I am attending the 2009 Consumer Electronics Show in Las Vegas and I am looking at a few very specific items. As I have been doing DTV information sessions throughout the state of Iowa, I have had an opportunity to listen to and answer many questions. However there are many more questions that still need to be answered and I have used those issues to determine what I am looking at.
Primarily there are four specific issues. First is recording over-the-air digital television. Many peopl who have purchased converter boxes have discovered that they make using existing VCR's very difficult. I am looking at what items are available to replace the analog VCR. The second area is indoor antennas. Although I am not a fan of indoor antennas because of the problems associated with indoor reception it is clear that many people want to continue to use them. I will be reporting on what is happpening on this front.
The third issue is about what is happening in display development. There are some exciting new technologies being unveiled at this year's conference. Many people are looking at new televisions and want to be sure that what they are purchasing is the right choice for them.
The fourth issue is audio. You don't have to watch too much digital television to recognize that there are some unresolved audio concerns. Audio/video synchronization is an issue and a number of vendors are offering the consumer some options for correcting these problems. And if you change channels you'll notice the other issue which is loudness or more precisely the inconsistent audio levels between channels. I will be reporting on what is happening on this front as well.
I will be filing my first report later today.
Bill
Friday, January 9, 2009
Tuesday, December 30, 2008
Beware of High Definition Hype
I recently had a question from a viewer who was receiving our digital signal and was quite happy except for the fact that occasionally he had what he described as “digitization” in the picture. Probably anyone that has watched any television for some period of time has noticed this artifact. It is sometimes called “pixelization” or “mosaic tiling” or “blockiness.” The professional term for it is macro-blocking and it is what happens to the picture when the digital decoder in the receiver starts to run out of data. Is it the edge of the abyss we call the digital cliff. The digital cliff is the reason why I stress taking all the steps possible to deliver as clean a signal to the receiver as possible. Those steps increase the margin or distance between the received signal and the cliff and the greater the margin, the better.
The viewer lives in a three story home with an outdoor antenna and uses splitters and cable runs to distribute the signal to five different television receivers. He had done some research regarding splitters and sent me a couple of links to websites that he had looked at and was wondering if there was any merit in the claims made about these splitters and if installing them would improve the reliability of his signal. I visited both websites and one was quite accurate in describing the splitter’s capabilities and function, although I am not sure why a splitter needs a “precision die-cast 24k gold-plated chassis.” Gold-plating the connector contact improves connectivity which gives some improvement in performance but I don’t know how gold-plating the outside of the splitter helps.
The other site was much more worrisome since it was full of misinformation. It started off with this statement “These 1080p rated 2, 3 and 4 Way, 2 GHz RF high definition splitters are solely designed for high definition systems.” Where do I start? An RF splitter’s function is to take an RF signal from an antenna or cable system and divide it equally. 2, 3, and 4 way splitters divide the single input into 2, 3 and 4 outputs respectively. They work with the radio frequency (RF) signal and therefore do not care if the content on the signal is digital or analog, high definition or standard definition. RF splitters have been employed since the very early days of broadcast so it is doubtful that this splitter was solely designs for high definition systems and 1080p is a high definition video display format and has nothing to do with the performance of this or any other splitter. The advertising copy went on to make numerous claims of performance of this splitter and inaccurately relating it directly to high definition television.
I have said it before, but what makes digital television digital is not the RF signal, but the content that is on the RF signal. So until the content is removed (demodulated and decoded), the DTV signal works pretty much just like the analog signal. In the RF domain, there is no such thing as a digital antenna, a digital splitter, or digital wire. These passives components are agnostic to the content and only care about the RF signal. To be sure, having good components will improve reception but the same good components will improve analog or digital reception. Don’t fall for the marketing hype.
Bill
The viewer lives in a three story home with an outdoor antenna and uses splitters and cable runs to distribute the signal to five different television receivers. He had done some research regarding splitters and sent me a couple of links to websites that he had looked at and was wondering if there was any merit in the claims made about these splitters and if installing them would improve the reliability of his signal. I visited both websites and one was quite accurate in describing the splitter’s capabilities and function, although I am not sure why a splitter needs a “precision die-cast 24k gold-plated chassis.” Gold-plating the connector contact improves connectivity which gives some improvement in performance but I don’t know how gold-plating the outside of the splitter helps.
