> > Date: Tue, 05 May 2009 21:14:37 -0400 > From: Andy Walls <[email protected]> > Subject: Re: [ivtv-users] Is HVR-1600 model 74591 supported by cx18 > driver? > To: User discussion about IVTV <[email protected]> > Message-ID: <[email protected]> > Content-Type: text/plain > > Test all the channels. Especially ones near the VHF-Low/VHF-High > boundary and the VHF-High/UHF boundary. The channel/frequency tables in > the ivtv-tune source can tell you the mapping of cable channels to > frequency. > > The file > > linux/drivers/media/common/tuners/tuner-types.c > > shows that for the FM1236 MK3 tuner, the VHF-Low/VHF-High boundary is > around 160 MHz and the VHF-High/UHF boundary is 442 MHz. > > There is only one other analog/only NTSC tuner in the tuner-types.c file > with a TDA9887: tuner type 46, the TUNER_PANASONIC_VP27. It likely > won't work. Please test tuner type 46 (I suspect it won't work or work > as well). >
Hmm. I finally had a chance to try this. From what I can tell the boundaries are around channels 21-24 and 59-63. What I see is that channels 21 & 22 are fine but 23 & 24 are just snow (25 works ok). However this is expected in my lineup and matches what I see on my PVR-500 tuners. So I don't think that really says anything bad about the HVR-1600 analog. Similarly channel 59 is bad on both PVR-500 and HVR-1600 analog. While channels 60-63 are ok on both. > As a follow up I'm having some issues with the ATSC channels on this > > card (beyond the listings problem I still have posted on the > > mythtv-users list). Occasionally the signal breaks up and/or stutters > > along with audio glitches and pops. > > I have a Core2 E6600 and when I'm playing live ATSC the cpu usage is > > around 44% but it's actually about 2% higher when I'm playing live > > NTSC so I don't think the system is too slow. > > That seems high for NTSC - you (MythTV) must be doing some software > scaling somewhere. mplayer doesn't do software scaling unless you tell > it to. > > You can load the cx18 module with the debug=15 module parameter and look > for "Possibly falling behind" messages to see how respinsive you system > is to CX23418 interrupts. If you get a lot of those messages in the > logs that come with sequence numbers that are close together, you've got > some system level inefficiencies. > I can't repro the 40% utilization now. It's more like 4% so not sure what I saw before. > > > > I thought it might be signal strength so I've cut out as many > > splitters as possible and this card is getting the 2nd cleanest cable > > I have (best goes to cable modem). > > You whole cable plant in your home affects the S/N ratio (e.g. voltage > wave reflections due to impedenace mismatches come back up from the far > end of the cable and can look like noise). > > Please review: > > http://www.ivtvdriver.org/index.php/Howto:Improve_signal_quality > Yep went though that wiki already. > > > > > When I tune an ATSC channel with mythtv it says "Signal 0% | SNR 2.5dB > > | BEXXX | LAM(lock)". The 0% part is what has me worried that I still > > don't have good enough SNR but I haven't poked around enough to figure > > what other people are getting for signal % and SNR? > > Meh. The signal 0% is a known deficiency. I can't remember if it's the > mxl5005s driver or the s5h1409 driver that's reporting junk. The SNR of > about 2.3 dB is what I get for OTA ATSC. LAM(lock) is good. BE (block > errors) should not be increasing, but a fixed non-zero number is OK. > good to know, thanks. So based on my testing I think this is working well for this model of HVR-1600. Anything else you want me to check or is this good to go? thanks Matt
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