On 08/18/2017 11:24 AM, Matheou, Konstantin J. (GRC-LCI0)[ZIN
TECHNOLOGIES INC] via USRP-users wrote:
Thanks for any help…
I ran the example file from Ettus called rx_samples_to_file.cpp.
I ran the file and it did extract a binary file that I named.
When I analyzed it in matlab using the function ‘read_float_binary.m’,
I received much Nan’s and zeros with actual data…
When I ran the function ‘read_cfloat_binary.m’, I received data that
makes sense.. but is it the correct way???
I realize the binary file has complex value that is interleaved….
But when I looked at the code rx_samples_to_file.cpp at the end of it
as shown below…
//recv to file
if (type == "double") recv_to_file<std::complex<double> >(usrp,
uhd::io_type_t::COMPLEX_FLOAT64, file, spb);
else if (type == "float") recv_to_file<std::complex<float> >(usrp,
uhd::io_type_t::COMPLEX_FLOAT32, file, spb);
else if (type == "short") recv_to_file<std::complex<short> >(usrp,
uhd::io_type_t::COMPLEX_INT16, file, spb);
else throw std::runtime_error("Unknown type " + type);
Where is the type defined? I could not find it in the code? Is it in
a header file? I could not find that either…
Each of the UHD examples support a "--help" option. For
rx_samples_to_file, you get:
[INFO] [UHD] linux; GNU C++ version 4.8.3 20140911 (Red Hat 4.8.3-7);
Boost_105400; UHD_4.0.0.rfnoc-devel-239-g89427e8c
UHD RX samples to file Allowed options:
--help help message
--args arg multi uhd device address args
--file arg (=usrp_samples.dat) name of the file to write binary
samples to
--type arg (=short) sample type: double, float, or short
--nsamps arg (=0) total number of samples to receive
--duration arg (=0) total number of seconds to receive
--time arg (DEPRECATED) will go away soon! Use
--duration
instead
--spb arg (=10000) samples per buffer
--rate arg (=1000000) rate of incoming samples
--freq arg (=0) RF center frequency in Hz
--gain arg gain for the RF chain
--ant arg antenna selection
--subdev arg subdevice specification
--bw arg analog frontend filter bandwidth in Hz
--ref arg (=internal) reference source (internal, external,
mimo)
--wirefmt arg (=sc16) wire format (sc8 or sc16)
--setup arg (=1) seconds of setup time
--progress periodically display short-term bandwidth
--stats show average bandwidth on exit
--sizemap track packet size and display
breakdown on
exit
--null run without writing to file
--continue don't abort on a bad packet
--skip-lo skip checking LO lock status
--int-n tune USRP with integer-N tuning
This application streams data from a single channel of a USRP device to
a file.
You can see the default in parenthesis--which in the case of "--type"
defaults to "short".
There is this if then tree within the matlab finction….
It seems that the Int16 was used because ‘short’ was used in the
Matlab complex function as shown below….
if(f < 0)
cv = 0;
else
v = fread (f, count, 'short');
fclose (f);
cv = v(1:2:end)+v(2:2:end)*j;
end
This was the output of the constellation…. Thus, noting was over
+/-32 in the ineger side. Since this kis a 16 bit representation do
we have 10 bits fractional resolution? S5.10 ???
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