Analog vs Digital TV during snowstorms.
Skybuck Flying
I am under the impression that Analog TV is better during snowstorms then
Digital TV.
With Digital TV the decoders (at local receiver/tv station?) get confused
because it's missing bits.
The results are strange blocks everywhere, strange hickups, loss of picture,
deformations and so forth.
While with Analog TV if I remember correctly, there is just a little bit of
snow over it... but most of it is very watchable still !
Why is Digital TV so bad during snowstorms... doesn't it have something
special like Turbo Codes ? to correct bit errors ?!?
If it does have Turbo Codes or other bit error correcting technology then
apperently it's not enough ?!
Bye,
Skybuck.
Skybuck Flying
worse ! ;) I made a video of it back then... maybe I put it on youtube for
the fun of it ! or maybe not ;) Video quality isn't that great of my
"camcorder" ;)
Bye,
Skybuck.
"Skybuck Flying" <IntoTh...@hotmail.com> wrote in message
news:e2e8e$4b72a16a$d53371df$13...@cache3.tilbu1.nb.home.nl...
Wolfgang Draxinger
> Hello,
>
> I am under the impression that Analog TV is better during snowstorms then
> Digital TV.
>
> With Digital TV the decoders (at local receiver/tv station?) get confused
> because it's missing bits.
>
> The results are strange blocks everywhere, strange hickups, loss of
> picture, deformations and so forth.
>
> While with Analog TV if I remember correctly, there is just a little bit
> of snow over it... but most of it is very watchable still !
>
> Why is Digital TV so bad during snowstorms...
Analog TV utilizes a huge amount of bandwidth, so if some of the signal is
distorted, there's still remains enough information to build a recognizable
image.
However in digital TV the signal is highly compressed, i.e. the bandwidth of
required for a single program greatly reduced. To get an impression: In
digital TV one can transmit up to 8 programs within the channel required for
one analog program required.
This makes digital TV signals more prone to damage. But it also strongly
depends on the used modulation. There are various methods, each with it's
pros and cons.
> doesn't it have something
> special like Turbo Codes ? to correct bit errors ?!?
Well, there is forward error correction to some degree, but at some point
there's just too many information lost. Google up "Shannon Limit".
Wolfgang
Paul Keinanen
<IntoTh...@hotmail.com> wrote:
>It also happens during thunder/rainstorms, then the distortion seems even
>worse ! ;) I made a video of it back then... maybe I put it on youtube for
>the fun of it ! or maybe not ;) Video quality isn't that great of my
>"camcorder" ;)
Good quality analog reception requires 40-50 dB of signal to noise
ratio (SNR). When the SNR drops by 10-20 dB, the picture is still
viewable, although a little snowy. Dropping by 30-45 dB, the frame and
line synchronization is finally lost.
Digital signals typically operate at 5-20 dB SNR at _normal_
conditions. If the signal level drops by 10-20 dB, this is below the
threshold level and no usable information can be extracted.
It appears that both in the US as well as Europe, the digital
proponents of digital-TV did not realize that in normal weather
conditions, the signal level could fluctuate by 10-20 dB.
In a line of sight communication system, the received signal strength
can be calculated quite accurately and on the TV-satellite to balcony
dish path, signal strength can be calculated within 1-2 dB (although
heavy rain will cause more loss).
However in terrestrial TV, the normal condition signal levels can be
quite different in adjacent places, but also the variability of the
signal strength is much larger.
WangoTango
IntoTh...@hotmail.com says...
> ello,
>
> I am under the impression that Analog TV is better during snowstorms then
> Digital TV.
My digital TV works fine, rain, shine, snow, wind.
Just don't let anything get inside that little coaxial connector coming
from the pole out by the road and everything works just fine.
George Herold
> On Wed, 10 Feb 2010 13:11:52 +0100, "Skybuck Flying"
>
I live at the edge of digital TV reception. One thing that would be
really nice is if they put a little more redundancy into the audio
channel. I can handle losing the picture.. but when the audio cuts in
and out.... I turn the TV off.
George H.
