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From: | Josh Blum |
Subject: | Re: [Discuss-gnuradio] UHD Announcement - July 6th 2010 |
Date: | Wed, 21 Jul 2010 10:27:36 -0700 |
User-agent: | Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.10) Gecko/20100527 Thunderbird/3.0.5 |
1.5 volts is too low for the pps. You need 5v cmos ideally. It may be possible that the load on the pps is too high. What is the pps level before the splitter? I recommend an active splitter that gives you 5v cmos out.
Since we have narrowed the problem down you can test this with a single usrp2.To debug this, take one usrp2, attach pps and ref with no splitter, modify the examples/rx_timed_example to set the clock config, and set the time at next pps, sleep(1). Readback the time and see if it is expected.
Thank you, -Josh On 07/21/2010 04:54 AM, Zohair wrote:
Dear Josh, I have used another set of 4 USRP2's to test my program. Unlike the error I see when using my old set I receive this output. Current recv sock buff size: 50000000 bytes Current send sock buff size: 50000000 bytes Current recv sock buff size: 50000000 bytes Current send sock buff size: 50000000 bytes Current recv sock buff size: 50000000 bytes Current send sock buff size: 50000000 bytes Current recv sock buff size: 50000000 bytes Current send sock buff size: 50000000 bytes Using: Flex 2400 MIMO B RX (0x0027) Using: Flex 2400 MIMO B TX (0x002b) Using: Flex 2400 MIMO B RX (0x0027) Using: Flex 2400 MIMO B TX (0x002b) Using: Flex 2400 MIMO B RX (0x0027) Using: Flex 2400 MIMO B TX (0x002b) Using: Flex 2400 MIMO B RX (0x0027) Using: Flex 2400 MIMO B TX (0x002b) RX samples per packet: 362 TX samples per packet: 363 Recv pirate num frames: 33967 Set time with unknown pps edge: 1) set times next pps (race condition) 2) catch seconds rollover at pps edge 3) set times next pps (synchronously) Error: time deviation between board 1 and board 0. Board 0 time is 102.881714 seconds. Board 1 time is 102.838705 seconds. Error: time deviation between board 2 and board 0. Board 0 time is 102.883991 seconds. Board 2 time is 102.798313 seconds. Error: time deviation between board 3 and board 0. Board 0 time is 102.889212 seconds. Board 3 time is 102.832728 seconds.DoneThe differnce here is that the program keeps running and I dont receive the "gr_block_executor: source<gr_block uhd mimo source (6)> produced no output. We're marking it DONE." Also, attached are the photos of the clock and the pps signal at the output of the splitters at the input of the USRPs. Any help with this please? I also want to know if my old set of USRPs has a problem. Best regards, Zohair Josh Blum-2 wrote:I pushed some changes to the uhd master that will check the deviation on the times between boards. This should help you to debug your setup. If you see an error message like the following, then you may have an issue with the configuration. In the following example, I disconnected the PPS on one of the boards. This is the result: Set time with unknown pps edge: 1) set times next pps (race condition) 2) catch seconds rollover at pps edge 3) set times next pps (synchronously) Error: time deviation between board 1 and board 0. Board 0 time is 0.008782 seconds. Board 1 time is 65.009945 seconds. gr_block_executor: source<gr_block uhd mimo source (3)> produced no output. We're marking it DONE. -Josh On 07/12/2010 07:14 AM, Zohair M. Abu Shaban wrote:Dear Josh, Thanks for the info provided and the help. I have 4 USRP2 boards, 2 separate function generators and 2 splitters to supply PPS and REF clock with specs as in the FAQ page. For testing only, I used a VRT version of the firmware that my colleague modified to send the REF clock to the debug pins, and I was able to see that the ref clocks are synchronized. I tried to work with 2 channels, 3 channels and 4 channels and wasn't lucky enough to get something working. I am also interested to know if anybody has tried the MIMO block and got it working/not working. Best regards, zohairDate: Fri, 9 Jul 2010 09:18:24 -0700 From: address@hidden To: address@hidden CC: address@hidden Subject: Re: [Discuss-gnuradio] UHD Announcement - July 6th 20103) set times next pps (synchronously) gr_block_executor: source<gr_block uhd mimo source (1)> produced no output. We're marking it DONE.This tells me that the alignment buffer is not finding a common timestamp among the 4 channels or one or more channels is not streaming (perhaps a timestamp/setup issue). What does your setup look like, is there a common pps and common reference split 4X to each usrp2? I forgot to add it to the notes but each device should have a common ref and pps attached to its front panel. Also, can you try to run with just two usrp2 to simplify the problem, does it work with 2 but not 3, 3 but not 4...?Sometimes I also receive these errors that disappear when I power cycle the USRP2's: Error (usrp2 recv pirate loop): bad vrt header or unsupported packet type Error (usrp2 recv pirate loop): assertion failed: if_packet_info.has_tsi and if_packet_info.has_tsf in void usrp2_impl::io_impl::recv_pirate_loop(boost::shared_ptr<uhd::transport::zero_copy_if>, boost::shared_ptr<usrp2_mboard_impl>, size_t) at /home/dave/uhd/host/lib/usrp/usrp2/io_impl.cpp:97Because the previous run did not exit cleanly and stop streaming, the recv loop is catching the middle of a packet from the previous run. This is safe to ignore. -Josh_________________________________________________________________ http://clk.atdmt.com/UKM/go/197222280/direct/01/ We want to hear all your funny, exciting and crazy Hotmail stories. 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