Digital television and the sun
Chuck B.
nighttime hours the reception is great, but poor during daylight
hours. Is this normal?
UCLAN
Does it get hot where you live? Are you using an old antenna/pre-amp,
and/or old/cheap cable for your downlead?
N_Cook
news:g1c184hciccig65h5...@4ax.com...
> We are having a problem with our over the air reception. During
> nighttime hours the reception is great, but poor during daylight
> hours. Is this normal?
I get the same effect, sometime I must get up on the roof and put up a yagi
with better, ie reduced rearward lobe/ higher forward lobe responses.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
New Jersey
change direction of antennas from night to day or wise versa
because of signal propagation which interfere with other networks
FCC regulation sorry KA2AYS
"N_Cook" <div...@tcp.co.uk> wrote in message
news:g5sd40$2j9$1...@registered.motzarella.org...
William Sommerwerck
news:vomgk.87$oU.8@trnddc07...
> I cannot say for sure but there is station that they must
> change direction of antennas from night to day or vice-versa
> because of signal propagation which interfere with other networks
This is plausible (in principle), but at the frequencies at which digital TV
operates, there isn't much difference between day and night propagation.
Doug Smith W9WI
> I can not say for sure but there is station that they must
> change direction of antennas from night to day or wise versa
> because of signal propagation which interfere with other networks
> FCC regulation sorry KA2AYS
That only applies to AM radio stations.
All TV stations (analog and digital) are licensed for the same technical
facilities 24/7.
I wonder if the OP's problems stem from interference from some device
that's only operated during the day? (say, neon lights at a nearby store?
Or a factory with large motors?)
Does *analog* reception change from day to night - do you get snowy
daytime reception, or funny patterns, etc., etc.?
Chuck B.
I have only been receiving digital tv for a few days. It has been
very hot and humid here, could that be causing the problem? As for
analog reception, it works well day and night. I use the same Channel
Master roof top UHF/VHF antenna and coax cable for analog and digital.
FWIW the stations I am trying to receive are in Indianapolis and I am
in Bloomington IN.
Dave Platt
>very hot and humid here, could that be causing the problem?
Water infiltration into a coax cable can cause signal loss. I suppose
it's possible you've gotten rainwater into the coax (due to inadequate
sealing of the F connector on the end) and that high temperatures
change how the moisture affects signal attenuation.
> As for
>analog reception, it works well day and night.
Hmmm. That would see to rule out simple temperature change or signal
strength, then.
> I use the same Channel
>Master roof top UHF/VHF antenna and coax cable for analog and digital.
>FWIW the stations I am trying to receive are in Indianapolis and I am
>in Bloomington IN.
ATSC digital signals are relatively sensitive to multipath (the same
phenomenon which generates "ghost" images on analog TV). Possibly
there's more multipath being generated in your area during the day, as
a result of (for example):
- More airplanes flying through the "field of view" between you and
the transmitter
- More wind, causing tree branches and leaves to move around nearby
- More surface vehicles (trucks, ships) travelling nearby
The idea that there might also be a locally-generated source of
interference which is more active during the day is also a good one.
Are you seeing "sparkles" on the weaker analog channels (from impulse
noise), or "herringbone", or something like that?
--
Dave Platt <dpl...@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!
Don Bowey
"William Sommerwerck" <grizzle...@comcast.net> wrote:
Ducting affects signals in the TV spectrum much more at night than at
daytime.
Curtis Brown
"Doug Smith W9WI" <w9...@invalid.nospam> wrote in message
news:pan.2008.07.19....@invalid.nospam...
> On Sat, 19 Jul 2008 13:56:43 +0000, New Jersey wrote:
>> I can not say for sure but there is station that they must
>> change direction of antennas from night to day or wise versa
>> because of signal propagation which interfere with other networks
>> FCC regulation sorry KA2AYS
>
> That only applies to AM radio stations.
>
Not change the direction of the antennas but go from 50,000 watts to 5
watts.
Doug Smith W9WI
> I have only been receiving digital tv for a few days. It has been
> very hot and humid here, could that be causing the problem? As for
> analog reception, it works well day and night. I use the same Channel
> Master roof top UHF/VHF antenna and coax cable for analog and digital.
> FWIW the stations I am trying to receive are in Indianapolis and I am
> in Bloomington IN.
As Dave suggests, take a careful look at your analog reception.
