I gotta say, first, it's very odd that us downtown Portland, OR OTA watchers seem to always have a problem with the SAME channels (KOIN and KATU). I have to wonder if it's a common problem.
My problems are: 1) specifically the degradation and now permanently loss of a viewable signal from KATU - channel 2.1 and 2.1 or UHF 43, 2) the degradation of signal, light during the day, but worse at night of KOIN - channel 6.1 or UHF 40 and 3) the occasional degradation of the signal from UHF channel 47 and 49. In all, the loss and the poor signals seem to be affected largely in the UHF 40 - 43 field and sometimes 44 - 49.
My home is 2 blocks west of I-405 and 1 block north of I-26, nestled in Goose Hollow. My wonderful HD antenna (from Denny's Antenna) is about 20 feet off the ground and pointed at approximately 270 azimuth. This and the following installation description worked wonderfully at installation a year ago, has degraded over the last 6 months and become permanently bad in the last few weeks. So this has been a problem that has slowly evolved - after working perfectly for 6 or more months.
The antenna signal is carried via coax cable (former DirecTV wiring) to a 3 way splitter. There the signal splits as follows: Split 1 goes to an Avermedia video tuner card in my Win7 PC. Split 2 goes to an RCA digital tuner and Split 3 goes to a digital LCD TV.
All 3 receivers found 23 strong channel signals when first installed October 2010.
About six months later, I noted that the RCA digital tuner on Split #2 was starting to have intermittent problems getting a strong signal from KATU (2.1 and 2.2). As this worsened, adding occasional problems with KOIN (6.1), I noted that the digital LCD TV on Split 3 was starting to lose KATU and having problems with KOIN. Eventually Split #2 lost all strength from all three channels causing the tuner to receive no picture, while Split #3 was seeing a worsening of all three channels (always 2.1 and 2.2 first and occasional problems with 6.1)
In the last 4-6 weeks, I have now lost 2.1 and 2.2 permanently on the split #2 and #3 tuners and both have regularly 6.1 problems, worsening at night.
In the last 2 weeks, my Avermedia tuner on Split #1 began having increasing problems with 2.1 and 2.2 and have now lost sufficient signal for a picture, while 6.1 is having regular problems, worsening at night.
Remember, all of these worked fine a year ago and the signal strength problems have steadily worsened to the point that I've permanently lost the picture on the KATU channels.
To begin, I tested the signal strength by removing the splitter. As you'll note below, there was no change to strength or picture quality. This does not appear to be signal loss due to splitting the signal. When feeding the antenna line direct to the Avermedia tuner card neither signal strength nor picture quality improves.
As the Avermedia card (with Windows Media Center) allows me to monitor and scan signal strength for each found channel, I can tell you that the 2.1 and 2.2 channels are coming in with poor strength (3 yellow bars out of five green). The 6.1 channels seems to flit from 4 yellow to 4 green at any given moment.
Okay, laugh. At first I assumed the problem was sun spots. But, the slow degradation resulting in failure makes that very unlikely.
At first, I assumed the problem might be solved with a signal booster. That seems unlikely after testing without the splitter. It's possible that these channels are getting too much signal, but the monitor shows the opposite is true (unless I am seeing the result post high signal interference.)
Yes, there have been a few recent modifications of cabling and WiFi in the house over the last 4 weeks. But, before describing them, please note that this slow degradation and loss was occuring LONG before these changes were made.
I recently replaced Clear WiMAX with Comcast cable internet. The Comcast signal comes in via coax to an outside box (where my 3 way antenna splitter resides) and enters the house via coax to a modem and router connected to the Avermedia PC. I can tell you that when the Comcast cable accidentally made contact with the antenna cable, there was sizable audio interference. But, it makes no contact now and does not affect the other 20 strong channels that the antenna receives.
Yes, I note that RF and WiFi can affect signals, but were the newly installed modem and router affecting the signals (just in this 40-49 range) they would not affect the signals going to Splitter #2 and #3 receivers. All of that antenna signal is outside and away from these WiFi devices. And, as stated earlier, the problems began and worsened long before this change was made.
I have no idea how strong these 3 channel signals are or how easily they are received by nearby metal components. It is possible, I suppose, that the Comcast cable or connection in the box shared with the antenna line and splits could be radiating some kind of added signal that is interfering with the signal split to all 3 receivers. I have not tried removing the Comcast cable to see if signal quality improves. But, the Comcast installer and I were very careful about keeping these two leads (cable and antenna) separated in the box and connected with reasonable cable shield. Well, the splitter is just a little metal box, so i have to count on the integrity of the connections to hope they are grounded. Ah...could added grounding be needed? This is not my area of expertise.
So I am stymied. Dunno what caused the slow loss of these channels. Any advice is greatly appreciated.
