Hi..
I found the mistake which i was doing in digital_bert_tx.py file.
i was always transmitting 1 but after scrambling when we do packing then according to this statement
self._pack = blocks.unpacked_to_packed_bb(self._mod.bits_per_symbol(), gr.GR_MSB_FIRST) in qpsk modulation in place of 1 it will take 2 bits 0 and 1 so in receiver there will be two bits in place of only 1 thats why the error is >10%.
i tried to correct it by replacing self._mod.bits_per_symbol() to a constant 1 both in qpsk and bpsk and calculated BER for both. For bpsk i used bit rate 250kbits/second and for qpsk i used 500kbits/second. By setting these data rates i am getting same SNR for Both but not same BER. Do i need to change any other parameter for qpsk? if any one has any idea about it please tell me.
Best Regards,