Especially the weaker stations - channel 29? channel 49? The appearance
of any interference on analog reception is a clue to the nature of what
might be affecting the digital.
Are *all* digital stations affected or only some of them? (channel 8's
digital is on a very different frequency from the other Indianapolis
stations)
Do you have a preamp on your antenna? Outside? Do neighbors have
preamps? We once had an interference problem in a small town when
someone's preamp malfunctioned & began acting as a small transmitter. It
was thermally-related - would only malfunction when it was cold. (i.e.,
at night...)
Doug Smith W9WI
>> That only applies to AM radio stations.
>>
>
> Not change the direction of the antennas but go from 50,000 watts to 5
> watts.
This too applies only to AM radio. No TV or FM station in the U.S. or
Canada is required to reduce power at night.
(and I'd be 99% sure that applies to the rest of the world as well)
Dave Platt
Doug Smith W9WI <w9...@invalid.nospam> wrote:
>Do you have a preamp on your antenna? Outside? Do neighbors have
>preamps? We once had an interference problem in a small town when
>someone's preamp malfunctioned & began acting as a small transmitter. It
>was thermally-related - would only malfunction when it was cold. (i.e.,
>at night...)
Oh, $DEITY, those preamps and distribution amps can be utterly evil.
As you note they'd prone to oscillation, which can generate all sorts
of interference. A couple of boat-born "active TV antenna" amplifiers
managed to knock out GPS reception in the Moss Landing area in
California for quite some time, which was not a good thing for ship
and boat captains who depend on GPS to get them safely through the
fog!
I've also had problems with amps of this sort when there's a radio
transmitter nearby... the strong signal from a transmitter will
saturate the amplifer, causing interference and signal loss on all of
the channels going through the amp.
Doug Smith W9WI
> I've also had problems with amps of this sort when there's a radio
> transmitter nearby... the strong signal from a transmitter will
> saturate the amplifer, causing interference and signal loss on all of
> the channels going through the amp.
That's a VERY good point, and it brings up another question for Chuck B:
when the digital reception is messed up, does it *stay* messed up
continuously, or does it work OK for awhile and then go bad & then come
back again?
Most radio transmitters either operate continuously day and night, or
operate intermittently. (I talk for a few seconds, then let go of the
mike & let the other guy talk) If the interference is intermittent, maybe
it's coming from a transmitter at a business that only uses it during the
day? (construction firm, factory, etc.)
If there is an amplifier, it might be worthwhile taking it out of the
circuit for awhile. You might lose some channels altogether but if it
allows the stations that do come in to continue to come in during the day
then you have a pretty good lead.
hr(bob) hofmann@att.net
If you could borrow another tv set, it would be worthwhile to see if
it too fails. There are differences in propogation characteristics
from day to night that do affect the UHF frequencies. With a good
strong signal, they will not be apparent. But with digita signals and
receivers, it is an all or nothing situation, sorry.
Bob Hofmannl
Franc Zabkar
finger to keyboard and composed:
>I have only been receiving digital tv for a few days. It has been
>very hot and humid here, could that be causing the problem? As for
>analog reception, it works well day and night. I use the same Channel
>Master roof top UHF/VHF antenna and coax cable for analog and digital.
>FWIW the stations I am trying to receive are in Indianapolis and I am
>in Bloomington IN.
Can you see a big difference in the numbers for day/night signal
quality in your TV's or STB's menu? Are you splitting your signal
between two or more TVs? Are your stations on different bands, eg
analogue on VHF and digital on UHF ???
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
Doug Smith W9WI
> Can you see a big difference in the numbers for day/night signal
> quality in your TV's or STB's menu? Are you splitting your signal
> between two or more TVs? Are your stations on different bands, eg
> analogue on VHF and digital on UHF ???
Most Indianapolis digitals are UHF, the exception is CBS which is on
digital VHF channel 9.
Four of the six most popular Indianapolis analog stations are VHF channels
4/6/8/13, but I would expect (maybe wrong?) the OP is also frequently
watching UHF channels 20 (PBS) and 59. (Fox)
New Jersey
the air
it is subject to interferences, propagation, ducting and many other
phenomena
which I can't explain I have no engineering degree but problems are real
from audio frequencies to your cell phone the difference is in how much
interferences can be tolerated
KA2AYS
"Doug Smith W9WI" <w9...@invalid.nospam> wrote in message
news:pan.2008.07.19....@invalid.nospam...