Re: [Discuss-gnuradio] Converting complex-short to complex-float with UHD

[Almohanad Fayez]

I want to use COMPLEX_INT16 in hopes of generating non-normalized fixed point data using UHD.  I ultimately want to send this data over to the DSP on the E100, if I receive the data as COMPLEX_FLOAT32 then UHD is performing

fixed-point -> floating point  and I will be performing floating-point -> fixed-point -> floating-point feeding into the FPGA.  Ultimately I want

FPGA ->fixed-point -> DSP -> fixed-point -> FPGA

instead of

FPGA ->fixed-point -> floating-point -> fixed_point -> DSP -> fixed-point -> floating-point -> fixed-point -> FPGA

however in my flowgraph I want to be able to use gr.probe_avg_mag_sqrd() and a scalar multiples before feeding into the DSP and it fails when I use  COMPLEX_INT16 because of data type confusion

al fayez

-----Original Message-----
From: Josh Blum <address@hidden>
To: discuss-gnuradio <address@hidden>
Sent: Mon, Sep 12, 2011 1:18 pm
Subject: Re: [Discuss-gnuradio] Converting complex-short to complex-float with UHD

On 09/12/2011 10:00 AM, Almohanad Fayez wrote:


> 


> I can't seem to find a direct way of typcasting COMPLEX_INT16 using


> gr-uhd as complex_float.  It seems that gnuradio assumes that a


> complex type is composed of floats by default which causes issues


> when I'm using gr-uhd, is there a direct way to do complex_short to


> complex_float conversion or should I just make a custom block for


> that?  thanks.


> 





The output signature for COMPLEX_INT16 is a vector of shorts length 2.


You can covert this to complex float with a vector_to_stream block, and


then a ishort_to_complex block.





BTW, if you want complex floats, it makes way more sense to just use


COMPLEX_FLOAT32. The real use of COMPLEX_INT16 is if you have a block


that produces or consumes complex shorts. Otherwise its just extra overhead.





-josh








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