indoor aeriel for HDTV

Frank.Dublin

hi, i'm trying to pick up RTE2HD with an indoor aerial, do i need to get an indoor aeriel with a hdmi connection to do this? i've seen a couple of aeriels in tesco and argos that say HDTV on the box but they are just using a coax connection, i would have thought that i need to use a hdmi connection for HD.

The Cush

Frank.Dublin wrote: »

hi, i'm trying to pick up RTE2HD with an indoor aerial, do i need to get an indoor aeriel with a hdmi connection to do this? i've seen a couple of aeriels in tesco and argos that say HDTV on the box but they are just using a coax connection, i would have thought that i need to use a hdmi connection for HD.

If you can get the Saorview signal with an indoor aerial RTÉ2 HD will be there, no special aerial required. All services are carried on a single frequency.

If you can't get a signal with the indoor aerial an outdoor aerial will be required.

zg3409

Hi Frank. The TV needs to be Saorview approved or you need to have a Saorview box. Try hanging the indoor aerial out an upstairs window on the South side of the house. The Dublin signal comes from the mountain over Sandyford so get as close as possible.

After putting the aerial outside do an automatic scan on the box and see if any channels are found. If you find channels then move the aerial inside and find the best spot for a signal, normally at a Window on the south side. You may need a coax extension lead for this.

If you find no signal try a manual scan on channel 30, failing that get a professionally installed outdoor aerial

reslfj

Frank.Dublin wrote: »

... a couple of aeriels in tesco and argos that say HDTV on the box but they are just using a coax connection,....

The HDTV is just a marketing text printed on the aerial box.

The HD signals are the carried by the very same UHF signal which also carry SD signals from the TV transmitter(s) to your aerial. It is just 'bits' which are carried and they may mean anything. (but is digitally encoded video and audio and text-tv)

A HD channel will need more bits/second to look great, so fewer channels can be carried - but to the aerial there is no difference.

To receive Saorview you will need a box with a DVB-T receiver and a MPEG-4 video decompressor.

TX >--UHF radiowaves-->your aerial>--->DVB-T>-->MPEG4>--hdmi-->TV-display 
   |      air         |           coax|  within box  | cable  |

If your TV set has support for Saorview, then the DVB-T MPEG-4 chips are moved into the TV set and no HDMI cable is used.

If you try to receive Freeview from NI, the MPEG-4 chip can and will decompress the freeview MPEG-2 bit-pattern.

If you replace the DVB-T chip with a DVB-T2 chip you get a FreeviewHD box, which will also receive DVB-T signals i.e. also receive and process both Saorview and Freeview signals.

Lars

PS!
Note indoor aerials are only for areas which have a very strong signal (near the TV mast). The standard is a rooftop directional aerial 10 m above ground and with a (passive) gain of 10 times (10 dBd).

Frank.Dublin

thanks all
when i watch a blu-ray movie on my tv the picture looks much sharper/better than while watching rte2HD, is this because the standard for blu-ray HD is much higher than the standard for HD on saorview?
or could it be because i live an area that's too far from the source signal?

homer911

Not all programs on RTE HD are in full HD - many are upscaled SD - you will notice a clear difference..

BostonB

Frank.Dublin wrote: »

thanks all
when i watch a blu-ray movie on my tv the picture looks much sharper/better than while watching rte2HD, is this because the standard for blu-ray HD is much higher than the standard for HD on saorview?
or could it be because i live an area that's too far from the source signal?

If you get a bad signal you'll get stuttering and digital breakup/tearing. The quality will stay the same though. If its lesser quality its because the programme is being broadcast in lower quality.

coylemj

The Ireland v. Germany match in the Aviva tomorrow will be broadcast on RTE2 in HD, that will be the one to watch.

As the signal is digital, any problem with reception will show up as picture breakage or severe pixelation, not simply a fuzzy picture or a program not being as sharp as you expect if it's being transmitted in HD.

