[DSP-10] A Clock Question

[Lee Scott - AA1YN]

At 11:29 AM 3/12/2006 -0800, you wrote:
>Hello All,
>
>I am in the process of "unifying" the clocks used inside the DSP-10 
>program UHFA.  This is spurred on by wanting to have automatic, precision 
>setting of the clock from a GPS.  I have that part more-or-less under 
>control, but I am seeing complications in the handling of time zones, and 
>particularly daylight time.
>
>First a couple of comments. DOS allows for time zones through the 
>environmental variable TZ, which can be read and applied.  The C routines 
>use this to automatically change the offset for daylight time, if this is 
>specified, i.e., "SET TZ=PST8PDT"
>
>DOS does NOT change the computer time in April and October, it only 
>automatically adjusts for it when computing GMT from local time. If you do 
>not use the DOS command TIME it will be wrong.  Windows (I don't know 
>which versions) allows for automatic time change, if Windows is run.
>
>All of this becomes very simple if the TIME command is set to GMT and the 
>environment is "SET TZ=GMT0"
>With this, the program never checks for daylight time, and, it turns out, 
>all the clock operations can run from a single software time source (the 
>source that has the daylight info does not have fractional seconds, and 
>visa versa).
>
>Tell me what kind of problems running everything in GMT would create for 
>people?  I have always done this, but I know others have used local time 
>in some way.
>
>Many thanks,
>Bob Larkin  W7PUA
>
>PS- It may not be obvious, but internally to UHFA GMT is a must, as it is 
>needed for Moon calculations, Sun calculations, and PUA43 code stirring.

I currently have my old laptop setup for the DSP-10 and it is already set 
to UTC with a 0 time zone adjustment.  When I use windows, it is only for 
some other ham related software and having the PC set to UTC makes life simple.



Lee Scott - AA1YN http://www.aa1yn.com
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