Re: [Discuss-gnuradio] Amplitude settings in uhd_siggen

[Martin Braun]

On 02/10/2015 10:15 AM, zealdeal wrote:
> In uhd_siggen_gui tool, u cant set signal amplitude more than 1. Is there any
> reason behind this?
> 
> I commented out the code where the limit checking is done. Then, when I
> increase the amplitude of the transmitted signal beyond 1, I dont see any
> change in amplitude of the recieved signal. What is the cause of this
> restriction?

Like the audio blocks, the UHD blocks normalize float data for 1.0 to be
full scale. So, you want to stay way below 1.0, in all cases. Going
above will cause clipping.

To further increase the signal amplitude, increase the Tx gain. Max Tx
gain can, in some cases, cause distortions but that depends on signal
shape etc. You would be able to see this on a spectrum analyzer
(clipping in particular very obviously distorts the spectrum).

M