How will the US local area stations commerate the end of System-M?

In alt.video.digital-tv Doug Smith W9WI wrote:
| On Sat, 03 May 2008 17:16:40 -0500, Bruce Tomlin wrote:
|
| In article ,
| wrote:
|
| OTOH, if you put 2 stations on _adjacent_ channels, with the same ERP, then
| they should be fine transmitting from the same tower.
|
| Except that from what I've seen, the maximum power UHF analog signal is
| 5 megawatts, and the maximum power UHF digital signal is 1 megawatt. So
| if the analog is over a megawatt, they _wouldn't_ have the same ERP.
|
| Do note that analog and digital powers are measured differently.
|
| Analog power is measured at the peak of the synchronizing pulse. Digital
| power is averaged over a period of time.
|
| 1 megawatt of DTV power is more like 2-3 megawatts of analog. (depending
| on analog program material...)

Adding to this: what matters is the actual energy level of the sidebands that
carry the information. Analog TV wastes most of the energy on a carrier and
the sidebands that carry the sync pulses (important to get, but it is overkill
in the energy amount). Digital has a small pilot carrier and the rest is
virtually all sideband information. Digital also has some amount of error
correction coding.

--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
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| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

On Sun, 04 May 2008 07:56:17 -0500, Doug Smith W9WI wrote:

On Sun, 04 May 2008 05:46:55 +0000, phil-news-nospam wrote:
A proper TV would detect the PSIP data mismatch and alert the viewer and
suggest the rescan. It may partially update its own channel table at that
point.

I doubt most DTVs are that smart.

Detecting this would require noticing that the TSID has changed. I can't

Ouch. Please pretend I didn't post this.

Detecting a change in the major_channel_number field would have the same
effect, and the major_channel_number also usually appears on the screen
when the "INFO" (or similar) button is pushed.

Still, I doubt most DTVs bother to monitor this for changes unless the
viewer initiates a scan.

"G-squared" wrote in message
...
On May 3, 8:18 pm, "Sal M. Onella"
wrote:
"Doug Smith W9WI" wrote in messagenewsan.
am...



On Fri, 02 May 2008 21:44:57 -0700, Sal M. Onella wrote:
KCAL and KCBS are a duopoly, that is owned by the same company.
I had
heard
that on Day Zero KCBS-DT might move to Ch 9 and KCAL-DT might
stay on Ch
43.
KCBS-DT must vacate Ch 60 on Day Zero and going digital on Ch 2
would
seem
to be a bad move, given the known low-band noise problems. We
shal see.

KCAL-DT has filed to return to channel 9 on Transition Day. Same
tower as
their current analog facility but it looks like they're going to
use a
different antenna. (a directional antenna 7m lower than their
existing
analog one) The permit hasn't been issued yet but 9 is their
assigned
channel in the FCC's post-transition channel table.

KCBS-DT has received a permit to take over KCAL-DT's channel 43
facility
on Transition Day. The power will increase about 10% but the
same antenna
will be used.

(one might guess that will confuse those viewers who don't
realize they
need to rescan: suddenly, when they punch up channel 9 on their
remotes
they're going to get channel 2!)

Thanks, Doug.

I saw that as another possibility and it means my life is just a
skosh more
complicated, since I need a phased pair of antennas to put a local
LPTV
outlet in a deep null on Ch 43 if I want to keep KCBS-DT as
reliable as it
has been on Ch 60. KCAL-DT is only "in" about 20 percent of the
time due to
the co-channel interference.

I already made one phased antenna pair for Ch 36 so I can get KNBC-
DT.
(It's the same situation -- analog LPTV co-channel. It works
perfectly.
The LPTV disappears.)

My house already looks like a pincushion with antennas, so I guess
another
mast won't collapse the roof. (I need a tower.)

I wonder ... if I spaced the antenna pair for a frequency mid-way
between Ch
36 and Ch 43, would partial phase cancellation be satisfactory on
both 36
and 43? I doubt it but it's cheap to try.

"Sal"
(really KD6VKW)

You may have seen this earlier but it sounds likeit may be helpful.
The page 2 garbage can version might work as well if it were made like
a shopping cart in welded wire and would offer much less wind loading.
Of course you could always put a 4 bay Channel Master in an actual
shopping cart. Heck homeless people take them. Might look a little
funny on the roof though.

http://www.prism.gatech.edu/~wn17/

GG

That is wonderful! I had not seen it before tonight.

I've toyed with using some sort of screen on the side of the antenna from
which the interfering signals arrive but not known how well it would work.
Apparently it's OK and needs exploring here.

There is however, the little matter of explaining to my neighbors why I have
a garbage can on the roof of my typical single family tract home. (The guy
in Atlanta had a flat roof, like maybe a condo building.)

I have a solution. If they whine about the garbage can, I'll just say
(completely without context), "Hey, would you rather it be a shopping cart?"
(Reminds me of the joke about the guy with the celery in his ear.)

