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From: Joerg on 2 Aug 2010 11:53
Jan Panteltje wrote:
> On a sunny day (Sun, 01 Aug 2010 18:01:01 -0700) it happened Joerg
> <invalid(a)invalid.invalid> wrote in <8bmjmfFeq1U1(a)mid.individual.net>:
>
>
>>> Sorry to hear that, I did read they improved multipath, maybe not
>>> enough.
>>>
>> It ain't good enough for multipath. Analog was better, way better.
>
> Even PAL, that still gave a picture when it was almost 100% noise,
> was sufficient perhaps to see what was 'going on', cannot compare in
> quality to high bitrate DVB-T.
>

I prefer to be able to see the news even when totally grainy versus what
happened yesterday night. About 80% of all digital channels pixelated
out, blue screen, and none of the channels with news was left. Time to
turn on grandpa's tube radio. Because those work.

>
>>>>> You should now about PLLs, Viterbi decoding, etc.
>>>> I do, but it seems the guys who developed and tested ATSC (or
>>>> shall I say didn't test enough?) may not :-)
>>> Politics played some role there I am sure. US had to use their
>>> own system. OTOH they say the distances are bigger than in
>>> Europe, making 8VSB a better choice. I have no experience with
>>> that system, so I dunno if that is reality.
>>>
>> It probably has other reasons as well. For example, people really
>> want hi-def, meaning 1080 interlaced or progressive scan. And I
>> have to say, if the channel doesn't pixelate out on us and a hi-def
>> event like "Dancing with the Stars" airs the picture is truly
>> stunning.
>
> I do not see the connection between 8VSB and hi-def you are making?
>

It seems the chosen standards over here were squeezed to the limits WRT
resolution. And obviously nobody really tested this under multipath.

>
>> In the US we do not have free satellite :-(
>
> Time to pack up and go Germany again :-)
>

For a visit, yes. Craving a nice Pilsener from tap, you can't get that
in the US. Gordon Biersch brew pubs come close but it still ain't the
real thing.

>
>>> I just watched starwars II, I have it on disc also, but it still
>>> is a big show. My advice is to use a PC card and or PC as
>>> receiver, both for terrestrial and satellite.
>>
>> Nah. I just wired up this new Magnavox box. Like the one before it
>> has upconversion and all that.
>>
>> A PC in the living room? Yuck. The most we ever do is connect one
>> to watch photos, a laptop, via a VGA cable tucked behind a cabinet.
>>
>
> I have a small box for DVB-T (terrestrial), it has an USB connection.
> ftp://panteltje.com/pub/haupppauge66.gif


That picture is smaller than a passport photo :-)

How large is that box?


> I even installed a new kernel on the eeePC that can use it, so how
> big is that? Of course the media centre PC is much bigger, But many
> modern laptops have a HDMI output, would not be a problem, and you
> would be able to tweak things in software. Add an other box, a 1TB
> external harddisk. Does not look so bad.
>

I can't imagine the eeePC to properly display a fast-changing 1080
hi-def image.

>
>>> Duration : 3h 7mn Bit rate mode
>>> : Variable Bit rate : 3 586 Kbps Nominal
>>> bit rate : 15.0 Mbps Width
>>> : 720 pixels Height : 576 pixels
>>
>> Hmm, we get a lot more resolution than that these days.
>
> So do we, the same station is available in HD too, but I think it is
> encrypted, look for 'ProSieben HD':
> http://nl.kingofsat.net/find.php?question=prosieben&Submit=Zap
>

Encrypted doesn't do you any good. Our terrestrial HDTV isn't encrypted.


> Now the fun part is, they finally bought HD capable scanners it
> seems. So now at least the normal 720p is top resolution (it always
> was low detail). And free. Unless you have 20/20 vision and a real
> big screen you cannot see the difference anyways :-) So that saves
> money :-) TV is far more advanced here, Sky will start broadcasting
> in 3D HD shortly.
>

I definitely can see the difference between 720 and 1080. Not that
mankind really needs that but looks nice. However, I would prefer NTSC
over it any time because that always worked.

>
>>> As you see it is much longer than the movie, because of the
>>> commercials. Because I view about an hour timeshifted I just fast
>>> forward the commercials, or more precisely just jump over those
>>> in xine.
>>>
>>> The PC as media server is cool,
>>
>> Yeah, but you can do the same thing with a DVD recorder. Ok, time
>> shift must be longer than the total play time including
>> commercials. But that is never a problem because we watch one movie
>> in the evening and that's it.
>
> TV recording and processing with a PC has way more possibilities.


Yeah, but what if one doesn't need those? All we want is to record
something and watch it later. That's it.


--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Joerg on 2 Aug 2010 12:09
Joel Koltner wrote:
> "Joerg" <invalid(a)invalid.invalid> wrote in message
> news:8bm6dmF9dpU1(a)mid.individual.net...
>> Just curious: Why is it that "modern" TV/VCR/DVD devices only allow
>> auto-scan for DTV channels but no "add some later"?
>
> Because not only are the end-users considered to be dumber today, but I
> suspect a lot of the designers and engineering managers are as well!
>

Many engineers as well. Looks like even the design of a simple and
functioning POR/BOR is a challenge these days. I never understood what's
so complicated about that. Yesterday we had three power outages. After
every one of them our "modern" stereo starts to squeal. The DSP in there
goes lala and the only way to fix this is cut power again until it stops
doing that. Pathetic. Many engineers seem to think that hanging a
resistor and a cap to an /RST pin is fine. And many IC designers don't
seem to have the foggiest how it's done right.

Oh, and the new VCR still goes 12:00 blinky-blink after each power
outage. I have given up hope that they will ever figure out how to do
that right. It would be so easy but ...


