[USRP-users] Late packet and phase issue

Leonard Foxes leonard.foxes at gmail.com
Mon Oct 5 10:58:15 EDT 2015


Hi list,

It's me again.

I use a USRP N210 with WBX daughterboards and loop back cable to connect TX
e RX. I have two problems:


   1. Late packet. I use set_time_now and set_start_time command and after
   few seconds I see some Ls printed.
   2. Phase. Phase offset changes between executions. (I'm trying to use
   set_time_command but nothing changes).

This is my python code about usrp:

self.samp_rate = samp_rate = 500e3
self.USRP_address = USRP_address = "addr=192.168.10.2"
self.tun_freq = tun_freq = 1.45e9
self.tun_gain = tun_gain = 19
self.rx_freq_off = rx_freq_off = 0


self.timeref1= timeref1=time.time()

self.uhd_usrp_TX = uhd.usrp_sink(
        device_addr=USRP_address,
        stream_args=uhd.stream_args(
        cpu_format="fc32",
        channels=range(1),
        ),
        )
self.uhd_usrp_TX.set_samp_rate(samp_rate)
self.uhd_usrp_TX.set_time_now(uhd.time_spec_t(timeref1), 0)
self.uhd_usrp_TX.set_command_time(uhd.time_spec_t(timeref1+0.1), 0)
        self.uhd_usrp_TX.set_center_freq(uhd.tune_request_t(tun_freq), 0)
self.uhd_usrp_TX.clear_command_time()
        self.uhd_usrp_TX.set_gain(tun_gain, 0)
        self.uhd_usrp_TX.set_start_time(uhd.time_spec_t(timeref1+1))


self.uhd_usrp_RX = uhd.usrp_source(
        device_addr=USRP_address,
        stream_args=uhd.stream_args(
        cpu_format="fc32",
        channels=range(1),
        ),
        )


        self.uhd_usrp_RX.set_samp_rate(samp_rate)
self.uhd_usrp_RX.set_time_now(uhd.time_spec_t(timeref1), 0)
self.uhd_usrp_RX.set_command_time(uhd.time_spec_t(timeref1+0.1), 0)
        self.uhd_usrp_RX.set_center_freq(uhd.tune_request_t(tun_freq +
rx_freq_off), 0)
self.uhd_usrp_RX.clear_command_time()
time.sleep(0.15)
        self.uhd_usrp_RX.set_gain(tun_gain, 0)
        self.uhd_usrp_RX.set_start_time(uhd.time_spec_t(timeref1+1))


Any suggestion will be welcome

Thanks in advance,
Leo
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