DTV antennas?

To me it sure looks like an absence of field tests and too few design reviews.

No, there ain't no drop in analog levels so digital levels whouldn't change either. Same towers, same band. Just the ghosting pattern changes and you can see some ghosts sharpen up significantly, then smoothing back out.

Might be faster whipping up a detector with a tuned circuit up front.

In a multipath situation goal posts move all the time :-)

Mather is behind the hill. When the aircraft is at 1000ft AGL the moving reflections stop.

I think it was more because of what people want, which is hi-def. AFAIK your system can't do 1080 line transmissions etc. I thought the stations would mostly stick to 720 line but now lots of programming is 1080. It's a stunning picture, especially for landscapes and wildlife. But it's a fragile transmission scheme :-(

Say Martin,

Out of curiosity, do you know why there was such a push for 8VSB rather than COFDM in the first place? Who stood to gain a lot of money by having 8VSB chosen rather than COFDM?

---Joel

I don't have a specific model for you, but I do recall reading the manual for at least one converter box that claimed it used "common" remote control signals that "any universal remote" would likely already have preprogrammed.

You seem like you might be the kind of guy who'd have one of those really fancy unviersal remotes with an LCD, USB connectivity, etc. anyway? :-)

Plus a security concern that, if the private keys got out, any kid in the neighborhood with the a laptop and a "black box" could drive around the neighborhood and disable a bunch of the converters.

This just reflects that fact that, on customer returns, there's usually no differentiation given between "hard defects" (it isn't working as designed at the factory) and "brain-dead designer defect" (it's so cumbersome/annoying to use that it's little better than nothing at all). These days with so much software running the show, the later show up far more often than the former... I think I've mentioned on here before how much lobbying it took to get some software guys to not use something like a 1/4 second "debounce" for pushbuttons on a standard LCD/directional keypad widget, having to convince them that "expert users" who had memorized the path to their desired function could press buttons a lot faster than four times per second. :-(

---Joel

There's theory and there's practice. I've got a couple months of practice trying to get digital TV in a location that would look hopeless on a coverage map.

That's resulted in an antenna that's pointed, about 160 degrees in the wrong direction, at a bluff on an island on the other side of a shipping channel.

Here's some rules of thumb I've found.

A clean ATSC signal can be picked up below the point where an NTSC signal is snowed out. In an urban or near fringe location signal strength does not matter.

A clean signal won't drop out if moving vehicle multipath is below some threshold. But you only get that if the station is in line of sight.

The units I've got (Digital Stream DTX9900 and '50) can adapt to a fair amount of static multipath, but it takes some number of seconds for them to adapt to any given signal, with the time related to how poor quality the signal is. There's a limit to what it can cope with. And they can't cope with the flutter from a moving source at all.

And the key lesson is to get a narrow antenna beamwidth (and good front/back ratio). This lets you find some magic spot in the local geography, limit the field of view to limit multipath to the point where the demodulator can cope with it, and keep the moving vehicles out the antenna's view so they don't screw things up. Gain doesn't matter, but they're connected. Unless someone has come up with some way to get a very narrow beamwidth but lossy antenna?

Looking at a California topographic atlas, I don't hold out too much hope for Joerg's reception. That airbase/airport is only 15-20 degrees off the line from his town to the antenna farm at Walnut Grove and that's a killer.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

In the UK we take the view that the advantages of DTV mean that most people have already bought into the capability. And it is now pretty difficult to buy new kit that lacks DTV.

Our digital switchover is rather more gradual and ad hoc. Out of the way places like Scotland and Whitehaven in Cumbria get used as a test bed. They will have it right before they switch London over!

Please

Tough. They will have to get off their backsides and buy a set top box.

You don't mean afford. You mean say they have cable/satellite TV.

I did like the reference to the "New America Foundation" or NAF for short. Do these people think about their acronyms? Or does naff not have unfortunate connotations for product quality in the USA.

Well for the over 65s then.

I would not trust most UK retailers to set up a toaster correctly. The box shifters have about a quarter of the sets on demo with terrible picture faults, hum bars, noise gliches and other stupid config errors.

If you buy a matched/compatible TV and DVD player you can share one. But I know what you mean about the huge number of remotes needed.

