How does digital TV broadcast prevent ghosting effects?

And against Germans, too?

Wasn't it at the times of Pompidou ?

SECAM was entirely bought by the USSR, including the schematics and the valves for the TV sets. NTSC was considered also (that was during the warming in relations of USSR and US (Sojuz - Apollo and such) ; SECAM was preferred for the number of technical and political reasons.

SECAM can tolerate the poor quality channels, NTSC can't. The tuning tolerances are much wider with SECAM, the delay lines do not have to be very accurate. That used to be very important considerations at that time. Phase distortions kill the NTSC. However in ideal conditions the NTSC picture quality is better.

I can understand why the robustness was critical to Russians, but why French did bother about at first time?

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

Not in my experience. ATSC works much better for me (high signal, high multipath environment).

If it had a good tuner, you wouldn't have such problems. Take it back and try a different brand. Who said anything about spending $2K?

You might not have to sacrifice any channels.

There is no such thing as a best TV antenna. It sounds like you could use one with lower gain and better directionality.

If TV isn't important to you, why have you been posting about it so much?

So do it and be happy.

So far you've rejected every possible solution.

Well, I think a $750 set ought to do :-)

Because I am not the only person out here and it is important to others, for example older folks who can't move about much anymore. Many of them don't have the means to plunk down another $40-50/month for cable. Those folks sometimes depend on people like us to fix it when technical stuff quits.

Some day I will. But the local news aren't one there (yet).

I've only rejected the ones that aren't acceptable to me, like "oh, just take it all back and spend more".

--
Regards, Joerg

http://www.analogconsultants.com/

In English, we typically would say "System Essentially Contrary to the American Method"....;-)

Bob M.

I can only say that NTSC is also very good in non-ideal conditions. Whenever this new ATSC stuff collapses I just switch to the old analog channel and that works fine. Some distortion or flutter but clearly visible. Of course, this will only work for another year or so.

Robust? Don't know about the hardware. I've heard some horror stories about their older Raduga TV sets. Apartment fires and all that.

--
Regards, Joerg

http://www.analogconsultants.com/

The main concern was the poor quality of the radio relay equipment.

Those are not the stories. Our TV caught fire right before my eyes. The horizontal scan module burned to ashes. After the repair shop refused, I had to rebuid the TV; that was one of my first endeavours with electronics.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

I was told that they had a nickname for the older Radugas in East Germany (when it was communist): "Zimmerbrand aus Freundesland". Loosely translated "apartment fire delivered by an ally". IIRC they kept using a really old stabilizing technology in the H-scan final: The ballast tube. All the energy not used by the CRT was converted to heat so that the stage load remained constant. Then, one fine day, phssst ... whoosh ...

--
Regards, Joerg

http://www.analogconsultants.com/

[snip]

I remember that circuit ;-)

IIRC, Mad Man Muntz also used that in his designs.

My father had a policy... "We don't service Muntz TV sets".

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

So they adopted SECAM in the East Germany to prevent the citizens from watching the enemy propaganda. There is some logic to it.

Yes. That was the exact copy of the original French design. In the later mods, they removed the ballast tube and used the voltage multiplier for the CRT anode; however the flammability remained about the same.

There was also a special shield with a warning about X-rays.

The flyback transformer was the most susceptible. High voltage, lots of dust, heat, plastic isolation - a disneyland for fire.

VLV

They sure were bone simple:

In Germany I staunchly refused to repair Kuba sets (just a name, they had nothing to do with Fidel and his country). Later I refused to repair any TV since their designs became so flimsy.

--
Regards, Joerg

http://www.analogconsultants.com/

Supposedly they had other tricks, too. For example the clock in the background was square and then they'd ask the kids in kindergarten to describe it. If one of them mentioned a round clock ... "Aha!".

A friend who was a TV repair tech asked about that. His boss: "Oh, it won't really harm you. It only causes impotence."

Plus that dreaded soaked paper that they called insulating paper.

--
Regards, Joerg

http://www.analogconsultants.com/

angle.

Etsi

the new receivers can adapt to multipath out to 50uS or so..

but they still have trouble when the mutipath is as strong as the direct signal, and they still have some trouble when the multipath changes with time i.e. dynamic multipath. The equalizer is adaptive but it takes time to adapt. It sounds like your situation with the aircraft in line with your antenna is a bad dynamic multipath situation. You should contact the demod design companies and the FCC and offer to them to use your location as a test site..

Sorry I don't have any helpful suggestions, get the receiver with the best adaptive equlaizer and put up the best antenna you can.

Mark

On a sunny day (Tue, 27 Nov 2007 13:43:04 -0600) it happened Vladimir Vassilevsky wrote in :

It had to be different from NTSC, and PAL did not exist yet. Yet SECAM was horrible on a BW set (bad BW compatibility), later BW sets had a special filter to get rid of the subcarrier that caused all sorts of bad patterns on colored edges.

On a sunny day (Tue, 27 Nov 2007 21:29:45 GMT) it happened Joerg wrote in :

The ballast tube (PD500) was used extensively also in PAL sets, until the fist transistor sets came. It was a great Röntgen source too (picture on the left).

It was mounted in a special metal screened box to prevent radiation. the glass got all blueish colored after some use.

Only very old ones. Most of the sets I parted out as a kid did not have a ballast tube. The ones that did were too heavy to carry on my bicycle.

--
Regards, Joerg

http://www.analogconsultants.com/

angle.

Etsi

It actually does. Some stations have echoes that far out and their digital channel comes through just fine. Until echoes become stronger than the direct path and this flips back and forth a lot. Then the DTV channels become blocky and freeze up while the analog just syncs onto the reflected signal and keeps humming.

Well, if they weren't interested in testing out here before writingh the standard they'll probably be even less interested now.

Yes, I will play with the antenna some more when I have time (meaning the honey-do list is worked down...).

--
Regards, Joerg

http://www.analogconsultants.com/

On a sunny day (Tue, 27 Nov 2007 14:57:22 -0800) it happened Joerg wrote in :

Well 'OLD' I dunno how old you are. in the Netherlands color TV started in 1967, and the first sets you could buy was the Philips K6 chassis,

I must have serviced a thousand of those. Parallel PD500 stabiliser. Of course I had one myself (was one of the first with color TV). Actually I put that one together myself. BW TV's did not have the ballast, the ballast stabilisation was needed to keep color convergence within spec.

I had some East German made sets too. Only in 1973 or so came the first 100% transistor Philips KTV, the K9. Serviced a thousand or so of those too.

[snip]

How much does cable cost in your area? Think on the positive side... no ugly antenna on the roof ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

| 1962 | America: Land of the Free, Because of the Brave

If it's coming from the back, then an antenna with a better front to back ratio should help. As long is the reflections are not coming from the forward direction, F/B and side lobe reduction should drastically reduce the ghosts. Have you considered positioning the antenna so that the back end faces a wall or creating an obstruction to the rear?

Ugh. That's bad.

Ummm, the subject suggested that you wanted to know how digital broadcast TV prevents ghosting. The patents offer a clue. I'm not a TV expert, but I suspect there are some tuners that already have some form of patented ghost suppression included. It's too obvious and common a problem to ignore.

Need yet another project? Build an RF ghost generator. Take a power divider and split the TV signal from a video modulated RF signal source. Run one leg through an adjustable delay line and attenuator. The other leg does direct. Recombine the two legs with a combiner, and feed it to the TV. See how well your TV does on removing the ghost. Try it on other TV's and compare results. My crystal ball suggests that there's going to be wide variations in quality.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
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