OK, all kidding aside, I clearly have some more building to do. Watch this
space.

On May 4, 9:42*pm, "Sal M. Onella"
wrote:
snip

You may have seen this earlier but it sounds likeit may be helpful.
The page 2 garbage can version might work as well if it were made
like
a shopping cart in welded wire and would offer much less wind
loading.
Of course you could always put a 4 bay Channel Master in an actual
shopping cart. Heck homeless people take them. Might look a little
funny on the roof though.

http://www.prism.gatech.edu/~wn17/

GG

That is wonderful! *I had not seen it before tonight.

I've toyed with using some sort of screen on the side of the
antenna from
which the interfering signals arrive but not known how well it
would work.
Apparently it's OK and needs exploring here.

There is however, the little matter of explaining to my neighbors
why I have
a garbage can on the roof of my typical single family tract home.
*(The guy
in Atlanta had a flat roof, like maybe a condo building.)

I have a solution. *If they whine about the garbage can, I'll just
say
(completely without context), "Hey, would you rather it be a
shopping cart?"
(Reminds me of the joke about the guy with the celery in his ear.)

OK, all kidding aside, I clearly have some more building to do.
*Watch this
space.

I was thinking along the lines of a commercial trash bin like cities
use where they're made of perforated metal. I wonder just how 'deep'
the container has to be to narrow out the beamwidth to an acceptable
angle

GG

On May 3, 4:40*pm, Albert Manfredi wrote:
On May 3, 1:24*am, G-squared wrote:

Who gives a hoot about those useless program guides anyway? Even if
they were all perfect, it is SO clunky to get the EPG updated as to be
useless. It takes the tuner minutes to go through all 18 carriers I
get. The TV is running on a computer anyway so Yahoo TV listings are
there in seconds and are more accurate besides

Stations don't have a choice, though. They need to comply, whether
users care or not.

As a viewer, I tend to agree with you. I have two older receivers that
make you wait while they gather the info from a few stations, before
drawing the matrix. Then, if you scroll down or to the rigth far
enough, another long wait until the received fetches the added
information. But this is entirely receiver-dependent. It doesn't have
to be done this way.

I have a new PVR/DVD recorder that takes a different approach. It only
shows the station you're tuned to, and basically devalues PSIP
entirely. It doesn't even provide the PSIP time.

I get the feeling there's a chicken and egg thing going on here. As
long as stations don't populate their EPGs well, e.g. including making
data available for a few days ahead of time, users will ignore the
EPG, and manufacturers won't spend time and money making it right.

Ideally, this EPG stuff COULD be a selling point for manufacturers,
just as the EPG is what made TiVo famous. Ideally, you'd see
manufacturers bragging about their great PSIP EPG in TV ads. Instead,
all you see in TV ads is the cable and DBS companies trying to lure in
more subscribers.

Bert

As I understand it, there are two forms of EPG. In the first form,
each Digital TV station can insert it's programming information (for
all subchannels) in the PSIP stream and TVs and other devices can
display it. This guide is relatively worthless because it is so slow
to fill and contains so little information. (At least on my TVs.)
There is also the GemStar TV-Guide that is broadcast (usually) by the
supplier of the clock signal used to automatically set the TV device
clock. The GemStar Guide (after the initial 3 days) displays 7 days
of programming for all stations (OTA, cable, sat) for your market. My
Sony OTA HD-DVR uses the GemStar guide. The guide comes in a standard
grid with indicators for HD vs SD, New vs Repeat and program
synopsis. Stations can be switched or recordings set by clicking on a
guide entry. *This* guide is very useful and fuctional. However, the
manufacturer must license the guide software from GemStar.

Dan (Woj...)

In article Doug Smith W9WI writes:
On Sun, 04 May 2008 05:46:55 +0000, phil-news-nospam wrote:
A proper TV would detect the PSIP data mismatch and alert the viewer and
suggest the rescan. It may partially update its own channel table at that
point.

I doubt most DTVs are that smart.

Detecting this would require noticing that the TSID has changed. I can't
think of any other reason to monitor the TSID. The number of cases where
the TSID on a given RF channel will change will be very small, and almost
all of them will happen on Feb. 18 2009. (unless the predictions of some
of massive RF channel swaps in the year or two after Transition come true)
I've my doubts most designers will bother.

I expect that most will get it right.

When a local station (univision) stopped transmitting their PSIP correctly,
their digital channel disappeared from 14.1 and appeared on 51.1. A few
months later when they figured it out and reset it, the next time the set saw
their signal, it moved them back to 14.1. (The set was a Sharp.)

Alan

"G-squared" wrote in message
...

In the most recent TV Technology magzine the manufacturers are asking
for an extension because they can't get the program guide info into
the PSIP scccurately when things change on the fly like a sporting
event running longer than expected. Like anybody uses that useless
'feature'.

==========================================
Anyone that gets OTA will use it!