I dont know the answer, but I went sniffing earlier when I saw the mention of real beam, and as I understand it, Real beam is a unprocessed real time raw radar return, which has fairly low resolution. Id imagine enough to detect a ship though. Looks like what the Viggen produces Id say.
RBGM is a Real Beam return.
DBS is a Doppler Beam Sharpening
SAR, dont think the APG 73 has this?