Symbols out-of-phase result in a high instance of errors.
Here the signal constellation points are close to the ideal.
cause the constellation points to circle around the desired constellation points. An increase in power of the interferers would result in a wider circle. Again, this would also show in an increase in Pre-BER. Interferers would also be present in the spectrum view of your analyser. It’s important to remember that the actual performance of DVB-S2 8PSK transponders is quite robust in the majority DTH and IRS situations. By analysing the constellation and BER we can identify what steps need to be taken to resolve reception issues where they occur.
high number of errors and a set top box would suffer equally. This is often a sign of a low SNR (Signal to Noise Ratio). Compression: When I and Q points appear grouped in unexpected areas, it can indicate errors caused by imbalances. Compression (saturation) can be a cause of imbalance, and this would present itself by the constellation points being pulled inwards away from their optimum points. Here you would also see an increase in Pre-BER (errors before correction). Interferers: Although not typically found satellite transmissions in-band interference can
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CAI Feedback Spring 2024
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