QPSK Signal Timing Offset Correction
Correct a fixed symbol timing offset on a noisy QPSK signal by using the Symbol Synchronizer block. The number of symbols output by the Symbol Synchronizer block is variable size. If a fixed size signal is required for downstream processing, you can use a Selector (Simulink) block to convert the Symbol Synchronizer output to a fixed size signal.
The Delay block adds a fixed timing error of 2 samples to the signal at the Raised Cosine Transmit Filter block output. Since the Raised Cosine Transmit Filter block configuration outputs 4 samples per symbol, the timing delay is 0.5 symbols. The output of the symbol synchronizer is converted to a fixed size signal by the Selector block.
To see how the symbol synchronizer improves QPSK symbol resolution, view the constellations of the signal before symbol synchronization, and the variable size and fixed size signals after symbol synchronization.