Hi Andy, Returning to the original thread...
Andy Walls wrote: > On Sat, 2009-04-18 at 02:10 -0400, faginbagin wrote: >> Hi Andy, >> >> First, I thought you might be interested in some testing I've done. I >> configured my card to match yours, i.e. standard, bit rates, stream >> type. And I still had static on channel 29. Then I ran through all the >> cable channels and tried to quantify the levels of static I heard on >> each station. It's subjective and I want to repeat it, and spend a >> little more time on each channel, because sometimes the longer I stay >> with a channel, there's a chance the static will clear up to some >> degree. Anyway, here are my notes from my first pass: >> >> No sound on 18, 41 >> Static not noticeable on 2, 3, 5, 16, 17, 20, 21, 54, 56, 59, 60, 61, >> 62, 63, 64, 65, 66, 67, 68, 69, 70, 81, 82, 83, 84 >> Not noticeable on 22 (although ivtv-tune did not report "Signal detected") > > Channel 22 is at 169.25 MHz which is the last channel freq at the high > end of the Low-VHF preselector filter in the tuner. It might be getting > knocked down by this preselector filter a little, compared to other > cable channels in the the Low-VHF range (2-6, 95-99, and 14-21). > > >> Slight on 23, 25, 56, 57, 87 >> Some on 4, 7, 8, 10, 11, 13, 14, 15, 24, 26, 27, 33, 34, 41, 43, 46, 47, >> 49, 51, 52, 53, 55 >> Annoying on 6, 29, 30, 31, 32, 36, 37, 38, 40, 42, 58 >> Not noticeable to annoying on 19 changed with image and/or speaker >> Really annoying to annoying on 12, 28 changed with image >> No sound to really annoying to annoying on 35 >> White noise & video on 39, 71-80, 85, 86, 88-116, 118-125, same on TV >> (no signal detected by ivtv-tune) > > What do you mean here? Sound is "white noise" but the video is > viewable? Is the video clear or very snowy? Both sound and video were "white noise" > Also, a separate TV set is exhibiting the exact same symptoms? Yes. IOW, these are channels that my cable company doesn't provide at my level of service, although I think I should be getting a couple of these channels, but maybe I'm wrong. I don't care about them, they're shopping channels, so it's not worth pursuing. > >> I should get 39 (HSN), 85 (JWLTV), 95 (TBN), 107 (GEMSTV) but not the others >> No sound to really annoying on 44 >> No sound to annoying on 45 >> Really annoying to annoying on 48 >> Really annoying to some on 50 >> No sound on 117 (test pattern) >> >> Hope they make sense. If it will help, I'll put them in a spreadsheet. >> Maybe a subjective scale from 0-4? Here are my definitions: >> >> 0, Not noticeable: I can't hear static at normal volume >> 1, Slight: I might not notice it if I weren't listening for it. >> 2, Some: I notice it, but it's lower than the other sounds. >> 3, Annoying: About the same volume as other sounds. >> 4, Really annoying: louder than the other sounds. > > Just to confirm, most of your observations are with the HVR-1600 and not > on the PVR-150 or another TV (except where noted)? Yes, only the HVR-1600 is exhibiting these symptoms. I haven't gone through the same process on the PVR-150, but then again, I'm not having a problem with static on the channels I normally record. But, if it helps diagnose what's going on, I can. >>> An unterminated splitter output can cause reflections that show up as >>> elevated noise floor. >> That is a possibility. I don't think we have TVs hooked up to all the >> outputs from the 8 way splitter, although I'm 99% sure they all go to >> one room or another. > > It's a good thing to do. It will improve signal to noise ratio. It > likely won't fix your static problem, but if you had any ghosting (a > faint shifted copy of the same channel on the video) it should help. We do have 7 TVs connected, so there's can only be one unterminated connection off the 8 way splitter. But I need to double check, I think I might have put one of those little terminal caps on the one unused wall jack. >>> You, however, may want to just try bypassing you in line amplifier and >>> seeing if the static goes away. >> I can probably do this as a test, move the computer to the office and >> use the cable modem's unamplified connection. If it works, I'll have to >> go into the attic to effect a more permanent solution. Not something I >> look forward to, it's got this fluffy insulation that gets all over the >> place. > > OK. But you're also taking a number of slitters (and hance loss) out of > the test as well. Each equal 2 way split is > 3dB of loss. Each equal > 4 way split is > 6 dB of loss. Each equal 8 way split is > 9 dB of > loss. Smaller in line amplifiers are ~ 10 dB of gain. The net effect > of moving to that cable modem drop could be a gain of a few dB and not a > loss. Just let me know how the static sounds. I did this test. The results were disappointing. Using the same terminology as my previous test: not noticeable 2, 5, 15, 16, 17, 19. 20, 21, 22, 56, 57, 60, 61, 63, 65, 66, 67, 68, 70, 81, 82, 83, 84, 87 slight 6, 9, 10, 23, 24, 58, 59, 62, 64, 69 some 7. 