TV Aerials
- Thread starter jj4091
- Start date
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generally, you need to have a "line of sight" to the transmitter.. ( no large obstructions such as other houses in the way.. )
this isn't so bad if there's a hill in the way but with houses and other large objects the signal is deflected round it as well as through it with the 2 ways arriving at slightly different times. that's what causes your ghosting..
this isn't so bad if there's a hill in the way but with houses and other large objects the signal is deflected round it as well as through it with the 2 ways arriving at slightly different times. that's what causes your ghosting..
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Thanks lookin, that was going to be my next question, we currently have our aerial mounted on the wall at the rear of the house pointing at the transmitter, unfortunately as colonel jack says, there is a hill between it & us & we suffer from slight ghosting on our analogue tv. I was not sure if it was because the aerial was wall mounted rather than on the chimney, thus the question & as we are due to be changed to digital shortly I wondered if the problem would be better or worse. I presume from your comment, digital tv can block out the second weaker signal then?
Reflections from directly behind the aerial are unlikley, they are designed out using the big plate (reflector) at the rear which is sized to the correct wavelength for the signals being recieved.
It focuses them back on to the important portion of the array.
If you are replacing your antenna best thing to do would be go to a website called wolfbane, a google search should hit it, type in your postcode find your closest transmitter/transmitters, check out it's group and polarisation then purchase from anywhere you choose to (although CPC (Farnell) are very reasonable) the correct kind of antenna for you.
It focuses them back on to the important portion of the array.
If you are replacing your antenna best thing to do would be go to a website called wolfbane, a google search should hit it, type in your postcode find your closest transmitter/transmitters, check out it's group and polarisation then purchase from anywhere you choose to (although CPC (Farnell) are very reasonable) the correct kind of antenna for you.
Thanks for that Lee, it tells me that I need a group A standard aerial, which is what I am fairly sure I have, but does quality of different manufacturers vary with aerials as it does with other things or is a group A, a group A, no matter who makes it. Also do you know if we will be able to use it when changed to digital or will we need to replace it for something else? Thanks again.
Not visually, no........but there is still going to be an impact on the signal and quality of reception.
Which transmitter are you pointing at? the wolfbane site should hopefully tell you which one you should be aiming at
It is then a case of finding out what channel the digital muxes are located at, because a few of them (along) with channel 5 are quite often outside of the group for the local area:
groupings:
Channels - Group - Colour
21-37 - A - red
35-53 - B - yellow
48-68 - C/D - green
35-68 - E - brown
21-48 - K - grey
21-68 - W - black (wideband)
Any group A antenna will get you a picture, but having said that you can get a picture with a few tie wraps, some bodge tape and some welding rod but i wouldn't recommend it, great when you're in the middle of nowhere in a bloody tent though.
Right as to type, that really depends on how strong a signal you want, how long you are prepared to spend tweaking it, and your distance from your transmitter.
Antenna materials don't vary greatly from manufacturer to manufacturer, some increase "apparent" gain by varying the design of the reflector, some add more directors. the important bit is the dipole in the middle and the are all pretty much identical on this front.
If you can tell me what distance wolfbane puts you at from your transmitter and the power output i can give you a better idea, but i would say that a 14 element triax will probably give you what you need.
As a rule of thumb the less the number of elements the easier they are to direct. If you have a group A and it's at about 14 elements then i would say you are unlikely to have problems with digital signal.
Just be aware that when the whole digital TV thing kicked off, almost everyone was being advised to have an aerial upgrade, and this was happening without people even going and seeing the types of antenna installed, it's not always the case.
Digital TV has this habbit of working either perfectly or not at all but there is certainly a limit to it's tollerance of multipath distortion (the radio affect that is visible as ghosting in analog TV).
I get ghosting on my freeview, and I think on the cable decoder too sometimes
Sorry John not to question what you are seeing, but it's definitely ghosting??? The only problem i have seen with a digital picture is the old jigsaw effect where it drops certain portions of the picture, ghosting in a digital system i would suspect will be down to noise/cross talk within the reciever rather than the aerial.
both are fed by scart from the box. both also have coax aerials for terrestrial channels. it's not droppout.
I also see ghosting on dvds recorded off cable and played on the other dvd recorder on the other TV, and I don't know if it's coming from the decoder, the dvd recorder, the dvd player, or the TV. but these are BBC3 progs, so def not terrestrial
I also see ghosting on dvds recorded off cable and played on the other dvd recorder on the other TV, and I don't know if it's coming from the decoder, the dvd recorder, the dvd player, or the TV. but these are BBC3 progs, so def not terrestrial
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