The stv090x driver uses the lookup table for signal strength already,
with this patch we use the lookup tables for carrier/noise ratio as well.
This has the advantage, that values for DVB-S and DVB-S2 are now
corresponding, while before they were way off. The values are now
proportional to real carrier/noise ratio, while before they were
corresponding to register values. So now applications are able to give
the user real carrier/noise ratio.
Because the output has to be within 0x0000...0xFFFF the three negative
values for DVB-S2 are omitted. This is no significant loss, because
reception is lost at 7.5 dB already (TT S2-1600, Cine S2), so the
negative values are not really important, and also for DVB-S they don´t
exist.
Signed-off-by: Joerg Riechardt <j.riecha...@gmx.de>
Regards,
Joerg
--- stv090x.c.bak 2013-09-06 20:59:01.132365872 +0200
+++ stv090x.c 2013-09-10 03:21:48.884115191 +0200
@@ -173,9 +173,9 @@
/* DVBS2 C/N Lookup table */
static const struct stv090x_tab stv090x_s2cn_tab[] = {
- { -30, 13348 }, /* -3.0dB */
- { -20, 12640 }, /* -2d.0B */
- { -10, 11883 }, /* -1.0dB */
+// { -30, 13348 }, /* -3.0dB */
+// { -20, 12640 }, /* -2d.0B */
+// { -10, 11883 }, /* -1.0dB */
{ 0, 11101 }, /* -0.0dB */
{ 5, 10718 }, /* 0.5dB */
{ 10, 10339 }, /* 1.0dB */
@@ -3697,9 +3697,10 @@
}
val /= 16;
last = ARRAY_SIZE(stv090x_s2cn_tab) - 1;
- div = stv090x_s2cn_tab[0].read -
- stv090x_s2cn_tab[last].read;
- *cnr = 0xFFFF - ((val * 0xFFFF) / div);
+ div = stv090x_s2cn_tab[last].real -
+ stv090x_s2cn_tab[0].real;
+ val = stv090x_table_lookup(stv090x_s2cn_tab, last, val);
+ *cnr = val * 0xFFFF / div;
}
break;
@@ -3719,9 +3720,10 @@
}
val /= 16;
last = ARRAY_SIZE(stv090x_s1cn_tab) - 1;
- div = stv090x_s1cn_tab[0].read -
- stv090x_s1cn_tab[last].read;
- *cnr = 0xFFFF - ((val * 0xFFFF) / div);
+ div = stv090x_s1cn_tab[last].real -
+ stv090x_s1cn_tab[0].real;
+ val = stv090x_table_lookup(stv090x_s1cn_tab, last, val);
+ *cnr = val * 0xFFFF / div;
}
break;
default:
