Hello Mauro, Acked-by: Abylay Ospan <aospan@xxxxxxxx> I have checked values with reference signal from my modulator for DVB-C. Formula is working fine. Thanks ! 2016-07-01 10:03 GMT-04:00 Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>: > Instead of using a relative frequency range, calibrate it to > show the results in dB. The callibration was done getting > samples with a signal generated from -50dBm to -12dBm, > incremented in steps of 0.5 dB, using 3 frequencies: > 175 MHz, 410 MHz and 800 MHz. The modulated signal was > using QAM64, and it was used a linear interpolation of all > the results. > > Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx> > --- > drivers/media/dvb-frontends/cxd2841er.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c > index e2f3ea55897b..6c660761563d 100644 > --- a/drivers/media/dvb-frontends/cxd2841er.c > +++ b/drivers/media/dvb-frontends/cxd2841er.c > @@ -1746,8 +1746,13 @@ static void cxd2841er_read_signal_strength(struct dvb_frontend *fe) > case SYS_DVBC_ANNEX_A: > strength = cxd2841er_read_agc_gain_t_t2(priv, > p->delivery_system); > - p->strength.stat[0].scale = FE_SCALE_RELATIVE; > - p->strength.stat[0].uvalue = strength; > + p->strength.stat[0].scale = FE_SCALE_DECIBEL; > + /* > + * Formula was empirically determinated via linear regression, > + * using frequencies: 175 MHz, 410 MHz and 800 MHz, and a > + * stream modulated with QAM64 > + */ > + p->strength.stat[0].uvalue = ((s32)strength) * 4045 / 1000 - 85224; > break; > case SYS_ISDBT: > strength = 65535 - cxd2841er_read_agc_gain_i( > -- > 2.7.4 > -- Abylay Ospan, NetUP Inc. http://www.netup.tv -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
