And the best part is - there is no excuse for an AC-powered device with a clock to drift at all, ever.
Who needs radio sync signals, NTP servers, or a freaking GPS module (lol) when we have this great hardwired 60 Hz frequency reference which is measured and adjusted for long-term stability...
> Today, AC-power network operators regulate the daily average frequency so that clocks stay within a few seconds of correct time. In practice the nominal frequency is raised or lowered by a specific percentage to maintain synchronization. Over the course of a day, the average frequency is maintained at the nominal value within a few hundred parts per million.[19] In the synchronous grid of Continental Europe, the deviation between network phase time and UTC (based on International Atomic Time) is calculated at 08:00 each day in a control center in Switzerland. The target frequency is then adjusted by up to ±0.01 Hz (±0.02%) from 50 Hz as needed, to ensure a long-term frequency average of exactly 50 Hz × 60 s/min × 60 min/h × 24 h/d = 4320000 cycles per day.[20] In North America, whenever the error exceeds 10 seconds for the east, 3 seconds for Texas, or 2 seconds for the west, a correction of ±0.02 Hz (0.033%) is applied. Time error corrections start and end either on the hour or on the half-hour.[21][22] Efforts to remove the TEC in North America are described at electric clock.
Power outages occur, and you probably want the time to be correct when the power comes back on.
The reason these clocks are so bad is that they use bad RTC units to save a couple dollars. A bad RTC can be had for pennies. A good one (like a DS3231) is $4! Thus, we are all stuck with bad clocks; AC powered or otherwise.
GPS/NTP/WWVB exist to get the time right initially. A clock will be wrong if you set it to the wrong time, even if you have a perfect frequency reference.
This reminds me of one of my favorite historical audio clips. A few minutes before the 1965 Blackout in NYC the power frequency dipped as low as 51Hz (US is 60Hz). Playback equipment with motors setting speed based on the power frequency sllllooowwwweeeeddd down.
Who needs radio sync signals, NTP servers, or a freaking GPS module (lol) when we have this great hardwired 60 Hz frequency reference which is measured and adjusted for long-term stability...
https://en.wikipedia.org/wiki/Utility_frequency#Long-term_st...
> Today, AC-power network operators regulate the daily average frequency so that clocks stay within a few seconds of correct time. In practice the nominal frequency is raised or lowered by a specific percentage to maintain synchronization. Over the course of a day, the average frequency is maintained at the nominal value within a few hundred parts per million.[19] In the synchronous grid of Continental Europe, the deviation between network phase time and UTC (based on International Atomic Time) is calculated at 08:00 each day in a control center in Switzerland. The target frequency is then adjusted by up to ±0.01 Hz (±0.02%) from 50 Hz as needed, to ensure a long-term frequency average of exactly 50 Hz × 60 s/min × 60 min/h × 24 h/d = 4320000 cycles per day.[20] In North America, whenever the error exceeds 10 seconds for the east, 3 seconds for Texas, or 2 seconds for the west, a correction of ±0.02 Hz (0.033%) is applied. Time error corrections start and end either on the hour or on the half-hour.[21][22] Efforts to remove the TEC in North America are described at electric clock.