to get a pro in to help, or should I just bite the bullet and buy a more decent ladder and attempt this myself?

Edited by webbiegareth, 20 October 2010 - 03:30 PM.

[M'bozo]

webbiegareth, on Oct 20 2010, 04:23 PM, said:

get a pro in to help

That's my suggestion.

[webbiegareth]

M'bozo, on Oct 20 2010, 04:36 PM, said:

That's my suggestion.

That's what I've been after but none of the local VIC installers on this forum come out this this far (and I'm only a 1/2 hour drive northwest of the CBD thanks to the new high extensions).  I really need to email debruis again, though he's from NSW but if he does end up heading over here for holidays I'm love to get some help, though I am hoping to have this all fixed up once and for all within the next few weeks, well that's the plan anyway.

I'm tempted to buy that shielded amp I linked to earlier, and get someone over for a few hours to test out various things... if I need an amp, I'll swap over the current one with the new one, if it turns out I don't need an amp (unlikely since I have four PC tuners), then I'll just sell them off again, even if it's at a loss.

I just want a decent working solution that will last, as I plan to be in the house for a while, and it's getting to the point where I'm happy to pay whatever is required to get that solution.

[debruis]

webbiegareth, on Oct 20 2010, 04:23 PM, said:

I like the idea, but actually doing this will be hard... as I have no idea in how to actually get onto the roof to bypass the amplifier in the first place. I just have a standard ladder, not something tall enough to get me safely on the roof Either I need to get a pro in to help, or should I just bite the bullet and buy a more decent ladder and attempt this myself?

Get Jims Antenna back

Ask him for SNR for VHF 6,8,11,12 & UHF 34 should be 28-31db. Levels of 60dbuv sound OK as mentioned in earlier post. Test on Sony TV and then on HTPC both directly connected. If OK you then require a m/h or distribution amplifier that will compensate for the losses of a 4 way splitter by the time the signal gets to you HTPC dual tuners. A model I have found good for the job is Matchmaster MA15P Metro Amp. It does not amplifier incoming signal from antenna but compensates for losses from splitting the signal.
Get technician to test SNR etc after splitters also

Edited by debruis, 20 October 2010 - 04:12 PM.

[bellotv]

There is a guy in Frankston .My mate Brendon Holmes from "Screen Antennas"

03 97836513

He is now clown.He likes a challenge.He has latest spectrum analyzer.He has been in the industry for over 25yrs .He does domestic and commercial.

Definitely worth a call

[webbiegareth]

bellotv, on Oct 20 2010, 08:08 PM, said:

He is now clown.

I'm hoping to hell this is a typo

[JK200SX]

How well do you know your next door neighbours?

You may want to do a test by running an extension lead from their place to power your TV equipment and masthead amp. You could do this with your mains power switched on and off and note if there is any effect? This may give you some indication in relation to the adequacy of the antenna system and isolating your power supply totally.

[debruis]

JK200SX, on Oct 20 2010, 10:34 PM, said:

How well do you know your next door neighbours?

You may want to do a test by running an extension lead from their place to power your TV equipment and masthead amp. You could do this with your mains power switched on and off and note if there is any effect? This may give you some indication in relation to the adequacy of the antenna system and isolating your power supply totally.

Very clever idea

[webbiegareth]

debruis, on Oct 21 2010, 09:11 AM, said:

Very clever idea

It is, but I'm not yet sure how I'm going to test it this way. The only way to test it would be to flick the lights on and off, so I'd still need my mains powered on to do this, but I guess the test would then see if the impulse noise interference is from the mains going directly into the antenna setup, or it's being radiated through the air. (if my logic is correct?)

I can't quite do it with a power lead to the neighbours (I'm new to the area, I haven't even met the neighbours yet - everyone seems to work different shifts out here), but I think I have another way to do it...

I have a couple of laptops, and I have a USB based dual-tuner, and I also have a UPS for one of my main computers. So.... I could emulate this by taking the UPS, disconnecting the computer gear from it, and disconnecting the UPS from the wall so it's running off its own battery. I'll plug the mastead amp power injector into the UPS.

The coax will then go into the USB tuner to the laptop, which is also unplugged from the wall and running off its own battery too.

That way the entire setup is running off battery and not connected to the mains.

Same thing, yes? (if not better as I'm then connected to the electricity grid at all this way).

Edited by webbiegareth, 21 October 2010 - 08:29 AM.

[debruis]

webbiegareth, on Oct 21 2010, 09:27 AM, said:

It is, but I'm not yet sure how I'm going to test it this way. The only way to test it would be to flick the lights on and off, so I'd still need my mains powered on to do this, but I guess the test would then see if the impulse noise interference is from the mains going directly into the antenna setup, or it's being radiated through the air. (if my logic is correct?)