> There's at least a silver lining that it's generally easier to figure
> out, e.g., which models *do* still assume you, the user, have at least a
> half-dozen brain cells still functioning than it would have been 20+
> years ago.
>

Some things are, because the manuals are often online. However, you are
pretty much stuck with what's available and with a lot of gear the
enclosures and names might look different but the innards are the same.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Joerg on 2 Aug 2010 12:11
Kevin McMurtrie wrote:
> In article <8bm6dmF9dpU1(a)mid.individual.net>,
> Joerg <invalid(a)invalid.invalid> wrote:
>
>> Just curious: Why is it that "modern" TV/VCR/DVD devices only allow
>> auto-scan for DTV channels but no "add some later"? As most of us know
>> DTV is unreliable, meaning sometimes channel 6-1 pixelates out,
>> sometimes 58-2 is gone. So upon setup it will only catch the ones that
>> are currently receivable, which in our case is never more than 80% of
>> digital channels. Changes all the time.
>>
>> But you can't add, it does a complete new setup, upon which Murphy says
>> it'll miss a few channels it had detected on the previous run. That I
>> find a rather daft technical decision. Is it just me thinking that or is
>> the cleverness in electronics designs really taking a nose-dive?
>>
>> Sorry for the rant, but I had to let it out.
>
> Some tuners will let you punch in the real channel in analog mode. For
> example, I can type "4 5 ENTER" (no dash makes it analog) and it will
> hop to 44-1. I use the trick to get Sacto stations that won't show up
> in a scan but are viewable at night.
>

With most gear that doesn't work because 44-1 could actually be near the
old Ch 35 or soemwhere else. Stations gave up their precious VHF
channel. HUGE mistake.


> I wish I could delete obsolete mappings.


Most gear actually lets you do that.

--
Regards, Joerg

http://www.analogconsultants.com/

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Use another domain or send PM.
From: Joerg on 2 Aug 2010 12:16
Paul Keinanen wrote:
> On Sun, 01 Aug 2010 14:14:29 -0700, Joerg <invalid(a)invalid.invalid>
> wrote:
>
>> Just curious: Why is it that "modern" TV/VCR/DVD devices only allow
>> auto-scan for DTV channels but no "add some later"? As most of us know
>> DTV is unreliable, meaning sometimes channel 6-1 pixelates out,
>> sometimes 58-2 is gone. So upon setup it will only catch the ones that
>> are currently receivable, which in our case is never more than 80% of
>> digital channels. Changes all the time.
>
> You seem to suffer from frequency selective fading, which is typical
> in multipath conditions. This may eliminate the signal with sharp
> notches (usually less than 1 MHz) and these notches are constantly
> moving around the TV band when the propagation condition changes.
> Thus, a few channels are suffering from multipath nulls during each
> channel scan and hence, these are not stored.
>
> The 8VSB modulation used in ATSC is not known for robustness in
> multipath situations. The help the situation, an equalizer is used at
> the receiver that tries to compensate for the amplitude and phase
> errors created by the RF path. The equalizer needs a known training
> signal so that the equalizer parameters can be set up correctly. There
> have been claims that with 5th (or was it 6th or 7th :-) generation
> equalizers, the multipath performance is similar to COFDM DVB-T.
>

I think they failed to achieve that level of performance. Yesterday
_all_ stations that carry evening news blue-screened. Meaning we could
not watch the news. I guess this is called progess.


> Apparently the 8VSB equalizer can somewhat track the slow RF-channel
> parameter changes (starting the training session from previously known
> good parameters), but during the initial channel scan, the equalizer
> parameters are completely unknown for each new channel, the equalizer
> is not capable of making any sense of some of the signals, even if the
> amplitude is quite strong.
>
> My guess is that if you connect a spectrum analyzer to your antenna
> signal, it will show a comb filter like spectrum.
>

No, it showed nice bricks for each station but the sets can't decode
some of them.


> Diversity receivers are available in DVB-T countries mainly for in-car
> receivers, but do you have diversity receivers for ATSC ?
>
> Having two antenna towers at slightly different locations (at least
> some wavelengths from each other) will have a different multipath
> pattern. When one antenna and receiver drops out, the signal may be
> good at the other antenna.
>
> Even simple RF summing of two antenna signals at different locations
> may help avoiding deep nulls.
>

Sure, I could build 3-4 towers and provide a remote selector switch in
the living room. That would really be technological progress :-)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Joel Koltner on 2 Aug 2010 13:30
"Joerg" <invalid(a)invalid.invalid> wrote in message
news:8bo8tlFnbvU1(a)mid.individual.net...
> Joel Koltner wrote:
>> There's at least a silver lining that it's generally easier to figure
>> out, e.g., which models *do* still assume you, the user, have at least a
>> half-dozen brain cells still functioning than it would have been 20+
>> years ago.
> Some things are, because the manuals are often online. However, you are
> pretty much stuck with what's available and with a lot of gear the
> enclosures and names might look different but the innards are the same.

I was thinking Amazon reviews and all the "dedicated to electronics" review
sites as well; sometimes they get incredibly detailed about what little
nuisances a product has and provide some comparisons with other products
available. It can even drive product development -- back in the late '90s a
lot of motherboards would have their ubiquitous dual-row header connectors
just wherever it was easiest for the PCB guy to place them, but it really
started improving after the review sites pointed out just how annoying that
was for "cable management" and these days it's clearly something all the
motherboard manufacturers think about with each new board they release.

But you make a good point that a lot of the same "guts" with a different
housing -- and the other trend, where there are, e.g., 50 new TVs released per
year, but they're just slight "evolutions" of the previous year's -- doesn't
provide as much choice as one might first expect.

--Joel

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