The other site was much more worrisome since it was full of misinformation. It started off with this statement “These 1080p rated 2, 3 and 4 Way, 2 GHz RF high definition splitters are solely designed for high definition systems.” Where do I start? An RF splitter’s function is to take an RF signal from an antenna or cable system and divide it equally. 2, 3, and 4 way splitters divide the single input into 2, 3 and 4 outputs respectively. They work with the radio frequency (RF) signal and therefore do not care if the content on the signal is digital or analog, high definition or standard definition. RF splitters have been employed since the very early days of broadcast so it is doubtful that this splitter was solely designs for high definition systems and 1080p is a high definition video display format and has nothing to do with the performance of this or any other splitter. The advertising copy went on to make numerous claims of performance of this splitter and inaccurately relating it directly to high definition television.
I have said it before, but what makes digital television digital is not the RF signal, but the content that is on the RF signal. So until the content is removed (demodulated and decoded), the DTV signal works pretty much just like the analog signal. In the RF domain, there is no such thing as a digital antenna, a digital splitter, or digital wire. These passives components are agnostic to the content and only care about the RF signal. To be sure, having good components will improve reception but the same good components will improve analog or digital reception. Don’t fall for the marketing hype.
Bill
Monday, December 15, 2008
IPTV DTV Information Sessions
In the coming months, Iowa Public Television's DTV experts will conduct free information and Q&A sessions about Digital Television. UPDATED JANUARY 23
And remember - if you'd like an Iowa Public Television staff person to speak to your community or civic group, please let us know! Contact Jennifer at 800-532-1290 or at jennifer.konfrst@iptv.org to schedule a session in your community!
And remember - if you'd like an Iowa Public Television staff person to speak to your community or civic group, please let us know! Contact Jennifer at 800-532-1290 or at jennifer.konfrst@iptv.org to schedule a session in your community!
Upcoming Free Digital Television Information Sessions
- Cedar Rapids Public Library - Westdale Mall - Wednesday, January 28 at 6:30 p.m.
- Ericksen Center - Clinton, Iowa - Thursday, February 12 at 1 p.m.
Tuesday, December 2, 2008
Why Does Digital Reception Behave Differently
As the February 17, 2009 analog shutoff approaches there has been a huge and very successful push to increase the public awareness that something is happening regarding television in the USA. When I first began explaining digital television to viewer in the mid 1990's the focus was on telling them what they would need to do to receive digital services. Television signals, whether digital or analog, essentially travel the same way so how the signal gets to the receive antenna is more a factor of what television channel and band (VHF or UHF) the signal is on rather then whether the content riding on that signal is digital or analog. The real observable difference to the end users is in the performance of the digital decoder in a DTV receiver.
I try to explain it to lay people this way. In analog television there is a direct connection between the quality of the received signal and the quality of the displayed content on that signal. Weak signal means noisy picture. A signal receiving self-interference (called multipath) has visible ghosting or after images in the picture. These and other common signal impairments are easily visible to the end user because although they are impairments to the television signal, they show up as impairments to the displayed content.
What makes DTV behave so differently is that when the content is created, before it is ever placed on a television signal, the content is digitized and from that point on we are not working directly with the content but rather with the numbers that represent the content. Those numbers can be manipulated and shipped around over many different forms of electronic transportation and as long as the number that gets to the decoder (this is what turns the number back into the content) are readable, the picture can be recreated perfectly.
So if we think back the things that impaired the analog television signal and recognize that the digital television signal travels those same paths, it makes sense then that those same impairments would happen to the digital television signal. And just like with the analog service, those impairments show up on the digital content (the numbers) but since the numbers have to go through the decoder before the content can be displayed, the direct connection that existed between the signal and the display of content no longer exists. Instead what happens is the decoder sees the noise from a weak signal but since all it has to figure out what the numbers are, even if they are noisy it will recreate the picture without showing any problems. If the numbers have ghosts it doesn't matter as long as the decoder can figure out the numbers it will recreate the picture.
