Tv aerial

[flying haggis]

Would this be good enough
https://www.screwfix.com/p/labgear-x-beam-mast-aerial/30515

that is a wideband aerial. you will be better off with grp A as I linked to in a previous post. SF sell that as it "will do" for most areas

you are much better to have an aerial with too much gain than an aerial with not enough and an amplifier

 

[Spectric]

Your Waltham transmitter is group A at 470-606Mhz so get a group A aerial, not wideband.

 

[flying haggis]

The transmitter is Waltham, I am in Loughborough.
I sort of assume that there is an online website that lists these things?

edit: it would appear that there is a relay station in Leicester which is were my new neighbours aerials seem to be pointing.

the leicester relay carries a "freeview lite" signal ie not all the channels so best avoided. stick with receiving from waltham

 

[HamsterJam]

Using an in roof aerial is only sensible in a strong signal area. The roof material especially when wet will lose a lot of the signal. It is NOT just a case of using an amplifier as once lost you cannot get the same quality of signal back again despite what anyone might tell you.

However now we have digital TV the signal will either be good enough and you’ll get perfect pictures or not good enough so you’ll get nothing or maybe a broken picture with a some blockiness as the receiver struggles to determine ones from zeros.

 

[Eric The Viking]

First off, identify exactly which transmitters are visible (line of sight) from your house. Take altitude into account, meaning not just yours and the TX, but any intervening hills, large buildings and trees (In leaf, trees very effectively block higher frequency radio signals such as TV and WiFi).

Terrestrial transmitters fall into two types:

Main stations such as Crystal Palace (London), Wenvoe (Cardiff), Mendip (West of England), Rowridge (IoW, serving area south of the North Downs) - these are powerful, usually 250,000W or more, radiate omnidirectionally (all points of the compass), and almost always horizontally polarized (this latter is important),

Relay stations, which fill in coverage holes, can be very low power, are usually directional (so there are directions from which you can't use them!), and are vertically polarized. Think of these as the Gaffer tape of the system. The drawback, apart from signal strength, is that they sometimes carry only a limited set of channels, for example, not all the HD stuff, or possibly the wrong region for you, etc.

From what you've said, it seems like everybody nearby is using a repeater. This may be because they need to, or because the cheaper end of the aerial installer business just looks at other roofs in the area, without checking signal strength, etc. The system is set up so that main stations and their repeaters interfere as little as possible with each other. This means an aerial for the main station may be unsuitable for one of its repeaters, and vice versa. Don't forget to use the correct polarization!

The other thing to watch out for is whatever is beyond your repeater. Here, Kingsweston repeater is closest, and we are in its coverage area, but "behind" it (from our house) is Wenvoe, which is around 200,000x "louder" and swamps it. There are various tricks to control which TX the TV uses, but we end up with both, which is unhelpful (I don't really want the Welsh output! Across the road (literally) the angle is better, so they can use it, but they can't get Mendip, whereas we are on the higher side of the street, and can.

There is no such thing as a "digital" aerial, by the way - it's all analogue at that part if the system (even satellite!), and the old issues from analogue TV days - ghosting, poor signal, etc. - still degrade the signal. The difference with digital TV is that it either works or it doesn't, and you don't usually get warning of bad signal - it either stutters, freezes completely, or just says "no signal".

It is unlikely you will get away with a loft aerial for TV (you might for DAB). A longer aerial might help, but probably not much.

These might help also:

https://www.ofcom.org.uk/tv-radio-and-on-demand/information-for-industry/tv/tv-transmitter-mapshttps://ukfree.tv/section/TV_TransmittersFull-Freeview vs Freeview Light: map (clickable map giving coverage contours)

Freesat might be a good option, but only if you are careful about the cabling in the house (it's more picky than terrestrial TV). And the more northerly you are, the less useful it is, as geostationary satellites orbit the equator, and the signal quality degrades as you move north or south from that circle.

