TVI in the digital age
 

HDTV is inexorably moving across the country, even some XX.1, XX.2 channel
leaking across from XE land.

Is this new digital product subject to the same TVI as analog, displaying the
same "sound bars", "herringbone", etc., or do we need to decode new artifacts to
know if our TVI is from radiated or conducted signals?

The Man in the Maze
QRM from Baboquivari Peak, AZ

--Iitoi

TVI in the digital age
 

HDTV is inexorably moving across the country, even some XX.1, XX.2 channel
leaking across from XE land.

Is this new digital product subject to the same TVI as analog, displaying the
same "sound bars", "herringbone", etc., or do we need to decode new
artifacts to
know if our TVI is from radiated or conducted signals?

The artifacts seen on digital TV, such as they are, are very different
from TVI artifacts on an NTSC broadcast signal. You won't see (or
hear) sound bars, hum bars, herringbone, buzz, at all (unless perhaps
your TVI is so powerful that it's getting directly into the final,
analog stages of the TV... not likely unless you're running a kilowatt
right next door).

You'll tend to see one of two types of interference artifact on DTV
signals:

(1) Macroblocking. Square or rectangular portions of the picture will
freeze, "tear up" or become monochrome.

(2) "Looking for signal" - the whole digital signal "drops out" and
the TV blanks the screen and complains.

The audio will exhibit analogous dropouts - momentary gaps in the
sound, or complete silence when the signal is lost entirely.

The character of the artifacts probably won't be terribly useful in
figuring out if a ham transmitter is involved... you'll have to depend
on the timing (e.g. if macroblocking starts happening when you
key-down, your transmitter may be involved).

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

TVI in the digital age
 

I wonder if this workshop would be useful for some hams to attend (or at least
plug into the audiocast and record it).

The Federal Communications Commission has announced the agenda topics and
tentative speakers for the Digital Television Consumer Education Workshop to be
held Wednesday, September 26, 2007, at FCC Headquarters, 445 12th St., SW,
Washington, DC, in the Commission Meeting Room. The Workshop will begin at 8:00
AM and end at 3:45 PM.

A live audiocast of the hearing will be available at the FCC's website at
http://www.fcc.gov/realaudio/#sep26 on a first-come, first-served basis. In
addition, the hearing will be recorded, and the recording will be made available
to the public.

For further information go to
http://fjallfoss.fcc.gov/edocs_publi...C-276258A1.doc

The Man in the Maze
QRM from Baboquivari Peak, AZ

--
Iitoi

TVI in the digital age
 

On Sun, 26 Aug 2007 21:51:07 -0400, Dave Platt wrote:
The artifacts seen on digital TV, such as they are, are very different
from TVI artifacts on an NTSC broadcast signal. You won't see (or
hear) sound bars, hum bars, herringbone, buzz, at all (unless perhaps
your TVI is so powerful that it's getting directly into the final,
analog stages of the TV... not likely unless you're running a kilowatt
right next door).

Though given so many people are on cable/satellite these days, I would
suggest that post-demodulator pickup will probably be the more common type
of interference...

Sound bars, hum bars, and herringbone are all a function of analog
reception. You won't notice any of that on a DTV receiver.

As Dave says, macroblocking and complete dropouts will be the most common
problem. I doubt you'll see any other type of interference to the picture.

Direct RF pickup on external audio wiring will probably be a bigger
problem. It'll sound just like RFI on stereo equipment. (since that's
essentially what it is...)