Re: [Discuss-gnuradio] IQ changing with restart
Hi, I've done my homework on this one, crawled through the web talked to colleagues. If I am missing something obvious please point it out - it's not for lack of effort on my part! I'm not really sure what you're expecting. Of course the phase alignement between the Tx and Rx is going to be random depending on restart. Using the same clock will prevent it from drifting, but the initial phase alignement is random. This is usually resolved by using training sequence, headers, differential encoding, ... Cheers, Sylvain ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] IQ changing with restart
On 11.02.2014 06:19, Sylvain Munaut wrote: Hi, I've done my homework on this one, crawled through the web talked to colleagues. If I am missing something obvious please point it out - it's not for lack of effort on my part! I'm not really sure what you're expecting. Of course the phase alignement between the Tx and Rx is going to be random depending on restart. Using the same clock will prevent it from drifting, but the initial phase alignement is random. This is usually resolved by using training sequence, headers, differential encoding, ... I had the same thought -- it looks like a phase change. This is a PSK signal, right? Have you looked at the constellation diagram? MB ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] IQ changing with restart
Is it an over-the-air transmission or TX and RX are connected with a wire and attenuators? -George - George Sklivanitis PhD Student and Research Assistant Signals, Communications, and Networking Research Group Department of Electrical Engineering University at Buffalo, The State University of New York Office: 238 Davis Hall, Buffalo, NY 14260 Web: http://www.buffalo.edu/~gsklivan On Feb 11, 2014, at 11:57 AM, Martin Braun martin.br...@ettus.com wrote: On 11.02.2014 06:19, Sylvain Munaut wrote: Hi, I've done my homework on this one, crawled through the web talked to colleagues. If I am missing something obvious please point it out - it's not for lack of effort on my part! I'm not really sure what you're expecting. Of course the phase alignement between the Tx and Rx is going to be random depending on restart. Using the same clock will prevent it from drifting, but the initial phase alignement is random. This is usually resolved by using training sequence, headers, differential encoding, ... I had the same thought -- it looks like a phase change. This is a PSK signal, right? Have you looked at the constellation diagram? MB ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] IQ changing with restart
On 02/11/2014 11:57 AM, Martin Braun wrote: On 11.02.2014 06:19, Sylvain Munaut wrote: Hi, I've done my homework on this one, crawled through the web talked to colleagues. If I am missing something obvious please point it out - it's not for lack of effort on my part! I'm not really sure what you're expecting. Of course the phase alignement between the Tx and Rx is going to be random depending on restart. Using the same clock will prevent it from drifting, but the initial phase alignement is random. This is usually resolved by using training sequence, headers, differential encoding, ... I had the same thought -- it looks like a phase change. This is a PSK signal, right? Have you looked at the constellation diagram? MB ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio Neither synthesizer will start with any particular phase offset, either. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