AlarmBelle

Frank.Dublin wrote: »

thanks all
when i watch a blu-ray movie on my tv the picture looks much sharper/better than while watching rte2HD, is this because the standard for blu-ray HD is much higher than the standard for HD on saorview?
or could it be because i live an area that's too far from the source signal?

you could try an amplified indoor ariel like OneForAll

coylemj

AlarmBelle wrote: »

you could try an amplified indoor ariel like OneForAll

If he can watch RTE2 and the picture isn't breaking up then the aerial he's using is fine. His query is why he can't see a HD picture and the answer he's been given is that not all programs on RTE2 are in HD. The match tomorrow night should settle it for him.

BostonB

AlarmBelle wrote: »

you could try an amplified indoor ariel like OneForAll

Do they make any difference for saorview?

coylemj

BostonB wrote: »

Do they make any difference for saorview?

In certain situations an amplified (vs. passive) indoor aerial will make a difference, especially if you live in an apartment and can't erect an external (rooftop) aerial.

I have UPC so am not dependant on Saorview but I've messed about with passive indoor UHF aerials, all of them can provide a fuzzy analog picture but none of them can find the digital signal. However an old amplified Philips indoor aerial can pick up Saorview though if I was relying it for my primary TV service I'd need a rooftop aerial because the picture often starts to break up.

Hotblack Desiato

coylemj wrote: »

In certain situations an amplified (vs. passive) indoor aerial will make a difference, especially if you live in an apartment and can't erect an external (rooftop) aerial.

It's very unlikely to do anything the signal amplifier (yes, there is one) in your Saorview box or TV can't do. There's no point amplifying an aerial unless it's feeding into a very long cable run which will cause losses too large for the receiver to cope with. You will be wasting money and probably making the reception worse as the crappy aerial amplifier is going to add more noise to the signal than a decent receiver's amplifier will.

Aerial system components -
the good, the bad and the ugly
Scroll down to 'the ugly'

They should make it a crime to make set-top aerials with internal amplifiers. This gets the award for worst value for money of all the options. It seems so obvious - a weak signal. Amplify the damn thing! And yet it's so wrong. Nobody would try to borrow a hearing aid if you're in a crowded pub and can't understand what your friends are saying above the noise. You have to get close to your friend (raising the aerial to get more signal), get him to shout louder (call up the BBC and get them to turn the transmitter up) or move outside to talk (move away from the noise). Amplifying it will just give you earache and you still won't understand what he says.

Also
What's wrong with Set-Top aerials

coylemj

ninja900 wrote: »

It's very unlikely to do anything the signal amplifier (yes, there is one) in your Saorview box or TV can't do.

You're effectively telling me to disregard what I can see with my own two eyes.

I have three indoor passive UHF aerials, they are not telescopic, VHF or 'all in one' aerials, they are UHF only and when any of them is attached to my TV, the TV cannot find any digital channels and the analog reception is very poor. The Philips aerial has a slot for 2 x AAA batteries and a DC socket for a 12V DC feed. If I insert two AAA batteries or plug in an old AC/DC adapter from a hard drive (12V) to it and plug the aerial into my TV, the TV can find 18 digital channels which are the TV and radio stations on Saorview. Without the batteries or the DC feed the TV can find nothing.

This is the aerial, it's no longer available but it's a Philips SBC TT 250.

lawhec

coylemj wrote: »

You're effectively telling me to disregard what I can see with my own two eyes.

I have three indoor passive UHF aerials, they are not telescopic, VHF or 'all in one' aerials, they are UHF only and when any of them is attached to my TV, the TV cannot find any digital channels and the analog reception is very poor. The Philips aerial has a slot for 2 x AAA batteries and a DC socket for a 12V DC feed. If I insert two AAA batteries or plug in an old AC/DC adapter from a hard drive (12V) to it and plug the aerial into my TV, the TV can find 18 digital channels which are the TV and radio stations on Saorview. Without the batteries or the DC feed the TV can find nothing.

