Hi Imad,
Thanks very much for your reply. Unfortunately that solution does not work.
Because if it reads 4 bytes (two int16_t in C/C++ parlance; <i2 in numpy
world) which for argument sake holds 15, 16 (which are integers). These
are then cast as floats which makes them 15.0 and 16.0 and then when
viewed as np.complex64 becomes 15.0 + 16.0j.
I have had a look at the converters section in the uhd API
(https://github.com/EttusResearch/uhd/tree/master/host/lib/convert) but
can't get my head around the code.
Thanks.
On 06/09/2019 10:26, usrp-users@lists.ettus.com wrote:
Hi Joeal,
You may try something along the lines of:
import numpy as np
def read_from_file(file_name, count=-1):
dt = np.dtype('<i2')
samples = np.fromfile(file_name, dt,
count).astype(np.float32).view(np.complex64)
return samples
So this reads samples as two-byte integers (assuming
little-endianness, hence the '<'), cast them to four-byte floats, and
then view the resulting array as an array of eight-byte I/Q complex
samples.
Imad
On 05/09/2019 22:51, Joeal Subash via USRP-users wrote:
Hi Michael,
I am having to save as ' sc16' because of storage restrictions using
a C++ program. I specifically need details on how to convert 'sc16'
to float. Thanks.
------------------------------------------------------------------------
*From:* michael.dick...@ettus.com <michael.dick...@ettus.com>
*Sent:* 05 September 2019 19:33:46
*To:* Joeal Subash (Electronic, Electrical and Systems Engineering)
*Cc:* USRP list
*Subject:* Re: [USRP-users] sc16 - complex<int16_t> to numpy float
Hi JS - Maybe check out this Python example from UHD <
https://github.com/EttusResearch/uhd/blob/master/host/examples/python/rx_to_file.py >
... it does Rx to file, and can save as NumPy format ... which could
then presumably be easily read back into NumPy. - MLD
On Thu, Sep 5, 2019 at 11:08 AM J Subash via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>> wrote:
Hi,
I am using a B200 to save samples on the host as 'short' (as
described in the uhd <https://github.com/EttusResearch/uhd>/host
<https://github.com/EttusResearch/uhd/tree/master/host>/examples
<https://github.com/EttusResearch/uhd/tree/master/host/examples>/rx_samples_to_file.cpp),
which I believe is complex<int16_t>.
I'd like to import this data into numpy and then convert it into
floating point values. Is sc16 a fixed point representation, if
yes what is the scaling factor. If no, how do I convert it into a
numpy float in Python. Any help would be much appreciated. Thanks.
BW
JS
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Joeal Subash
Research Fellow
Space Environment and Radio Engineering (SERENE) Group
LF04, Mechanical engineering building
University of Birmingham
Edgbaston Birmingham B15 2TT
j.sub...@bham.ac.uk
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