Joerg
In the US it often has nothing to do with SNR. Our digital channels are
nearly all >50dB yet collapse a lot. It seems that multipath throws our
DTV off the rocker really fast. In analog we saw slight ghosting when
clouds rolled in, in digital it pixelates, turns into a blocky Picasso,
freezes and that's it. The spectrum analysis shows no noticeable changes
in signal strengths.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Jim Thompson
wrote:
In other words... DTV is not really ready for prime-time... wonder who
"designed" it ?:-)
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Greegor
1. Wanted backup for when storm knocks out cable.
2. Access to those secondary channels X.2, X.3 etc.
Even LOCAL transmitters don't come in without
the antenna up on a mast. Transmitters only 3 miles away!
My impression is that rabbit ears, even
ones MADE for HD won't work at all now.
I went to an FCC web site and found that there
is apparently a big problem with lack of
reception and one explanation says that the
HDTV system is more line of sight than the old VHF was.
Trees and terrain screw it up and it's very directional.
A guy from a TV station told me that the
new channels use frequencies comparable
to the old UHF.
In a few months when the freezing winter
weather is gone I intend to try a mast.
Indeed it seems that the FCC really
SCREWED UP this television changeover!
I noticed that there are some lobbying groups
trying to stop some moves to eliminate free
over the air television as well.
Was this crappy transmission system part
of some kind of plan to eliminate free broadcast TV?
From the standpoint of disaster preparedness
this new Over The Air TV transmission system
looks really BAD.
This situation has got to be good for the cable TV outfits!
Robert Baer
Sylvia Else
One issue is that the amount of information passed through the channel
has been hugely increased. Not just a HD signal, but typically a SD
channel of the same program and an additional SD channel.
This is possible - but at an inevitable reduction in noise immunity
(someone's already mentioned Shannon). If just one SD channel were being
transmitted, and the bit rate set accordingly, I dare say you'd see a
much better handling of poor tramission conditions.
Sylvia.
Mark
> On 10/02/2010 11:11 PM, Skybuck Flying wrote:
>
>
>
>
>
> > It also happens during thunder/rainstorms, then the distortion seems even
> > worse ! ;) I made a video of it back then... maybe I put it on youtube for
> > the fun of it ! or maybe not ;) Video quality isn't that great of my
> > "camcorder" ;)
>
> > Bye,
> > Skybuck.
>
> >news:e2e8e$4b72a16a$d53371df$13...@cache3.tilbu1.nb.home.nl...
> >> Hello,
>
> >> I am under the impression that Analog TV is better during snowstorms then
> >> Digital TV.
>
> >> With Digital TV the decoders (at local receiver/tv station?) get confused
> >> because it's missing bits.
>
> >> The results are strange blocks everywhere, strange hickups, loss of
> >> picture, deformations and so forth.
>
> >> While with Analog TV if I remember correctly, there is just a little bit
> >> of snow over it... but most of it is very watchable still !
>
> >> Why is Digital TV so bad during snowstorms... doesn't it have something
> >> special like Turbo Codes ? to correct bit errors ?!?
>
> >> If it does have Turbo Codes or other bit error correcting technology then
> >> apperently it's not enough ?!
>
> >> Bye,
> >> Skybuck.
>
> One issue is that the amount of information passed through the channel
> has been hugely increased. Not just a HD signal, but typically a SD
> channel of the same program and an additional SD channel.
>
> This is possible - but at an inevitable reduction in noise immunity
> (someone's already mentioned Shannon). If just one SD channel were being
> transmitted, and the bit rate set accordingly, I dare say you'd see a
> much better handling of poor tramission conditions.
>
>
> - Show quoted text -
the sad fact is that our police and fire two way radios are also going
from analog to digital so when the signal gets a litte weak, instead
of hearing a little static along with an important call..., they hear
nothing...
the solution then being $old is to erect more tran$mi$$ion tower$..
analog does have some advantages..
Mark
Joerg
Not really, at least not in multipath situations and that seems to be a
_huge_ weakness of ATSC. When SD channels run on empty without
programming it doesn't get better.
VWWall
--
Virg Wall, P.E., K6EVE
Michael A. Terrell
Do you want some idiot cop trying to send CW while driving at 90+
MPH?