11, 12, 13, 36, 40, 43, 44, 50, 52 annoying 3, 4, 8, 26, 28, 29, 30, 31, 33, 34, 37, 38, 42, 45, 46, 47, 49, 51 really annoying 27, 32, 34, 41, 48, 53, 54, 55 14 started not noticeable but some static came in & out 18 no sound, but sound on TV 25 no sound for a few seconds, then some static 31 had whiny whistle during moment of silence 39, 71-80, 85-86, 96-116, 118-125 white noise (no signal detected) on TV, too (both video and audio - snowy picture & pure static) 59 no signal detected although static was only slight 95 mostly white noise, really weak video/audio signal 117 test pattern, no audio with slight static > I have that fluffy (cellulose?) insulation as well. Good stuff, but you > never want to open the attic - the stuff goes everywhere. Yep, plus my access panel is in a walk-in closet and I have to put sheets up to protect the clothes. >>>> Hmm, I do have an old Gemini cable box. I think it's 20+ years old. >>>> Would it be a useful data point if I hooked it up to the HVR-1600? >>> Well. We know a cable box will only output on channel 3. There is no >>> chance for intermodulation products and you will also only exercise the >>> low VHF part of the analog tuner. Your problem on channel 29 manifests >>> with the UHF part of the tuner with many channels available. If the >>> static persists with the cable box attached, we'll know it's not a >>> signal problem if one assumes the analog tuner is not defective. >> So it wouldn't be a waste of time, right? > > If the static persists with just a cable box that outputs on channel 3, > the problem is likely a problem in setting up the front end digitzer in > the CX23418 or a defective analog tuner on the HVR-1600. I also did this test, using the cable modem connection, i.e. avoiding the in-line amplifier & 8 way splitter. What I found was when I changed channels on the STB, roughly half the time I got either annoying static or no sound. No sound was more common. It happened across the channel spectrum. I found that if I waited as long as a minute, more often than not, the sound would return, usually with some static, and then clear. And if it started out with static, it would clear after a few seconds. If the sound did not return, I could clear it, either by switching channels on the STB or using ivtv-tune to 4 and then back to 3. I'm really curious to know what you think this means. Could it be evidence of a defective card, or something else? > As another test, you may also want to try this with v4l2-dbg with a > staticy sounding station tuned. It will switch the CX23418 to use the > mono audio out directly from the analog tuner through the CS5345 audio > chip, much like the audio line-in for Svideo or compsitie video-in. If > the static goes away, I'll know it's a CX23418 digitizer front-end > problem: > > # v4l2-dbg -c host0 -g 0x2c72014 > ioctl: VIDIOC_DBG_G_REGISTER > Register 0x02c72014 = 325h (805d 00000011 00100101b) > > # v4l2-dbg -c host0 -s 0x2c72014 0xb05 > Register 0x02c72014 set to 0xb05 > > # v4l2-dbg -c host0 -g 0x2c72014 > ioctl: VIDIOC_DBG_G_REGISTER > Register 0x02c72014 = 305h (773d 00000011 00000101b) > > > Listen for a difference... > > Then change it back: > > > # v4l2-dbg -c host0 -s 0x2c72014 0xb25 > Register 0x02c72014 set to 0xb25 > > # v4l2-dbg -c host0 -g 0x2c72014 > ioctl: VIDIOC_DBG_G_REGISTER > Register 0x02c72014 = 325h (805d 00000011 00100101b) > > These commands use the syntax of the newest v4l2-dbg utility. If you > are using the older one, the command line args are slightly different. > You must have root privleges to use v4l2-dbg. > > FYI, This sequence didn't make static go away for me on channel 32. I will try this, hopefully later tonight. Real life is beckoning. As I mentioned in my reply to the VBI thread, my priority is getting my new machine working. I have promised my sister my old machine, but have been putting her off, in case I need it to troubleshoot the static issue. If using mono audio eliminates the static, then that is something I can live with, IF mythtv lets me do that. If not, I need another plan. Unless you tell me it's a waste of time, I'm thinking what I should do is use that old machine to do a more robust check out of my HVR-1600, namely: - See if I have the same problems using Hauppauge's WinTV application under WinXP. I can't do that with the new computer, because it doesn't have WinXP and I don't see why I should pay M$ for a license I shouldn't need. - If WinTV has the same problem, maybe exchange the card and see if another one works. The one I have is a model 1199, the store also has model 1178s, which are functionally equivalent. I think the 1178s are older than the 1199s, but the odd thing is the store is charging $10 more for them. - If WinTV doesn't have the same problem, then install a newer kernel on this box, probably the same as is on the new computer. The old computer has 2.6.24 (ubuntu hardy 8.04). Then compile & install the same cx18 drivers I've got on the new computer. I'm assuming the new drivers will need, or at least behave better, with a 2.6.28 kernel. And then repeat the same mplayer/ivtv-tune test. - If this configuration allows me to get static free recordings on the old computer, then that suggests something about the new mobo is the problem. Maybe the kernel needs more time to catch up with my new mobo and chipset (ASUS m3n78 PRO with Nvidia 8200 chipset). FWIW, I've already had an inkling that's the case with USB. I tried to set up a wireless USB adapter without success. Linux thinks it's operating at USB 1.1 speeds, although the same device works at 2.0 speeds on my old computer. I worked around this by running ethernet cable into the room, tricky but doable. Does my plan sound reasonable? One implication is that I would be giving my sister the old computer with the HVR-1600, which means that, as of next weekend, I won't be able to help test the cx18 drivers. But if my mobo and linux kernel support for it are the root cause of my problems, then maybe I don't really have the piece parts to make a useful contribution to development of the cx18 drivers. Regards, Helen _______________________________________________ ivtv-users mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-users
