Ten questions on the “indicator” parameters of terrestrial and satellite signals: what they are, how they are measured, what are the optimal values ​​for perfectly receiving television programs in DVB-T / T2 / S / S2 format.Do you have any further doubts?Write to us and our experts will get back to you.There are various “indicator” parameters of the level and quality of reception of DVB-T / T2 and DVB-S / S2 signals.The most important are the signal strength, the C / N (signal to noise ratio), the noise margin, the BER (Bit Error Rate), the cBER, the vBER and the MER (Modulation Error Rate).The technical standards of the sector (Guide CEI 100-7) set a minimum and a maximum value that ensure optimal reception of terrestrial and satellite television channels, but only when the other parameters (C / N, BER, MER, etc.) they are correct.For DTT signals (DVB-T / T2 COFDM) the range is between 47 and 67 dBµV (decibel-microvolt) while for SAT signals (DVB-S / S2 QPSK) it is 47-77 dBµV, with direct measurement at the TV / SAT socket.The choice to establish such a wide range is dictated by the fact that the signal undergoes various attenuations along the path that goes from the antenna (VHF, UHF, LNB parabola) to the home TV socket.These attenuations are generated by the coaxial cable, dividers / diverters, DiSEqC switches and multiswitches.Thanks to this interval, the designer can set an initial optimal value (antenna) near or above the maximum ceiling (see screenshot above) and then calculate "how much signal" will reach the TV sockets at home after the various attenuations.If the “final” value (TV socket) falls within the range with a certain safety margin (eg: 60 dBµV), it means that the designer has done a work to perfection.Conversely, if the final value is close to the minimum limit or, worse, below, during the design, calibration or maintenance phase, you will have to try to keep the initial value higher by increasing the gain of the TV switchboard, replacing it with a more powerful one ( more dBµV output), increasing the diameter of the dish, etc.Absolutely yes.The C / N is the ratio between the carrier and the noise and allows us to understand if the quantity of “useful” signal is sufficiently greater than the noise present.The higher this value (expressed in dB), the better the signal quality.The CEI standards establish a minimum value of 11 dB for DVB-S / S2 and 24 dB for DVB-T / T2.Below this threshold there may be squaring or temporary blocks in the images even if it is good to know that the measured values ​​(and the "limit" ones) may vary by a few decibels depending on the type of modulation (QPSK, 8PSK, 16APSK, 32APSK) and FEC (Forward Error Correction - error detection and correction mechanism - 1/2, 2/3, 3/4, 5/6, etc.).The C / N ratio refers to a single carrier among the 7812 (UHF / COFDM) of the television channel considered because it is calculated after modulation.The S / N (Signal to Noise), often mistakenly equated to C / N, instead refers to all the carriers and is calculated before modulation.The BER (Bit Error Ratio) is a value of fundamental importance in the design and maintenance of a digital reception system.Measures the ratio between the number of incorrect bits arriving at the decoder or television and the total of those transmitted.It is represented in these ways:2 × 10-5 (3 errors every 100,000 bits received)4 × 10-3 (4 errors every 1000 bits received)If the error rate is below a certain limit (<2 × 10-4), i.e. the wrong bits are few compared to total (in our case 2 errors every 10000 received), signal does not undergo any degradation in terms of quality with result that images and sounds will be faithful those encoded at source.ber varies according modulation fec used dvb-t >