Digital is at full strength, but reception may improve on Fe

[mm]

I wrote to channels 9 and 4 in DC and asked if they were at full power
on digital. Both wrote back immediately to say that they were, but
one answer confused me. It said 100% power broadcasting on UHF ch.
34. But after the switchvoer they would be back on channel 9. Just
as two network stations he named in Baltimore are doing.

Does this mean that a standalone converter box, or my
I-forget-the-brand DVDR with HardDrive is capable of receiving the
same digitial station at different times on different frequencies??

It scans frequencies looking for one that calls itself channel 9??

Is this why it takes so long to tune in a digital channel?

Will tuning be quicker when it goes back to the traditional channel 9
frequency?

The Channel 9 man said that he thought I would have greater sucess
when they moved back to the VHF frequency. Is that because VHF
generally has longer range?

Thanks

 

[Rich Webb]

On Thu, 08 Jan 2009 11:52:05 -0500, mm <NOPSAMmm2005@bigfoot.com> wrote:

I wrote to channels 9 and 4 in DC and asked if they were at full power
on digital. Both wrote back immediately to say that they were, but
one answer confused me. It said 100% power broadcasting on UHF ch.
34. But after the switchvoer they would be back on channel 9. Just
as two network stations he named in Baltimore are doing.

Does this mean that a standalone converter box, or my
I-forget-the-brand DVDR with HardDrive is capable of receiving the
same digitial station at different times on different frequencies??

It scans frequencies looking for one that calls itself channel 9??

More or less. See http://en.wikipedia.org/wiki/Virtual_channel

Is this why it takes so long to tune in a digital channel?

Not really. Once it has learned where to go, it just tunes it in.

Will tuning be quicker when it goes back to the traditional channel 9
frequency?

Probably not.

The Channel 9 man said that he thought I would have greater sucess
when they moved back to the VHF frequency. Is that because VHF
generally has longer range?

Modulo your antenna configuration. Lots of folks have been sold "HDTV
antennas" that are optimized for the UHF range (470 - 698 MHz). Channel
9 is down at 190 MHz. Some gain vs channel charts here:
http://www.hdtvprimer.com/ANTENNAS/comparing.html So, you may have a
stronger signal at your location as compared to the UHF station but may
lose more through the antenna.

--
Rich Webb Norfolk, VA

 

[Dave Platt]

I wrote to channels 9 and 4 in DC and asked if they were at full power
on digital. Both wrote back immediately to say that they were, but
one answer confused me. It said 100% power broadcasting on UHF ch.
34. But after the switchvoer they would be back on channel 9. Just
as two network stations he named in Baltimore are doing.

Does this mean that a standalone converter box, or my
I-forget-the-brand DVDR with HardDrive is capable of receiving the
same digitial station at different times on different frequencies??

Yes, although you might have to tell it to "scan for channels" again
after the switcheover on The Big Day.

It scans frequencies looking for one that calls itself channel 9??

Yup. There's no longer a fixed relationship between the "channel
number" in the signal, and the frequency at which the signal is being
transmitted.

Is this why it takes so long to tune in a digital channel?

Probably not.

Analog TV signals transmit a full frame of video 30 times a second
(two interlaced fields, at a 60-field-per-second rate). You can start
watching the signal as soon as the tuner gets the RF pathway set up.

Digital TV works differently. It doesn't send the complete picture
very frequently... typically only a few times a second. The other
(intermediate) frames are described during transmission in terms of
differences from the most recent complete frame... or sometimes in
terms of differences from the most recent complete frame and the
*next* complete frame (the one not yet actually transmitted). This
saves a lot of transmission bandwidth, which is part of how it's
possible to send a high-definition picture over the same amount of RF
bandwidth used to send a standard-definition analog signal.

What this means is that the TV set can't start displaying a meaningful
image until it has waited long enough to receive at least one, and
often two of the occasional "complete" frames. Depending on how the
station is choosing to encode its digital transmissions, this could
take a second or more.

Will tuning be quicker when it goes back to the traditional channel 9
frequency?

I'd tend to doubt that.

The Channel 9 man said that he thought I would have greater sucess
when they moved back to the VHF frequency. Is that because VHF
generally has longer range?

That might be part of it.

It might be that their "full power" UHF transmitter actually has lower
power output than their "full power" VHF transmitter.

It might be that their VHF antenna is better (higher gain, or in a
better location) than their UHF antenna.

--
Dave Platt <dplatt@radagast.org> 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!

 

[(PeteCresswell)]

Per Dave Platt:

Digital TV works differently. It doesn't send the complete picture
very frequently... typically only a few times a second. The other
(intermediate) frames are described during transmission in terms of
differences from the most recent complete frame... or sometimes in
terms of differences from the most recent complete frame and the
*next* complete frame (the one not yet actually transmitted). This
saves a lot of transmission bandwidth, which is part of how it's
possible to send a high-definition picture over the same amount of RF
bandwidth used to send a standard-definition analog signal.

Would it be technically feasible to have a set with, say, six
tuners - each tuned to one of the user's "Favorite" channels and
near-instant response when hopping between those already-acquired
channels?
--
PeteCresswell

 

[Dave Platt]

Would it be technically feasible to have a set with, say, six
tuners - each tuned to one of the user's "Favorite" channels and
near-instant response when hopping between those already-acquired
channels?

