Multipath WLAN problem?

I've heard some stations do that (not so much in our area though) but that sets them up for a serious black eye. Viewers buy new converter box, most don't have analog pass-thru, they tune in ... nada ... whoops ... numbers go down ... ad revenue goes down ... pink slips. In the current economic condition that almost amounts to suicide from a business point of view.

Ch29 digital is where Ch48 used to be. On the analyzer it almost pegs to overload. But signal strength can mean nothing in this area.

But it's all of them :-)

Did that already. It just keeps its beacon going. Traffic slows to a crawl. Seems to be trying but can't get through.

Ah, thanks! Time to open it up and hanging the scope onto the rail. It appears to have a buck switcher that takes a wide input range. Of course, if the cap before the buck can't hold its water then it's all hosed.

Not in this neighborhood, it's rather rural. But if I can't fix this quickly I'll just buy another one and try that.

I've also tried at night where all the lights were off at the neighbors. Unless one of the kids snuck out and reach into the freezer ...

The only option would be outdoors here. Inside it's like a metal maze from an RF point of view.

Yeah, it might be needed. But right now it has to wait. My wife just started ripping out the floor in the next office. Meaning a slight hint "Hey, get over here with them tools, will ya?" If I was a bachelor I'd have left the old flooring in there and not moved a thing. But ...

Often this wasn't their choice at all.

Putting ATSC and NTSC on different frequencies is, of course, completely necessary.

Using different transmitter sites, or much lower power, is sometimes a matter of economics (e.g. independent station can't afford a second full-power UHF transmitter).

In quite a few other cases (especially in crowded market areas) it was mandated by the FCC. In some of these areas, the stations and the FCC have really had to juggle around, to find "interim digital" frequency slots for stations to use which did not result in unacceptable interference to existing NTSC stations in the same or adjacent coverage areas.

Most stations which have been running their ATSC feeds at reduced power (compared to their NTSC feeds) will be going up to full ATSC power as soon as they can. In some cases they'll simply switch their digital signal over to the frequency/transmitter/tower/antenna that they were previously using for NTSC. In other cases, they may have to wait until June, to let other stations go throught *their* frequency switch and "get out of the way" in order to raise their own ATSC transmit powr to their full post-transition level.

True... multipath can be the big issue.

I was speaking at lunch yesterday with a local ham who works for an MPEG/ATSC-encoder manufacturer. He tells me that the chipsets used in DTV converters (and HTDV sets) have gotten significantly better at dealing with multipath in the past couple of years. The comparison a few years ago of the multipath resistance of ATSC (8VSB modulation) and the European DTV-T standard (which uses COFDM) rather gave 8VSB a black eye - it's significantly less multipath-resistant than COFDM. The silicon folks reacted by producing significantly better chips and firmware - "3D" filters with more taps and more sophisticated filter management.

Enh? Don't follow...

It'd be interesting to look at the spectrum in your living area at a time when this happening, to see if any new noise spurs are showing up

Or, if the post-buck cap is going bad, there might be more HF ripple and noise than the hardware can handle.

It surprises me that station owners haven't created a ruckus in the media about that. Especially since they _own_ a media outlet.

Another thing they forgot to tell folks is that frequencies will change and that they must run the auto-search again once the switch cometh. I don't want to be manning the phones in that week.

Well, we got here two DTVs and two converter boxes, brand new. They all pretty much keel over simultaneously. Typically when clouds roll in or Fedex lumbers into Mather Field.

All of the PCs with wireless in there do the same.

It is an absolute nightmare to open that Linksys. Plus I need to fix the dang printer now, has all the supply voltages (I think) but won't work.

Jump online and find and buy a pair of better antennas. Problem solved.

You also may be able to download third party firmware for it that allows you to boost the power beyond the factory, consumer accessible setting window.

Also make sure you are using a newer, more secure access methodology. The old simple password, open broadcast method is insecure. Limit wireless ports to the number you use. You can also turn it on and off via an operating PC or even via web access, depending on your router.

Well... it isn't 'true diversity'. You can also buy a long coax that allows you to place an antenna away from the actual router.

The best thing to do is buy on ebay, an already upgraded router that runs Linux and the WRT firmware upgrade that allows you professional router setting and power levels on your consumer level router.

That router is: The world famous Linksys (Cisco owned) WRT54GS v3 for max internal memory and CPU speed capacity. Mine was about $79 IIRC, shipped. I upgraded the firmware on it as soon as I got it, so I know it has nothing on it tucked away somewhere in the settings (these sellers are legit).

Anyway, you can boost the piss out of it, if the new antennas don't work.

Those damned round threaded fuses! You try soaking them out, you try scrubbing them out... and still you get... ring around the collar!

No. It's an intranet router, and the other is your Internet side router.

Your router WLAN is a LOCAL radiation device. You are not bouncing anything off the nearby hills that is interfering with your WLAN usage.

Some had to erect VERY expensive antennas.

Maybe tack against the wind and -reduce- the Tx signal strength?. I.e hamstring some of the strong contenders fighting to open the door.

I know. You had snipped Jan's remark that he doesn't believe in multipath which I was responding to. If he had lived in this neck of the woods he'd know different. ATSC in heavy multipath is the pits.

Signal strength ain't the problem, plenty of signal.

That's what I am afraid it's doing as well. Maybe it just slowly switches between the antennas and on one of them it just doesn't see some PCs.

Well, I'm not giving up this easy :-)

Who wants to open the door? Other than our signals there really ain't much to be seen. A wimpy signal on Ch1 (cordless phone) and a neighbors WLAN router above Ch6. That's pretty much it.

It usually uses the one most used as a favored stick kind of thing. Again, I doubt that it is 'true' diversity.

That unit you have may well have 3rd party firmware for it that boosts it as well, and gives you other options.

Actually not just an AP, it's your wireless host (unless you have some other always-on central unit that gives a name and other attributes to the wireless environment).

As host, it determines the channel (they go from 1 to 12 in the US), and it might be that some neighbor is using the same channel (and having the same problem with your interference). Try different channels, it may help.

Most recent firmware for the BEFW11S4 is 1.52.02, last time I checked; updating is usually a good idea, too.

Could you please include a notice in the subject line when you're trollfeeding?

Thanks, Rich

Here is a wild, off-the-wall idea: Run a chunk of low(er) loss coax from the router to the lab and put an antenna in there. Mught want to be thoughtful about antenna design and placement so as to minimize intereference with the rest of the house.

Doesn't help. Again, signal strength ain't the issue. I did make a reflector and got a fat >10dB boost. This did not increase the link reliability by one bit.

I guess I must open it and chase bad electrolytics. Opening that thing is a bear.

Efficient use of your time ?:-)

...Jim Thompson

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