The Difference Between HDTV and TV
If you’ve been researching subscription TV services you’ve probably come across terms like “digital video signal,” “basic cable HD” and “digital TV regulations.” But to the uninitiated these terms can seem like obscure jargon. So what exactly is the difference between digital video signals and basic cable HD formats; and what role do digital TV regulations play in determining these differences? Here at InterneLion.com we’ve put together the following, short explanation of the difference between HDTV and TV to answer those very questions. And, assuming you’re in the market for HDTV, we’ll also tell you where you can find the best HD picture and programming options in the business.
What Are Digital Video Signals?
Explaining the difference between HDTV and TV for laymen is no small task because the HD and digital technologies we use today resulted from some major 20th century engineering, computing and physics breakthroughs. However, if there is a good place to start it’s with an explanation of the kind of basic, over the air (OTA) TV many U.S. citizens can have access to currently. And this television service relies on the transmission digital video signals.
So what is a “digital video signal”? Well, first and foremost, it’s a telecommunications transmission sent via satellite or ground wire to convey images to a TV. Such transmissions began in the 1930s in Germany and today they take place continually all over the planet.
And yet, this isn’t the whole story because for most of the 20th century such transmissions were what we now term “analog.” This means that telecommunications companies sent such signals so that they traveled as full energy waves over wires or through the air. The best way to visualize this is that the signals were like the sine waves that look like a set of ocean waves with crests and troughs rolling through an ocean.
This system was very inefficient because the troughs and crests of these waves did not carry much useful information; but they did take up a lot of room in the finite space usable for conveying such signals. This space is called bandwidth, and because there is only so much of it in any contained environment, including the air or a wire, the analog television system limited the amount of TV programming broadcasters could transmit at the same time.
Adding to this problem was the fact that TV signal-senders had to share this limited amount of space with the radios police and firefighters used. The federal government mandated that this be the case so that emergency responders were not vying with TV for the communications space they needed. So, ultimately, for many years only a handful of TV channels were available: ABC, NBC, CBS and PBS.
But then came computers and with them a totally new way of packaging these transmissions. You see, for many years cable companies had been able to send far more signals to TVs because they were sending their transmissions over closed-off wires, not over the air. But what the TV industry discovered it could do with computers blew even this expanded number of channels away because it allowed them to cut off the peaks and the troughs of the transmissions’ waves.
The process of doing this, called “digital compression,” made signals “smaller” so that more could travel over the air or through wires without taking up the valuable communications space emergency workers needed. The only thing left to do, then, was for cable, satellite, and free-to-air broadcast companies to create more networks.
Digital TV Regulations
In 2009 all U.S. broadcasters stopped transmitting analog signals, as per new federal government regulations. The new digital TV regulations required those who owned older TVs to purchase digital converter boxes that switched incoming digital signals into analog signals compatible with their TVs.
But, to its credit, the federal government did issue free coupons for the converter boxes to anyone who requested one. And President George W. Bush signed into law digital TV regulations that also dictated electronics retailers had to label merchandise that would become obsolete or face millions of dollars in fines.
All this government control might have startled people in the U.S., but it was ultimately for the best. The TV signals they received after the switch-over were much crisper and they were also able to receive several more channels than they once could.
Basic Cable HD Formats
Digital TV signals, as we noted above, are simply TV signals that have their troughs and crests lopped off. And though some can be, they are not all, by definition, high-definition, or “HD.” Really what differentiates HD from SD, or “standard-definition,” signals is that HD transmissions carry information for images with more pixels in each frame than comprise an SD image.
Or think of it this way: A TV is like a Pointillist painting, like the one of all the French people lounging beside a river (“A Sunday Afternoon on the Island of La Grande Jatte” by Georges Seurat) in that the picture is made up of hundreds of thousands of tiny, colored dots. On TV screens one line of dots, called a “scan line,” shows up at a time, though obviously it happens so fast that you don’t notice.
Now, there are two types of scan lines, one type that is “interlaced,” which means that the scan lines show up so that all the odd-numbered lines display first, then all the even-number lines; and one called “progressive,” meaning the lines appear in ascending or descending order on the screen. Neither type is particularly important because most TV sets display progressively even when the signals they receive are interlaced. And the differences between quality are so minute as to make all determinations subjective.
What is more important in determining the difference between HDTV and TV than the order in which scan lines appear on a screen, rather, is how many pixels, or colored dots, make up each line. Going back to our Pointillism analogy, an HD painting would have more dots than an SD painting. How many more? Well, typically an SD TV scan line has 480 pixels per horizontal line, whereas an HD TV scan line can have 720 pixels to 1080 pixels per line. And when a picture is comprised of more pixels the amount of shading and color detail possible is far greater.
So that, really, is the difference between HDTV and TV; most regular digital signals today have 480 pixels per line, while HD signals can have over twice as many. The only thing that might confuse you beyond this point is the letters that sometimes follow the numbers 480, 720 and 1080. Essentially these indicate whether a signal’s scan lines are interlaced or progressive. So, for instance, “1080p” means that there are 1080 pixels in each of a group of progressive scan lines; while “1080i” means that there are 1080 pixels in each of a group of interlaced scan lines. DISH Network®, for example, broadcasts their HD channels in 1080p, which offers the highest quality HD picture in the business.
The DISH Network HD Difference
Finally, you might be wondering what all this has to do with DISH Network, so of course we here at InternetLion.com are going to make our pitch: Now that you’ve learned about the difference between HDTV and TV, you know that HDTV is the best, most advanced broadcast option possible. And DISH Network is where you can get the best of the best when it comes to HDTV.
Not only does the DISH Network technology and 1080p broadcast offer the best picture in the business, DISH Network also offers the most HD channels – more than DIRECTV or any cable company in America. With the best picture, breakthrough HD DVR technology, over 200 HD channels and DISH Network’s current offer of HD FREE for Life (with 24-Mo. Agreement and AutoPay with Paperless Billing), if you’re in the market for HD service, the choice is clear – DISH Network is the leader in HD.
Click here to learn more about switching to DISH Network today or call the number on your screen to speak to a live representative.
Disclaimer: Please note that this article was written when the satellite TV provider DISH was branded as DISH Network. As of 2/1/2012 DISH Network has changed their branding name to DISH. Article post date: 03/13/2011.