At first let us appoint the in-phase component of the carrier as phase reference.
Each QPSK symbol assigns a specific phase shift to the carrier wave.
Now let's generate a QPSK signal from a bit sequence.
- Two bits are mapped to a symbol.
- The symbol specifies a phase shift that is imposed on the carrier. For the symbol duration the phase shifted carrier signal is transmitted.
Now it's your turn! Work out the transmit signal for this bit sequence.
- Switch to random bit sequence and see the generated QPSK signal.
- Note that for the signals shown above the carrier frequency has been selected in a way that it fits nicely to the symbol duration. Now change the carrier frequency to any arbitrary value.
1. The bit sequence on the left shall be QPSK modulated. Assign the corresponding transmission signal on the right per drag & drop!
The figure below is the in-phase component of the carrier.