In your post prior to this you stated that the picture often breaks up using that aerial - that gives a good indication that it's not the aerial doing the work but the amplifier and the tuner in the receiver doing the work. I've talked about this before - what's happening is that the signal strength being received by the aerial is low, but local noise levels on the frequency being received are also low. The signal strength on its own is not enough for the tuner to work with in extracting the signal or carrier. What the amplifier does is raise the signal strength to a strong enough level for the receiver to be able to extract and work with - however the increase of signal strength is matched by an increase in the noise level that enters the amplifier AND the amp will also introduce noise itself so that at the amp's output, the signal to noise (S/N) (also known as carrier to noise (C/N)) ratio is worse than what went into the amplifier.

Before amplification the C/N ratio might have been just about OK - after amplification you may be able to get a usable signal provided the signal strength gets above a minimum needed by the tuner but since the original signal is unlikely to have had a good C/N ratio in the first place and you have added additional noise into the system, you will end up with a signal that is "brittle" as you've found out. Your receiver will already be working hard with the signal quality being thrashed and hoping that the bit-error rate isn't too high that it becomes unusable, while the signal itself will have little immunity to changes in propagation e.g. effects from weather, movement of air or even someone walking about in an upstairs bedroom, and anything that raises the noise floor at the aerial (e.g. ignition interference, thermostats) will just kill the C/N ratio before it reaches the amplifier which it can never recover until the noise floor returns to its previous state. One of or a combination of the above will regularly disrupt your signal reaching your receiver and hence why the picture often breaks up. The aerial system set up is simply unreliable.

If the unamplified aerials you have were to have their aerial connection plug inserted into a set-back amplifier with the amplifier output then connected to the receiver, I would say that you would have a similar outcome to the amplified aerial in question. In fact the unamplified aerial, if it's designed is based on Yagi or log-periodic principles which can make it directional and give a small amount of gain (e.g. 4-5db over a simple dipole) and it is fed into a set-back amp on its way to the TV, it would probably work slightly better than many amplified aerials that simply consist of a loop, a whip or flat panel aerial - but it would still be brittle. Any amp that is used in the process should be a variable one that starts effectively at zero and should be set just slightly above the minimum strength required by the receiver so that the C/N ratio is kept as healthy as possible.

As a temporary and last resort method of reception it may prove useful in some situations - but I would never rely on it as a primary means of reliable reception to either watch a programme at an appointed time or to feed into a PVR because it's simply too easy for reception to fail. Garbage In Garbage Out.

Hotblack Desiato

coylemj wrote: »

I have three indoor passive UHF aerials, they are not telescopic, VHF or 'all in one' aerials, they are UHF only and when any of them is attached to my TV, the TV cannot find any digital channels and the analog reception is very poor.

Do yourself a favour and get something, anything, better. The effect of this will far outweigh any crappy amp. Even take (as we did for a while) the passive indoor aerial and mount it as high in the house as possible i.e. attic. It's replaced with a proper aerial now, but when we positioned it high up it gave far better reception than at set-top level even though the cable run was far far longer.

lawhec

ninja900 wrote: »

Do yourself a favour and get something, anything, better. The effect of this will far outweigh any crappy amp. Even take (as we did for a while) the passive indoor aerial and mount it as high in the house as possible i.e. attic. It's replaced with a proper aerial now, but when we positioned it high up it gave far better reception than at set-top level even though the cable run was far far longer.

Even with the amplified aerial, as long as when it is unamplified it can receive a half-decent enough signal on its own before amplification, if you have a power point plug the 12v DC adaptor in to power the amp and that will help compensate for downlead losses - one of the 'right' ways for using an amp.

Of course this depends on a signal being viable in the attic (aluminium clad insulation will kill it) and ensuring that anything involving electrical power is steady on a surface that isn't a fire risk e.g. fibreglass insulation.

coylemj

lawhec wrote: »

In your post prior to this you stated that the picture often breaks up using that aerial - that gives a good indication that it's not the aerial doing the work but the amplifier and the tuner in the receiver doing the work.

So why does that aerial get some signal but the three passive UHF aerials get nothing when I search for digital?

The signal does break up but only sometimes and I was able to watch most of the hurling final in HD from it.

