Welcome to the built-in stereo decoder. To receive a stereo signal you need a suitable SDR receiver, for example a simple DVB-T dongle with the Realtek RTL2832U chip and a suitable antenna.
The currently active VFO must have BFM (Broadcast-FM) selected with a wide bandwidth, the maximum available is 250kHz (+/- 125kHz).
If you are listening to a stereo transmission you should see a strong peak at 19kHz in the Spectrum window - this is the stereo pilot tone. If the decoder detects this and can lock a phased-lock loop to it the text 'Stereo' will be displayed in the middle of the window.
Don't forget to use the program options to select the correct de-emphasis for your region (just click the cogs icon in the toolbar).
For more information about FM broadcasts and the signal format see Wikipedia, http://en.wikipedia.org/wiki/FM_broadcasting .
Remote
The stereo decoder is not supported when the console is running in network mode (connected to a remote server).
RDS Display
When RDS (in the USA RBDS) is decoded the display is updated:
1.	Program Type
2.	Various:
i.	ST(ereo) or MO(no),
ii.	TP if the transmission carries traffic announcements
iii.	TA if a traffic announcement is being broadcast
iv.	Music or Speech as appropriate, default is Music
1.	Station callsign (RBDS in USA only)
2.	Program Service name (maximum of 8 characters)
3.	Radio text, up to 64 characters

Notes
1.	Select the demodulator which generates the best RDS decoding, you see the RDS data signal on the 57kHz subcarrier in the spectrum display.
2.	if you select both Quadrature and PLL you will see a significant increase in CPU load. PLL uses more CPU than Quadrature.
3.	Forward Error Correction (FEC) is not ennabled for Block A as this generates far too many false decodes. FEC is enabled for blocks B, C and D.
4.	When Partial decoding is enabled only blocks A and B are required to be available. This is enough data for the program identification, extended country code information and station name.
5.	For full RDS information read the European Standard EN 50067.