High Definition Signals vs. Standard Definition Signals
At this point you probably know how much better HD picture and sound are compared to what regular, old standard definition broadcasts offer. And maybe you even know a thing or two about how 1080i and 720p high definition signals differ. But when it comes to receiving high definition signals there are so many other things to take into account if you want to watch HDTV. For instance you’ll not only need to order an HD package from a TV service provider, like DISH Network® satellite TV which offers the most HD channels in the business, but you’ll need to have hardware made for receiving high definition signals.
Here at InternetLion.com we’ve covered these details extensively, from describing the best HD TVs and HDTV cable tuners on the markets to explaining which satellites have the satellite bandwidth to handle reception of HD satellite signals. We’ve also, often enough described which dish antennae DISH Network customers will need for reception of satellite HD signals.
This time around, then, we’ve decided to concentrate on some of the more technical aspects of the industry—things such as what makes an HDTV cable tuner an HDTV cable tuner and how reception of satellite HD signals differs from reception of non-HD satellite signals. Naturally, this isn’t information you necessarily need to order one of the DISH Network deals on our site. But it might help you better understand how satellite TV works and, at the very least, you’ll definitely find it interesting.
High Definition Signal vs. Standard Definition Signals
To understand how HDTV cable tuners, antennae and satellites work you must first understand what HDTV is. Originally the television industry coined the term “high-definition” in the 1930s to describe what many of us would consider standard-definition broadcasts. Prior to this early juncture in TV history, you see, both TV broadcasts were formatted in and TV sets displayed only 30 lines of pixels per static frame.
Probably the best way to imagine how terrible the definition of these early broadcasts and sets was is to liken it to that of an Etch A Sketch® crossed with a flip book. But the most important thing about them as far as governments were concerned was that they did not eat up valuable bandwidth needed for security, emergency and military uses. In fact, they ate up next-to-no bandwidth at all, meaning that if someone could come up with a better format governments wouldn’t be so bothered letting broadcasters and TV manufacturers do as they pleased.
The first to make this logical upgrade were the British, who introduced both 240- and 405-line services in 1936. Never the ones to be shown-up by the British, the French followed suit with their own 441-line “High-Definition” service in 1938. And in 1941 the U.S. introduced its 525-scanline NTSC system.
Again, these systems’ definitions are very basic compared to what we call “HD” today. And even a 1949 819-line French system—which had a definition comparable to some current HD transmissions—was still monochrome. It wouldn’t be until 40 years later that we call “HD” today, then called the Japanese MUSE system, was demonstrated in the U.S. for president Ronald Regan.
This newer system is the one we now have and it supports both color and a 1080i resolution, meaning that unlike previous transmission systems its lines are interlaced. But it would be another whole decade before it became possible to use this standard for regular broadcasting in the U.S. The main reason for this was that such high definition resolution ate up a lot of bandwidth, a big no-no as far as the FCC was concerned.
But, instead of simply saying that, maybe we should slow down for a moment and explain what’s actually at work technically here that made this HD system suck up so much bandwidth. You see, most of those earlier forms of “HD” from the 30s and 40s were lined up on TV sets as interlaced systems. This meant that as a TV converted the signals it received into pictures it would do so by replacing the odd-number pixel lines, then the even number pixel lines.
The problem with this interlaced system was that it undermined the vertical-resolution quality, but it was beneficial insomuch as it required less bandwidth to transmit. And, of course, bandwidth was highly important because it is always limited by the range of signal waves information can be transmitted on; because only a certain number of wave ranges can effectively carry signals and because there are many more important telecommunication systems than consumer television—police and ambulance radios, for instance—as long as high-resolution techniques sucked up to much of the overall wave range they were out of the question.
It was not until enough progress had been made in computer technology that digital compression obviated these issues. But in the early 2000s a system was finally perfected for lopping off the highest and lowest ends of signals’ waves, regions of signal waves that typically carried no information in transmissions. This freed up immense amounts of bandwidth. And it became much easier for TV providers and networks to send and receive signals with higher pixel counts and with scan-in and projection systems that were progressive—meaning that TV signals’ scan lines were sent, received and displayed in numerical order.
HD TVs and HDTV cable tuners had to be able to handle the new work load though. And so the major difference between these devices and their predecessors is that they not only are capable of receiving, converting and displaying a higher number of pixels, but they can also “read” digitally compressed signals.
What’s more they can often convert interlaced signals received from a service provider or broadcaster into a progressive image. And this, of course, means that broadcasters and service providers are happy because they get all the bandwidth benefits of interlaced transmission, while their viewers enjoy all the picture and sound quality of progressive scanning systems.
As for other devices like satellites and dish antennae, the major factors at play with both have to do with how much satellite bandwidth they can handle. The introduction of Ku band signal use for commercial TV service allowed subscription TV companies like DISH Network to send and receive high-strength satellite signals that required only very small dish antennae on the receiver’s end.
Still, even with the strength of Ku band transmissions and digital bandwidth conservation these companies had to allocate a greater amount of a satellite’s overall transmission capacity to sending high definition signals. What’s more, they had to increase their user-end dish antennae’s reflector sizes slightly to allow for more signal capture. And many companies began adding extra low noise blockers, or “LNBs,” to their dish antennae’s horns to allow for the capture of both HD and SD signals.
These limits on the amount of satellite bandwidth a single satellite can offer HD systems is the reason why, today, subscription satellite TV companies like DISH Network use separate satellites for HD and SD signals. It is also the reason those who do not lease their antenna equipment from a service provider have to be mindful of whether a dish antenna can provide reception from HD satellites. Simply put, without the correct number of LNBs and an optimally sized reflector dish, reception of satellite HD signals will be out-of-the-question for a given antenna.
So what does all this technical jibber-jabber mean to you precisely? Well, for one thing, if you want to receive HD signals you will need a TV with the scanning and pixel capacity to display such images. And you will need a tuning device capable of converting them from digitally compressed and often interlaced signals into pure, progressive, high-resolutions signals your HD TV can use.
But even these two devices won’t work properly together if you do not have a large enough HD satellite dish with enough LNBs to capture the signals as they fall from heaven. And, even more importantly, that HD satellite dish must be aimed at a satellite that’s actually transmitting HD signals your way.
Ultimately, syncing all these devices is usually the business of satellite TV service providers. The DISH Network technician that installs your system will make sure that everything is set up and working properly for you to receive optimal HD signals. But there are perks to understanding how an HD system works for yourself. For this reason, we here at InternetLion.com suggest you continue reading through the technical articles published on our site until you’ve mastered the concepts underpinning satellite TV systems.
DISH Network HD
We also recommend checking out the DISH Network HD channel options featured here on InternetLion.com. With DISH Network you get the most HD channels available – over 200 - more than DIRECTV or any cable company in America. DISH Network is also now offering HD Free for Life, with 24-Mo. Agreement and AutoPay with Paperless Billing. DISH Network also has the highest quality HD picture with 1080p Video on Demand.
If you’re considering HD, then click here to read more about the many benefits of switching to DISH Network for the most HD programming options in the business!
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: 01/28/2011.