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• (December 12, 2010, 01:23 pm)

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[Jam Pro]

For approximately the last week, I've been getting wildly varying signal levels from WISC-TV.  This has caused the BER to soar, making for many blocks of garbage in the visual signal, and many drop-outs in the aural portion of the broadcast.  Note that I live so close to the shared transmitter site that WISC uses, that I can see all of the antennas on the tower with my naked eye.  This puts me in the shadow of their main beam, but still I've never had reception problems like this in the past.

I have made several attempts to contact the engineering department at WISC, and either don't get an answer, or someone picks up the phone and sets the handset down without talking to me.

Fortunately the front desk of the station has been more accommodating, and informed me that they have been operating at reduced power.  They couldn't say why, but it's better than nothing.

I took a drive around the shared facility that WISC-TV shares with WMSN, WKOW and WHA, and noticed that the entire area around the antenna site, that was once just open field, is now under active construction.  It looks like the west tower will soon be surrounded by a new subdivision.  I don't know for sure if that has anything to do with my reception problem, but all of the heavy equipment operating around the tower can't help tower stability.

Any body else have similar problems?

[hoophead]

Yes; and for a longer period of time than you mentioned.

I live in Watertown and a few months back I repointed my UHF only antenna from Milwaukee towards Madison and was getting 100 signal strength from 3 and 27 and 95 from ch15.

Recently it is like you said about ch3. Also 27 is well below what it once was. WMTV not as reduced near what the other two are.

[hoophead]

Turned on Letterman at 11:30CT (CH3) and there was a crawl saying: We are shutting down for transmitter maintenance. We are sorry for the inconvenience. (or some sort)

Do not know how long that crawl had been running or when it will go down as it is now 12:10am and The Late Late Show is still on.

Let's hope it resolves this thread's concerns. 

EDIT: Noticed the next morning my Madison channels had improved somewhat so maybe my antenna might need another tweaking. WISC is up to 77-82% signal strength, WMTV is 74-83%, and WKOW is 89-94%.

[Jam Pro]

When I pull out of my driveway, I get a very nice view of the west tower, where all of the action has been going on lately.  I've been watching gin poles go up and down, the sudden appearance of the well-known red warning colors on what appear to be radomes covering the actual antenna structures...something new almost every day.

I'm sure that all of the residents of the west tower are taking advantage of the late-season WMSN installation to button down all of their stuff.  They have tower workers on-site, and an ounce of prevention is better than braving the Madison wind chills at 1500 feet in the air!

BTW, although signal strength is still important for ATSC reception, the most important thing is the bit error rate (BER).  ATSC allows for some correction, but even at 100% signal strength and 34dB S/N, my 3.1 stats for the last 100 minutes I got 600 errors, of which 64 were unrecoverable.  (That's extremely good!)  In contrast, 15.1 has 10359 errors with 4249 corrected, over a similar period of time and signal/SNR.

The bottom line is to let your signal strength and SNR (a.k.a. S/N) be your guide, but make the BER your goal.

[i4tas]

Jam Pro,

Are you using a pc tuner and tsreader for BER and signal information?

[Jam Pro]

Jam Pro,

Are you using a pc tuner and tsreader for BER and signal information?

I'm using a pair of stock (aside from the 1GB HDs) HD TiVo boxes.  That gives me 4 ostensibly identical tuners, and by switching between them I get a statistical average that should negate any manufacturing tolerances or other differences.  At any one time I can get a statistical sample of up to two readings.  But for plotting trends I have as many as four readings.  In other words, if I'm seeing a problem for days or weeks, I can be assured that it's not a flaky tuner, feed line etc. that could be causing false readings.