花7 块钱在“线路城”买了一个原价59的。这个东西不会有问题的,但是回去用起来发现数码讯号对拉杆 天线的要求比模拟讯号高。我用拉杆天线能够收到的讯号,换成数码的时候,画面出现破碎状。也就是说信号稍弱就不行了。模拟讯号弱的时候,图像有雪花,但是声音是好的。数字讯号则不然,声音跟着断断续续的。
上网查,这个问题很严重,说明美国在这方面技术上做得不好。 广告里给人的印象是只要买了转换器就一样接收, 看来不是那么一回事。大概还得投资改造天线。
这是网上看到的一个帖子:
The FCC has severely limited the power of digital television signals. The digital channels in my area are only 4 percent as strong as their analog counterparts. It is no wonder people living any distance from the broadcast antenna can’t make their converter boxes or expensive new TV’s work. If the FCC had allowed the digital signals to be just as strong as the analogs, anyone who had even marginal analog reception would have been able to get crystal clear digital service. The exceptions would include those who were watching analog stations with visible “ghosts”.
It isn’t right to be robbing rural viewers of their television experience. How will we get the news? From talk radio? From all music all-the-time? Let the FCC know that these digital ripples need to be upgraded to respectable waves.
纽约时报的报道:
Mr. Duffy had discovered that over-the-air digital signals behave differently from analog signals. That won’t matter to most Americans come the switchover. They either own a digital TV or get their signal through cable or satellite. But 17 million households have an analog TV that receives its signals over the air — 13 million of them use a rabbit-ear antenna. That means that not only do they have to buy a digital converter box; they may have to buy a new antenna. An additional 18 million homes have TVs that get over-the-air signals, but the residents have other TVs that are connected to cable or satellite services.
。。。。。
Furthermore, analog degrades gradually, with the picture displaying snow or ghosts (image echoes) as the signal becomes weaker. But the digital signal stays uniformly crisp until the signal gets weak; then the picture suddenly drops out, a phenomenon that engineers call the “cliff effect.”
。。。。
For those locations suffering the cliff effect, a new antenna is needed to pull the signals in. For TV reception on UHF and VHF frequencies, an indoor antenna like rabbit ears may work if the signal is very strong. A weaker signal may require a disc-shaped outdoor antenna that receives signals from all directions. An even weaker signal will require a V-shaped outdoor antenna, perhaps with a motor to point it directly at each broadcast signal tower.
- Re: 数码电视讯号的问题posted on 02/16/2009
Saw a TV ad yesterday saying you have to have a right antenna for the digital signal. - Re: 数码电视讯号的问题posted on 02/16/2009
- posted on 02/27/2009
Technical aspect aside, ...
$49 from home depot, digital HD antenna(I think made by GE). If possible use the external version. That's what I use to receive local HD channels. Works great. A+. And believe me of all the antennas out there I've tried a few and then some.
拉杆天线? I almost never had luck with that, even when I was living in an area that had excellent signal strength.
fanghuzhai wrote:
花7 块钱在“线路城”买了一个原价59的。这个东西不会有问题的,但是回去用起来发现数码讯号对拉杆 天线的要求比模拟讯号高。我用拉杆天线能够收到的讯号,换成数码的时候,画面出现破碎状。也就是说信号稍弱就不行了。模拟讯号弱的时候,图像有雪花,但是声音是好的。数字讯号则不然,声音跟着断断续续的。
- Re: 数码电视讯号的问题posted on 03/05/2009
“$49 from home depot, digital HD antenna” - this is a good one except it's not strong enough to support wild birds standing on it. Put it up somewhere so your neighors can't see it unless you've a house surrounded by a nice evergreen forest.
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