This version, 3.11.1, also fixes a surprising (to me) bug that affected users in the UK. As dates and times are in UTC and so is the UK for some reason my date parsing was failing for those users. I'm astonished that I hadn't heard about this before now.
My thanks to Paul, G0DIH, for the bug report and for working with me to test builds until the issue was sorted out.
Here's how the SNR, and other, graphs look now.