Hello. My task is to make a broadband spectrum analyzer on the usrp b200
board. For this, the standard functions for reading samples in python are
not suitable for me. Therefore, I edited them. When reading samples using
the start_con method, I cannot specify a band greater than 5 MHz.
Therefore, I use the num_sams_and_done method. But I have problems with
him. The fact is that my frequency which I know appears in the wrong place.
For example, I generate a frequency of 910 MHz and it appears at 930 MHz
(with a bandwidth of 20 MHz). I can not understand what caused it. Here are
my reading functions in two ways. I would be extremely grateful for the
help.
def test_reciev(self,freq,bandwich):
complex_buffs=np.array([])
buffs = np.array([])
result = np.empty((len([0]), self.samples), dtype=np.complex64)
for i, freqq in enumerate(freq):
recv_samps = 0
#self.usrp.set_rx_rate(bandwich[i])
k=uhd.types.TuneRequest(freqq)
#k.args(uhd.types.device_addr("mode_n=integer"))
self.usrp.set_rx_freq(k)
self.stream_cmd = uhd.types.StreamCMD(uhd.types.StreamMode.start_cont)
self.stream_cmd.stream_now = True
self.streamer_rx.issue_stream_cmd(self.stream_cmd)
while self.usrp.get_rx_sensor("lo_locked").to_bool() != True:
continue
samps = np.array([], dtype=np.complex64)
while recv_samps < self.samples:
samps = self.streamer_rx.recv(self.recv_buff, self.metadata_rx)
if self.metadata_rx.error_code !=
lib.types.rx_metadata_error_code.none:
print(self.metadata_rx.strerror())
if samps:
real_samps = min(self.samples - recv_samps, samps)
result[:, recv_samps:recv_samps + real_samps] =
self.recv_buff[:, 0:real_samps]
recv_samps += real_samps
#print (self.usrp.get_rx_sensor('rssi'))
#print(self.streamer_rx.get_max_num_samps())
#while samps:
# samps = self.streamer_rx.recv(self.recv_buff, self.metadata_rx)
#self.stream_cmd.time_spec = lib.types.time_spec(0)
self.stream_cmd = lib.types.stream_cmd(lib.types.stream_mode.stop_cont)
self.streamer_rx.issue_stream_cmd(self.stream_cmd)
complex_buffs=np.append(complex_buffs,result).ravel()
#correct_result=result
correct_result_1=result-(np.mean(result.real)+np.mean(result.imag)*1j)
#correct_result.real=result.real-np.mean(result.real)
#correct_result.imag = result.imag - np.mean(result.imag)
PSD = self.fft_test(result)
#PSD[8188:8202]=np.mean(PSD[8180:8188])
buffs = np.append(buffs,PSD)
return complex_buffs,
buffs#np.append(buffs[value.samples:],buffs[:value.samples])
def test_reciev(self,freq,bandwich):
complex_buffs=np.array([])
buffs = np.array([])
result = np.empty((len([0]), self.samples), dtype=np.complex64)
for i, freqq in enumerate(freq):
recv_samps = 0
#self.usrp.set_rx_rate(bandwich[i])
k=uhd.types.TuneRequest(freqq)
#k.args(uhd.types.device_addr("mode_n=integer"))
self.usrp.set_rx_freq(k)
while self.usrp.get_rx_sensor("lo_locked").to_bool() != True:
continue
while recv_samps < self.samples:
samps = self.streamer_rx.recv(self.recv_buff, self.metadata_rx)
if self.metadata_rx.error_code !=
lib.types.rx_metadata_error_code.none:
print(self.metadata_rx.strerror())
if samps:
real_samps = min(self.samples - recv_samps, samps)
result[:, recv_samps:recv_samps + real_samps] =
self.recv_buff[:, 0:real_samps]
recv_samps += real_samps
#print (self.usrp.get_rx_sensor('rssi'))
self.stream_cmd.time_spec = lib.types.time_spec(0)
self.streamer_rx.issue_stream_cmd(self.stream_cmd)
complex_buffs=np.append(complex_buffs,result).ravel()
correct_result=result
correct_result_1=result-(np.mean(result.real)+np.mean(result.imag)*1j)
correct_result.real=result.real-np.mean(result.real)
correct_result.imag = result.imag - np.mean(result.imag)
PSD = self.fft_test(result)
#PSD[8188:8202]=np.mean(PSD[8180:8188])
buffs = np.append(buffs,PSD)
return complex_buffs,
buffs#np.append(buffs[value.samples:],buffs[:value.samples])
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