-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Pengyu,
could you elaborate on your measurement procedure? What did you send on tx? 46dB attenuation does make sense in a output to input configuration, yet it is "only" about 30dB stronger than what I'd expect of crosstalk. Also: Did you use or bypass the SAW filters? What are the units on your graphs? An average amplitude of 3700 looks strange to me for such a measurement... also: scale! You're using 250px for 1e6 samples, that's 4000 samples per pixel, so if there was but a single sample that would have a high phase deviation, it would look the same as if all of the 4000 samples were phase jumping unceasingly. Anyway, your constellation diagram looks relevant, it shows the typical rotational widening of a constellation point that would appear in a communication receiver due to channel influences, inperfect synchronization and phase jitter. Maybe you should share the software you used to measure this, so that we can get a better understanding of what's happening :) Greetings, Marcus On 10.02.2014 23:18, Pengyu Zhang wrote: > Hi, > > We have tried to measure the phase noise of RFX900 daughter board > when the daughter board is mounted on a USRP 1 mother board. When > we directly connect the TX/RX port to the RX2 port through a 46dB > attenuation signal, we still observe significant amount of phase > noise as shown in the attached figures. Those figures suggest that > the phase noise is about 8 degrees which cannot be tolerated by > many communication systems. Would be great if you guys can provide > some suggestions on reducing the phase of the USRP platform. > > Pengyu > > [image: Inline image 1] > > [image: Inline image 2] > > [image: Inline image 3] > > > > _______________________________________________ Discuss-gnuradio > mailing list Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJS+VdcAAoJEAFxB7BbsDrL6osIAIAteXbMWsiOXn5tcO4D8lq7 xfTy7sMGMhFIiE9cf41AerZZx/D0Nu7dSbDr0xkJsByLN0Xm0+KgGEr5gnGBP0XK 58dZWtsSpQJOo0dS63ko9Eiq7zegXOK5vrSKXYE919FfbM7qEiGL4lXG8WchIGLQ oZbw+0dyoNvLM+1nSleixPrZ9pxK0gTQvYHn6ig7abNaY8qynFeUUgXyk9ik+5fn SJ+CqIVPcAFOzmZSVquHtj7pqRZ33UIR4CvDP+b1ExrBYzaNfuE4l8WeWWjlpFA/ +1IpDDGBXyATyfoNgDPoiJkd/xdKNVuMKgswqDj6XwylQbsUU9P5mTSOysAQGos= =gtrn -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
