Differences

This shows you the differences between two versions of the page.

--- early-television-technology-frequently-asked-questions [2026/03/08 06:32] – cynic
+++ early-television-technology-frequently-asked-questions [2026/03/12 00:14] (current) – cynic
@@ Line 1: / Line 1: @@
+====== Frequently asked questions about television technology ======
+{{ ::crt_460.jpg?400|}}
+As  we look at the history of television, I wanted to tackle some of the  frequently asked questions about the origins of the technology, as well  as share some cool resources on movies and television.
+One  commonly asked question is why the early televisions had round screens.  The television picture tube was a vacuum tube that contains one or more  electron guns and a phosphorescent screen used to display images known  as a cathode ray tubes (CRT).  When the original cathode ray tube was  invented it was an experimental device, television was not yet  developed. The natural shape of the cathode ray tube was round, as shown  here in the diagram. The cheapest and easiest way to manufacture a CRT  was to make it round.
+The television picture is created on the  surface of the cathode ray tube by drawing it rapidly line by line. The  entire front area of the CRT is scanned repetitively and systematically  in a fixed pattern. Before 1940 there was no standard in the United  States for how the picture was created electronically using the cathode  ray tube.
+In 1940 the Federal Communications Commission (FCC)  established The National Television System Committee (NTSC) to resolve  the conflicts that were made between companies over the introduction of a  nation wide analog television system in the United States.  The NTSC  standard selected 525 scan lines, an aspect ratio of 4:3, and frequency  modulation (FM) for the sound signal. The number of 525 lines was chosen  as a because of the limitations of the vacuum-tube-based technologies  of the day.
+**Why an aspect ratio of 4:3?**
+The  term aspect ratio is used in many fields to describe the proportional  relationship between width and height, expressed as two numbers  separated by a colon. For example when we say that the early televisions  had an aspect ratio of 4:3, that means they are 4 units wide and 3  units high.  The early television standard of the 4:3 aspect ratio was  chosen because movies in that era were filmed in a 4:3 aspect ratio.  Movies originally photographed on 35 mm film could be satisfactorily  viewed on early televisions.
+Motion pictures, a series of still  images which, when shown on a screen, creates the illusion of moving  images, or as we sometimes call them, movies, are a different field from  television.  But the early days of motion pictures actually set the  standard for the concept of aspect ratio, the relationship of height to  width of an image. For many years the standard movie screen, as well as  the standard analog television, had an aspect ratio of 4:3.
+**The evolution of round screens to rectangular**
+The  cheapest and easiest way to manufacture a CRT was to make it round. But  the aspect ration of 4:3 lends itself to a more rectangular design. The  CRT slowly evolved to being essentially rectangular in shape but it had  rounded edges because it was a glass tube. You could not create a  perfect rectangle using the process that created the glass cathode ray  tubes in the early days of television.
+If you look at the photo of various televisions you see a variety of  screen sizes as well as shapes, and you can see the evolution of round  screens to rectangular. The attached photograph was taken at the  National Capital Radio and Television Museum, a cool little geek history  museum located in Bowie, Maryland. It is a small house jam-packed with  displays on the history of radio and television. The extremely  knowledgeable staff was full of stories about everything on display and  ready to answer any question. The museum does a great job of preserving  technology history.
+**Increasing the number of channels**
+During  the 1940s and the 1950s broadcast television stations in the United  States were primarily transmitted on the VHF band, channels 2-13.  If  you live in a large city you will notice the long established stations  usually are lower numbered.  Television manufacturers like RCA, ran  their own networks, such as NBC. Since the major TV networks were  well-established on VHF, many smaller stations on the UHF band, channels  14 to 83, were struggling for survival. Fourth-network operators such  as the DuMont Television Network were forced to expand using UHF  channels due to a lack of available VHF channels.
+In 1961 the  United States Congress passed the All-Channel Receiver Act (ACRA) to  allow the Federal Communications Commission to require that all  television set manufacturers must include UHF tuners. All new TV sets  sold after 1964 had built-in UHF tuners.  The All-Channel Receiver Act  allowed the UHF TV stations to grow and eventually would outnumber the  long established VHF stations.
