Ghosting, what is ghosting? This is
when the appearance of a faint duplicate image runs alongside the actual
image on your television screen. This occurs when two sets of the same
signal are going into the receiver at just very slightly different
times. These two signals lead to the “ghost” image being projected. If
the picture is being projected to the left on the main image it is a
leading ghost and if it trails to the right it’s a trailing ghost.
Leading ghosts are caused by
signals that arrive at the receiver just a split-second ahead of the
direct or the primary signal. These are caused by direct pick up or in
other words a pick up other than the antenna. To fix
leading ghost, shield and downlead splices, if the ghost is still
present after this, reposition the antenna to minimize the ghost.
Trailing Ghosts are caused by TV
signals that are bouncing off hills or tall buildings. These signals are
taking a longer path to the antenna, and show up on the screen just a
fraction of a second later than the primary/direct signal. These
trailing ghosts can also be caused by shorted-out or defective
connections that are producing mismatched signals. This ghosting can
also be caused by signal that is reflected back through the system by an
unterminated output terminal in a distribution system. To fix
this problem, use terminators on all unused distribution terminals. Use
a high directive antenna that will not pick up reflected signals.
Reposition the antenna, just moving the antenna slightly often helps
eliminate the ghosting. Last resort to fix this problem would be to try
a special “ghost killer” antenna.
Sometimes pictures appear to be
Smeared or Blurry. These are caused frequently by mismatched
impedances or incorrect connections to the transmission line or other
type of equipment. To fix this problem, make sure to check
all the connections and ensure they are tight and not corroded or
damaged or rusted. Check to make sure there are no crimps, kinks in the
downlead. Make sure the wires aren’t being crushed by stabilizing
staples and are not being bent sharply. Use high quality coaxial cable,
hardware and other equipment to ensure you have a good impedance.
Sometimes an adjacent channel will
interfere with the current channel being watched. This happens when the
receiving antenna is midway between transmitter towers of two adjacent
channels, these frequencies of the channels are close, so the TV tuner
amplifies both. To fix this problem there are traps and filters
that are available that can help minimize this time of interference. Use
a directional antenna and a rotor and the combination of the two is
necessary in extreme situations.
Electromagnetic interference is
one of the most common TV interferences. This causes a bight static
across the screen, may be some grinding or whining sounds. It can come
from many sources like household appliances, power lines, cars, or
hospital equipment. These appliances in the house like mixers,
hairdryers, furnaces, etc produce electromagnetic interference, and this
interference from the devices is carried to the receiver through the
house wiring. To fix its recommended to have a highly directional
antenna and this should solve the problem if it still persists, you may
suspect the power line. Contact the power company, most times they can
find the loose connector or clamp that causes this problem. The use of
coaxial cable reduces the probability of electromagnet interference.
FM Interference is the
interference from the FM band. FM interception is common to affect TV
high band channels 7-13. It’s typical to cause a “herringbone” patter on
the screen. To fix this use a coaxial cable instead of a twinlead.
Use a FM trap or filter for severe problems.
Preamp overload occurs when the
transistorized circuitry of an antenna mounted amplifier is fed
excessively strong signal. It looks almost exactly as an FM interference
and the two are commonly mistaken for each other. To Fix, use a
preamp with a high input capacity. Input capabilities are specified as
microvolts. Measure the strength of the overload signal. Always mount an
FM trap prior to the preamp to avoid this problem