More bad digital TV news for Joerg?

services.

Well, it is bad enough that the loco dictatorship forced this on us, and worse that digital TV cannot fail gracefully like analog TV does, but now everyone and their pet goldfish wants to pollute the spectrum and further destroy what little TV one can get.

services.

That has been around since a long time. Our church uses wireless mikes as a secondary UHF user. Of course we made sure that this doesn't bother anyone. Love thy neighbor :-)

DTV is a whole 'nother ballgame. It falls apart every other night around here. And when it goes then most of the channels turn into a blocky Picasso, not just one.

--
Regards, Joerg

http://www.analogconsultants.com/

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On a sunny day (Sun, 19 Oct 2008 17:25:41 -0700) it happened Joerg wrote in :

services.

Now those wireless sets, that do not have a good antenna, may decide there is no station at your digital TV transmitter's frequency, and output some watts at that frequency, killing your last TV. Or just next to it will likely do too. They talk about sets with GPS and a list of transmitters for that location, but that could consider 175 miles to be too far away...

I really think satellite is the only solution in large areas. Here even the locals are on satellite these days. It would probably be cheaper to rent some sat channel then build all those transmitters, from a broadcaster POV. And everybody needs to buy a converter anyways, may as well be a sat box. In the big cities cable perhaps. Would be good if the Americans could watch some other countries too, might prevent confusion about their intentions, as in Iraq.

But don't let your wife catch the two of you.

{;-)

Jim

-- "It is the mark of an educated mind to be able to entertain a thought without accepting it." --Aristotle

That was a good one!

-- Greetings, Joerg

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services.

I'm eagerly looking forward to the riots in the streets when they cut off our free TV. Like David Letterman says, TV should be free, the way God intended it!

Cheers! Rich

wireless services.

/meldung/117556

Even though I can see the Emley Moor TV transmitter from my window and have a steerable Yagi and have just replaced my set top box with a new one and know I've an excellent signal cos the spectrum analyser says so, I still see a crap picture. A year ago it used to be 'nearly acceptable' now it's not even nearly. Constant freezing, blocking out, loss of sound, paint-it-by-numbers colours and Max Headroom staccatos. An inbuilt tendency to conspiracy theory has deduced I'm losing bit bandwidth to that HD thing the broadcasters seem to be pushing. They switch off analogue in a couple of months, the telly's (and STBs) look like they'll be heading down the council recycling centre at the same time.

Sounds like you're suffering from heavy multi-path distortion just like Joerg is. If it's dynamically changing multipath, all the signal strength in the world won't help, and the receivers' "echo cancellers" aren't fact enough to track it and remove it. Result: Poor picture quality.

I'd have thought that close to a transmitter a piece of wet string might be more appropriate.

I only have that problem when it rains heavily (like last night). And only then on the weaker stations but wrecked MPEG effect is pretty annoying. The low signal degradation is anything but graceful and very cubist. The diagnostics on my various set top boxes and internal dtv shows that at what it calls signal = 5/10 the results are fine and at

4/10 it is worse than useless. The weaker stations hover around 6/10 in fine weather most of the main ones are 10/10 (and 9/10 in heavy rain).

What diagnostics does your set top box provide? Mine shows signal strength and bit error rate (the latter typically scores 10 or 0 so is a pretty useless measure). I'd wonder about front end overloading as they wind up the wick if you are within visual range of a nearby transmitter. Maybe worth trying an attenuator...

It is a bit worrying that electronics engineers are having trouble getting adequate performance out of dtv. What chance the general public?

Regards, Martin Brown

On a sunny day (Tue, 21 Oct 2008 02:48:23 -0700 (PDT)) it happened Martin Brown wrote in :

In fact the bit error rate is about the only important thing :-) I do not how it is specified in your box, but bit errors should not normally be present. A few, up to a few hundred perhaps, can be corrected, above that you will quickly hit serous picture breakup.

Bit errors can come from other sources too, I have a small USB fan, one of those things you can connect to your PC and uses USB power to run (bad idea, not even a chip in there), but anyways it has this small DC motor with brushes, and those sparks cause noise all the way up to GHz range, causing lots of bit errors... Took me a while to figure that out, until I noticed the errors where only there when the fan was running. Tried to put some caps in it, helped a bit, finally stopped using that fan. So check electric equipment in the area...

Yep.

Or present only at a very low level. They claim BER < 1e-15 as the target. I reckon in practice it is one uncorrected every couple of hours ~ 1e-12 back of the envelope (usually manifested as an audio glitch as they seem to be by far the most obtrusive). Typically a few ms of click or near ultrasonic hiss.

But it would still be useful to see a log BER display where 10 is nominally perfect and 1 still has something vaguely resembling a picture. And same for the signal level - it is no use at all having half the signal scale reserved for stuff so weak you cannot hope to decode it.

Single bit error per frame should be fixable, two bit errors detected and after that all bets are off. The diagnostics are pretty ropey even on high end TVs and converters. It either works or it doesn't and the diagnostics are equally binary! It would be nice to make small adjustments to try and improve things but the diagnostics are simply not sensitive enough.

Unfortunatly mine all seem to stem from the pitter patter of rain on the roof. It is worse at this time of year with the trees still in leaf and nicely coated with rainwater in wet weather.

n.

External aerial and as I said it is specific to heavy rain (not thunderstorms) and only then on the weaker channels. There is uniform attenuation of all channels it is just the weaker ones that go AWOL.