--
Greed is the root of all eBay.
VWWall
That's better than the idiots "texting" on their cell phones at freeway
speeds! We see that all the time in California.
--
VWW
Michael A. Terrell
Were you chasing a suspect while weaing in and out of traffic? They
can't use the damn police radio and keep their eye on the roads. :(
> That's better than the idiots "texting" on their cell phones at freeway
> speeds! We see that all the time in California.
--
Glenn Gundlach
You know you had many _years_ to try this stuff out. In LA the major
stations were on the air starting in fall 1998. I bought ours in
December of 2003. Line of sight is not required but it helps a lot.
Newer receivers have faster reaction to dynamic multipath meaning the
adaptive equalizers can correct more quickly. Our OTA receivers (2 PCs
with tuners and 1 Samsung set top box) have the older generation
tuners and I have little problems and while it doesn't snow here, it
sometimes rains like you wouldn't believe. Breakup is a very rare
event. After spending a chunk of time with a spectrum analyzer (Tek
2712) observing DTV, the old tuners get cranky when there are dips >
10dB within a channel. Broad tilt seems a little less troublesome than
dips, especially multilple dips. Stable is much better than changing
meaning if you can find a reliable bounce you can be OK. I wish the
tuner people would put a display that shows the amount of EQ
processing required as that would be far more useful that 'signal
strength' which by itself means little. FWIW the ATI HDTV Wonder
tuners (2 on line) work reliably down to "50%" signal and they seem to
agree with spectrum variations as observed on the Tek. By itself I
don't find the ATI readout sufficient especially with reflections.
G²
Robert Baer
Greegor
GG > You know you had many _years_ to try this stuff out.
The closest I came early on was junking out
somebody's unrepairable $5K set.
You know, the early plasma ones with only 3 year life span?
Of course I waited until 2009! LOL
The $1500 one in 2009 was vastly superior and now sells for $1000.
GG > In LA the major stations were on the air starting in fall 1998.
And nobody noticed that the coverage sucked?
How did this coverage issue get missed?
http://www.fcc.gov/dtv/markets/maps_current/Cedar_Rapids-Waterloo-Iowa_City-Dubuque_IA.pdf
Notice the little yellow splotch over Cedar Rapids in Linn County?
That's the heart of the metro area I live in!
Highest population density.
"Coverage lost but still served by same network"
Why do I care about the network serving me
if the coverage is lost? (but.. but... but... )
These yellow sploches are all over the country.
http://www.fcc.gov/dtv/markets/
LA you said?
http://www.fcc.gov/dtv/markets/maps_current/Los_Angeles_CA.pdf
They left off the key for yellow on the first few stations?
But they have sploches of yellow on the maps! LOL
On some at the top they show in text stats 0 persons lost
yet they show yellow sploches? wierd.
Yellow Sploches mean "Coverage lost but still served by same network"
Apparently even the LA area has these dead spots.
http://www.fcc.gov/oet/dtv/tvchfreq.html
47 CFR § 73.603 Numerical designation of television channels (a)
Television Channel Number Frequency band (MHz)
2 54-60
3 60-66
4 66-72
5 76-82
6 82-88
7 174-180
8 180-186
9 186-192
10 192-198
11 198-204
12 204-210
13 210-216
14 470-476
15 476-482
16 482-488
17 488-494
18 494-500
19 500-506
20 506-512
21 512-518
22 518-524
23 524-530
24 530-536
25 536-542
26 542-548
27 548-554
28 554-560
29 560-566
30 566-572
31 572-578
32 578-584
33 584-590
34 590-596
35 596-602
36 602-608
37 608-614
38 614-620
39 620-626
40 626-632
41 632-638
42 638-644
43 644-650
44 650-656
45 656-662
46 662-668
47 668-674
48 674-680
49 680-686
50 686-692
51 692-698
52 698-704
53 704-710
54 710-716
55 716-722
56 722-728
57 728-734
58 734-740
59 740-746
60 746-752
61 752-758
62 758-764
63 764-770
64 770-776
65 776-782
66 782-788
67 788-794
68 794-800
69 800-806
(b) In Alaska, television broadcast stations operating on Channel 5
(76-82 MHz) and on Channel 6 (82-88 MHz) shall not cause harmful
interference to and must accept interference from non-Government fixed
operations authorized prior to January 1, 1982.
