Hi,
I am testing my TX which is a MUX based TX for pi/4 DQPSK modulation. I am using an AWG to generate the random binary sequence for the state machine controlling the MUX.
First I tried the sequence so that all phases (0,45,90,...315) get transmitted. The corrs dig seq is 00011011 .
But due to periodicity of this sequence  the output spectrum has narrow lobes.

Then I tried a 2000 bit random sequence but still I have those lobes.

1. What is the standard method of generating sequences for testing TX. If random what should be the length of the sequence?

2. Is there a way to look into the PSD of a random binary sequence? IN MATLAB?