gadgarra Posted April 9, 2007 Posted April 9, 2007 Has anyone else noticed a degradation in signal quality and strength from the Cairns Bellenden Ker transmitter over the past few weeks? I am experiencing intermittent pixellation and sound dropouts, particularly on WIN, and almost always in the evenings. My setup has not changed for 2 years, but the signal strength meter on my Topfield 5000 is showing a reduced reading, and I have checked all aspects of my antenna and cabling.
alanh Posted April 10, 2007 Posted April 10, 2007 gadgarra, Read Get the Best Reception, Regional Queensland and read the links. If you have a band 3 antenna pointed at Mt Bellenden Ker, then what is 7 Qld (STQ) like as it is on channel 11 and WIN (RTQ) is on channel 12 Is SBS bad as well? High density rain will absorb the signal, so if your set up is not sensitive enough it is likely that channel 12 will be affected most along with SBS. What type of antenna are you using To identify your antenna type look at all 4 pages of Scaled drawing including dimensions on page 1 and what town do you live in? AlanH
gadgarra Posted April 10, 2007 Author Posted April 10, 2007 Alan, thanks for your interest. First let me describe my antenna. It was installed new 7 years ago (pre-digital). It is horizontally polarised, and has 13 elements, although elements 11 and 12 are joined together as a double loop. Dimensions are as follows: Overall length 1135 mm Element lengths, working from end closest to transmitter: Elements 1-8 160 mm Element 9 vertically oriented loop, 270 mm Element 10 285 mm Elements 11 & 12 form a double loop 670 and 885 mm, made out of a single length of tube. Element 13 838 mm. The antenna is roof-mounted and points directly at Bellenden Ker (line of sight) which is 20 km due east of our location. The antenna output feeds via good quality co-ax, (F connectors at all joints) through a Matchmaster 10MM-MA32 amplifier and various splitters to the set. I have just taken some signal strength readings on my Topfield 5000. I’m not sure if you are familiar with this, but you can get a reading of signal level and signal quality for each channel. Here are the stations, with level shown first, then quality Channel 6 (TEN) 80-99% 99% Channel 8 (ABC) 75-99% 99% Channel 11 (Seven) 75-99% 98-99% Channel 12 (WIN) 86-99% 98-99% Channel 29 (SBS) 65-99% 97% When I quote a range for signal level, the resting position is typically at the top end of the range, and then it intermittently drops to a lower level. There are 2 adjustments on my amplifier, Gain control and Slop control. I have tried changing these (in a totally unscientific way) but this has no effect on the Topfield signal level readings. At the time I took the above readings there was no pixellation. As I said in my original post, this typically occurs in the evening or at night. I do not watch SBS much so cannot really comment on its susceptibility to pixellation. Of the other channels, WIN is the worst, and the others about equal, but much less than WIN. The really strange thing is that, as I said, my setup has not changed for 2 years. This problem started quite suddenly about 2-3 weeks ago, and is highly variable, from no pixellation to the point where the picture and sound break up is so bad that the program is unwatchable. Other than time of day, it does not seem to be weather-related, although we have had some particularly strong winds recently. One final point: I just tried bypassing the antenna amplifier. This caused the signal level on all channels to drop to the 60-75% range, but did not cause any pixellation for the 10 minutes or so that I watched. Maybe all this suggests that the fault is in the Topfield receiver? I would much appreciate any suggestions you can make.
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