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For Analog TV the Answer is:
The TV picture image is being received multiple times
a fraction of a second from the main picture signal.

For Digital LCD TV the Answer is:
The speed at which the LCD screen up dates or a
damaged screen circuit board edge connector(s).


Ghosting on Analog & Digital TV

Any station can have ghosting as the TV signal is bounced off objects like buildings, overpasses, hills etc. Your analogue TV receiver picks up the "main TV signal" as well as any "TV signal echoes" and displays them as ghosts.

Your digital TV receiver picks up these signals to but the TV smarts filter out the weaker signal(s), sometimes they can be too smart, if a ghost and the main signal are of equal strength, the TV smarts might not be able to find a picture and report "no or bad signal" when clearly a dumber TV set can see a signal.

Signal Ghosts are caused by the TV stations use of "high power" to get the signal into your home, so people with rabbit ears, "in roof" antenna and wet pieces of string can receive some watch-able form of picture & sound; this in turn creates powerful signal echoes.

It is a trade off to maximise people watching (for advertising revenue) over quality watch-able TV signals.


Ghosting LCD TV (technology limitation)

Can display a false ghost effect when fast moving objects are shown on screen, a type of trailing effect which is caused by the little Red, Green & Blue LCD cells not switching off/on fast enough. It is not a fault with the TV it is a limitation of the technology. As the LCD TV gets older this effect may be more noticeable or less depending upon the light conditions in the TV viewing room and back illumination of the LCD screen (the fluorescent tubes or LEDs with-in the LCD TV)

Also a damaged, aged or over heated LCD screen can also have what is termed a ghosting effect. It is more of a flare or wave in part or most of the LCD screen. this is caused by the screen circuit board edge connector not being able to maintain electrical continuity. These connectors are very delicate and are more like a flat ribbon cable held by clamping pressure to the circuit board. Fixing one is very much a 'hit and miss' affair as there can be several causes, mechanical connection, electrical connection and electrical supply level(s) or combination of all... What is the cost of a new one compared with cost of repairing, especially if it is out of warrantee and after fixing, it still and out dated model... The sad fact of a global throw away society.


RF Solutions: (Signal Level from station to your TV)

Twist the TV antenna around a few degrees to acquire a stronger signal (ghost or main, digital doesn't care which one) Because of poor signal problems, TV stations may also re-transmit their signals from other location in your area (UHF TV band Ch 21 to 69)

Usually from different location from the main signal broadcast site and may be with a different antenna polarity (vertical / Horizontal) A polarised antenna is either "Vertically" (the long sticks go up and down) or "Horizontally" (the long sticks go side to side).



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Terminology

North, South refers to magnet direction usually quoted as a compass heading for pointing your TV antenna towards the TV transmitter antenna. Positive and Negative refer to electrical power connection and usually only quoted when a "mast head" (at antenna) or an in-line TV amplifier is used to boost the TV signal, which usually needs DC power injected into the coax (antenna lead) to work.

AM / FM radio signals also suffer ghosting, you hear them as distorted audio, especially in a moving car on the road in the wet or passing by / under electrical power transmission lines.

Signal Ghosting Answer:

Is nothing more than the signal being received more than once, usually a micro to a millisecond later, it is the basic principle of Radar but that is another story.


73
Gary, VK3KHB


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