[ivtv-users] Is HVR-1600 model 74591 supported by cx18 driver?

[Matt Beadon]

>
> Date: Tue, 05 May 2009 21:14:37 -0400
> From: Andy Walls <awalls at radix.net>
> Subject: Re: [ivtv-users] Is HVR-1600 model 74591 supported by cx18
>        driver?
> To: User discussion about IVTV <ivtv-users at ivtvdriver.org>
> Message-ID: <1241572477.3152.73.camel at palomino.walls.org>
> 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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