[ivtv-users] PVR-500 w/ Samsung missing channel problem - Fix

Michael Sebastian msebast2 at yahoo.com
Fri Jan 27 18:16:23 CET 2006


Andrew,

I have tried your suggested numbers and they improve things for me.

US Cable channels 7, 19-22, and 55 are now working properly.

But channels 18 and 45 still have static.

I looked at every channel my cable company delivers (2-78, 98, 99) and
these are the only problems I saw. 

I also want to try the change suggested by Charlie (137.25).
I will report tomorrow on how Charlie's numbers work for me.

I agree that anyone testing changes to this code should do a reboot. I
recommend a complete power cycle with a 30 second wait while the power
is off.

Are the Samsung tuners being sold outside the US? I hope someone who is
NOT using us-cable can plese test these code changes on a Samsung
tuner? You should look at every channel both before and after the
change. Please report back on your results.

Thanks,
Michael Sebastian



--- Andrew Dodd <atd7 at cornell.edu> wrote:

> I just got a PVR-500MCE which turned out to have the Samsung tuner
> for which
> support was just added.
> 
> I discovered over the past two days that all of my History Channel
> recordings on
> US cable channel 55 were borked.  I looked on the list, and noticed
> that a lot
> of people were having problems with US Cable channel 55, and US Cable
> channels
> 7 and 19-22.  I managed to confirm that US Cable channels 7 and 19-22
> were also
> not functioning properly for me.
> 
> I dug through tuner.c and a US cable frequency table
> (http://www.jneuhaus.com/fccindex/cablech.html), and discovered the
> following:
> 
> Channel 55 at 409.25 is approx 1 MHz below the 0.4.2 driver's upper
> band switch
> threshold of 410.25 MHz.
> 
> Channels 19-22 and 7 consist of all channels between 145.25 MHz
> (Channel 18) and
> the driver's lower band switch threshold of 175.25.
> 
> Changing the thresholds to 146.75 and 404.25 respectively has fixed
> all problems
> I had with the aforementioned channels.  (See attached patch)  It
> seems that the
> thresholds in the 0.4.2 release were wrong (in the case of the lower
> threshold,
> off by nearly 30 MHz).  The above two thresholds work much better,
> and will
> probably work perfectly for anyone on a standard US Cable channel
> table.  They
> MAY cause problems with people on other channel tables who have a
> channel
> carrier frequency close to those thresholds, as they are not exact. 
> They were
> merely chosen to occur between the highest frequency working channel
> and the
> lowst frequency nonworking channel for each band switch.
> 
> Also, someone made a post to the list indicating problems with fuzzy
> channels on
> the VHF lowband - I suggest rebooting.  It seems that fiddling around
> a lot with
> the drivers (i.e. trying to get it to work initially) can potentially
> put the
> tuner into a wonky state that can't be fixed by simple module
> reloading.  I had
> the same problem on my system initially but haven't seen it at all
> since a
> reboot.> diff -ur ivtv-0.4.2/driver/tuner.c
ivtv-0.4.2-newtuner/driver/tuner.c
> --- ivtv-0.4.2/driver/tuner.c	2006-01-12 13:29:42.000000000 -0500
> +++ ivtv-0.4.2-newtuner/driver/tuner.c	2006-01-26 18:20:54.000000000
> -0500
> @@ -333,7 +333,7 @@
>          { "Philips TD1316 Hybrid Tuner", Philips, PAL,
>            16*160.00,16*442.00,0xa1,0xa2,0xa4,0xc8,623 },
>  	{ "Samsung TCPN 2121P30A", Samsung, NTSC,
> -	  16 * 175.75, 16 * 410.25, 0x01, 0x02, 0x08, 0xce, 732},
> +	  16 * 146.75, 16 * 404.25, 0x01, 0x02, 0x08, 0xce, 732},
>  };
>  
>  #define TUNERS ARRAY_SIZE(tuners)
> > _______________________________________________
> ivtv-users mailing list
> ivtv-users at ivtvdriver.org
> http://ivtvdriver.org/mailman/listinfo/ivtv-users


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