Forgot to say: polarization: look at the fins on the front end of the aerial (towards the transmitter). If those bits are horizontal, it's horizontal, if vertical...

Bill Wright's Aerial pages have a lot of good and bad practice in fitting aerials, useful if you intend to DIY.

If you want to find a good quality contractor, look for the roof with the neatest, reasonably new installation on it, and ask the owner who did it. Neatness and quality usually go together in that business.

 

[HamsterJam]

First off, identify exactly which transmitters are visible (line of sight) from your house. Take altitude into account, meaning not just yours and the TX, but any intervening hills, large buildings and trees (In leaf, trees very effectively block higher frequency radio signals such as TV and WiFi).

Terrestrial transmitters fall into two types:

Main stations such as Crystal Palace (London), Wenvoe (Cardiff), Mendip (West of England), Rowridge (IoW, serving area south of the North Downs) - these are powerful, usually 250,000W or more, radiate omnidirectionally (all points of the compass), and almost always horizontally polarized (this latter is important),

Relay stations, which fill in coverage holes, can be very low power, are usually directional (so there are directions from which you can't use them!), and are vertically polarized. Think of these as the Gaffer tape of the system. The drawback, apart from signal strength, is that they sometimes carry only a limited set of channels, for example, not all the HD stuff, or possibly the wrong region for you, etc.

From what you've said, it seems like everybody nearby is using a repeater. This may be because they need to, or because the cheaper end of the aerial installer business just looks at other roofs in the area, without checking signal strength, etc. The system is set up so that main stations and their repeaters interfere as little as possible with each other. This means an aerial for the main station may be unsuitable for one of its repeaters, and vice versa. Don't forget to use the correct polarization!

The other thing to watch out for is whatever is beyond your repeater. Here, Kingsweston repeater is closest, and we are in its coverage area, but "behind" it (from our house) is Wenvoe, which is around 200,000x "louder" and swamps it. There are various tricks to control which TX the TV uses, but we end up with both, which is unhelpful (I don't really want the Welsh output! Across the road (literally) the angle is better, so they can use it, but they can't get Mendip, whereas we are on the higher side of the street, and can.

There is no such thing as a "digital" aerial, by the way - it's all analogue at that part if the system (even satellite!), and the old issues from analogue TV days - ghosting, poor signal, etc. - still degrade the signal. The difference with digital TV is that it either works or it doesn't, and you don't usually get warning of bad signal - it either stutters, freezes completely, or just says "no signal".

It is unlikely you will get away with a loft aerial for TV (you might for DAB). A longer aerial might help, but probably not much.

These might help also:

https://www.ofcom.org.uk/tv-radio-and-on-demand/information-for-industry/tv/tv-transmitter-mapshttps://ukfree.tv/section/TV_TransmittersFull-Freeview vs Freeview Light: map (clickable map giving coverage contours)

Freesat might be a good option, but only if you are careful about the cabling in the house (it's more picky than terrestrial TV). And the more northerly you are, the less useful it is, as geostationary satellites orbit the equator, and the signal quality degrades as you move north or south from that circle.

Forgot to say: polarization: look at the fins on the front end of the aerial (towards the transmitter). If those bits are horizontal, it's horizontal, if vertical...

Bill Wright's Aerial pages have a lot of good and bad practice in fitting aerials, useful if you intend to DIY.

If you want to find a good quality contractor, look for the roof with the neatest, reasonably new installation on it, and ask the owner who did it. Neatness and quality usually go together in that business.

This is probably way more detail than the OP needs and I understand where you are coming from when you say everything in the RF domain is analogue. However the digital TV network uses COFDM to convey the information which is a a digital modulation system.
This has a lot more immunity to interference and multipath (which causes ghosting on analogue TV) compared to the previous analogue system, helped by built in error correction. This means the digital system is capable of delivering a perfect picture on a relatively weak signal.
It is not infallible however and as you say there is a point where the receiver cannot sort ones from zeros s and it’s game over.

