Hi, I am trying to transmit 2x1 MISO OFDM. The two transmit USRPs are connected by MIMO cable, and the USRP sink section of the .py file is:
self.uhd_usrp_sink_0_0_0 = uhd.usrp_sink( device_addr="addr0=192.168.10.2,addr1=192.168.10.7", stream_args=uhd.stream_args( cpu_format="fc32", otw_format="sc16", channels=range(2), ), ) self.uhd_usrp_sink_0_0_0.set_clock_source("mimo", 1) self.uhd_usrp_sink_0_0_0.set_time_source("mimo", 1) self.uhd_usrp_sink_0_0_0.set_samp_rate(samp_rate) self.uhd_usrp_sink_0_0_0.set_center_freq(uhd.tune_request(center_freq, rf_freq=(center_freq + lo_offset),rf_freq_policy=uhd.tune_request.POLICY_MANUAL), 0) self.uhd_usrp_sink_0_0_0.set_gain(tx_gain, 0) self.uhd_usrp_sink_0_0_0.set_antenna(tx_ant, 0) self.uhd_usrp_sink_0_0_0.set_center_freq(uhd.tune_request(center_freq, rf_freq=(center_freq + lo_offset),rf_freq_policy=uhd.tune_request.POLICY_MANUAL), 1) self.uhd_usrp_sink_0_0_0.set_gain(tx_gain, 1) self.uhd_usrp_sink_0_0_0.set_antenna(tx_ant, 1) At the receiver I sometimes get a very strange response - see attached picture. If I use an external PPS signal, and set sync to 'Unknown PPS', the occurrence of this strange signal - where some parts of the signal seem to just be a noisy sinusoid, is *dramatically* reduced - but not avoided always. Using 'PC Clock' does not improve the situation. Is there something obviously wrong with the way I am trying to transmit over two USRPs simultaneously? I am not clearly why the problem is intermittent. All 3 USRPs are connected two one PC, they are N210s with XCVR2450s, tx gain = 0, rx gain = 0, centre freq = 2.4GHz, samp rate = 1M. Regards, David ________________________________ NOTE: The information in this email and any attachments may be confidential and/or legally privileged. This message may be read, copied and used only by the intended recipient. If you are not the intended recipient, please destroy this message, delete any copies held on your system and notify the sender immediately. Toshiba Research Europe Limited, registered in England and Wales (2519556). Registered Office 208 Cambridge Science Park, Milton Road, Cambridge CB4 0GZ, England. Web: www.toshiba.eu/research/trl Scanned by MailDefender - managed email security from intY - www.maildefender.net
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