DTV transition headaches

Well, Feb 17th has come and gone, but not without some issues for me here in southeast MN. Some of it is due to partial transitions, much of it is due to multipath problems as stations changed their real channel frequencies.For folks close to the tower, no problem, for folks like me in fringe areas, big problem.

The huge issue, is I can’t go buy any gear off the shelf to solve the problems. First the economy is down, and my business was anything but immune, to say nothing of 2 floods in under a year. Secondly, even if I had a few hundred bucks to buy something, the traditional devices available in the consumer domain wont work in this area (adjacent channels pretty much kill off jointennas and the like, and I dont want a stand alone rotor) Granted, if I were to set up a full MATV system, with a high tower, multiple antennas, tuned filters, amplifiers… basically a small rack, I could make it work, but then we are talking many thousands of bucks, and cable or satillite at that point would be a bargain.

Thus the game plan, a smart antenna system… Many CECB’s (convertor boxes) have a smart antenna interface. Basically, its a communications setup to allow the box, and in the future tv’s to talk to the antenna system. It may be as simple as sending channel information such that an automate switch could select from different antennas, or as complex as setting a variable gain amplifier notch filter, and in the middle, control a antenna rotator.

Of course, that  turns out to not be simple either. The product offering is exceedingly limited, so limited in fact, there doesn’t seem to be any gear in the VHF domain, and smart antenna compliant switches, filters, preamps, and rotators are non-existant for now. I figure this is due to 3 big issues.

1 The smart antenna standard is evolving from a separate cable to a provision to also drive signals on the antenna coax. Add in the use of a MMJ connector, and the resulting installer headaches, its a good call… but change means more development costs to the manufacturer.

2. Smart antennas are likely going to be a bear to sell. The consumer says, hey I have a problem. The sales guy says, here, this smart antenna will work. The consumer gets home, and it does diddly, or even makes it worse as it was a bad application. There is a huge amount of education that would need to occur both on the consumer, as well as the retailor side. No one should need to have MATV experience to pull this off, but I’m afraid with the complexities, at least initially, those are the only folks that could spec out a system… and they likely won’t as MATV is old tech, even when I did installs in the late 70’s with my mentor, it was on its way out. And even then, a full MATV install is thousands of bucks, so why should they mess with a $200 oppurtunity if that.

3. The economy tanked and the market is small, an oem is unlikely to spend money on development in this economy to start with, and if they do, it will be for projects with a high return/low effort arena, not the domain of smart antennas.

The end result, if I want a smart antenna, I’ll need to build one, and being its for me and not a commercial product, I don’t have to spend a kazillion hours taking every penny out of the design, nor jump through the hoops of compliance testing. I’ll likely whip up some code for an AVR microcontroller, such that I can play around with different options just by reflashing the program. (also, being there is a fair amount of ambiguity in the CEA-909 standard)… I really need to be able to look at the data stream to see whats possible, and whats not.

For those in southeast MN, here are the problems

KTTC went from UHF channel 36 in Grand Meadow to VHF channel 10 in Ostrander, resulting in multipath going through the roof here at my location, I have great signal, but terrible BER, the end result, my CECB has intermittant audio and the video is filled with hash, or says no signal. Being in a valley with huge grain dryers directly in the line of sight is a big problem. I have ideas to work around this at low cost, thats where the diy smart antenna comes into being.

WKBT changed from a UHF signal I could not recieve to VHF channel 8. Now it comes in pretty clear, but its CBS, not NBC…

WXOW will be in transition for quite some time. Currently the antenna is on the east side of the tower, and they are running on lower power levels. The end result, no signal for me. This summer when they can relocate their antenna to the top of the tower and up to the power levels this should change.

WHLA the pbs station was the one I really wanted works great, and even without careful antenna positioning, it comes in like a dream.

WEAU may be a deadend, it appears their coverage area really shrank.

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