 

[Spectric]

Hi all

Our transmitter is Caldbeck and freeview is very weather dependant and pixelation all to common on many channels. I will add that nearly everything is analogue, ie continous data unlike digital that is discrete. We bring the analogue world into the digital domain to control but nearly always have to return it as analogue for it to be useful.

 

[flying haggis]

Eric said
"It is unlikely you will get away with a loft aerial for TV (you might for DAB). A longer aerial might help, but probably not much."

I have my tv aerial in the loft and get a perfect pic despite being 30 odd miles from tacolneston whereas you are about 15 from waltham

 

[lurker]

Eric said
"It is unlikely you will get away with a loft aerial for TV (you might for DAB). A longer aerial might help, but probably not much."

I have my tv aerial in the loft and get a perfect pic despite being 30 odd miles from tacolneston whereas you are about 15 from waltham

Thanks
Being deaf the lack of dab is not an issue.
Her majesty's radio isn't dab and I doubt she knows nor cares.

This forum is a wonderful place, getting the specific aerial rather than a generic one was the critical information that had passed me by. I feel almost expert on the subject now

 

[Eric The Viking]

This is probably way more detail than the OP needs and I understand where you are coming from when you say everything in the RF domain is analogue. However the digital TV network uses COFDM to convey the information which is a a digital modulation system.
This has a lot more immunity to interference and multipath (which causes ghosting on analogue TV) compared to the previous analogue system, helped by built in error correction. This means the digital system is capable of delivering a perfect picture on a relatively weak signal.

I know about COFDM (not the maths, mind!), however sending 1/4 MW up a tower isn't cheap. so the broadcasters (well, the TX company that now does it for them, Arqiva or Crown Castle or whoever owns it this week) used digitization as a reason to drop the output power of many transmitters, usually by at least 3dB. So although for many it is better, it's not hugely so.

The old practical considerations still apply. Do the aerial right and the TV will work fine; do it badly and it might but usually won't work well. Aerial rigging is an industry of cowboys, too. I know good people here, but their reputation goes back decades. From the window of this room I can count 32 UHF aerials on the other side of the street. Roughly half of them are wrongly installed, and several more have failed.

And there are new problems caused by the digital switchover: although we get a strong signal from Mendip, it's diffracted over a hill, so not as overwhelmingly good as it ought to be. Wenvoe still gets in on a back lobe of our Yagi, so one awkward telly in the house gets a 24dB pad temporarily in the aerial downlead when scanning, otherwise we get loads of Welsh stuff that's not relevant. The main TV seems not to need it - it still finds Wenvoe channels but can be told to ignore them.

 

[Eric The Viking]

Eric said
"It is unlikely you will get away with a loft aerial for TV (you might for DAB). A longer aerial might help, but probably not much."

I have my tv aerial in the loft and get a perfect pic despite being 30 odd miles from Tacolneston whereas you are about 15 from waltham

Distance is but one of the issues. My comment was merely an educated guess. The fact that there seem to be few houses that don't have an external aerial (as described) was my hint.

 

[flying haggis]

Distance is but one of the issues. My comment was merely an educated guess. The fact that there seem to be few houses that don't have an external aerial (as described) was my hint.

its probably easier for your average cowboy installer to stick a cheap bacofoil aerial on to a pressed steel chimney mount and tack the nasty cheap brown coax down the wall and in through a hole drilled in the window frame hence most people have external aerials. it usually involves more work for a loft install ie finding a cable route through the house but if you are prepared to do it yourself you might as well do it properly and once

 

[HamsterJam]

I know about COFDM (not the maths, mind!), however sending 1/4 MW up a tower isn't cheap. so the broadcasters (well, the TX company that now does it for them, Arqiva or Crown Castle or whoever owns it this week) used digitization as a reason to drop the output power of many transmitters, usually by at least 3dB. So although for many it is better, it's not hugely so.