My point simply is that I get some reception from an amplified aerial and nothing at all from three different passive indoor UHF aerials. That's all I'm saying and it's based on experience, I don't care about the theory. In an apartment where the tenant can't erect an external aerial, an amplified aerial might make the difference between TV and no TV.

coylemj

ninja900 wrote: »

Do yourself a favour and get something, anything, better. The effect of this will far outweigh any crappy amp

As I said in my earlier post, I was only messing about with those aerials, my primary TV is cable (UPC).

lawhec

coylemj wrote: »

So why does that aerial get some signal but the three passive UHF aerials get nothing when I search for digital?

All four aerials are getting some signal - but on their own the signal being received, sent into the downlead (in the case of the aerial with built-in amp, bypassing the amp) and into the aerial socket in the receiver is not of a sufficient strength (voltage) for a picture to be viewed.

Only when the aerial which has an amp built in and is powered up does a signal strength reach the receiver for it to work with. At the price of also a noisier signal.

The amp on its own cannot give a picture - the aerial connected to it has to provide something for it to amplify. It just happens to be in this case the amplifier and aerial are built into one case.

If an unamplified/passive aerial is connected to a set-back amplifier (the name's a bit of a misnomer as behind the TV is usually one of the last places they should be placed at) the same principle applies except a small bit of signal will be lost between the aerial lead and the input of the set-back amplifier.

The amplifier in such indoor aerials, set-back amplifiers, masthead amplifiers, distribution amplifier etc. for TV reception works along the same principles as an audio amplifier - whereas an audio amplifier is designed to cover the hearing range of humans (0 to approx 20kHz), a TV amplifier is designed to amplify a part of the radio frequency spectrum - for a UHF aerial this will be about 450MHz to 900MHz (some 'grouped' ones cover a narrower selection of that), any which claims to cover all TV bands and FM radio etc. will be from about 40MHz to 900MHz - normally the quality of the latter one isn't as good as one which covers a narrower frequency range.

If you feed an audio amplifier with rubbish, the output will be rubbish. Louder rubbish. No Jedward jokes please. :pac:

If you feed an RF amplifier with rubbish, your output will be louder (higher voltage) rubbish. The only difference is that if this was with an analogue TV signal the receiver would detect that the voltage received on a certain frequency would be high but your picture will still be covered in snow, teletext unable to be decoded and still sh*t. With digital's "cliff effect", the receiver can work with a rubbish signal provided it's strength - provided for by the amp - goes past a certain threshold. But an amp cannot improve the signal quality. Only signal strength.

Provided it passes the minimum signal threshold, your receiver can try and work out the rubbish signal and hope that it can understand enough of it, depending in what way the signal has been sent, to give you a picture. Sometimes this works, quite often it doesn't. And if it does work, it will not take much to tip it off the cliff and give no picture.

Take for example someone in or around Dublin looking to get the new Freeview post-24th Oct service from Divis. One person (A) gets a good aerial with a claimed gain of 13-15db gain over the frequencies required, mounts it on a 20ft pole on top of the roof, a mid-powered 14db masthead amp with power supply and good quality satellite-grade coax cable. Person (B) gets all of what person (A) gets except the masthead amp & power supply. Person (C) again is the same as (A) except they use a simple dipole cut to frequency with no gain and a 30db masthead amp.

Only one of the three above gets a good enough signal for the person to be able to watch BBC Three on their Saorview approved TV. Guess which one is it?

Person (B)'s setup mimics your experience with the unamplified/passive aerials (assuming they are shaped like an outdoor aerial and are just not a single element) - despite a decent set up in general (good aerial, good coax downlead, aerial outdoors and at a good height) the available signal reaching the receiver is not strong enough even though at the aerial itself it is - because the signal is weakened going down the coax cable. The solution is to copy person (A) and install a powered masthead amp, enough to overcome the coax cable losses.

In case you think your amplified indoor aerial is like person (A), it's not. It is more like person (C) whose aerial is not only crap, but the amp cannot make up for this - even though the total gain of the system is better than person (A). The amp is mostly amplifying noise and very little signal. Even if the signal reaches the tuner threshold, likely to say that signal strength is between 'good' and 'excellent', the quality of the signal is so bad the receiver cannot make head or tail of it. Where in your case the signal being received isn't quite as bad because your receiver can make a go of understanding it, the signal is still rubbish. GIGO.

