A question that's going to come up...

Ray Minich · From: Bradford, Pa. Frozen Tundra

Of course we use the TV to watch for steel stuff, so there's the connection.

Now, does anyone have any idea how the new digital signal is going to compare to the old analog signal in terms of propogation distance and reception? We can get Buffalo, NY stations 80 miles away with a deep fringe antenna. Will that be possible with the new modulation sheme?

Thanks in advance...

Larry Robinson · From: Peachtree City, Georgia, USA

I have a deep fringe antenna with a 30db gain preamp. I live in Atlanta area(south of Atl) and can recieve both digital and analog tv signal. Some tv stations may change from VHF to UHF during the digital conversion so you may have to upgrade your antenna if it won't recieve VHF and UHF channels. Reception will either be good or you will not be able to view the station. There is no fading in. However, weak signals will pixel and you won't see anything.

Sam Marshall · From: Chandler, AZ USA

Larry is right,the new HDTV modulation format does not bode well for video DXing. Old analog TV degraded rather gracefully with either an increased propagation distance or a poor signal-to-noise ratio.

HDTV needs a specific signal to noise ratio (Eb/No technically) to exist for everything to synchronize correctly. Below that, the digital television system quits working completely because the data and RF carrier synchronization control loops fall out of lock.

Reports are that HDTVs degradation from excellent to non-functioning is only a few dB. This is consistent with my professional experience developing high-speed RF data modems.

There is a discussion on this in this month's issue of Popular Communications magazine.

Best Regards,
Sam

Benton Allen · From: Muscle Shoals, Alabama, USA

Hi Ray!!

Good to see that your still alive and kick'in up there in NY!!!

I have High Def Satellite feeding my big screen LCD's so I'm already all digital. I get good reception picturewise and very good Dolby Stereo Surround Sound audio.

Have a great weekend!

Benton

Donny Hinson · From: Glen Burnie, Md. U.S.A.

The one big flaw in all digital stuff is that it either works - or it doesn't. There's no in-between. I can't tell you how many computer programs I've had to dump because they had an un-correctable 1-byte error. At least with a record or audio tape, the rest of the recording was unaffected if a tiny spot got damaged. Get a tiny spot of damage on a music or software CD, and you get to enjoy that lovely message "READ ERROR!"

Lynn Oliver · From: Redmond, Washington USA * R.I.P.

Jim Sliff · From: Lawndale California, USA

Antenna?

Don't they have digital cable, or FIOS (fiber-optic) around there? Or what about a Sat dish?

I don't even know anyone who uses an antenna. Even guys I know with RV's use Satellite. I mean, what are you getting, like 15 channels?
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b0b · From: Cloverdale, CA, USA

I can barely get radio stations here in Cloverdale. I don't think it's possible to get television with an antenna. Everybody has cable or satellite.
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Jack Stoner · From: Kansas City, MO

I'm in the "sticks" - 65 miles north of Tampa and the same distance west of Orlando. There isn't much TV reception with an antenna. I've only seen two houses in my area with a TV anntenna and I don't know if they are actually using them.

We have a combo package, TV, Internet and telephone from our cable provider (Brighthouse).

Ray Minich · From: Bradford, Pa. Frozen Tundra

Yes, antennas may seem silly in this age of cable and pizza dishes.. BUT, we just had a controversy between Time Warner and the CBS affiliate out of Buffalo that led to the suspension of CBS (and the Bills games) from the cable channel. Those with antennas could still receive the broadcast ('cause it's free over the air). They were even giving out free rabbit ears in Buffalo. With the old "cross-fire" we can still get Ch-4 Buffalo from 80 miles away.

Thanks for the input, I kinda suspected that propogation was gonna be reduced by the new scheme.

I know the new digital TV antenna systems for sale at Wally World sure are different from the old Channel Master bird perches...

Blake Hawkins · From: Florida

I live 18 miles North of Tampa and use an attic antenna for the local channels.
With analog, I get 12 channels, 5 of them so fuzzy
as to be unwatchable. Channel 66, which broadcasts
the Ray's Baseball games does not come in.

With the digital converter, I get 28 crystal clear
channels including 66.

