DTV antennas?

On a sunny day (Mon, 14 Jul 2008 08:44:17 -0700) it happened Jeff Liebermann wrote in :

Sorry, what do you mean by that? I have a motorized dish, the signal indicator in my soft is intantanious (ms) and I often use it to fine poition to a sat (to find the best signal position). In fact without signal strength indicator you are lost in digital, unless you take to middle of 'east nothing-west nothing'.

Yes: ftp://panteltje.com/pub/xdipo2.jpg

There are many PC cases that are specifically meant to look like "stereo equipment" these days -- like brushed black aluminum cases with tasteful VFDs, stylish buttons, etc. Just the thing that many guys found they needed to obtain a positive WAF. :-)

Well, there's still regular AM/FM radio found in almost 100% of cars (and HD radio in many bigger cities). Plus you'll definitely find a few RVers who've gone to the effort to put in a satellite TV system... and you can bet that as soon as, e.g., the Red Cross sets up shop they'll have satellite TVs.

The amateur radio guys come out in force as well when disasters strike, although while they're typically set up to be able to pass messages into and out of the area, in many cases today what people really want is just access to an Internet connection to send e-mail to their family/friends to let them know they're OK. Oh, and to upload videos to You Tube. :-) (Of course, many people already have this as soon as cell phone service is available...)

You can already find relatively small LCD TVs with ATSC tuners, and some probably even run off of 12V DC... that's probably your best bet if you figure that regular TV is going to be a useful source of information in a diaster.

Require? Read the titles, they provide the chicken exit for the manufacturers on a silver platter: "Recommended".

They don't even provide that. It's either "picture is there" or "no signal", with many seconds of wait time. Gives you a royal leg cramp on a ladder.

In medieval Europe they had a "corrective action procedure" if bakers cheated by selling rolls that were too small at regular price. They would be dunked into the city's moat a few times in full public view. Sometimes I have a feeling this custom would help in modern times as well.

--
Regards, Joerg

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But they are huge.

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You're right, Jan, but Steve Jobs still does a good service in that he introduces people to shit: There's very little an iPhone does that plenty of other phones didn't already do, but except for techno-nerds/geeks like us most people didn't realize that a phone could also be a reasonably good web browser, e-mail client, eBook reader, full-fledged media player, etc. A rising cesspool raises all ships, you know?

I thought you preferring SSHing into your phone over Bluetooth to dial? :-)

He designed it primarily for the U.S. market, I think, where DVB is non-existant.

That where packet radio should excel.

I would not want to bet on that. If a strom went through and only te more distant towers are still intact chances are DTV falls apart.

--
Regards, Joerg

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Not really... people being able to get words to their family/friends that they're OK in the hours immediately after a disaster -- even if they then can't contact them again for some days -- is a huge improvement over no contact at all for several days.

On a sunny day (Mon, 14 Jul 2008 09:27:31 -0700) it happened "Joel Koltner" wrote in :

Oh I greatly respect Jobs for how he turne Apple around. However indeed much of teh stuff an Apple can do a normal PC can do cheaper, He has some nice soft though.

Yes, that is a very deep question. But no bluetooth here, never appealed to me, you know, with all them NSA and FBI and whatever maybe Bush personally tapping into the RF, I give them a strong WiFi signal, so they know what I am up to. Actually I have written some nice SMS scripts, so indeed SMS from the command line, the PC sends it to one of those forward SMS services..... For .nl if you need the script, and run sendmail on a Linux system let me know.

It will pick up over time I am sure, unless the whole place goes bankrupt before that. I have offered 1$ for the US, so far no go.

All that is needed here are clouds. Maybe the movers and shakers behind DTV overlooked the slight inconvenience that clouds move. My impression is they never tested all that thoroughly.

And then I am down to maybe 2-3 stations and the big dish would fly into the street in every major storm. Yeah, that would be true progress :-(

Result: "No applications matched the search criteria"

As expected ...

--
Regards, Joerg

http://www.analogconsultants.com/

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Methinks that's an understatement. The FCC is run by lawyers, not engineers. It should have been a technical decision. Instead, it was almost arbitrary.

DTV REPORT ON COFDM AND 8-VSB PERFORMANCE (1999)

"The consumer electronics (CE) manufacturers all viewed multipath performance as an issue that will be worked out in the normal process of improving new products."

