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Re: Hiker's Satellite Predictions



Thanks to Steve, WI2W who found the original.  
Here is my revised response.

>>...I will commence a ... trek...I''m looking for a 
>>"trail angel" to... provide me with regular 
>>updates on APRS satellite passes and frequencies
>
>This is a good idea, but failing that, it is also easy to
>keep track of these satellites as long as you have
>a watch on your wrist and a pencil and notepad.

All you need to know is the period of the satellite.

100 minutes: PCsat, and AO-27
 98 minutes: SO-50
 92 minutes: ISS

If you hear a pass of any of them, unless its the 
last one for the day, then you will hear it again one 
period later (or 1 period earlier).  In addition, the
overall pass geometry is moving earlier a fixed
amount each day...

For PCsat  and AO-27:
  - Each pass is 30 minutes earlier each day.
  - Then once a week, ADD 100 minutes for PCsat
  - Once every 3 days add 100 minutes for AO-27
    (At least this works at my latitude.)

For ISS:
  - Each day, the best pass is either 32 minutes later 
    or 62 minutes earlier.  Again, you may hear another 
    one 92 minutes earlier or later  too.. 

If you ever completely lose track, you still generally
know what time of day the satellite comes over.
just turn on your receiver for 90 minutes and during that
time frame and when you DO hear a pass, mark it,
and then apply the above timings to keep on track
again.

I used this while on a 2 week family trip in remote 
areas  of Utah.  By not bringing along a laptop, 
wife never knew I was "playing satellite" while driving 
along.   To get in sync, I just monitored for half a day 
for ISS, and once I heard it, then, a pencil and note 
pad let me estimate passes the rest of the trip.

de WB4APR@amsat.org, Bob
----
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