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

In article
,
Albert Manfredi wrote:

On May 1, 9:26Â*pm, Bruce Tomlin wrote:

I'm wondering if this is a coincidence, or if an adjacent analog channel
(even from the same antenna farm) really does make an ATSC station hard
to tune in.

If this is true, then the shut-off can't come any too soon for me.

Yup. It's not a coincidence. Analog stations tend to transmit at much
higher ERP than their digital counterparts, and this was especially
true in the early days of the transition. So what happens is that
receivers with less than ideal selectivity, as many of the older
models are, will detect the strong analog adjacent channel and clamp
down their AGC. This will then cause the much weaker digital station
you're tuned to disappear in the noise level.

Ah, AGC. I'm not too strong on radio technology, but I do seem to recall
that AGC is what can cause volume to flutter on radio signals. And
crappy AGC is also what makes Macrovision possible. That would certainly
correspond with one of my situations, channel 30 (analog 29) in San
Antonio being good and bad in a constant 1 or 2 second cycle.

Anyway, I've noticed things improving over time, mostly because
broadcasters have either increased the power of the digital signal, or
improved the digital antenna location on the tower, or both. And since
adjacent digital stations don't seem to cause any problem, even with
my two older receivers, I can't help but believe that shutting off
analog will help matters.

Maybe that's the _real_ reason why Bob wants to see the analog cutoff
delayed... :-)

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.

In article ,
"Sal M. Onella" wrote:

Funny, the Samsung finds two PBS subchannels that are blank - no A/V - and
the Magnavox doesn't. No idea what's up with that.

Do they show a different main channel number?

On the PBS here in Austin, two subchannels popped up recently on -5 and
-6, without PSIP channel reassignment (22-x instead of the renumbered
18-x). (They used to have subchannels on -3 and -4, but did away with
those over a year ago.) My old Panasonic tuner picked them up right
away, and even picked up both disappearing the other day, followed by -5
re-appearing. (They also used to have a blank -7 a few years ago, but I
deleted it and it didn't come back.)

My two other tuners, a DirecTV receiver with no dish, and a Sylvania,
won't tune the -5 or -6 by manually punching in the channel number, and
I don't want to do a rescan. So apparently some tuners are smarter than
others about mixed PSIP channel numbers, as well as subchannels
appearing and disappearing.

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...)

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!)

"Doug Smith W9WI" wrote in message
news
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)

In alt.tv.tech.hdtv Doug Smith W9WI wrote:
| 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!)

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.

--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| 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) |

In alt.tv.tech.hdtv Sal M. Onella wrote:

| 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.

Are you at the fringe of these stations, or is the FCC's method to figure
the interference defective (as I have for some time suspected)? Be sure to
file a complaint of interference with the FCC. LP stations are on the air
subject to not causing interference. You could end up forcing them to get
another channel.


| 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.

Let us know.

--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| 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 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

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.