In the UK the total national DTV band ended up a fair bit wider than the previous analogue local spectrum and old aerials were pretty ropey at the extremes. This may not be true in the USA - I don't know.

Even my earliest one had OTA firmware updates. But there is something tricky coming with the newest revision that apparently may not be fully supported in the very earliest chipset(s). The result is they go blank.

The most infuriating thing about firmware updates is that after one the entire unit goes back to factory defaults and all custom channel ordering is lost (so you have to wade through the shopping channels deleting them again).

Or they could be no fault found return units going round the loop. About

Regards, Martin Brown

Yep. That saves the cost of supplying a remote control.

That was last year. This year, I'm into downsizing, simplification, and de-trashing the house.

The number of boxes in the 19" racks and on the "home entertainment" pile has grown since I took that picture.

I do have a Radio Shock universal remote control buried somewhere in a box. I bought it because it would run some obscure C band satellite receiver I found at a thrift shop. However, for running the TV, I have several Windoze Mobile PDA's setup with IR remote software. I also have a home made IR repeater in an other room. The big advantage is that I can setup the screen with only the buttons I want, and not have to deal with buttons that I'll never use. Macros are also handy so that I have a "shutdown" button that turns everything off.

Yep. Security is a real problem. I'm sure some manner of security arrangement can be contrived, like having the customer go online and authorize a firmware update.

Soon, every kid will have an ATSC 8VSB modulator and transmitter in a black box. Actually, I did a search for a do-it-thyself 8VSB modulator or transmitter, and couldn't find one. Lots of professional broadcast equipment, but nothing suitable for the neighborhood TV hacker. One the kid has the transmitter, he needs to guess the channel the receiver is watching. Since the encryption will probably be keyed to the unit serial number, he also needs to break in and obtain the serial number.

True. Most stores do not have personnel that are even capable of determining if it's defective. That's one reason for why the existence of the Geek Squad and Fire Dog people attached to the US electronic retailers. The stores have realized that the abilities of the salesmen are limited and need some expertise.

My test and example was for a device that had absolutely no software. Todays versions would be exactly as you described, and probably have additional software issues. This was strictly the customers perception of proper operation. Incidentally, when I traced the source and complaints on the 5 units that were returned, I found 3 operator errors, and 2 that simply changed their minds and wanted their money back. The only way to do that was to claim the units were "defective" and to not accept a replacement.

I didn't catch that posting, but I can certainly see the problem. User hostile interfaces are all too common. Unfortunately, many such user interface requirements have undesired consequences. For example, one product received complaints that the button labels were too small and difficult to read. The revised model had larger buttons and labels that could be read from about 3m away. The result was that sales dropped like a rock. My job was to figure out why. It didn't take long to discover that the customers perceived anything with huge buttons and labels as something suitable for a child. In other words, it looked like a toy. The buttons were replaced with the older smaller versions, and sales resumed at their normal pace.

I expect an element of NIH. US manufacturers and broadcasters profit from essentially a lock out spec. And they had already tooled up for

One review summary is online at:

But it wasn't the clear success for COFDM that I would have expected.

Regards, Martin Brown

Yes, but when I tried a read message showed up "Currently not available online". Great.

The gvt gets to pocket a huge profit auctioning off the "freed" frequency range. So I guess it was a deal to make the people whole. Then the $40 boxes remained a fairytale. Who'll end up holding the short end of the stick will remain to be seen. Althought I'd venture to guess who it'll be ;-)

Old rule: When it comes to electronic media do not be an early adopter.

Oh man, my wife would have a hissy fit if she came home and saw a pile like on the floor of the room in the back.

Hi Jeff,

Agreed, but realistically most people would probably never actually authorize the upgrades... look at how many access points out there have "linksys" or "dlink" or "airlink101" as their SSIDs!

Probably the best thing you could do would be to have the box alert the user that new firmware was available, and would they like to install it? -- With the big warning about, "blah, blah, only do this if you trust the TV station channel 6 that it came from, etc." And then give them the option to "rollback" to the last installed version if there's a problem... which then does require some extra memory to keep an old image around.

The GNUradio guys have a *demodulator* for it; someone over there is probably working on a modulator as well. It's certainly not a trivial undertaking!