To provide a similar experience with UPC cable, take the coax cable that plugs directly into your TV to give you analogue channels, and put in an 20db attenuator that covers the frequencies used by UPC for analogue TV between the coax cable and the TV aerial socket. Turn the TV back on and the pictures should start looking snowy. Turn it off, take the coax cable & attenuator out from the TV, connect it to an amplifier that gives a gain of at least 20db and connect a lead between the amp and TV aerial socket. Turn it on again. While the signal level reaching the TV will be at least the same without the attenuator and amp, the picture will still be snowy. The amp will raise the signal level, but can do nothing about it's quality. I'm not familiar with UPC's digital TV network, but if you connected it to a UPC digital receiver which can give a readout of signal strength and quality levels, you'll find that with the attenuator and amp in the network the strength will be the same without both items in the signal, but the quality will be worse. That's if you can get a picture in the first place.

The lesson - in the same way that guns don't kill people, only wannabe gangstas from Moyross or Tallaght do, amplifiers don't give you a signal, the aerial does.

coylemj wrote: »

I don't care about the theory.

If you don't make an attempt to understand what is going on, then don't be surprised if people pull you up on it. A little knowledge can be a dangerous thing. Just because I can wire a three-pin electrical plug doesn't mean I can rewire my house.

AlarmBelle

ninja900 wrote: »

It's very unlikely to do anything the signal amplifier (yes, there is one) in your Saorview box or TV can't do. There's no point amplifying an aerial unless it's feeding into a very long cable run which will cause losses too large for the receiver to cope with. You will be wasting money and probably making the reception worse as the crappy aerial amplifier is going to add more noise to the signal than a decent receiver's amplifier will.

Aerial system components -
the good, the bad and the ugly
Scroll down to 'the ugly'


Also
What's wrong with Set-Top aerials

nonsense i have a friend with an indoor amplified ariel and they can get all the saorview channels with a vision box. excellent picture and sound no noise amplified or otherwise

Ronnie Raygun

Read the post previous to your own. It's often just pure luck that these amplified aerials work where others have failed.

watty

AlarmBelle wrote: »

nonsense i have a friend with an indoor amplified ariel and they can get all the saorview channels with a vision box. excellent picture and sound no noise amplified or otherwise

I bet my €6 aerial that is useless here 14km from TX would work for you as well



Amplified aerials are a con unless it's a very long coax to TV.


(It does work in Kitchen, but not in Living Room as window faces wrong way.)

Another €6 one as it comes ready to pop together:

coylemj

watty wrote: »

I bet my €6 aerial that is useless here 14km from TX would work for you as well



Amplified aerials are a con unless it's a very long coax to TV.

Watty, I'm reluctant to take on someone as eminent as you with your vast knowledge but in this case I'm going to.

That exact UHF aerial (I think I bought it in Maplins) is one of the three passive aerials I have tried and it gets zero Saorview signal according to my Philips 42PFL8404 TV. On the other hand the amplified Philips indoor aerial mentioned in my earlier post does get Saorview though the signal does sometimes start to break up. I watched most of the hurling final on RTE2 HD from the amplified aerial.

Despite all the technical reasons that have been trotted out as to why it should not make any difference, in my case an amplified aerial makes the difference between no signal and a half-acceptable Saorview signal.

My primary signal is UPC so the testing I did with the various indoor aerials was just messing about and the cable from the aerial to the TV is no more than 2m.

Peter Rhea

coylemj wrote: »

Despite all the technical reasons that have been trotted out as to why it should not make any difference

Lawhec's post explains exactly why amplification would make a difference in some cases, by raising the signal level above the receiver threshold.

watty

Be a pretty rubbish tuner head.

AlarmBelle

watty wrote: »

I bet my €6 aerial that is useless here 14km from TX would work for you as well



Amplified aerials are a con unless it's a very long coax to TV.


(It does work in Kitchen, but not in Living Room as window faces wrong way.)

Another €6 one as it comes ready to pop together:

it is not a long coax. as for saying it is luck... well maybe it is just luck the sats work. and actually an ariel similar to yours was tried and would not work