I have problem with transmitting IQ data, in all cases, the spectrum looks like this.
The problem occurs both in the control by Matlab and over IIO Scope. (Windows).
The resulting spectrum is identical for sine, QAM, QPSK; same on two PackRF kits.
( IQ signals are from IIO Scope examples - qam16_20M.txt, sinewave_0.6.mat ... )
Spectrum is OK just if is generated CW from internal DDS. Also I try Adalm Pluto kit, and it works without problems with similar IIO Scope settings. Received signal on PackRF looks also all right.
SW on PC - Matlab 2015b, I/O Oscilloscope master-g76b8e59, libiio version : 0.15-c80412c
Firmware on PackRF : Linaro 14.04 (GNU/Linux 4.9.0-04126-gf9739f0-dirty armv7l)
( Firmware on Adalm Pluto : 4.14 )
Please have an idea why it behaves like this?
Screen from ADI IIO Scope v0.9 (acutal ver.) and settings
What is the frequency of the sine wave which you are sending?Can you send the waveform files which you are using?
Thank you for your response. Good question.
file: sinewave_0.6.mat , I and Q part of signal, looks OK, cca Fsin = Fs/(x-1) = 10M / (150-1) = 67.1 kHz (150 is length of sin - pictures below).
So I try sending : Fout = Fc + Fsin = 2300 MHz + 67.1 kHz = 2 300 067 kHz .
Same setup with AdalmPLuto HW works perfect. .. As expectation is. (same file with IQ sin signal)
So it looks like problem in PackRF paltform.
Here is compare transmitting QAM 16 on AdalmPluto and PackRF. QAM 16 is from examples signals in IIO Scope folder. AdalmPLuto works, PackRF not. Bad spectrum from PackRF is same like sinus signal above.
What HDL version are you using?