ATSC PSIP PDF
ATSC Program and System Information Protocol (PSIP). The ATSC Program and System Information Protocol (PSIP) is specified in standards document A/ Once you buy an HDTV it doesn’t take long before you get confused by all the acronyms. We love us some HD, but the days of simply bringing. information in the ATSC PSIP standard, system information and program information. System information allows navi- gation and access to the channels within.
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Once you buy an HDTV it doesn’t take long before you get confused by all the acronyms. We love us some HD, but the days of simply bringing a new set home and plugging into a coax cable are long over — at least for most.
It is pretty obvious by the latest surveys that most people don’t understand exactly what it takes to enjoy HD on their HDTV, but even if you do, you may not understand what most of it means.
Now while this isn’t the typical make sure you have your HDTV configured to watch HD post, it will help you understand the different ways HD is delivered.
Broadband Typical for the psi industry that the term broadband isn’t exactly used correctly, but it’s probably more fair to say that word just change meanings as the technologies evolves. Originally, broadband just meant more than one frequency was used to send a signal over the same medium — as apposed to attsc which only uses one frequency.
The easiest example to understand is FM Radio. There is one station at Television stations work the same way, but the frequencies are mapped to channel numbers to make things simple — so for example, channel 8 in the US is at Each of these channels is like real estate — they aren’t making any more of it — and broadcasters get a license from the FCC to use it with some non-monetary strings attached.
Packet switched vs circuit switched Now before we get into specific broadcasting encoding methods used for over-the-air TV, cable, and satellite; lets cover something that can be a little difficult for internet geeks to understand.
HD 101: What is ATSC, PSIP, QAM, and 8-VSB?
Unlike the internet where all the data is broken up into little packets and sent across the same shared pipe, digital TV is more like a traditional phone system. What this really means is that everyone gets their own dedicated channel.
So even if channel 10 is off the air, channel 12 can’t use the throughput. The two channels have no affect on each other, they each have their own discrete channels. Encoding video vs encoding bits and modulation Another topic that is useful to understand is the differences between encoding video vs encoding bits. In fact encoding just means transforming information into different formats, but more importantly, in order to send these bits across a wire or through the air, they must be modulated.
And just like AM Radio Amplitude modulation wasn’t as good as FM Radio Frequency modulationtechnology continues to evolve and thus we discover more efficient ways to modulate data. So in other words as technology evolves we find new ways to send more bits across the same 6MHz channel. While understanding the ins and outs of either standard is well beyond the scope of any article, you should know that both use the same size channels 6MHz and that until a channel goes all digital, it is actually broadcasting on both frequencies simulcasting.
This enabled the broadcasters to send specific data like programming information, but more importantly it supports channel mapping information. The key here is to realize that when you do a channel scan your TV will automatically know that when it discovers channel 24, that you expect to find this station at channel As the digital transition is completed and broadcasters move frequencies — either away from VHF so other services can use it, or are simply moving back to their original channel assignment — most ATSC tuners will require users to rescan in order to update the table.
This equipment generates PSIP information. Interestingly, p30 is actually a part of the spec, but most don’t expect it to ever be utilized because QAM This is a term thrown around a lot these days because it’s actually pretty useful to understand.
The coolest thing about QAM is that since it doesn’t need all the error correction of an over-the-air modulation technique, it is much more efficient. The real problem with QAM — no fault of it’s own though — is that when a cable operator uses QAM, it can also inexpensively encrypt the signal, which is why you might have heard about clear QAM. All this really means is that the QAM psi; is not encrypted, which means all you have to do is plug the coax pskp your tuner and start watching HD. The bad news is that there isn’t any guarantee that your TV will be able to find all the channels.
Well, it isn’t that it can’t find them as much as it is the fact that some providers strip out the PSIP data when shaving bits out — atsd on that later.
The cable provider’s STBs don’t have the channel mapping problem because they have access to a virtual atzc table. QAM Modulator With the advent of HD bandwidth has become a problem for all content providers, but it helps if you understand how it is psiip. Expanding a cable plant’s QAM infrastructure can be very expensive, especially when you move closer to consumer’s homes because you need more equipment.
And of course Ats doesn’t evolve overnight, so operators have to find new ways to make more efficient use of the bandwidth currently available. One way they do this is by putting multiple HD streams on one channel. This isn’t really a aysc when you take two So what operators do is put three i channels per QAM channel, which doesn’t take 11th grade math to figure out there isn’t always going to be enough bits to go around — bet you wish this was packet switched now.
So the operators deploy a technology called statistical multiplexing to try to dynamically allocate enough throughput to each stream.
Program and System Information Protocol
The theory is that none of the streams will need all the bandwidth at the same time. Unfortunately in practice this isn’t the case, and our beautiful HD turns into block city. The more recent technology that operators have turned to is switched digital video SDV. This is where instead of sending every channel to every house, all the time, only the channels that are being watched are being sent.
This is actually pretty cool technology but the problem is there is the off chance that a channel won’t be available when you want to watch it — very rare — and even more common, your one-way CableCARD enabled Media Center or TiVo won’t be able to tune in the channels at all.
Recently operators have been giving out a ” tuning adapter ” which enables one-way CableCARD host devices to work with SDV, but this is all pretty new and Microsoft has yet to even support it — although we fully expect support in Windows 7. The good news is that while technology continues to change, due to compatibility reasons these technologies evolve slowly.
ATSC Program and System Information Protocol (PSIP)
So now that you understand most of this — hopefully — it should serve you well for years. The one thing we didn’t touch on though was satellite technology and mostly this is because both of the providers in the Atec require you to psup their STBs anyways, and there really aren’t many reasons you’d need to know what atsv of modulation they used — at least not in the context of this port.
Got a basic HD topic that you’d love for us to explain? Tired of Google’s complicated answers when you asked for a simple explanation? Hit us up at ask at agsc dawt com and keep an eye on this space — your topic could be psup. Where are the adults. Typical for the tech industry that the term broadband isn’t exactly used correctly, but it’s probably more fair to say that word just change meanings as the technologies evolves.
Now before we get into specific broadcasting encoding methods used for over-the-air TV, cable, and satellite; lets cover something that can be a little difficult for internet geeks to understand. Another topic that is useful to understand is the differences between encoding video vs encoding bits.
This is a term thrown around a lot these days because it’s actually pretty useful to understand. With the advent of HD bandwidth has become a problem for all content providers, but it helps if you understand how it is managed. From around the web.