The website is excellent and may provide something (not yet) about Berck. Also, I will try the British Library.
The Luftmeldkopf at Berck hadn't been operational for long when the action occurred, in fact it is possible it had only been manned a week or so. My impression, gained solely from the nature of the information they were able to pass on to the artillery command posts, is that Berck may have housed a Horchdienst unit and radar/IFF: certainly they were able to distinguish which were the Allied ships attacking the German convoy even when the plots overlapped. It certainly appears that this was done by locking on to the British ships radar transmissions, but I am unfamiliar with what German equipment would have been used for this task so I would be guessing.
By the way, the KM senior staff were very grateful for the help, suggesting that the officer of the watch at Berck, a 'Lt B.', receive official recognition from his superiors for his good work. Was this interservice generousity common? Finding 'Lt B.'s name is high on my list.