Re: Missing Positive Spectrum

Hi Jay,

On 2/12/21 12:08 AM, Jay Patel wrote:
> I am trying to create an OFDM transmitter using GNU Radio Companion and
> an Analog Devices ADALM-Pluto SDR (attached my *grc file). It looks like
> i am missing something. When i visualize my spectrum, it only have
> negative side, I am expecting both side of spectrum (something like
> attached).

The problem seems to be with your 'Occupied Carriers'. This should be a
vector of vectors of indexes, so I'm assuming that it should be
integers, whereas arange gives you floats.

Try: [list(range(-15, 0)) + list(range(1, 16))]

This results in a symmetric spectrum.

Likewise, the format of the Pilot Carriers should be as a vector of
vector of integers: [[-(ncarrier+1),(ncarrier+1)]]

Note that this puts the pilot carriers quite far away from your main
signal, you may want to use some form of ncarrier//2 there. To actually
see the carrier, use a symbol like [[1,1]] so that there's actually some
energy in them.

The documentation of the block uses () whereas in Python, you need [] to
create a vector.

Disclaimer: I know very little about how OFDM works, but this should
help you make some progress.

Regards, Paul Boven.