On Fri, Jan 29, 2010 at 10:06 PM, Timothy Lawrence Sitorus
<address@hidden> wrote:
Hello All,
I have problems in demodulating code from benchmark qpsk. please help me with answering my question.
1. Why there are no bpsk, qpsk or 8psk in the modulation option ?there are only dbpsk , dqpsk, d8psk.
2. Is there any different synchronization besides gr_mpsk_receiver_cc?
3.I don't know about costas loop in detail, but in my knowledge, this module using modified Muller for the algorithms and I see that this method is just using 1 sample per symbol in recovering symbol timing with mu as a base for correction? am i right? if yes, may i know why they use just 1 sample per symbol?
3. Is this costas loop just for differential modulation ? I have a problem in decoding the qpsk if frequency offset occurs.
* In the transmitter side , I just took of the diff dec . and in the receiver side, I made diff_phasor as a delay detector and recovered it into qpsk based on preamble.
(it works while i am using bencharmark loopback without frequency offset and time error)
4. if no 3 is yes, please help me in solving this problem. I have no idea.
Best Regards,
Tim