Regards, Martin Brown

On a sunny day (Tue, 21 Oct 2008 05:36:32 -0700 (PDT)) it happened Martin Brown wrote in :

Here is some code sniplet of 'xdipo', my Linux sat receiver / recorder /positioner,

you can see screen shots here: With bit errors: ftp://panteltje.com/pub/xdipo1.jpg Without bit errors: ftp://panteltje.com/pub/xdipo2.jpg

I know the code is not perfect, and I should fix things, but it works 100%, so I leave it like it is for now:

/* get front end info */ /* bit error rate, multiple of 10-9,

2500 = 2.5 10-6 is 1 error in 400000 */ a = ioctl(fd_frontend, FE_READ_BER, &bit_error_rate); if(a < 0) { fprintf(stderr, "xdipo: print_status(): error=%d reading fd_frontend bit_error_rate\\n", a); perror("reason "); }

sprintf(temp, "%d", bit_error_rate); fl_set_object_label(fdui -> main_form_bit_error_rate_text_field, temp);

if(bit_error_rate > 20000) { fl_set_object_color(fdui -> main_form_bit_error_rate_text_field,\\ FL_RED, FL_RED); } else if(bit_error_rate > 5000) { fl_set_object_color(fdui -> main_form_bit_error_rate_text_field,\\ FL_DARKORANGE, FL_DARKORANGE); } else if(bit_error_rate != 0) { fl_set_object_color(fdui -> main_form_bit_error_rate_text_field,\\ FL_YELLOW, FL_YELLOW); } else { fl_set_object_color(fdui -> main_form_bit_error_rate_text_field,\\ FL_GREEN, FL_GREEN); }

So I use colors (I think many soft receivers do that).

I have gone one step further, I write the bit errors to a file with time stamp, this so when I need to edit mpeg2 material I know where to look for dropped / bad frames and especially the associated audio / video sync problems. When for example a frame is dropped, audio may get out of sync in the editor. So recording generates 2 files, just a quick test: -rw-r--r-- 1 root root 0 2008-10-21 14:47 Astra2_BBC2.12h00.21-10-2008-20m.ts.bit_errors -rw-r--r-- 1 root root 2341164 2008-10-21 14:47 Astra2_BBC2.12h00.21-10-2008-20m.ts

I found an other unexpected source of RF noise, I have this insect kill lamp, it is a blue lamp with electric wires around it, if an insect flies into the wires it gets electrocuted by some 500V DC. I noticed on shortwave it creates a constant noise, coming from minuscule arcs from the wires to the remains of insects (legs, wings). It does not seem to cause bit errors in the sat bands at 10GHz.

I wonder who voted for that crap, or have we returned to the days of emperors?

Thanks, Rich

Mark my words, there will be riots in the streets.

Cheers! Rich

Maybe not riots but that's what I said before we even had DTV: I would not want to be a politician in February 2009. And most certainly not manning the phones there.

--
Regards, Joerg

http://www.analogconsultants.com/

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The real result is worse: No picture, no sound. You'll see a static Picasso or Salvatore Dali, or a blue "no signal" screen. Analog is much better because you can always see and hear something. Out here dynamic multipath happens already when clouds move in fast because of high winds. This whole DTV was IMHO never properly field tested, just hastily slapped together and shoved through. In fact it's so bad that when we see bad weather rolling in we crack out the card game or read.

Heck, the TV sets don't have a BER display to help aim an antenna. Not even a field strength meter. Pathetic.

It reminds me of GSM, touted as the best thing since sliced bread. ROFL. European engineers say our CDMA system is so yesterday. Little do they know: The reality is that our neigbor can only get reception on his GSM phone with a vertical yagi mounted on a piece of schedule 80 pipe above his roof line. My CDMA phone gets good signal in every location out here and according to maps the cell tower densities aren't very different.

--
Regards, Joerg

http://www.analogconsultants.com/

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AFAIR someone decided that it is better , people will like it and shoved it through the FCC. Because he was way up top there ...

The guys who have to take all the grief from voters next February will be the next generation.

--
Regards, Joerg

http://www.analogconsultants.com/

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It's all an outgrowth of a failed FCC experiment relating to "interference temperature". The basic idea was harmful interference between the various services could be controlled by means other than licensing. This was a nebulous concept at best - I sat through several FCC presentations on the process back when Michael Powell was still Chairman.

Wisdom prevailed (mostly), and the FCC's OET terminated the ideas circa Summer 2007.

You can still see traces of this line of thinking though with ultra- wideband, through-wall imaging, and ground penetrating radars. Also, re-use of satellite spectrum in terrestrial mode (an interesting off- axis idea in more ways that one), and even the TV white space initiatives.

Obviously, intermod studies are pretty much useless when you're dealing with large swaths of spectrum. Many (perhaps most) of the new technologies are either spread-spectrum or employ exotic modulation schemes...

Prior to this, you can see how this train actually left the station. The FCC (circa 2000) created the whole Telecommunications Certification Bodies (TCB) process in Part-2 of its Rules. They (FCC OET) don't even bother to certify the certifiers anymore - leaving that task to NIST. Which might be better suited, granted.? Clearly, the FCC felt it could not keep up with innovation through licensing & rule-making alone - the latter being a protracted process even on a good day.

The point is, like everything else Republican the last 8 years, the FCC also deregulated.

-mpm

Joerg schrieb: ...

Could that be a problem of the distance to the base station? My reality is, that GSM works perfect everywhere here, but CDMA does not, even if I would use a Yagi.

*I* know, that it is a matter of distance, since the closest CDMA base station is located some 1.000 Miles away ;-)

Falk