On Sun, Jan 25, 2009 at 05:18:56PM -0500, Andy Walls wrote: > ... > My experience is that if reception sucks for an analog channel, digital > stations on a physcial channel freq near that same analog channel freq, > in the same direction, will not be available to you. It is becoming more and more obvious that the (maybe only?) problem is lousy reception. I have taken a couple of small steps and in each case the situation has improved. First, I found a better PS for the UHF pre-amp. The original one had the power pick-up in a 75 Ohm to 300 Ohm transformer, requiring another one to go back to the coax cable. This found a few more channels and improved the signal strength, but still no picture. But scan finally reported some success: scan /usr/share/dvb/atsc/us-ATSC-center-frequencies-8VSB scanning /usr/share/dvb/atsc/us-ATSC-center-frequencies-8VSB using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0' After lots of "tuning failed" and "filter timeout" messages I ended up with this: dumping lists (3 services) [0e03]:653028615:8VSB:0:0:3587 [0004]:653028615:8VSB:0:1194:4 [0003]:653028615:8VSB:0:0:3 Done. > Ground the coax shield, a point on the cable close to the antenna, to > your home's green wire ground - eliminates EMI (in the cable at least) > in the VHF & UHF band from your PC and other household items. (But your > antenna's right there inside to pick it up of course...) This next step resulted in a few more channels being picked up: dumping lists (8 services) [4364]:653028615:8VSB:0:0:17252 [d9ff]:653028615:8VSB:0:0:55807 [ffbf]:653028615:8VSB:0:0:65471 [ffff]:653028615:8VSB:0:0:65535 [c7ff]:653028615:8VSB:0:0:51199 [efff]:653028615:8VSB:0:0:61439 [fff1]:653028615:8VSB:0:0:65521 [bfff]:653028615:8VSB:0:0:49151 Done. Good call! > Also try turning off or turning down the UHF pre-amp to see if you may > be overdirving the Creator's front end (If it's really overdriven, you > may see other analog channels showing up on top of the one you're > watching.) I started the whole process without the UHF pre-amp. I got absolutely nothing then. Unfortunately, mythtv still doesn't display a picture, but at least it's telling me that it can get a "(L__) Partial Lock". Sometimes, it even reports the name of the current program. This is what I get now: 41 WNBC-DT 17% 3.2dB 42 WXPLUS 16% 3.2dB 44 WNBC4.4 16% 3.2dB 51 WNYW-DT 16% 3.2dB 52 WWOR 18% 3.2dB > If you see a herring bone interference pattern on any analog VHF > channel, you likely have a strong FM broadcast interferer in the antenna > beam - set the pre-amp's FM trap to filter him out (if it has an FM > trap). No, no such pattern. Only random noise in the analog channels that make the picture almost invisible behind the noise. I'm actually going to get a Winegard AP-8275 pre-amp. It does have the fm trap just in case. Hopefully the high gain and moving the antenna to the roof will finally allow me to see some hihg definition pictures... > ... > I love MythTV as an end app, but I find it useless as a troubleshooting > tool - too many variables. I agree, but MythTV has been the only app so far that has allowed me to see anything and to control the device to some extent. However... > I like to use the dvb apps (femon, scan, dvbtraffic, etc), ivtv-tune, > v4l2-ctl, and mplayer for troubleshooting. I'm going to keep trying with these tools. Thanks for taking the time to reply. A. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
