Re: [Discuss-gnuradio] Constellation Object

[Tom Rondeau]

On Tue, Nov 4, 2014 at 9:11 PM, Richard Bell <address@hidden> wrote:

The symbol map feature of the constellation object doesn't seem to do anything. In fact, you can leave it blank. The index of the constellation points is used to map the complex points to bits. The documentation leads one to believe otherwise. Working as intended?

v/r,

Rich

The symbol map is a list that maps to the constellation points. So constellation_points[i] holds the symbol defined in symbol_map[i]. An easy test to see this working is to take the default Constellation Object in GRC, which is defined for QPSK, and change the map to [0,1,3,3] and notice that the symbol 2 (10b) is missing in the output constellation. Without a symbol map defined, it defaults to it being [0, ..., i-1]. The alternative is to crash or catch that the vector is empty and exit on an error.

There is the Digital Modulation page in the manual that describes these things. If you have suggestions for how to improve them, please send them along:

http://gnuradio.org/doc/doxygen/page_digital.html

Tom