[Discuss-gnuradio] scope display bug? distortion of sine wave at high frequency

[Milo Wong]

Hi all,

I found sine waves will be terribly distorted when they are generated at relatively high frequency(above 5khz) from signal source in GRC. I set the
sampl_rate of scope sink to 2Ghz(high enough, I think), and there are always
spikes on generated sine wave. This problem is especially distinct when generated
sine wave reaches 20Khz and the waveform displayed on scope sink is
almost "saw wave". There will be nothing to dispaly if I keep on increasing frequency to 1Mhz. Is there anybody who met this problem before? or it
might only be the display problem in GRC? I guess it might be the problem of scope sink which could not achieve that high sweep (sampling) rate even I set it correctly. 

Attached are snapshot of generated sine waves at different frequencies:


Your comments will be very much appreciated.

Thanks,

Milo

5Khz.png
Description: PNG image

10Khz.png
Description: PNG image

20Khz.png
Description: PNG image