So when digital service fails, what is really failing is the decoder not the receiver. What has happened is that the impairment to the signal has gotten so great, the decoder can not get enough of the number to recreate the picture. In the analog world this would show up on the screen as a picture that is so noisy and or ghosted that it would be unwatchable. The display would unlock (picture roll) or distort diagonally or be too noisy to make out any images. Digital receivers just can't display that.
So one of the fundamentals that people need to understand about digital reception regardless of whether it is via a new digital television or a coupon eligible converter box is that even though the same things impact the both the digital and analog television signals, the receivers will behave differently and essentially the same things that make analog reception work better (outdoor antennas, high quality wire, etc.) will make digital work better.
Bill
I try to explain it to lay people this way. In analog television there is a direct connection between the quality of the received signal and the quality of the displayed content on that signal. Weak signal means noisy picture. A signal receiving self-interference (called multipath) has visible ghosting or after images in the picture. These and other common signal impairments are easily visible to the end user because although they are impairments to the television signal, they show up as impairments to the displayed content.
What makes DTV behave so differently is that when the content is created, before it is ever placed on a television signal, the content is digitized and from that point on we are not working directly with the content but rather with the numbers that represent the content. Those numbers can be manipulated and shipped around over many different forms of electronic transportation and as long as the number that gets to the decoder (this is what turns the number back into the content) are readable, the picture can be recreated perfectly.
So if we think back the things that impaired the analog television signal and recognize that the digital television signal travels those same paths, it makes sense then that those same impairments would happen to the digital television signal. And just like with the analog service, those impairments show up on the digital content (the numbers) but since the numbers have to go through the decoder before the content can be displayed, the direct connection that existed between the signal and the display of content no longer exists. Instead what happens is the decoder sees the noise from a weak signal but since all it has to figure out what the numbers are, even if they are noisy it will recreate the picture without showing any problems. If the numbers have ghosts it doesn't matter as long as the decoder can figure out the numbers it will recreate the picture.
So when digital service fails, what is really failing is the decoder not the receiver. What has happened is that the impairment to the signal has gotten so great, the decoder can not get enough of the number to recreate the picture. In the analog world this would show up on the screen as a picture that is so noisy and or ghosted that it would be unwatchable. The display would unlock (picture roll) or distort diagonally or be too noisy to make out any images. Digital receivers just can't display that.
So one of the fundamentals that people need to understand about digital reception regardless of whether it is via a new digital television or a coupon eligible converter box is that even though the same things impact the both the digital and analog television signals, the receivers will behave differently and essentially the same things that make analog reception work better (outdoor antennas, high quality wire, etc.) will make digital work better.
Bill
Monday, November 10, 2008
More DTV Resources for You
To help prepare you for your switch to all-digital tv, Iowa Public Television in continually adding resources to our Web site and on our air.
Digital TV Q&A: An Iowa Journal Special aired Thursday, November 6, and is available here on our site. You can also see segments, answers to common questions, and other resources there.
In addition, this special program will be broadcast again Monday, November 24 at 8 p.m. You can call in that evening to have your digital television questions answered by IPTV engineers and staff.
And of course, you can always email Iowa Public Television at programming@iptv.org or iowajournal@iptv.org, or you can call us during business hours at (800) 532-1290. We have staff ready to help you with your questions, from basic installation to reception issues and more.
We want to make this transition as smooth as possible. If there's anything we can do to help, please let us know.
Thank you!
Digital TV Q&A: An Iowa Journal Special aired Thursday, November 6, and is available here on our site. You can also see segments, answers to common questions, and other resources there.
In addition, this special program will be broadcast again Monday, November 24 at 8 p.m. You can call in that evening to have your digital television questions answered by IPTV engineers and staff.
And of course, you can always email Iowa Public Television at programming@iptv.org or iowajournal@iptv.org, or you can call us during business hours at (800) 532-1290. We have staff ready to help you with your questions, from basic installation to reception issues and more.
