| Message ID | 2a0edab5ab7b0e0743b04a64c935d798d3930856.1467381792.git.mchehab@s-opensource.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello Mauro, Acked-by: Abylay Ospan <aospan@netup.ru> 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@s-opensource.com>: > 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@s-opensource.com> > --- > 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 >
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(
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@s-opensource.com> --- drivers/media/dvb-frontends/cxd2841er.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)