Nat, this is Ken, you may know me from TFF. Got a question for you- I saw down below that youre a TV engineer. Can you tell me why if digital TV is suppose to be so much better why can't I see half the stations I could before they switched last year? And why do some stations come in at night but not during the day?
Hi Ken, glad you found us at Potpourri. Digital TV is great- IF you have a good signal. The problem is the FCC greatly underestimated the amount of power it would take for a digital signal to replicate analog coverage. Many (including me) think this underestimation was deliberate because they had to squeeze all the stations that were in 68 channels into 45 channels because chs 52-69 were removed from TV service and chs 2-6 are unsuitable for digital. So with more stations sharing fewer channels the FCC limited power to prevent them from interfering with each other. Add to this- digital TVs are more fussy about the signal they receive- reception problems that only degrade analog TV will completely kill digital.
As for why you can't get some stations during the day- TV signals generally don't go as far during the day because propagation loses are higher and if a digital signal does not reach a certain threshold of strength you don't see (or hear) it at all. Some people have the reverse problem- they can get a station during the day but not at night. In this case it's because a more distant station on the same channel comes in stronger at night and the two signals interfere with each other. With analog the stronger one wins but two signals totally confuse digital decoders and you see nothing.
In short, digital TV can be beautiful when it done right- with a good clear signal, but with marginal signals we were better off with analog.
Well I wouldn't say the change was a mistake, but the way it was implemented. With a good signal digital picture quality is much better- wider, more detailed and without many problems inherent in analog. It's just that it requires a good signal to make it work properly which many people aren't getting.
As to why we switched- it began back in the 1980s when Japan came up with a hi-def TV system as a way to sell new TVs in a stagnate industry. But Japan's system was analog and took too much bandwidth and could not be implemented here. But by the 1990s digital chips had become fast enough to work at video frequencies so a consortium of companies came up with a digital system that was much more bandwidth-efficient. In fact it possible to transmit 4 different programs in a standard 6-Mhz US TV channel.
And about this time the cellular and communication industries were screaming for more frequencies to use so it was decided by switching to digital, stations would need fewer channels and then many TV channels could be auctioned off to the telecommunication industry bringing considerable revenue to the government. It's also more energy efficient. Our digital transmitter uses about a third what the old analog did saving the station thousands of dollars in power bills.
I think in the future the current concept of central high power transmitters for radio and TV broadcasting will be replaced by some sort of super WiMax system.
The problem with digital is that any station that stayed on VHF (chs 2-13) stinks. Where I live near NYC, 3 stations Ch 7(ABC) 11(CW) & 13(PBS) are unwatchable, however the ones that moved to UHF are just fine.
I learned this the hard way. My cable company had a dispute a few months back with ABC. This resulted in WABC Ch 7 being pulled from our cable service the day of the Oscar Telecast. I bought a cheap digital antenna and could not see ABC at all, but CBS, NBC & FOX, which all migrated to UHF were fine. Ch 6 in Philly had to quadruple their power and their signal is still bad in the suburbs!!
Yes, it was well known that low-band VHF (2-6) was a no-go for digital but most engineers thought high-band V (7-13) would be ok- but a combination of impulse noise (which digital decoders hate), phase-shifting (also a problem with digital) and late-night tropospheric ducting- which brings in distant stations to interfere has been problematic for high-band-Vs. So UHF is the place to be- especially in metro areas. Ironic since broadcasters use to hate UHF- but times change. VHF's longer range is still advantageous for stations in rural areas where noise and reflection (which causes phase shift) are less of a problem.
I just got a flat panel (LCD) television. I never owned one before. I was anticipating all the great pictures and am a bit disappointed. Set is name-brand, 1080p, 120 Hz and connection is HDMI, but the picture still doesn't look crystal clear (better on stationary image than with movement). My cable service is not HD (didn't go to that expense when I took out the contract, as I had no HD TV's). Think that could be it . . . the signal is not hi-def, so the TV cannot give hi-def?
Bob, you sound like the guy who bought a color TV back in the 1960s and then complained that most of the programs were black & white. No, you can not see a hi-def picture if you are not watching a hi-def signal! In fact, standard-def pictures look worse on a hi-def TV because it shows all the imperfections of a standard-def picture that you didn't notice on smaller tube screens. What's more, the quality of even so-called hi-def pictures varies a lot- some stations are blowing up SD video to fit HD-format- but it isn't really HD. And cable companies are notorious for compressing the bandwidth of digital video to squeeze more channels onto their system so even what they say is hi-def is not as hi-def at it should be. To see really good HD- you should watch a live or taped off-air broadcast using a antenna. Even then stations that are running subchannels may compress the video a bit. In short picture quality varies a lot- but when you see true uncompressed 19.39-Mbit/S video- you will be impressed!
