Digital clocks and A/D converters - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: June 01, 2022, 08:32:37 am
content: Most digital clocks have a one minute display resolution. That means that even when set right they can be at timesup to 60 second in error. I propose that all digital clocks should be set with a 30 second offset so they click over at the half of the minute and therefore be only plus or minus 30 seconds max error. Same deal as an A/D converter having a 1/2 LSB offset so it spans either side of any given value. Who is with me?

author: tom66
author_rank: Super Contributor
timestamp: June 01, 2022, 08:55:26 am
content: If the average error is 30 seconds in both cases, who loses from either option?

author: tggzzz
author_rank: Super Contributor
timestamp: June 01, 2022, 09:08:38 am
content: I propose they should all beVetinari clocks.Benefit: that will get people to instinctively understand the difference between precision and accuracy, and that all instruments lie to a greater or lesser extent.Examples:https://entertaininghacks.wordpress.com/2015/02/23/vetinari-digital-clock/

author: BrokenYugo
author_rank: Super Contributor
timestamp: June 01, 2022, 04:05:02 pm
content: All you need to set one of those within a few seconds is a calibrated clock with a seconds readout, I use time.gov or a cell phone. Set the clock a minute or two behind, then advance it to the correct time just as the beginning of the minute comes up on the cal clock and quickly exit set mode.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 01, 2022, 05:28:42 pm
content: I dunno what kind of digital clock you've been using. Many these days display seconds, which can be also set.But even when only the minutes can be set, the non-stupid ones just start at 0 second when you validate the new setting. Meaning you just need to validate the setting when the minute just changes on your reference clock, and there you have an error of only a couple 100s ms, unless your reflexes are compromised.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 01, 2022, 07:07:23 pm
content: Obviously, you are absolutely right. If as accurate as possible timekeeping is of importance to you, and for some weird reason you are limited to using hours:minute clock (for example, the clock is integrated part of some control device, and their designers didn't anticipate the importance of high resolution time, hence did not support setting/displaying seconds), you will need to set the clock to show 12:00 at 11:59:30. This way, you halve the absolute error. Nothing special here, it's the usual rounding rule; nearest neighbor instead of floor function.Butusually, you just choose to have enough resolution so that you can ignore rounding. Even in math where you are usually "supposed" to round results of calculations, this is wasted effort because the effect is so small (and if it matters, you should have added one digit anyway). If you go to the lengths oflookingat the next digit and making a decision based on it, you could just write it down.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 01, 2022, 08:24:51 pm
content: If you're very concerned and don't want to have to bother with setting the right time, use a DCF-77 driven clock (if you're in Europe), or a GPS-based one otherwise. (Dunno if there are equivalents to DCF-77 in other parts of the world?)

author: TimFox
author_rank: Super Contributor
timestamp: June 01, 2022, 08:45:55 pm
content: There are many applications, such as Swiss railroads and network broadcasting, where one needs to do something at the "stroke" of the clock, i.e. the transition from xx:x:59 to xx:(x+1):00.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 05, 2022, 05:52:12 pm
content: In the UK we just used to dial TIM on 123. Its much cooler now its calledtimeline.OMG it still works! That'll cost me.

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 05, 2022, 10:58:43 pm
content: Of course there are clock that can display in seconds too but for clock that can only display down to the minutes I set it so the minute display changes exactly at the 0 second.