We want to make this transition as smooth as possible. If there's anything we can do to help, please let us know.
Thank you!
Thursday, September 25, 2008
No reason to wait - start watching DTV now!
By now, you have heard a lot of messages about digital television and what you need to do to prepare for digital-only broadcasting. In fact, you're probably getting tired of all those messages!
But it’s not enough just to know – it’s important to act now to make sure you’re ready. And besides, you can watch digital programming right now, so there's really no need to wait.
Set up your digital television, or connect your converter boxes, and make sure you receive the all channels you expect to see. We hope you find you’ll see even more.
If you can’t get a digital signal even with the right equipment, contact your local retailer. They can help you determine if your antenna needs an upgrade too. Better to find out now if you need to get on the roof to install a new antenna than in January!
And feel free to contact us with questions or to schedule an information session. We want your transition to digital television to be as smooth as possible.
But it’s not enough just to know – it’s important to act now to make sure you’re ready. And besides, you can watch digital programming right now, so there's really no need to wait.
Set up your digital television, or connect your converter boxes, and make sure you receive the all channels you expect to see. We hope you find you’ll see even more.
If you can’t get a digital signal even with the right equipment, contact your local retailer. They can help you determine if your antenna needs an upgrade too. Better to find out now if you need to get on the roof to install a new antenna than in January!
And feel free to contact us with questions or to schedule an information session. We want your transition to digital television to be as smooth as possible.
Tuesday, August 26, 2008
Are You Receiving Me?
I have been on the road a lot doing DTV information sessions across the state of Iowa. As part of the presentation I bring along my Philips Silver Sensor antenna and few different converter boxes and generally hook them up to an analog television so I can show the attendees how the boxes work. The reason I bring along the Silver Sensor is because it is small and easy to set up but I frequently have people ask me about it because a number of them have tried traditional rabbit ears and are not entirely satisfied with the results. Many folks marvel that the Silver Sensor is not amplified and yet it works in areas where their amplified rabbit ears don't. I am often asked where to acquire this antenna and if I recommend it and it is those questions that I would like to answer in this message.
First, a simple statement of fact. Indoor reception in inherently difficult and unreliable. The reason for this is that in order to just get to the antenna, the transmitted signal has to pass through walls and windows and all of the trees and anything else that is a ground level just to get to the antenna and all of these items degrade and disrupt the signal. In addition everything in the room with the antenna is a potential source of reflection which further degrades the receivability of the signal. On top of that add to the mix that anything in the room that moves, like the viewer, the kids, the dog or the cat will also dynamically disrupt the signal and further degrade received service and unlike analog television where the picture on the screen gives you a clear indication of how poor the incoming signal actually is, digital gives no indication until the decoder realizes it doesn't have enough information to make a picture and it either freezes, macro blocks (blockiness) or goes away. So I will never recommend indoor reception or an indoor antenna.
So why then does the Silver Sensor work when I am doing demonstrations? It is pretty simple really, the Silver Sensor is a directional antenna where as rabbit ears are omnidirectional. Plainly stated the Silver Sensor receives very well from one direction at a time so in a room where there may be signal coming from all directions, it ignores them and delivers a much less disrupted signal to the receiver than rabbit ears in the same location. Directional antennas also act a little like a satellite receive antenna (dish) in that they tend to gather more of the signal coming in from a specific direction and add it all together. This is referred to as the gain of the antenna and is specified in decibels (dB) which is a ratio. In the case of most antennas, the gain specified in dB is a comparison to the directional antenna and a dipole and guess what, rabbit ears are a dipole. In the case of the Silver Sensor, it has a gain of about 6 to 7 dB compared to a dipole but don't jump the gun, that doesn't mean it is 6 to 7 times better. The way the math and physics work out, the Silver Sensor probably collect about 2.5 times as much signal as a dipole (rabbit ears) and probably as important it ignores signals coming from other directions. That is why it works better than rabbit ears. I have had people say but my rabbit ears have a 10 dB amplifier built in so that should overcome the gain improvement of your Silver Sensor. This is not entirely true because remember that dB is a ratio so an amplifier with 10 dB of gain is taking the signal coming in to the amplifier and increasing the amount of signal by 10 dB. Okay but the amplifier is after the antenna so that the signal that is being amplified in the rabbit ears has already been degraded by all of the items I mentioned above and therefore all you are doing is increasing the size of the degraded signal but the receiver and decoder still can't figure out what the message is no more than yelling at someone who doesn't understand English makes them understand.