Sure. You could build this out of off-the-shelf gear today, at least
if you're satisfied with composite or S-Video quality.

Buy half-a-dozen of the "converter boxes" now available. Tune each
one to a different channel. Feed the six A/V outputs to a six-input
A/V switchbox, and run the output to your screen and speakers.

There *might* be converter boxes with composite or HDMI outputs, to go
to a high-definition monitor, but I haven't see any myself.

In principle you could build the necessary tuners, MPEG decoders, and
banks of memory into a single chassis. I doubt that you'll see such a
device on the consumer market, though - insufficient demand and high
cost.

--
Dave Platt <dplatt@radagast.org> 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!

 

[mm]

On Thu, 8 Jan 2009 12:42:54 -0800, dplatt@radagast.org (Dave Platt)
wrote:

Does this mean that a standalone converter box, or my
I-forget-the-brand DVDR with HardDrive is capable of receiving the
same digitial station at different times on different frequencies??

Yes, although you might have to tell it to "scan for channels" again
after the switcheover on The Big Day.

Thanks. Your reminder will keep me from fainting that day.

Is this why it takes so long to tune in a digital channel?

Probably not.

Analog TV signals transmit a full frame of video 30 times a second
(two interlaced fields, at a 60-field-per-second rate). You can start
watching the signal as soon as the tuner gets the RF pathway set up.

Digital TV works differently. It doesn't send the complete picture
very frequently... typically only a few times a second. The other
(intermediate) frames are described during transmission in terms of
differences from the most recent complete frame... or sometimes in
terms of differences from the most recent complete frame and the
*next* complete frame (the one not yet actually transmitted). This
saves a lot of transmission bandwidth, which is part of how it's
possible to send a high-definition picture over the same amount of RF
bandwidth used to send a standard-definition analog signal.

What this means is that the TV set can't start displaying a meaningful
image until it has waited long enough to receive at least one, and
often two of the occasional "complete" frames. Depending on how the
station is choosing to encode its digital transmissions, this could
take a second or more.

But it takes 3, maybe 4 seconds to change from one channel to the
next. Even based on what you said, that seems bad. This is a
Philips DVDR and I think there are tuners that take longer.

Will tuning be quicker when it goes back to the traditional channel 9
frequency?

I'd tend to doubt that.

The Channel 9 man said that he thought I would have greater sucess
when they moved back to the VHF frequency. Is that because VHF
generally has longer range?

That might be part of it.

It might be that their "full power" UHF transmitter actually has lower
power output than their "full power" VHF transmitter.

It might be that their VHF antenna is better (higher gain, or in a
better location) than their UHF antenna.

OK, might be. So I don't have to ask the guy at the station. I guess
we'll find out in June!

 

[mm]

On Thu, 08 Jan 2009 14:49:28 -0500, Rich Webb
<bbew.ar@mapson.nozirev.ten> wrote:

On Thu, 08 Jan 2009 11:52:05 -0500, mm <NOPSAMmm2005@bigfoot.com> wrote:


I wrote to channels 9 and 4 in DC and asked if they were at full power
on digital. Both wrote back immediately to say that they were, but
one answer confused me. It said 100% power broadcasting on UHF ch.
34. But after the switchvoer they would be back on channel 9. Just
as two network stations he named in Baltimore are doing.

Does this mean that a standalone converter box, or my
I-forget-the-brand DVDR with HardDrive is capable of receiving the
same digitial station at different times on different frequencies??

It scans frequencies looking for one that calls itself channel 9??

More or less. See http://en.wikipedia.org/wiki/Virtual_channel

Is this why it takes so long to tune in a digital channel?

Not really. Once it has learned where to go, it just tunes it in.

Hmmm. It takes 3, maybe 4 seconds to change from one channel to
another.

Will tuning be quicker when it goes back to the traditional channel 9
frequency?

Probably not.

The Channel 9 man said that he thought I would have greater sucess
when they moved back to the VHF frequency. Is that because VHF
generally has longer range?

Modulo your antenna configuration. Lots of folks have been sold "HDTV
antennas" that are optimized for the UHF range (470 - 698 MHz). Channel
9 is down at 190 MHz. Some gain vs channel charts here:
http://www.hdtvprimer.com/ANTENNAS/comparing.html So, you may have a
stronger signal at your location as compared to the UHF station but may
lose more through the antenna.

I"m willing to wait until the changeover to work on that some more. I
get Baltimore digital channels fine, and I'm just using a 6 foot piece
of single strand wire, plugged into the center of the coaxial
connector on the back of the DVDR, and lying on the floor of my
bedroom.

I usually use an amplified antenna in the attic, but it broke and then
I injured myself and had to have surgery at the end of August. I'm
getting put back together again in another surgery this coming
Thursday, and in a few weeks I'll be able to climb up to the attic and
change antennas if necessary. Until then I'll live with only
Baltiomre stations.

The lack of the amplified antenna might be the reason I'm not getting
DC digital, even though I can still get most DC analog channels pretty
well. The DVDR seems to have a better analog tuner than most of my tvs

Thanks.