I’ve been reading this morning about WWVB, the NIST time signal broadcast from Boulder, Colorado.
The data format is…curious: simple BCD encoding, low bit rate – each packet takes a full minute to transmit – and no error detection. I imagine it was very high-tech, sixty years ago; now it seems a bit musty.
My alarm clock relies on the WWVB signal, which means I don’t have to set the time after a power failure; but the clock will accept a garbled signal just as readily as an intact one, and set the time & date to inaccurate (or nonsensical) values.
The other day, I was reading a bit before bedtime, and fell asleep. When I woke up, after what felt like just a few minutes, the clock said 1:58am.
That didn’t feel like a two-hour nap, thought I; but the clock insisted: 1:58am. My other bedside electronics, when queried, claimed 11:58pm, which made more sense. After a while, the alarm clock rectified itself, and all my gizmos agreed once more.
Relying on the WWVB signal to get me out of bed in the morning is a bit reckless. If a run of bad packets should come in just before getting-up time, the alarm might never go off. Or, it could go off at any time during the day or night.
I’ve had this clock for a long time – ten years? fifteen? – and neither of these improbabilities has ever happened. Even so, I worry, and contemplate a more reliable replacement.