Re: [Discuss-gnuradio] about phase sync MIMO X310

[Marcus Müller]

Hi Sanjoy,
On 21.07.2015 00:40, Sanjoy Basak wrote:

Dear Mr. Marcus,

I need some help regarding MIMO phase sync. I asked you previously about the time sync issue for MIMO (2 * 2) on ruby forum.

To say this clear and loud: ruby forum is **NOT** the GNU Radio discuss mailing list. I urge you to not use ruby-forum but to directly write mails to the mailing list.
Ruby forum was never, and will never, be the official way of discussion with the mailing list; GNU Radio and the ruby forum are totally unaffiliated. In fact, it's much less comfortable than e.g. subscribing to the list directly with a gmail account:
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

The time sync worked perfectly after checking the next_pps as you suggested.

That's a good thing to hear!

My problem now is the phase sync between 2 RX signals. According to the concept, if I initiate set_center_freq after timing command, then I am supposed to get time aligned and phase aligned RX signals. Regarding time alignment, I am getting time aligned RX signals. However, I am not really getting any phase alignment.

The question whether the phase differences will be static depends on your daughterboard, as explained in
http://files.ettus.com/manual/page_sync.html#sync_phase

This is how I defined for 2 TX 2RX where TXs are on GPSDO and RXs are on external ref.

self.usrp_source0.set_time_next_pps(uhd.time_spec_t(0.0))

self.usrp_sink0.set_time_next_pps(uhd.time_spec_t(0.0))

Sanjoy, I told you *three* times now to get rid of all the "set_time_*" calls. I'm getting a little tired of telling you to remove these lines. You use the time coming from the GPSDO automatically.

now = self.usrp_source0.get_time_now()

starttime = now + uhd.time_spec(1.5)

self.usrp_source0.set_start_time(starttime)

I've told you in my last mail to use set_command_time(). You didn't. You have to!

        self.usrp_source0.set_center_freq(f, 0)

        self.usrp_source0.set_center_freq(f, 1)

self.usrp_sink0.set_start_time(starttime)

the same :)

        self.usrp_sink0.set_center_freq(f, 0)

        self.usrp_sink0.set_center_freq(f, 1)

Could you please tell me what exactly is going wrong or what is the mistake? I am not really understanding why this should not work.

You're not following clear advice. Please carefully read my last emails, and my responses on StackOverflow.
I think this might actually happen because instead of using the mailing list with your email address, you, for some reason, use ruby forum's html mirror. It's really not good. don't do that.


Best regards,
Marcus