EKB stands for Echostar Knowledge Base. Each DBS MPEG2 transponder typically carries about a dozen standard definition programs, or several dozen audio programs. That is true for both Echostar and DirecTV DBS. DirecTV owns and operates all 32 DBS transponders available at its "core" 101 degree satellite slot. Each transponder broadcasts data within a specified, fixed band that is approximately 30Mz wide.
Not all DirecTV receivers begin their self test on the transponder that was most recently being watched. I think the Hughes "D" series and earlier being the transponder test on the transponder last tested. Maybe even the "E" series as well. I think all of the RCA and Sony begin it on the transponder of the program most recently watched.
Hughes has a neat test feature that many people never find. On all the models up to and including "E", it is called Cable Test. You go to the test screen, move the cursor two clicks to the right and select. It rapidly develops a table displaying the strength of all 32 transponders. On the GAEBO/GCEBO models, I think that feature might actually be called Transponder Test, but I don't have such a receiver handy to check at the moment.
Reversing the polarity of successively numbered transponders broadcast from the same satellite slot allows them to overlap and thus the DBS bandwidth at each satellite slot can be used twice with minimal cross polarization interference. I tend to think of 1, 3, 5 and 7 as adjacent channels, and they are similarly polarized.
Interference from identically numbered transponders broadcasting from what might be called adjacent slots is actually co-channel interference. With digital, circularly polarized signals, the difference in interference from adjacent satellite transponders that are similarly polarized versus from ones with reversed polarity is insignificant, and thus, adjacent circularly polarized DBS satellite slots have the same polarization plan as one another, whereas adjacent, linearly polarized, analog satellites benefit from having reversed or "flipped" polarity plans.