"Most of the industry representatives stated that, in theory, 8-VSB and COFDM should be able to perform nearly the same where there is static multipath. Most also stated that COFDM can generally be expected to perform better in situations where there is dynamic multipath, e.g., in mobile operations."

I have yet to see any "static multipath" outside a lab environment. Even reflections off allegedly immoveable buildings and hillsides tend to generate reflections that move around.

This is a bit more readable:

More detail:

Note that this article disagrees with the FCC OET on the susceptibility of COFDM to impulse noise. Also: "The COFDM system has a strong immunity against multipath distortion. It can withstand echoes of up to 0 dB."

A tolerable summary:

Some comments from 2000 on 8VSB versus COFDM.

Scroll down to "Subject: COFDM vs. 8VSB". Note the field test results for COFDM and comments on multipath.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

On a sunny day (Mon, 14 Jul 2008 09:22:32 -0700) it happened "Joel Koltner" wrote in :

There was a good CB packet radio network, slow, but with email connection to the internet here, large part of Europe in fact. However I can no longer get to the BBS as many stopped and went internet. Not even sure if any BBS is still active in this area. Some people will know about 'soundmodem', ax25, etc.

Perhaps because medical equipment is second only to military equipment in being given a blank check for R&D costs? :-)

In some of the early RF receivers I did I made the mistake of thinking "it's all about sensitivity" and designed in excess gain at the expense of dynamic range; I wouldn't be surprised if many a TV receiver designer did the same. (And there are some more bullet-proof RF designs out there than what I can currently do; with you around I often figure you should be able to get a

500MHz 40dB amplifier with a 1dB NF and 100+ dB dynamic range out of a $0.25 transistor... :-) )

Ironically, if you already have a fast and reliable Internet connection, getting stuff like movies is easy... it's local news that's difficult at times.

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respectfully, your evidence does not support your conclusions. either that, or you have no real idea what you are talking about.

-mpm

One of my side lines is setting up satellite DBS and internet antennas. It's the price one pays for owning the required test equipment, tools, and clues. The only way to initially aim the dish is with a satellite meter at the dish. I've tried it by dragging the receiver and a small TV on the roof. That's when I discovered the time lag. My current DirecTV DVR has a built in signal indicator. My guess(tm) is about a 1 second delay between moving the dish, and when the bar graph indicator shows a change. Several previous receivers had the same problem. However, I've played with a DreamBox and several FTA receivers, that are almost instantaneous. I guess it varies by manufacturer.

I live in a dense forest with 60 meter tall trees. I can see one satellite (101) through a hole in the branches. Every spring, I have to move my dish as the hole moves up. I get LOTS of practice using various dish aiming tools.

Very nice. However, that's for a satellite receiver. Joerg has an ATSC TV, which lacks the necessary interface. Most of the cheap ATSC to NTSC video converter boxes have no way to extract diagnostic info. Maybe if I can find a converter with an accessible JTAG port.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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Personally, in a storm, I would not be that reliant on TV for news and info. But many people are.

When the WCIX TV-6 tower collapsed in Hurricane Andrew (1992), it took three full power FM's with it.

In the hours after Hugo (1989?), the only station that could make the trip up there was 690, which had a 100,000 watt transmitter. I think they got permission to run it up to 60kW, which made the trip. Very impressive transmitter - which I think has since been deconstructed...?

I have no plans to go buy a DTV portable. I can think of several things that would be in front of that line..

-mpm

Actually, you only get the forms filed in CDBS, with links to ULS. But for most purposes, it's enough for the general public.

renewals, CP mods, stuff like that.

-mpm

Absolutely not. Those days are long gone. But it seems we design in a more diligent fashion, writing hazard analyses and adverse effects studies in parallel with the design process. Not as hindsight or not at all.

Just give it lots of quiescent current :-)

I think I can get those as well now.

--
Regards, Joerg

http://www.analogconsultants.com/

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So it's dragging the spectrum analyzer up there just because the TV designers could not figure it out. Sad. Maybe they should teach them what the letters RSSI mean.

Converter boxes? You do not get to pick. It's calling the stores every day until one has stock. Then get there as fast as legally possible. Step on it. It's almost like when tomatoes or bananas show up in Moscow.

--
Regards, Joerg

http://www.analogconsultants.com/

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