Comparison of various methods for on-line BER measurements in digital radio relay systems

The subject of this paper is practical realization of methods convenient for bit error rates (BER) on-line measuring in digital radio relay systems (DRRS). The final goal is the realization of quasi error-free DRRS (BER<1E-11) by a combined diversity and FEC technique. An experimental system is realized in DRRS IMTEL RRU13/8, where three methods are compared: (i) synchro-word inspection, (ii) parallel channel with smaller signal to noise ratio and (iii) decision window inside eye-pattern.