[linux-dvb] Technotrend C-1500 reception

Per Olofsson pelle at dsv.su.se
Mon Nov 26 22:54:07 CET 2007


Hi,

I've also been bitten by the bad reception problem with the Technotrend C-1500
card with the new tuner (TD1316AL/IHP instead of TD1316A/SIHP).

However, I managed to improve the quality of some of my channels by doing this
change:

diff -r 85f583ec85d6 linux/drivers/media/dvb/ttpci/budget-ci.c
--- a/linux/drivers/media/dvb/ttpci/budget-ci.c Sun Nov 25 20:44:20 2007 -0200
+++ b/linux/drivers/media/dvb/ttpci/budget-ci.c Mon Nov 26 22:41:52 2007 +0100
@@ -925,7 +925,7 @@ static int dvbc_philips_tdm1316l_tuner_s
                cp = 6;
                band = 2;
        } else if (tuner_frequency < 620000000) {
-               cp = 3;
+               cp = 7;
                band = 4;
        } else if (tuner_frequency < 830000000) {
                cp = 5;

I have no idea why increasing the charge pump has any effect, but suddenly the
channel unc goes down to a steady zero, and it's watcheable again. This trick
works on several channels on several frequencies (if cp is increased for them
too), but not all. It also seems that low frequency channels worked before.

I'm very new to this, so I would be thankful if someone knowledgable could help
here. I don't understand why the tuner change broke things, or what the "S" in
TD1316A/SIHP stands for. The new charge pump value also doesn't agree with the
TD(M)1300AL spec I found[1], so I don't understand why it improves the signal.

[1] http://www.sacg.com.tw/sacweb/marcom/epaper/images/TD(M)1300AL_revA.pdf

-- 
Pelle




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