[time-nuts] NTP Clock suggestions?
Bob Camp
lists at rtty.us
Mon May 27 18:30:25 UTC 2013
Hi
Is there a price shown somewhere on that sheet?
Bob
On May 27, 2013, at 2:23 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
> One more idea: Buy one of those "Atomic Clocks" that run off WWVB. Then
> use time code to modulate a very low power 60KHz radio transmitter. The
> clocks will pick up your signal and sync to it. The clocks run on
> battery power and you don't need wires.
>
> But then I did notice you can buy exactly what you asked for $99.
> /DS%5FTimeDisplays.pdf<http://www.symmetricom.com/media/files/downloads/product-datasheets/DS%5FTimeDisplays.pdf>
>
>
>
>
> On Mon, May 27, 2013 at 9:40 AM, Bob Camp <lists at rtty.us> wrote:
>
>> Hi
>>
>> If you are doing this from scratch today, would you go IRIG or would you
>> go RS-485 for a wall clock? Both will drive more cable than you are likely
>> to have in a house. Both are reasonably noise immune. With RS-485 there's
>> less to do. It's a serial stream like any other bunch of "stuff" into a
>> UART.
>>
>> Some math:
>>
>> YYMMDDHHMMSSCR = 13 ASCII characters. With one check byte it would be 14.
>> A baud rate of 115.4K isn't stretching things on RS-485 or on most UART's
>> these days.
>> Sent it at 7N1 you have 9 bits per character, 126 bits in the message.
>> Message takes a bit over 1 ms.
>>
>> Time it to anywhere in the string and the clock should be within <+/- 2
>> ms. That's better than I can see on a clock. Better yet, time it to the
>> first (or last) character in the string. More or less a 10X improvement.
>> You could also drop the year / month / day if the clock isn't going to use
>> them.
>>
>> Take any of the Arduino (or what ever) LED display boards and drive them
>> with something cheap. I doubt the "clock" end plus the drivers would be
>> over $30. I suspect IRIG would cost a bit more once you got it all worked
>> out.
>>
>> Bob
>>
>> On May 27, 2013, at 11:03 AM, Chris Albertson <albertson.chris at gmail.com>
>> wrote:
>>
>>> I've seen LLCD computer monitors used as clocks. Seems this would be
>>> the perfect use for a Rasbury Pi. and a cheap monitor. $100 or maybe a
>>> low-end Android tablet.
>>>
>>> The way it is more commonly done is you have you computer that is
>>> using NTP produce an IRIG time code. Then there are any number of
>>> commercial clocks and large digital LED displays that will use IRIG.
>>> IRIG displays are not cheap but they sure are easy to find.
>>>
>>> On Mon, May 27, 2013 at 6:29 AM, Miguel Barbosa Gonçalves <m at mbg.pt>
>> wrote:
>>>> Hi!
>>>>
>>>> I was wondering if anyone knows about a not so expensive wall digital
>> clock
>>>> that gets its time from an NTP server...
>>>>
>>>> TIA,
>>>> Miguel
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>>>
>>>
>>>
>>> --
>>>
>>> Chris Albertson
>>> Redondo Beach, California
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>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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