I can't quite do it with a power lead to the neighbours (I'm new to the area, I haven't even met the neighbours yet - everyone seems to work different shifts out here), but I think I have another way to do it...

I have a couple of laptops, and I have a USB based dual-tuner, and I also have a UPS for one of my main computers. So.... I could emulate this by taking the UPS, disconnecting the computer gear from it, and disconnecting the UPS from the wall so it's running off its own battery. I'll plug the mastead amp power injector into the UPS.

The coax will then go into the USB tuner to the laptop, which is also unplugged from the wall and running off its own battery too.

That way the entire setup is running off battery and not connected to the mains.

Same thing, yes? (if not better as I'm then connected to the electricity grid at all this way).

Yes it is better as it filter power supply to all equipment mentioned above. Also would provide excellent earth isolation from lighting and the appliances. I would do this anyway if you have the equipment available and the rating on the UPS is high enough once you have sorted out the reception issue.

[webbiegareth]

debruis, on Oct 21 2010, 09:44 AM, said:

Yes it is better as it filter power supply to all equipment mentioned above. Also would provide excellent earth isolation from lighting and the appliances. I would do this anyway if you have the equipment available and the rating on the UPS is high enough once you have sorted out the reception issue.

I'll give it a try after work tonight, I'm very curious what will happen. I'll first set up the USB tuner on the laptop and connect the coax via my current setup, just to verify I see glitching on it before I try isolating everything onto battery power.

I used to have the m/h amp injector on the UPS but it still glitches, but that's because my particular UPS still runs off the mains until there's a power cut, at which point it switches to the battery. The UPS is used for my HTPC (which is also my file server), modems and phone gear.

[webbiegareth]

Ooooookay.... the end result is no real difference.

I took the coax from the wall, and instead of using the coax protection on the powerboard + splitter, I just had the coax from the wall going straight to a USB TV tuner. I found my USB TV tuner a bit better, it didn't glitch as easily, but I was still able to do it.

As a test, I put the washing machine on and then just started flicking the light swtich on and off.

I got glitching for the following two cases.

1. m/h power injector plugged into the wall, and the laptop plugged into the wall.

2. m/h power injector plugged into the UPS (running off battery, disconnected from wall and nothing else plugged in), with the laptop running off battery (unplugged from wall).


So I guess that points to the original signal not being clean/strong enough, than a power problem through the mains itself? (unless there's a major power probem radiating way more interference than normal, overloading everything)

Edited by webbiegareth, 22 October 2010 - 09:23 AM.

[debruis]

webbiegareth, on Oct 22 2010, 10:18 AM, said:

Ooooookay.... the end result is no real difference.

I took the coax from the wall, and instead of using the coax protection on the powerboard + splitter, I just had the coax from the wall going straight to a USB TV tuner. I found my USB TV tuner a bit better, it didn't glitch as easily, but I was still able to do it.

As a test, I put the washing machine on and then just started flicking the light swtich on and off.

I got glitching for the following two cases.

1. m/h power injector plugged into the wall, and the laptop plugged into the wall.

2. m/h power injector plugged into the UPS (running off battery, disconnected from wall and nothing else plugged in), with the laptop running off battery (unplugged from wall).


So I guess that points to the original signal not being clean/strong enough, than a power problem through the mains itself? (unless there's a major power probem radiating way more interference than normal, overloading everything)

Correct.

[webbiegareth]

debruis, on Oct 20 2010, 05:10 PM, said:

If OK you then require a m/h or distribution amplifier that will compensate for the losses of a 4 way splitter by the time the signal gets to you HTPC dual tuners. A model I have found good for the job is Matchmaster MA15P Metro Amp. It does not amplifier incoming signal from antenna but compensates for losses from splitting the signal.
Get technician to test SNR etc after splitters also

Actually, I have a question about this... what's the real difference between a masthead amplifier and a distribution amplifier? I can’t find the specs on the MA15P Metro Amp, so I’ll ask about the Kingray stuff since they’re easy to find.

I’m running a Kingray MHW24FE which is a wideband amp, single input for VHF 44-470 and UHF 470-860 (i.e. a total 44-860), and it’s been said this really isn’t the best type for my antenna.

The Kingray MHW24FS is a wideband amplifier, for VHF 44-230 and UHF 520-820. It’s got two inputs so it’s good for my particular antenna (DC21A).

Then there’s the Kingray MDA20H masthead distrbution amplifier, which has one combined input and is for VHF 174-470 and UHF 470-860... Which basically means it seems to amplify 174-860. This one seems to have a really low noise figure, but it seems to not have adjustable gain?

Which would be better to reduce the effects of impulse noise?  Do they yet make amps in Australia that only amplify the actual frequencies we used for digital TV?

Edited by webbiegareth, 22 October 2010 - 01:48 PM.