# [amsat-bb] Re: Easy Predicting GO-32 for the mobile!

Robert Bruninga bruninga at usna.edu
Fri Oct 12 13:08:05 PDT 2007

```OOPS.  The pattern repeats, but the times do not.  So I have
more work to do on how many of these tables are needed or how
each location can compute offsets.  So ignore my assumptiosn
about the 26 degree and 2.6 degree repeats..  But the table does
work for a given area...  Bob

> So All you need on your dash board is this strip of paper.
>
> Day1 Day2 Day3 Day4 Day5 Day6 Day7 Day8 Day9 Day1
> ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
> 0930 0910 1025 1005 0940 0920 1040 1015 0950 0930
>      1050                1055
> 2050 2030 2005 2125 2100 2040 2015 2135 2110 2050
>      2210 2145                2155
>
> For example, today is Day3 in Wash DC.
>
> If you print these in fixed font, it will show you the pass
> times for any day and time zone and location, as long as you
> know what day sequence to be on in your area.  And we can have
> GO-32 send down a table-of-days in its bulletins!  So if you
> ever hear GO32 once, then you will have all you need for
> tracking for the next few months or so for your area!
>
> Initially, I assumed this table would be only for Washington
DC
> (77 deg Longitude) and 40 deg latitude where I calculated it.
> But it should also apply anywhere at this longitude north or
> south and be off by less than 5 minutes or so.
>
> Then I thought we would need a different one for every 5
degrees
> of longitude... But then realized that just as the pattern
> repeats every 10 days in time, it also repeats incrementally
in
> longitude!  Since the longitude increment of GO-32 is about 26
> degrees, that means these multiples of 26 degrees from
> Washington DC will have the same pattern on the same day as we
> do.  And that every 2.6 degrees in between will have an
> additional day offset from ours.
>
> Wow, it can't get any simpler than that for mobiles to know
when
> to use their rigs on GO-32 when traveling in wilderness areas.
> A similar table could be predicted for ECHO (AO-51) maybe.
>
> ELEVATION ANGLE:  To keep the chart simple, I did not include
> max elevations, but that can be added in the final version.
It
> is also easy to infer.  The days with double passes are near
30
> degrees each (barely detectible by the mobile)  The days
midway
> between these lowest peak passes are the highest elevations
(75
> or more degrees).  And you can interpolate inbetween these.
>
> UPLINKS!  The above table gives you only the BEST pass of the
> day for your location (passes above 30 degrees).  This is the
> pass where you can expecet to receive the GO32 downlink on
your
> mobile whip antenna.  HOWEVER, every day, there is a pass
> exactly 100 minutes before and after each of those passes too.
> So now you have 6 chances a day to report your position in the
> wilderness and 2 chances a day to receive any APRS message
> traffic.
>
> Happy wilderness traveling!
> (Oh, and of course, make sure there is someone in your
footprint
> that is SATgating your data into the APRS system so that your
> position and status and any emails get delivered.)...
>
> Bob, WB4APR
>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of
> the author.