Hi,
I have 2 USRP N200 devices equipped with an SBX daughterboard
each.
I want to build a 1 Tx, 2 Rx system, where everything
is synchronized.
I have an external generator to provide 10MHz ref clock and
PPS input for both USRP devices with equal length cables.
The 1st USRP, with the SBX daughterboard, is both Tx and Rx.
The 2nd
USRP, with the SBX daughterboard, is
just Rx.
Phase synchronization is crucial to my application and thus I
really need to know if I am doing it right or not.
Therefore, I am attaching the following code in Python,
that I use to synchronize the devices and I would like to know
if it's correct or not.
def usrp_init(self):
self.source = [None, None]
self.source[0] = uhd.usrp_source(
device_addr=self.usrp_address_source[0],
stream_args=uhd.stream_args(
cpu_format="fc32",
channels=range(1),
),
)
self.source[1] = uhd.usrp_source(
device_addr=self.usrp_address_source[1],
stream_args=uhd.stream_args(
cpu_format="fc32",
channels=range(1),
),
)
self.sink = uhd.usrp_sink(
device_addr=self.usrp_address_sink,
stream_args=uhd.stream_args(
cpu_format="fc32",
channels=range(1),
),
)
self.source[0].set_clock_source('external', 0);
self.source[0].set_time_source('external', 0);
self.source[0].set_time_unknown_pps(uhd.time_spec())
self.source[0].set_samp_rate(self.adc_rate)
self.source[0].set_gain(self.rx_gain0, 0)
self.source[0].set_antenna("RX2", 0)
self.source[1].set_clock_source('external', 0)
self.source[1].set_time_source('external', 0)
self.source[1].set_time_unknown_pps(uhd.time_spec())
self.source[1].set_samp_rate(self.adc_rate)
self.source[1].set_gain(self.rx_gain1, 0)
self.source[1].set_antenna("RX2", 0)
self.sink.set_clock_source('external', 0);
self.sink.set_time_source('external', 0);
self.sink.set_time_unknown_pps(uhd.time_spec())
self.sink.set_samp_rate(self.dac_rate)
self.sink.set_gain(self.tx_gain, 0)
self.sink.set_antenna("TX/RX", 0)
time.sleep(1)
cmd_time0 = self.source[0].get_time_last_pps()
cmd_time1 = self.source[1].get_time_last_pps()
cmd_time2 = self.sink.get_time_last_pps()
real_seconds0 = uhd.time_spec_t.get_real_secs(cmd_time0)
real_seconds1 = uhd.time_spec_t.get_real_secs(cmd_time1)
real_seconds2 = uhd.time_spec_t.get_real_secs(cmd_time2)
future_real_seconds0 = real_seconds0 + 1
future_real_seconds1 = real_seconds1 + 1
future_real_seconds2 = real_seconds2 + 1
future_cmd_time0 = uhd.time_spec_t(future_real_seconds0)
future_cmd_time1 = uhd.time_spec_t(future_real_seconds1)
future_cmd_time2 = uhd.time_spec_t(future_real_seconds2)
self.source[0].set_command_time(future_cmd_time0)
self.source[1].set_command_time(future_cmd_time1)
self.sink.set_command_time(future_cmd_time2)
self.source[0].set_center_freq(uhd.tune_request(self.freq,0), 0)
self.source[1].set_center_freq(uhd.tune_request(self.freq,0), 0)
self.sink.set_center_freq(uhd.tune_request(self.freq,0),
0)
self.source[0].clear_command_time()
self.source[1].clear_command_time()
self.sink.clear_command_time()
Thanks in advance.
Konstantinos
Your RX streams need to be coming from a SINGLE multi_usrp object,
not separate objects.