Meglio così almeno mostri loro direttamente il tuo problema, se di problema si tratti, perchè secondo me il segnale in arrivo è accettabile.
@ venue: il 100% come fondo scala non è standard per tutti i ricevitori.
Esiste uno standard che è complesso da interpretare al quale i seguenti produttori di IRD si attengono in quanto compilato insieme a loro:
https://nordig.org/members-org/
tra i quali in qualifica di Associati:
Philips
https://www.philips.com
Vestel
http://www.vestel.com/
e in qualifica di PARTNERS:
LG
http://www.lg.com/dk
Panasonic
http://www.panasonic.eu/
Samsung
http://www.samsung.com
Sony
http://www.sony.com/
TPVision
http://www.tpvision.com/
...estratto dalle NorDig Unified Requirements ver. 3.2.1:
3.4.4.7 Requirements for the signal quality indicator (SQI)
The terrestrial NorDig IRD shall be provided with a signal quality indicator (SQI).
For DVB-T signals the value for the SQI shall be referred to the NorDig IRD RF signal input.
For DVB-T2 signals the value for the SQI shall be referred to a PLP in the received signal at the NorDig IRD RF signal input.
The absolute accuracy of the C/N value shall be of ±1dB for C/N values of 17 dB to 27 dB at the IRD RF signal input.
The signal quality indicator shall have a relative value within a range from 0% to 100% and with a resolution of 1%.
The integration time for the signal quality shall be over a period of 5 seconds.
The signal quality indicator shall be updated regularly once per second.
For DVB-T signals the signal quality indicator (SQI) in [%] shall be calculated according to the following formulas.
SQI = 0 if C/Nrel < -7 dB
SQI = (((C/Nrel -3)/10) + 1) * BER_SQI if -7 dB ≤ C/Nrel < +3 dB
SQI = BER_SQI if C/Nrel ≥ +3 dB
where
C/Nrel is DVB-T mode depended of the relative C/N of the received signal value in [dB] and C/Nrel = C/Nrec - C/NNordigP1 where C/NNordigP1 is the required C/N value in [dB] for the non-hierarchical DVB-T mode in profile 1 defined in Table 3.10 for the hierarchical DVB-T modes, required C/N value in [dB] is specified in Annex B.
C/Nrec is the C/N value in [dB] of the received signal
BER_SQI is calculated with the formula
BER_SQI = 0 if BER >10-3
BER_SQI = 20*LOG10(1/BER)-40 if 10 -7 < BER ≤ 10-3
BER_SQI = 100 if BER ≤ 10-7
where BER is referenced to Bit Error rate after Viterbi and before Reed Solomon decoding.
The integration time for the BER_SQI calculation shall be over a period of 5 seconds.
For DVB-T signals the signal quality indicator (SQI) in [%] shall be calculated for the received PLP according to the following formulas.
SQI = 0 if C/Nrel < -3 dB
SQI = (C/Nrel +3) * BER_SQI if -3 dB ≤ C/Nrel ≤ 3 dB
SQI = 100 if C/Nrel > 3 dB
where
C/Nrel is DVB-T2 mode depended of the relative C/N of the received signal value in [dB] and C/Nrel = C/Nrec - C/NNordigP1 where C/Nrec is the C/N value expressed in [dB] for the entire received DVB-T2 signal.
C/NNordigP1 is the required C/N value in [dB] for the received PLP in DVB-T2 mode independently of the pilot pattern in profile 1 defined in Table 3.11.
BER_SQI is calculated with the formula.
BER_SQI = 0 if BER > 10-4
BER_SQI = (100/15) if 10-7 ≤ BER ≤ 10-4
BER_SQI = (100/6) if BER < 10-7
where BER is referenced to Bit Error rate before BCH for the received PLP.
The integration time for the BER calculation shall be over a period of 5 seconds.
In sintesi, per il DVB-T il Quality Index 100% è per un BER ≤ 10-7 dove il BER è riferito al Bit Error rate post Viterbi e prima della decodifica Reed Solomon.
é possibile che alcuni produttori "secondari" di tuner che non rientrano nell'organizzazione risparmino nella compilazione dell'algoritmo di calcolo e le indicazioni siano a "cacio cavallo".