Matt Blaze on Nostr: that would be either NIST’s (formerly NBS’s) WWV on 2.5, 5, 10, 15 and 20 MHz, or ...

that would be either NIST’s (formerly NBS’s) WWV on 2.5, 5, 10, 15 and 20 MHz, or Industry Canada’s CHU, on 3.330 and 7.850 MHz.