Digital TV Philadelphia-Whats up?

[policefreak]

First off will NBC channel 10 be going digital sooner than other stations? Also, what range will the new digital audio frequencies be? Can the audio frequencies be picked up with a scanner like the Uniden BCD396T? Also and most importantly, do you need a special antenna to receive the digital channels at full capacity?

 

[gmclam]

Digital TV in the USA

First off will NBC channel 10 be going digital sooner than other stations? Also, what range will the new digital audio frequencies be?

There have been several threads here on RR regarding the switch from analog to digital TV in the USA. Analog TV currently uses channels 2-69, each 6 MHz in width. ATSC (over-the-air digital) uses the SAME channels, except that after 2/17/2009 channels 52-69 will be "given back" to the government. Those channels will become the new 700 MHz band. Therefore, in addition to the requirement that all full power NTSC stations must cease broadcasting after 2/17/2009, all OTA TV broadcasting will be limited to channels 2-51.

Unlike analog where there are separate video and audio carriers, ATSC is entirely "digital data" modulated 8VSB. In order for a receiver to only decode the audio, it must first receive the entire stream and parse out the audio data. No current analog or digital scanners can do this. Who knows if there will be a market for such a receiver, and if so, how much people will pay for it. To make it happen, I think someone would have to come up with a chip or chipset that performs this specific function. Then scanner manufacturers would have to add it, and pass the cost along (with a profit of course).

Can the audio frequencies be picked up with a scanner like the Uniden BCD396T?

If your scanner can pick up the US TV frequencies, then yes. But ATSC is actually a "noise-like" transmission. So the end result is fruitless.

Also and most importantly, do you need a special antenna to receive the digital channels at full capacity?

LOL. Special? No!!! It surprises me that there are companies out there selling people "analog antennas" or "digital antennas". The antenna does not know if a signal is analog or digital, nor does it care. What is import with regard to an antenna is the FREQUENCY (or frequencies) you want to receive. One issue for many people is that their local TV has been on VHF (channels 2-13) ever since it went on the air. Although a station may be numbered 7.1 or 10.1 in digital, it is most likely NOT currently on VHF channel 7 or 10 (in my example) - you KNOW this is true if analog channel 7 or 10 is still on the air!

So you go out and pick up a new ATSC TV or converter box. You bring it home and connect it to the outside antenna you've used for years. The digital signal is not detected or "doesn't work". What you don't realize is that the digital channels are (currently) broadcasting on UHF! Is your antenna able to pick up UHF signals? Go to antennaweb.org or tvfool.com and find out where your local channels really are. Also pay attention to their "final channel" as well, because many stations will change their physical digital signal back to where their analog signal is now once the analog signal is turned off.

Bottom line; if you want to pick up both UHF and VHF (TV) signals, you need a UHF and VHF antenna!

 

[policefreak]

Ok thanks for the info. So I guess there wont be any channel 6 audio on 87.7 FM after the switchover. Also I wonder whats up with digital channel NBC 10. Living no more than 20 miles outside of Philly I get all the digital channels with a digital converter box except channel 10. Analog channel 10 comes in beautiful, though being its on a different freq that may not be a perfect barometer, but its got to be coming from the same antenna. So what gives? I've tried it at several locations around the house. The best I had was in the downstairs kitchen where the signal is very broken up.

 

[gmclam]

Wcau-dt 10.1

Ok thanks for the info. So I guess there wont be any channel 6 audio on 87.7 FM after the switchover.

Correct. Not unless there is a low power analog station broadcasting on channel 6.

Also I wonder whats up with digital channel NBC 10. Living no more than 20 miles outside of Philly I get all the digital channels with a digital converter box except channel 10. Analog channel 10 comes in beautiful, though being its on a different freq that may not be a perfect barometer, but its got to be coming from the same antenna. So what gives? I've tried it at several locations around the house. The best I had was in the downstairs kitchen where the signal is very broken up.

I went to antennaweb.org an supplied 08009 for a zip code. It comes back and tells me that channel 10.1 is currently boradcasting on channel 67. That is the 3rd worse channel they could be using from a standpoint of coax loss. The good news is that they will be on channel 34 after 2/17/2009.

To get channel 10.1 you need a UHF antenna. It needs to be pointed in the correct direction. You need to have good low-loss coax between the antenna and tuner/converter. The shorter the coax the better; meaning don't "coil up" unused coax between the antenna and tuner. 24.4 miles is fairly close, but the signal could be blocked/reduced if a large building/etc is in the signal path.

 

[Audiodave1]

I will miss the Ch6 audio for sure.
Unlike many stations whom will stay on the current digital UHF channel, ch6 will move it's digital transmissions down to it's current analog frequency shortly after analog goes away. Guess I'll still neeed the VHF TV antenna....
In general, VHF is more desirable for it's propagation properties. now if we could just get them to put a full time IFB on the air like Ch3 (I believe) in the 450 band.

Dave

 

[gmclam]

... Unlike many stations whom will stay on the current digital UHF channel, ch6 will move it's digital transmissions down to it's current analog frequency shortly after analog goes away. .... In general, VHF is more desirable for it's propagation properties.

while I agree that VHF has some better properties than UHF, VHF low band gets a lot of electrical interference which plays havoc with ATSC. So broadcasters are generally selecting VHF high first, then UHF and avoiding low band. Of course for many who have antennas and transmitters in place, if they don't have to make a change on 2/17/2009 other than to pull the plug on their analog transmitter, that's their first choice.