There was a nice short shower earlier and for once synch wasn't lost, and even better I saw it coming and managed to grab an extra few snapshots. The pre-rain snapshot is at 5:31 (was just starting) and one a few minutes later when errors were starting to appear (I also grabbed a SNRperTone in between and it was in between the two i.e. not as bad as the 5:35). This ties in with what I'd seen before with the QLN being significantly higher after the rain, if a resynch happened i.e. the average noise had increased.
Has anyone any idea what could cause this effect?
It sort of looks like crosstalk that lasts for a short period - is there a way another line could cause this? In the past I've lost synch with a margin of 16