Smart Source Selection offers alternatives not available before with diversity combiners and simple best data selectors. It first passes the signals through cutting edge bit synchronizers and then repeatedly compares different signals – dynamically adjusting one signal’s timing to ensure data coherency. Large latencies between diversity streams are accounted for through buffers. ACRA CONTROL’s smart source selection uses an all-digital design utilizing two independent programmable matched filters and PLLs to track deviations in the bitrate of the received signal pair. Multi-stage equalizers are used to compensate for pulse-shape inter-symbol interference while a delay between switching operations eliminates switching noise

The selection of what portions of data to use from each diversity source is based on SNR metrics and the alignment status of each stream. Either a single stream is selected, or multiple steams are added and their polarities used to generate a result. As Smart Source Selection uses soft bit estimates, all possible diversity strategies (polar, frequency, spatial etc.) are supported. Even encrypted diversity signals can be resolved into a single PCM stream. Smart Source Selectors lead to theoretical BER improvements of 3dB with 2 channels, 6dB with four and 9dB with eight. The ACRA CONTROL GTS/DEC/004 employs smart source selection and this technology is being extended to stand alone bit synchronizers for even greater flexibility and improved signal quality.