I misread this statement. I assumed that no retune happens if the freq/rate are the same across restarts (not reboots). Disregard the previous email. [cid:7de6267c-4b73-4777-b7a0-f9fd3b6bb878]
________________________________ From: Eugene Grayver Sent: Tuesday, March 3, 2026 11:36 AM To: usrp-users <[email protected]> Subject: X440 - Phase alignment between two USRPs I have two X440 w/ X4_200 FPGA image. I need to get consistent phase between channels on USRP1 and USRP2 across multiple runs. I must be doing something wrong because I observe consistent phase between channels on any ONE USRP, but not across two. The phase appears to be random between the two on each run. Here's my setup: * Common 10 MHz and 1 PPS * Addr0=192.168.10.2,second_addr0=192.168.11.2,mgmt_addr0=192.168.1.10,addr1=192.168.15.2,second_addr1=192.168.16.2,mgmt_addr1=192.168.1.20,time_source=external,clock_source=external * I modified the 'stock' rx_samples_to_file as follows: * Usrp->set_time_next_pps(uhd::time_spec_t(0.0)); std::this_thread::sleep_for(std::chrono::milliseconds(1000)); * usrp->set_command_time(uhd::time_spec_t(COMMAND_START_S, 0)); // Set the rate, freq, gain, etc std::this_thread::sleep_for(std::chrono::milliseconds(COMMAND_START_S * 1000)); usrp->clear_command_time(); * Each streamer is created in a separate thread * stream_cmd.stream_now = false; // Time was reset to zero before thread was created stream_cmd.time_spec = uhd::time_spec_t(STREAM_START_S, 0); rx_stream->issue_stream_cmd(stream_cmd); What am I missing? I assume commands apply to both USRPs since I create a multi_usrp. Do I need to explicitly specify the motherboard for some of the commands? Eugene Grayver, Ph.D. Principal Engineer 310-336-1274
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