(c) Channel 37, 608-614 MHz is reserved exclusively for the radio
astronomy service.
(d) In Hawaii, the frequency band 488-494 MHz is allocated for non-
broadcast use. This frequency band (Channel 17) will not be assigned
in Hawaii for use by television broadcast stations.
[28 FR 13660, Dec. 14, 1963, as amended at 35 FR 11179, July 11, 1970;
39 FR 10576, Mar. 21, 1974; 47 FR 16789, Apr. 20, 1982; 47 FR 30068,
July 12, 1982; 47 FR 35989, Aug. 18, 1982; 51 FR 18450, May 20, 1986]
Skybuck Flying
http://www.zie.nl/video/nieuws-actualiteit/Man-slaat-29-televisies-kapot/m1czomafx16g
Bye,
Skybuck ;) :)
Greegor
Quite a testimonial for Effexor.
http://www.wopular.com/cops-man-smashes-29-tvs-bat-wal-mart-1
Police in Georgia say a 23-year-old man grabbed a baseball bat inside
of a Wal-Mart and smashed 29 flat-screen televisions. Police in
Lilburn near Atlanta have charged Westley Strellis with 29 counts of
criminal damage to property in the second degree. Witnesses tell
police he grabbed a metal baseball bat from the sporting goods section
Wednesday, walked to the electronics department and destroyed the TVs
on display.
http://www.huffingtonpost.com/2010/02/11/westley-strellis-walmart_n_458652.html
Westley Strellis Walmart Rampage: Man SMASHES 29 Flat Screen TVs
First Posted: 02-11-10 01:19 PM | Updated: 02-12-10 06:41 AM
A Georgia man went on a rampage yesterday at a Walmart outside of
Atlanta, smashing dozens of flat-screen televisions with a baseball
bat he found in the store.
The man, 23-year-old Westley Strellis, bashed in 29 flat-screen
televisions worth $22,000, reports the Atlanta Journal Constitution.
He was charged with a whopping 29 counts of criminal damage to
property.
WATCH video from the store surveillance cameras:
Strellis invoked his Fifth Amendment right to stay mum, so his motive
remains a mystery. According to the police report, when officers
arrived on the scene, Strellis was sitting in an aisle in the store's
electronics department. When approached, he held out his wrists,
signaling for the officer to handcuff him. Police found a bottle of
Effexor XR, an anti-depressant, in Strellis's possession.
Paul Keinanen
<To-Email-Use-Th...@My-Web-Site.com> wrote:
>In other words... DTV is not really ready for prime-time... wonder who
>"designed" it ?:-)
The large scale digital TV transmission started in satellite TV. This
was easy to implement, since the transmission path was very predicable
and linear.
For he broadcasters, digital systems made it easy to implement
efficient scrambling algorithms for pay-TV.
It also made possible to send multiple programs over a single
transponder instead of just one analog program, thus reducing the
distribution costs per program significantly.
It appears that all over the world broadcasters think that multiplying
the number of programs, the number of seconds that could be sold for
advertisement also multiplied and hence the income would multiply.
Apparently, they did not notice that the audience is also split among
a larger number of programs, thus, the advertisers are not going to
pay the same amount for the seconds any longer :-).
Anyway, the terrestrial broadcasters also wanted more programs to
compete with satellite broadcasters and going digital appeared to
solve the problem.
Unfortunately, the terrestrial propagation is far more complex than
the simple satellite downlink path. Several manufacturers proposed
various systems and the ATSC committee then tried to find a
compromise.
In hindsight it appears that they picked the wrong option by selecting
8VSB, since the OFDM based systems such as DVB-H/T/T2 are much more
flexible, from handheld mobile systems to large HDTV SFN networks,
depending on parameters selected.
Paul Hovnanian P.E.
>
> Hello,
>
> I am under the impression that Analog TV is better during snowstorms then
> Digital TV.
Neither. Turn the TV off and shovel the sidewalk.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
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