FMCW Transmitter on LimeSDR-USB using LimeSuite API C++

Hey Good people

I am new to LimeSDR and I am trying to transmit a FMCW signal using LimeSuite.h API. defining a chirp signal of different BW doesnt seem to work. I did use LMS_SetLPFBW(…). code is at

I then tried Transmitting a signal cos(2* M_PI * f * t) + jsin(2 MP_I *f *t) where f=10MHz with LO frequency set to 500MHz. I am expecting to see a signal at 510MHz on the Spectrum Analyzer but I am still getting a signal at 500MHz

I recommend first testing your setup in GnuRadio using

Gr-limesdr has all the initialization and calibration code needed.

Also, there is a transmit example “basicTX” included in LimeSuite 18.06.

If you have a LimeSDR-USB that is updated to the firmware in LimeSuite 18.06 and “LimeUtil --find” returned “media=USB 2.0”, then you have run into this issue:
Which means you either downgrade to LimeSuite 18.04 or you find a USB 3.0 connection.