[Discuss-gnuradio] Continous PSK/ FSK transmitter with discrete data

Dear All,

 I have been playing with the blocks shown in " Guided Tutorial PSK Demodulation" and want to 

implement my own Transmitter/ Receiver pair.

 First I tried to replace the "Random Source" or "File Source" blocks with a "Socket PDU-TCP Server". I observed that modulation happens only when I sent some characters and of course the demodulator could not lock properly and the data sent is not received correctly.

 What I want is a continous transmission (no burst solutions please). Maybe something where the flowgraph generates "0" s if there is no data from the "Socket PDU" and enters a scrambler.

 Which blocks should I use.

 Thank you in advance.