Don Sulesky · From: Citrus County, FL, Orig. from MA & NH

If you are not on a cable or satelite link come February you'll need the converter box that has been offered for you to buy.
Otherwise all the antennas in the world won't help you.

Jim Sliff · From: Lawndale California, USA

Don, sorry but that's not correct. Digital signals come in fine with an antenna and a digital receiver - most new TV's have a built-in digital receiver and you do NOT need a box for broadcast channels.

When I bought my 37" LCD we had analog cable - I ordered FIOS (fiber optic digital) but it was going to be a few weeks before installation, so I picked up an antenna, plugged it into the digital input, used the map I found online for antenna orientation (your antenna has to be pointed towards the broadcast antenna for each station - if a few stations broadcast from different tower clusters, like here in LA, you have to move the antenna for some stations) and got all but a few HD broadcast channels for free. THOSE will not go away with the upcoming change...only the analog signals will.

Johnne Lee Ables · From: Minnesota, USA

Ned McIntosh · From: New South Wales, Australia

A lot depends on the modulation method used for terrestrial digital. If QPSK (quadrature Phase-Shift Keying) is used, coupled with a robust Forward Error Correction (FEC) rate such as 2/3(meaning two out of three packets carries data, the third carries error-correction data) is used, then it will still give useable pictures without blanking or pixellisation even during large signal fades (6dB or greater). QPSK is very robust, but it doesn't have all that many megabits in the available bandwidth.

Also, digital compression (especially MPEG2) does a real number on video, throwing away detail it thinks the eye won't notice. If you've never seen the original material, you wouldn't really know the difference...except for the "crushed" blacks (shadows have no detail in them, they're just totally black) and the inability to handle massive rates of change in picture data (such as a large splash in a pool of water where just about every pixel on-screeen is changing at once). The encoding algorithms just collapse, and a frame of pixellisation or even "aliasing" is the result until the rate of change reduces and the sampling and encoding algorithm can catch up again.

Now, to save bandwidth and try to increase the number of megabits per second so the pictures look half-decent, (something like high definition,) what are called "higher-order" digital modulations are usually used. Such schemes as 8PSK (orthogonal phase-shift keying), 16QAM (16 Quadrature Amplitude Modulation, or even 64QAM) give more bits in the available bandwidth but reduce the immunity to signal fade. In other words, a really good carrier-to-noise ratio (C/N) and a high "Energy Bits Over Noise" (Eb/No) ratio are required to prevent pixellisation or complete video and audio muting - no pic, no sound! From great pix to a blank screen may need as little as a 2dB fade. BTW, 3dB is half the original signal (10 raised to the power 0.3 equals 2)

Keep in mind the reason the networks have gone digital is not to give you a better picture or sound, it is to save money by cramming more bits into less bandwidth, as competing carriers vie for available bandwidth in which to deliver their services. Also, going digital is certainly the end of all your old problems, but it is also the beginning of all your new ones, and most of them are worse than the old ones! Get a single number wrong with digital (such as a PID - packet ID - on an audio stream, for example) and it won't be decoded correctly at the other end.

I work with this stuff on satellite MPEG2 digital transport streams all the time, and I'm pretty much over digital SD or HD television. Interestingly enoough, although I can put a full PAL HD stream onto a satellite (1920 X 1080 pixels, 25 frames per second, interlaced), not one network here in Australia actually broadcasts true Hi-Def. They cut bits off the top or the sides, and have the hide to advertise this as "High-Def". Strictly speaking it isn't.

Sorry for the acronyms and techno-speak. Also your HDTV systems in the USA will be based on NTSC, but the principles I have outlined above will remain the same. You may have different modulation schemes, but the sad truth is the higher-order modulations sacrifice robustness for megabits per second and that's inevitable. If you don't have a very good antenna to give you the gain and carrier/noise ratio, digital will frustrate you no end. It does exactly that to me.
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Ray Minich · From: Bradford, Pa. Frozen Tundra

Thanks for the info Ned. I've been driving NTSC uncompressed down to various web flavors for a few years now. Each day there's a new codec. I remember in the early days of satellite video (C-Band) the docs said it didn't take much signal loss for the signal to go "into the quieting"... Kinda figured it was gonna be the same effect here. Thanks again.

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