The old practical considerations still apply. Do the aerial right and the TV will work fine; do it badly and it might but usually won't work well. Aerial rigging is an industry of cowboys, too. I know good people here, but their reputation goes back decades. From the window of this room I can count 32 UHF aerials on the other side of the street. Roughly half of them are wrongly installed, and several more have failed.

And there are new problems caused by the digital switchover: although we get a strong signal from Mendip, it's diffracted over a hill, so not as overwhelmingly good as it ought to be. Wenvoe still gets in on a back lobe of our Yagi, so one awkward telly in the house gets a 24dB pad temporarily in the aerial downlead when scanning, otherwise we get loads of Welsh stuff that's not relevant. The main TV seems not to need it - it still finds Wenvoe channels but can be told to ignore them.

Yep, the maths for OFDM is pretty hairy.

 

[Phil Pascoe]

In the days of 405 lines my grandmother lived in a valley. The TV picture varied from bad to dreadful, and one day her neighbour had a huge H shaped aerial put up. That evening her picture got worse (as it did regularly) and she complained that it had got worse only because the bittsch next door had stolen her signal.

 

[Spectric]

Phil you are giving away your age, the days when you waited for the Tv to warm up and watched ant wars when it was turned off. Twin tunners, big clunky rotary knobs, one for 405 the other 625. The engineering was so different, wooden cabinets that were really well made with aluminium chassis inside and those valves helping to keep the house warm. Very expensive items back then so many people rented them!

 

[flying haggis]

when i was a kid i remember the tv repairman arriving on a regular basis with a large brown case full of replacement valves. as my parents rented the set of course there was nothing to pay(hence renting was popular) when we got our first colour tv (a hitachi) we never saw a repairman again. that colour tv never went wrong for at least ten years till i left home and i think it soldiered on for many many more trouble free years

 

[artie]

of course there was nothing to pay(hence renting was popular)

Never ceases to amaze me, how the human mind works.

Who exactly do you think paid for it?

 

[Lons]

The engineering was so different, wooden cabinets that were really well made with aluminium chassis inside and those valves helping to keep the house warm.

Like these?
My old man was an amateur repair man who fixed the tvs and radios for everyone in the village, he had a huge chest of drawers full of parts, I saved these as a memento when he died 20 years ago.

 

[Phil Pascoe]

when i was a kid i remember the tv repairman arriving on a regular basis with a large brown case full of replacement valves. as my parents rented the set of course there was nothing to pay(hence renting was popular) when we got our first colour tv (a hitachi) we never saw a repairman again. that colour tv never went wrong for at least ten years till i left home and i think it soldiered on for many many more trouble free years

Yes. I remember in the mid '70s getting a Hitachi for my grandmother - £200. She insisted she didn't need colour and for years kept the front door locked so she could turn it back to b & w before anyone came in. If I went in quietly through the back door she'd have the colour turned up so vivid it hurt my eyes. She'd insist she'd just turned it on and hadn't had time to adjust it back to b & w. We had Sony Trinitrons that seemed to be everlasting.

 

[Eric The Viking]

Trinis were very good - bright and clear. For probably 15 years the BBC used them as on-set monitors on outside broadcasts, but they were a bit awkward to service, apparently (not my dept). Sony's selection of phosphors was a bit unusual though, so Trinis weren't used as production monitors because the tubes couldn't be colour-matched with other brands. That said, we dubbed most of the big Attenborough series in the 1980s with the main picture monitor being a domestic Sony 27" Trini (biggest screen available at the time).

Other manufacturers brought out in-line gun tubes as fast as they could, as the idea was so much better and simpler than the original triple-spot-triangle ones (Trinitrons had the electron guns in a line of three, horizontally), but they had to put breaks in the vertical strips of phosphors on the front of the tube, to avoid infringing Sony patents. Those ended up in most of the British brands of TV, and most of the Far Eastern ones too.