Hello , I’m a beginner of the USRP and UHD software. I’m sorry l may deliver my
question unclearly with my broken English.
What I want:
I need to receive the real-time radio signals with a B210 USRP device,
according to my sample rate,I need an external hard disk to achieve at least
245.76MB/s using fc32 in my host. But the USB3.0 hard driver I connecting to
the host only get 180MB/s in write mode. Therefore，I want change the CPU_format
from fc32 to sc16 to decrease the load in the USB3.0 transmission.
What problem I confronted:
I’m not familiar with CPP language, So I choose to drive the B210 with python
API.When I refer to the source code in Github/UHD , I find an example in
/UHD/host/python/usrp.py. It tells me how to initialize a RX streamer and start
receiving samples.These code are
….
st_args = lib.usrp.stream_args("fc32", "sc16”)
….
recv_buffer = np.zeros((len(channels), buffer_samps), dtype=np.complex64)
….
samps = streamer.recv(recv_buffer, metadata)
...
I have some confusion as follow:
1、Must the recv_buffer be the numpy complex array? As far as I know, numpy only
has the dtype complex64 and complex128. If I use the sc16 as the cpu format,
what kind of numpy array should I create to act as the ‘recv_buffer’?
2、I try something workarounds, but I’m not sure the receive data are correct.
First: st_args = lib.usrp.stream_args(“sc16", "sc16”) # I change the CPU
format to sc16
Second: recv_buffer = np.zeros((len(channels), buffer_samps*2),
dtype=np.int16) # I create the array with double size buffer_samps, and
assign the ’np.int16’ to the dtype.
Finally: samps = streamer.recv(recv_buffer, metadata) # receive the data in
the int16 array
I guess the recv() function will return I and Q samples in pairs.I can print
the integer from the array, but cannot confirm the correctness of this ‘method’.
Please give me some suggestions about how to use ’sc16’ in python, I will
appreciate it in advance!!
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