So I can't recommend an indoor antenna with any degree of certainty because the number of things that will disrupt the service using an indoor antenna are virtually unlimited and constantly changing. I will always tell people to look at outdoor antennas as their best option. I have had a number of people tell me that they are not permitted to put up an antenna because of local restrictions. I would suggest that you follow this web link (http://www.fcc.gov/mb/facts/otard.html) and I believe you'll find that many of those restrictions are superseded by federal rules that in most cases will allow you to install an outdoor antenna, even in rental properties. So you might want to look at antenna reception again. Remember, rabbit ears work great on rabbits but not so well on television signals.
Bill
First, a simple statement of fact. Indoor reception in inherently difficult and unreliable. The reason for this is that in order to just get to the antenna, the transmitted signal has to pass through walls and windows and all of the trees and anything else that is a ground level just to get to the antenna and all of these items degrade and disrupt the signal. In addition everything in the room with the antenna is a potential source of reflection which further degrades the receivability of the signal. On top of that add to the mix that anything in the room that moves, like the viewer, the kids, the dog or the cat will also dynamically disrupt the signal and further degrade received service and unlike analog television where the picture on the screen gives you a clear indication of how poor the incoming signal actually is, digital gives no indication until the decoder realizes it doesn't have enough information to make a picture and it either freezes, macro blocks (blockiness) or goes away. So I will never recommend indoor reception or an indoor antenna.
So why then does the Silver Sensor work when I am doing demonstrations? It is pretty simple really, the Silver Sensor is a directional antenna where as rabbit ears are omnidirectional. Plainly stated the Silver Sensor receives very well from one direction at a time so in a room where there may be signal coming from all directions, it ignores them and delivers a much less disrupted signal to the receiver than rabbit ears in the same location. Directional antennas also act a little like a satellite receive antenna (dish) in that they tend to gather more of the signal coming in from a specific direction and add it all together. This is referred to as the gain of the antenna and is specified in decibels (dB) which is a ratio. In the case of most antennas, the gain specified in dB is a comparison to the directional antenna and a dipole and guess what, rabbit ears are a dipole. In the case of the Silver Sensor, it has a gain of about 6 to 7 dB compared to a dipole but don't jump the gun, that doesn't mean it is 6 to 7 times better. The way the math and physics work out, the Silver Sensor probably collect about 2.5 times as much signal as a dipole (rabbit ears) and probably as important it ignores signals coming from other directions. That is why it works better than rabbit ears. I have had people say but my rabbit ears have a 10 dB amplifier built in so that should overcome the gain improvement of your Silver Sensor. This is not entirely true because remember that dB is a ratio so an amplifier with 10 dB of gain is taking the signal coming in to the amplifier and increasing the amount of signal by 10 dB. Okay but the amplifier is after the antenna so that the signal that is being amplified in the rabbit ears has already been degraded by all of the items I mentioned above and therefore all you are doing is increasing the size of the degraded signal but the receiver and decoder still can't figure out what the message is no more than yelling at someone who doesn't understand English makes them understand.
So I can't recommend an indoor antenna with any degree of certainty because the number of things that will disrupt the service using an indoor antenna are virtually unlimited and constantly changing. I will always tell people to look at outdoor antennas as their best option. I have had a number of people tell me that they are not permitted to put up an antenna because of local restrictions. I would suggest that you follow this web link (http://www.fcc.gov/mb/facts/otard.html) and I believe you'll find that many of those restrictions are superseded by federal rules that in most cases will allow you to install an outdoor antenna, even in rental properties. So you might want to look at antenna reception again. Remember, rabbit ears work great on rabbits but not so well on television signals.
Bill
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