...and that people are willing to pay for that expertise. That's the part that amazed me -- realizing that someone actually would pay, e.g., $50 just to have someone else install a virus scanner or some more memory or something else very "mundane." They clearly didn't grow up in the Joerg school of "do it yourself." :-)

---Joel

Thanks for the link Martin; good reading.

I willing to wager that, as soon as the government voucher program ceases, you'll start seeing plenty of $40 boxes.

Wal*Mart has'em for $50, which isn't too bad.

I wouldn't be surprised if Jeff is single. :-)

No, it has no meaning at all, like most European slang. We would call that low grade crap, trash, garbage, worthless, substandard or something in that vein. We have plenty of words that work for that problem, so why import more? Most of the worthless crap is already imported.

I solved that problem many years ago. I'm not married. Incidentally, the mess is considerably larger at this time as I'm going through all my boxes of magazines and junk, desperately trying to reduce the volume. Unfortunately, some of my friends and neighbors are doing the same thing and giving me their junk. I think I have more broken toys, in need of repair, than working toys.

When I bring various ladyfriends to the house, the usual comment is something like "You live like this?" It's usually downhill from there.

For completeness, my palatial office:

Hmmm... last photo is 2 years old. Time for a new one (after I clean it up).

For entertainment, what I do all day:

Wait until it's done loading. Then, move the mouse around the picture. The hard part was not smiling or laughing while the pictures were being taken.

I don't think so. It's a timed market. Mid-2009 you'll see many vendors and mfgs vanish. Or at least their boxes. There was always this talk about an Echo-something $40 box. IMHO if there really was a company behind it they blew it, big time.

Yeah. Everytime I called they had none. During the last call the guy said something like "If you live more than a half hour drive from here you won't be here fast enough after a pallet has arrived even if someone tipped you off".

That's one of my pet peeves about commodity routers. Search alt.internet.wireless for one of my numerous rants about "secure by default". At least 2-wire does it right and ships their products with security enabled by default instead of wide open. They've also demonstrated that even if you attach a bright yellow label to the router, with the password and security keys inscribed in plain text, the typical customer will not notice.

Memory is cheap. Bricked routers and comatose ATSC converters are not. Your method is as good as any I could contrive. The point is that it OTA firmware updates can be done. I don't see adding an ethernet or USB port to the ATSC converter, so OTA is probably the only way to do it effectively. Something simpler like: An update is available for your converter box. Please tune to channel 99 to download and install the update. The update takes between 10 and 30 minutes to complete. Please do not play with the controls during the update. You will be informed when you may safely resume watching whatever mind numbing drivel that we are interrupting.

Yep. I was thinking in terms of setting up a bootleg (illegal) DTV station. Pirate FM and TV stations are so commonplace, that methinks to attract the necessary audience, pirate HDTV transmissions will be necessary. Finding IBOQ (HD-Radio) or European DRM decoders are easy. Finding encoders are not. I wanted to do a streaming MP3 FM bootleg radio station but couldn't find an economical encoder. Same problem with 8VSB/ATSC encoder/modulators.

My guess(tm) is that some test equipment manufactory (e.g. Sencore), will arrive with an 8VSB/ATSC test generator. Add power amplifier and antenna, and I'm on the air.

I prefer the "Learn By Destroying" skool of computing. I consider myself somewhat of a computer witch doctor or priest. The GUM (great unwashed masses) observe various phenomenon on their computers. However, they are unable to adequately interpret the meaning or predict the future (i.e. is my HD going to blow up?). My purpose is to act as a middle man between the GUM and the computer gods and attempt to supply meaning and logic in an industry that lacks both.

Incidentally, I charge good money to clean up the mess left over when Norton or MacAfee blow up. Also, plugging marginal memory into a working machine is a great way to scramble the drive contents. Expertise and experience have their place. I don't install programs I don't trust and I always test the hell out of RAM before I install it in a live system.

Same with me. Until I met the one. Then I had to get rid of 15 TV carcasses and all kinds of other stuff.

I know a VP in an electronics company who had to ask the CEO whether he could borrow his office for a meeting with a business visitor. I also know the engineer who won the "Messiest Office Desk" contest of the San Jose Mercury.

There also must have been a mild earthquake at the 90 degree position ;-)

I remember all the mice from a thread long ago. What do you do with all those?