Could I watch a blu-ray movie on suitable player, with HDMI connection, and see what you are referring too? (First, I'd have to buy a blu-ray player!)
(Speaking of HDMI, I didn't realize how expensive those cables are! I didn't expect to get the HDMI cable thrown in with the TV, given the price I payed, but neither was I expecting to see the prices for those cables be so high. "Cheap" cables -- $40 Mid-range price/quality -- $60-70 High end cables can run $90-$150! For a cable! Yes, the sales guy told me about all the individual wires in each cable, and about the insultation around each to shield from interference. He said the cheap cables allow more interference and degrade the signal, and he recommended against them. But, $90 or more?! That sounded crazy to me. I felt ripped off enough paying $60 for a "good, not great cable", and only did so when the sales guy pointed up, "You are going to spend several hundreds of dollars on a TV and then scrimp on the cable and not be able to see what the TV can really do?" They know they have you -- once you have the set, they know you will pay an exhorbitant price for cables to watch the TV)
My current cable TV provider has all these different tiers/packages. As noted, being frugal, I opted for non-HD. Reception requires use of a cable box to select the channels. The cable enters the cable box and from there you can either run coax cable or an HDMI cable to your set.
However, my former cable service just runs coax cable directly into the TV, yet that cable service claims that all of its channels are HD. Why do I need an HDMI cable to see a good picture on my current cable service (assuming the signal I pay for is the HD variety, of course) but the other cable system delivers HD TV without need for the HDMI? Just wondering.
In order to feed the signal by coax it must be RF-modulated. This can be either NTSC (analog) or QAM- which is the cable's industry version of digital. All TVs will get NTSC and most digital TVs will get QAM. Which your cable system is using I don't know because it varies from system to system- but you can hook it up and push the "info" button on the TV remote and it should tell you. If it is NTSC it is definitely not HD! And I would use the HDMI connection. If it is QAM- it can be HD- but is not necessarily so.
As I mentioned before there are various grades of HD- depending on the quality of the original source material and how much digital compression has been used on it. And some people- especially cable people- tend to call all digital video "Hi-Def" which it is not! A highly compressed digital channel can look worse than analog. Imagine watching Youtube videos blown up to 40 inches- it would look like crap!
Just how much compression can be done before it is no longer "HD" is a matter of debate. A lot depends on the picture content and amount of motion. I can switch our subchannel on and off and sometimes I see a noticeably difference in the main video and sometimes none at all. A fast moving hockey game would require much more bits than a picture of people siting at a table talking.
Now cable companies have a great incentive to compress video because it allows them to get more channels on the same cable. Most now run on-demand channels which are highly-profitable but they have to make room for them. So they compress everything as much as they can without customers bitching. And compared to the quality of picture that cable customers were use to in the analog days even fairly compressed digital looks comparatively good.
But the short answer is- I would use HDMI over coax just because it is already in a digital form and doesn't have to go through a RF-to-digital conversion in the TV.
Actually, HDMI is almost certainly better. HDMI gives an uncompressed digital signal. Digital broadcasts, whether ATSC over the air or QAM from cable, are always compressed. To give a couple numbers to this, an uncompressed 1080p video stream (with chroma subsampling, not counting audio) takes over 700 Mbps, but QAM transports up to 38 Mbps (including audio). In contrast, HDMI transports over 5,000 Mbps. QAM encoders are getting cheaper, but I think NTSC is way cheaper and more suitable. TVs without HDMI aren't likely to have QAM, anyway, so the cable provider will use NTSC.
I doubt that you really need to get those overpriced HDMI cables. Deals web sites are always publishing HDMI cable deals, like 3 6-foot cables for $10 or whatever. I don't have the patience, so I get cheaper cables from monoprice.com.
Well first of all- there is no such thing as "uncompressed" video- rather it's OTA, cable or DVD- the video coming out of a camera is compressed to some extent. The question is how much it can be compressed and still be called "HD". The ATSC standard uses a 19.39 Mb/s data stream which can produce an excellent picture on a home-size screen. But many stations are adding second, third- sometimes as many as six subchannels and ancillary data services. All these must share the 19.39 Mb/s data stream- so like cutting a pie- the more pieces you serve the smaller (less bits) each gets. Just how much you can shave off and still call it "Hi-Def" is a matter of debate. I'd say one HD and one SD channel is the limit. When you start cutting the pie more than that PQ definitely begins to decline.
I agree about the HDMI- get the cheapest cable you can find- your TV won't know the difference.
An added benefit of posting here --- all the tech support! Thanks!
(btw, I think I will take your suggestion to use my flat panel monitor as a second monitor for the new laptop. I still have the old CRT monitor to use on my old desktop. I just need to figure out how to enable dual monitor use on the laptop -- go to "Display" in control panel?)