TV Ghost Cancellation System Using Switched Capacitor Circuits
In the TV reception, picture quality has been one of the primary criterion in its design. The presence of ghost signals, which are due to reflections of TV signal from high rise building, towers, mountains, etc., is one of the major causes of distortion and is Iiot avoided at the receiver end. Th...
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| Format: | Thesis |
| Language: | English English |
| Published: |
1998
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/10133/1/FK_1998_9_A.pdf |
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| Summary: | In the TV reception, picture quality has been one of the primary criterion in its
design. The presence of ghost signals, which are due to reflections of TV signal from
high rise building, towers, mountains, etc., is one of the major causes of distortion and
is Iiot avoided at the receiver end. The ghost signals are in fact time delayed versions of
tht:: actual transmitted signals at the receiver and have many adverse effects on picture
quality due to partial cancellation of main signal. The perceptibility of the ghost signal
is strongly subj ective and is a function of picture content and quality. Thus it is essential
to filter the ghost signals for better reception. In this thesis we present the design of a
television ghost cancellation system using switched capacitor circuits.
Ghost cancellation is a nullifying operation and allows one to reduce its effect
on the picture quality as much as possible. In this thesis two-stage switched capacitor (SC) transversal filter has been used for reduction of distortion. The system has been
able to suppress ghosts with delays ranging from 0.1 µs to 20 µs with ghost suppression
threshold at 1 % amplitude. The algorithm uses a special training signal to determine
the ghost's characteristics. For a single ghost once the ghost's parameters have been
determined, the transversal filter delays the incoming signal by td (the time delay of
ghost) and multiplies it by a factor - G (G being the gain of ghost). The result signal is
added to original signal. We obtain an output which gives no output due to original
ghost but adds up another ghost. The process is repeated until the ghost's amplitude is
within acceptable limits. In this thesis we have simulated the system at the block
diagram level using MATLAB and at component level using PSpice. The results of the
simulation are in close conformity with the theoretical value. This suggested circuit can
be fabricated using the MOS technology allowing the manufacturer to provide a better
quality in TV reception. |
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