[Hackrf-dev] 16-QAM Mod/DeMod problem

[Dominic Spill]

On 13 November 2015 at 08:45, 김상혁 <tkdgur7896 at gmail.com> wrote:
> I tried sending/receiving a text file using 'GMSK Mod' and it worked.
> When I replaced 'GMSK Mod’ to ‘QAM Mod’ (also DeMod), however, it doesn’t
> receive anything.
> My flow graph and result like below:
> freq : 325MHz, samp_rate : 2MHz
> - Tx
> file source(.txt) -> packet encoder(samp/symb: 8, bit/symb: 4) -> 16QAM
> Mod(samp/symb: 8) -> osmocom sink
> - Rx
> osmocom source -> 16QAM DeMod(samp/symb: 8) ->packet decoder -> file sink

I'm not sure that I can help without knowing some more details.  Could
you attach or upload your working and non-working flowgraphs?

> I think two-possible reason
> 1) Tx power limit ; then how can i control Tx power ?

You can control the gain levels in the osmocom_sink block.

> 2) center frequency not clear ; but, i cannot find fine frequency.

On the receiving end you could use gqrx or a flowgraph with a
waterfall plot to find the frequency of the signal.