Em Wed, 18 Sep 2013 01:05:20 +0200
Joerg Riechardt <j.riecha...@gmx.de> escreveu:
> 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 */
Instead of commenting, just truncate the value at the DVBv3 stats
function.
> @@ -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;
> }
As, with this patch, C/N will be a properly scaled value, the best
is to add support for DVBv5 stats. With DVBv5 stats, the scale can
be sent to userspace.
> break;
> default:
Regards,
Mauro
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