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From: | Marcus D. Leech |
Subject: | Re: [Discuss-gnuradio] How to synchronize two transmitters |
Date: | Fri, 27 Jan 2012 13:43:48 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 |
On 27/01/12 01:16 PM, André Selva wrote:
What I think that might be a solution is using only one computer with two USRPs. In the flowgraph, you will have two sinks. If your network card are both identical and the distance between the USRPs are not large enough to be considered, I don't see why the signals would not be syncrhonized (or, at least, very similar to each other).If you have a USRP that can take external synchronization signals (1PPS and 10Mhz clock), then you can use the raw UHD primitives to have transmit streams start at a particular time. You'd first do a "setup" where you'd use set_time_at_next_pps(), and have the two hosts agree on what time to set on the two USRP units. Then both hosts would start a TX stream at a particular time in the future--some point *past* where the set_time_at_next_pps() is set. Or if you run on a single host, you can use a uhd_usrp_sink block with multiple channels--one for each USRP, and set it up for PPS synch, etc. I believe UHD will arrange to time-align all the channels when they're inside a single block. UHD source/sink block can be used to talk to multiple USRP units, and conceptually form a "synchronization domain", when the appropriate synch hardware is in use. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org |
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