World Library  
Flag as Inappropriate
Email this Article

Pal-s

Article Id: WHEBN0027115681
Reproduction Date:

Title: Pal-s  
Author: World Heritage Encyclopedia
Language: English
Subject: Distortionmeter, Zero reference pulse, Downlink CNR, Television lines, White clipper
Collection: Broadcast Engineering, Television Technology
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Pal-s

PAL-S is the system of television receiver sets in the early days of PAL system. Here PAL stands for Phase alternating at line rate and S stands for simple.

Contents

  • PAL system 1
  • The PAL-S receiver 2
  • The problems in PAL-S 3
  • Electronic averaging 4
  • See also 5
  • References 6
  • External links 7

PAL system

The color hue modulates the phase of a subcarrier named color carrier. In PAL system the polarity of the phase in each frame is reversed to neutralize the undesirable phase shifts introduced during transmission. Thus the effect of undesirable phase shift is positive in one frame and negative in the second frame. Averaging the two, the effect of the undesirable phase shifts in two consecutive frames cancel each other.

The PAL-S receiver

In the early days of the PAL system, it was proposed that, the human eye can average the slightly different color hues in two consecutive frames and perceive the original color. The television receiver sets which rely on optical averaging were called PAL-S receivers.

The problems in PAL-S

However, it soon turned out that the optical averaging had problems. When the distance between the viewer and the receiver set is not large, the viewer can distinguish the lines. The phase reversion takes place in every frame. But each frame is composed of two fields. So the viewer watches two consecutive lines without reversion. The next two lines are reverted phase lines. That means that when there is undesired phase shift the viewer watches a thin horizontal bar with one color and another thin bar with another color. This pattern is known as Hanover bar.[1]

Electronic averaging

In the standard analogue PAL receiver, the color differences between the consecutive bars are averaged electronically (by the use of delay line). This system is known as PAL-D.

See also

References

  1. ^ Gordon J.King:Beginner’s Guide to Color Television, Newness Technical Book, London, 1978; ISBN 0-408-00101-1, p 69-71

External links

  • [1]
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.