I mean that different ships are being retrofitted in this same place, each ship taking its turn. It always appears there is one ship in this part of the dock, but they are never the same ship, the ships keep changing.Why keep changing pennant numbers? Are they swapping pennant numbers among ships?
I believe the Type 052Ds are being retrofitted with new equipment, most possibly this on top. Many 052Ds don't have them when they are new and at the time of their commissioning, even some point afterwards. They are also fitted on 054As and has been retrofitted on the 052Cs. This is likely some kind of high speed communication or datalink, and my theory is that it involves cooperative engagement.
Another potential upgrade is a new ESM unit. This has been retrofitted on most of the 052Cs and has appeared on newest 052Ds, but there is still a whole range of earlier 052Ds that still have the older ESM. But I need to see more recent pictures of 052Ds to see if more of these new units are installed.