<div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Date: Tue, 05 May 2009 21:14:37 -0400<br>
From: Andy Walls <<a href="mailto:awalls@radix.net">awalls@radix.net</a>><br>
Subject: Re: [ivtv-users] Is HVR-1600 model 74591 supported by cx18<br>
driver?<br>
To: User discussion about IVTV <<a href="mailto:ivtv-users@ivtvdriver.org">ivtv-users@ivtvdriver.org</a>><br>
Message-ID: <<a href="mailto:1241572477.3152.73.camel@palomino.walls.org">1241572477.3152.73.camel@palomino.walls.org</a>><br>
Content-Type: text/plain<br>
<br>
Test all the channels. Especially ones near the VHF-Low/VHF-High<br>
boundary and the VHF-High/UHF boundary. The channel/frequency tables in<br>
the ivtv-tune source can tell you the mapping of cable channels to<br>
frequency.<br>
<br>
The file<br>
<br>
linux/drivers/media/common/tuners/tuner-types.c<br>
<br>
shows that for the FM1236 MK3 tuner, the VHF-Low/VHF-High boundary is<br>
around 160 MHz and the VHF-High/UHF boundary is 442 MHz.<br>
<br>
There is only one other analog/only NTSC tuner in the tuner-types.c file<br>
with a TDA9887: tuner type 46, the TUNER_PANASONIC_VP27. It likely<br>
won't work. Please test tuner type 46 (I suspect it won't work or work<br>
as well).<br>
</blockquote><div><br>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.<br>
<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">> As a follow up I'm having some issues with the ATSC channels on this<br>
> card (beyond the listings problem I still have posted on the<br>
> mythtv-users list). Occasionally the signal breaks up and/or stutters<br>
> along with audio glitches and pops.<br>
> I have a Core2 E6600 and when I'm playing live ATSC the cpu usage is<br>
> around 44% but it's actually about 2% higher when I'm playing live<br>
> NTSC so I don't think the system is too slow.<br>
<br>
That seems high for NTSC - you (MythTV) must be doing some software<br>
scaling somewhere. mplayer doesn't do software scaling unless you tell<br>
it to.<br>
<br>
You can load the cx18 module with the debug=15 module parameter and look<br>
for "Possibly falling behind" messages to see how respinsive you system<br>
is to CX23418 interrupts. If you get a lot of those messages in the<br>
logs that come with sequence numbers that are close together, you've got<br>
some system level inefficiencies.<br>
</blockquote><div><br>I can't repro the 40% utilization now. It's more like 4% so not sure what I saw before. <br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
<br>
> I thought it might be signal strength so I've cut out as many<br>
> splitters as possible and this card is getting the 2nd cleanest cable<br>
> I have (best goes to cable modem).<br>
<br>
You whole cable plant in your home affects the S/N ratio (e.g. voltage<br>
wave reflections due to impedenace mismatches come back up from the far<br>
end of the cable and can look like noise).<br>
<br>
Please review:<br>
<br>
<a href="http://www.ivtvdriver.org/index.php/Howto:Improve_signal_quality" target="_blank">http://www.ivtvdriver.org/index.php/Howto:Improve_signal_quality</a><br>
</blockquote><div><br>Yep went though that wiki already.<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
><br>
> When I tune an ATSC channel with mythtv it says "Signal 0% | SNR 2.5dB<br>
> | BEXXX | LAM(lock)". The 0% part is what has me worried that I still<br>
> don't have good enough SNR but I haven't poked around enough to figure<br>
> what other people are getting for signal % and SNR?<br>
<br>
Meh. The signal 0% is a known deficiency. I can't remember if it's the<br>
mxl5005s driver or the s5h1409 driver that's reporting junk. The SNR of<br>
about 2.3 dB is what I get for OTA ATSC. LAM(lock) is good. BE (block<br>
errors) should not be increasing, but a fixed non-zero number is OK.<br>
</blockquote><div>good to know, thanks.<br><br>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? <br><br>thanks<br>Matt <br></div>
</div><br>