+What happened to Channel 1?
+When  I was young, and the television had a rotary dial that took me from  channels 2 through 13, I always wondered, what happened to channel 1? In  1948, Channel 1 frequencies were deleted from those allocated to  television use and given over completely to radio services. The FCC  decided not to renumber the channels since many televisions were being  made using the existing channel numbers.
+**History of Television resources**
+If  you want to learn more about television, from the perspective of the  appliance that sits in your living room, rather than from the  broadcasting side, there is a great pair of videos by RCA.  Reasons Why,  The (Part I) (1959) and Reasons Why, The (Part II) (1959) are two  videos that can be watched online or downloaded for later viewing.
+Reasons Why, The (Part I)  https://archive.org/details/reasons_why_1
+Reasons Why, The (Part II)  https://archive.org/details/reasons_why_2
+Classic  scenes of geeks from the 1950s showing various facets of television set  design, engineering, and quality control. The RCA manufacturing videos  are part of a section of the Internet Archive known as the Prelinger  Archives, a collection of over 60,000 advertising, educational,  industrial, and amateur films.
+Created in 1992 primarily to  document the history of the Cathode Ray Tube it does a nice job of  illustrating the basic concept of the CRT. It also includes a bit of  television history showing the evolution of the CRT.
+Cathode Ray Tube https://archive.org/details/KF.BraunCathodeRayTube
+A  propaganda infomercial by RCA to brag about what they have done in the  world of television. Not the most historically accurate account of  television, but still a very interesting bit of geek history.
+Story of Television  Published 1956 https://archive.org/details/Story_of_Television_The
+Free online movies great digital library
+Spending  a Saturday morning at the Internet Archives (archive.org) is like going  to the library or your favorite museum, and the best part about it is  that you don't need to leave the comfort of your home computer desk.
+All  of the video files can be viewed for free online, and many are  available to be downloaded and viewed offline. The Internet Archive does  a decent job of making sure copyrights are not violated.  Most of the  files are public domain, but some may occasionally have some  restrictions for use and are marked as to how they may be used.  Because  copyright laws have changed from time to time over the years, many of  the files are considered public domain, or copyright free, for a variety  of reasons.
+The Internet Archive does a decent job of making  sure copyrights are not violated.  Most of the files are public domain,  but some may occasionally have some restrictions for use and are marked  as to how they may be used.  Because copyright laws have changed from  time to time over the years, many of the files are considered public  domain, or copyright free, for a variety of reasons.  All of the video  files can be viewed for free online, and many are available to be  downloaded and viewed offline.
+National Capital Radio and Television Museum, a cool little geek history museum in Bowie, Maryland.
+The Internet Archive is a non-profit organization on a mission to build a digital library. Just like a visit to your favorite museum or traditional paper library, they provide
+free access to researchers, historians, scholars, and the general public to digital files on a wide variety of topics.
+The Internet Archive is non-profit organization on a mission to build a digital library providing free access to researchers, historians, scholars, and the general public
+While the Internet Archive has a large collection of videos on a wide variety of topics, in this article we will take a look at some of the videos that would be a great
+resource for anyone studying the history of television. The file descriptions contain links to the site from where the files can be viewed or downloaded.
+http://geekhistory.com/content/early-television-technology-frequently-asked-questions

Sorry if some of the pages having missing graphics or a bookmarked page is missing. We are migrating our site over to DokuWiki from Drupal. The last major overhaul of our site was in 2016, and we were due for some freshening up.

The collection of material for the study of geek history dates back to my early days in technology as far back as the 1970s. You will find specific footnotes and references on many pages with links to current websites. Anytime a claim is made, or a fact is stated from a website or blog that does not appear to have firsthand knowledge of the subject I make a note to follow up on it. I can assure you that anything I have written is based on verification of facts from a source as close to the events and individuals as possible or multiple sources of information from leading publications or references.

Geek History

Differences

Footer Notes | GeekHistory Update 2026 | Major update in progress