Re: Time ticks on a computer

From: Frank@reednavigation.com
Date: Mon Nov 14 2011 - 06:23:17 UTC

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    Jay, 
    
    I have one other idea that might solve your problem on the cheap. Since it's now clear that you don't need a "perfect" time source for recording observations and this is more for planning observations, you might just want to make your own digital audio recording. You could record an hour of WWV, for example. Or you could make your own: just watch an online synchronized clock (like this one: http://tycho.usno.navy.mil/simpletime.html) or one of the smartphone apps that have been mentioned and announce the time every minute yourself. If you want seconds ticks to go with it, crank up any digital metronome (google "online metronome" ...there are many). Record for an hour (or ten minutes and let it loop), and you're done! Then when you want to use it, you just start the audio file at the top of the hour based on one of those reliable time sources (probably better to include a one minute intro and then pause the audio a few minutes ahead right on the start of the main hour's recor!
     ding then un-pause at the exact start of the hour). Digital audio playback is generally pretty consistent in terms of frequency (and therefore time) but you may have to experiment to find the right device for this. I doubt you would even notice a second of error after an hour of playback. You could even keep this base time announcement track and add a daily satellite events audio track to it. 
    
    Paul, you noted:
    "(phone company network time is useless - it can be close then jump to be 30 seconds off)"
    
    There are many steps involved going from the network to the display on a particular type of phone, but the actual network time is probably very accurate on most mobile phone networks. The real issue is the commercial market for accurate time. Very few users care whether a phone is accurate to better than 30 seconds. Ironically, ten years ago, the time as displayed on mobile phones was frequently exact to less than a second, but today on smartphones, with the devices so busy with other tasks, the exact time is hidden away. Fortunately, there are now various apps that can deliver exact UT (exact enough for satellite observing and other astronomy-related tasks) like the one you mentioned for iOS. And there are two distinct, complementary sources for the exact time: Internet time servers and the GPS network. The former works well when a data connection is available (and cheap), while the latter works well even when there's no network access.
    
    -FER
    
    
    
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