Just How Bad Is DTV? June 1, 2009

Digital television is supposed to revolutionize how we watch free TV; high definition, interactive menus and crystal clear pictures. Or so they say. In reality, DTV is more likely to drive people away from watching local broadcast stations than anything else. In theory, it’s a great technology that has a lot of advantages over its analog counterpart, but it just doesn’t live up to its expectations. Ironically, DTV’s greatest strength is also its greatest weakness: it’s digital. Yes, it allows broadcasters to compress HD quality pictures, but it also means that your signal is either on or off. There is no in between.

To be sure, I’m not the only one complaining. So I conducted a little test: I live 20 miles from one of the top 20 largest cities in the US, and according to the FCC, I should be able to receive eighteen DTV stations with a strong signal. I outfitted my analog TV with a DTV converter box and an amplified indoor antenna. My TV is located on the second story of my town house, so the antenna was as high as I could possibly get it without putting up an exterior antenna. I re-positioned the antenna a couple of times, performing a channel scan each time; I then cycled through each channel and noted the picture quality and signal strength of each station. Of those eighteen “strong” signals, only one was what I would consider watchable:

Channel

Station

FCC Estimated Signal Strength

Observed Signal Strength

Observed Signal Quality

2-1

ABC

Strong

Weak

Choppy, skipping image, some audio

54-1

CW

Strong

Moderate

Watchable with occasional freezing and skipping

45-1

FOX

Strong

Very Weak

Frozen image, no audio

24-1

MYTV

Strong

Weak

Choppy, skipping image, some audio

13-1

CBS

Strong

Weak

Choppy, skipping image, some audio

14-1

UNI

Strong

None

None

22-1

PBS

Strong

Weak

Choppy, skipping image, some audio

5-1

FOX

Strong

Very Weak

Frozen image, no audio

11-1

NBC

Strong

Weak

Choppy, skipping image, some audio

66-1

ION

Strong

None

None

4-1

NBC

Strong

Weak

Choppy, skipping image, some audio

67-1

PBS

Strong

None

None

20-1

MYTV

Strong

None

None

7-1

ABC

Strong

Very Weak

Frozen image, no audio

50-1

CW

Strong

None

None

32-1

PBS

Strong

None

None

9-1

CBS

Strong

Very Weak

Frozen image, no audio

26-1

WETA

Strong

None

None

So what do I define as “watchable”? Well, a signal that doesn’t freeze and skip like a burnt DVD every 5-15 seconds would be nice:

DTV Picture Quality

DTV Picture Quality

Interestingly, here is the exact same program from the same station, only this time on the analog side. Perfect picture (note that the red horizontal line is the picture refresh being picked up by the camera and was not visible to the human eye) and audio:

Analogue Picture Quality

Analogue Picture Quality

In fact, nearly all of the analogue signals that I can pick up are watchable; most are not perfect, but even the worst are watchable; clear audio and an intelligible image:

Channel

Station

Observed Signal Quality

2

ABC

Snowy picture but watchable, clear audio

4

Unknown

Very snowy, watchable with some difficulty, clear audio

5

Fox

Very snowy, watchable with some difficulty, clear audio

7

Unknown

Poor picture, understandable audio

11

NBC

Snowy picture but watchable, clear audio

13

CBS

Slightly snowy picture, easily watchable, clear audio

20

MYTV

Clear picture, clear audio

22

MPT

Clear picture, clear audio

24

MYTV

Clear picture, clear audio

32

Unknown

Very snowy, watchable with some difficulty, clear audio

50

CW

Snowy picture but watchable, clear audio

67

MPT

Very snowy, watchable with some difficulty, clear audio

So using the same equipment I have significantly more viewable stations with analog than I do with digital. Now, to be fair, this test was conducted on a cloudy day; no rain, no thunderstorms, just cloudy. On a perfectly clear day, I can watch one or two other DTV stations, but even that says something: if DTV is so badly affected by clouds, heaven help you if you run into any real interference.

DTV is great…when it works. Unfortunately, unless you’re sitting right next to a TV station, it probably won’t work very well. Good-bye local broadcasters, hello Hulu.

3 Comments
uggyuu July 8th, 2009

you have to adjust the antenna for every station, i get way more channels than with analog

Craig July 15th, 2009

I get way more channels too, but they aren’t watchable.

I did adjust the antenna for each station and found that the best signal for a given station could be achieved in one of two positions (the positions were perpendicular to each other, which I assume is a result of the typical DTV antenna prorogation lobes, although I really haven’t looked into it). I performed scans in both positions in order to find the maximum number of stations, and then adjusted the antenna for each station; the above results were the best that I could achieve.

I’m glad that DTV worked out for you; I’d be interested to know what type of antenna and DTV converter you are using, what your distance from the stations is, and what type of area you live in (rural, residential, city, etc?).

Jack March 2nd, 2010

DTV was tested using a yagi with a rotator. In order to get the number and
quality, you need to aim your antenna. Early front ends were very poor, and
yeilded miserable results. I had a wintv-d board running on redhat with
myth, and got a few miserable channels. the Tube network was a brightspot.
Later front ends are much better. Low cost/quality converter boxen are not
good, but (I’m an EE) I did design a miserably complex DTV antenna that
provided man channels and very good quality, especially the audio. Various
channels provide various quality transmissions.
I’m going to test the boxee, based on your appraisal. I have been running
GBPVR.
j

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