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[aprssig] Can we use satellite digipeater for power outage region?

Bob Bruninga bruninga at usna.edu
Sun Mar 13 15:24:03 UTC 2011


Toyo san,

A few more ideas.  It is easy to manually estimate ISS pass times every day once you have heard a pass.  
See: http://aprs.org/MobileLEOtracking.html

1) ISS over Japan today is between about 0830 to 1830 JST.

2) When you hear the first pass, then you will have additional passes every 91 minutes or so that day.

3) Each day a given GOOD pass is 23 minutes later.

4) But overall-long-term pattern is moving earlier every other day by 51 minutes.

5) So in one week from now, the time window will be 0600 to 1600

6)  The pass pattern is the same.  First 2 passes peak to the SE, then NW.  Then a low northern pass, then the last two passes are NE and then SW.

You can get EXACT pass times from http://heavens-above.com and select a city.  However, this web page does not show the 1 or 2 low passes each day below 10 degrees elevation. 

The problem with using the ISS digipeater is that the survivors in the devistated area do not know the frequency (145.825).  One way to solve this is to look for opportunity for someone to take a portable digipeater on an airplane over devistated area.  The new TH-D72 HT can digipeat now!  So have someone with a D72 catch a ride in an aircraft one day.

The D72 can BEACON on 144.64 a MESSAGE BULLETIN with info about the ISS digipeater and the time-window.  WHile it is aloft, it can also act as a digipeater on Japaneese APRS channel 144.64 and can also capture a list of any APRS stations or mobiles on the air.

The short bulletins might say something like this:

TO: BLN1
MSG: ISS Digi on 145.825 between 0830 to 1830

TO: BLN2
MSG: Passes are 6 min long every 91 minutes

TO: BLN3
MSG: Every day, passes are 23 minutes later

TO: BLN4
MSG: Time window moves EARLIER 51m every 2 days

Keep bulletins to under 45 characters to make sure that every radio display can see the full bulletin (D7 screen limit).

But in small area like Japan, I think it might be easier just to try to drive APRS mobile digipeaters to nearby hill tops on 144.64 normal APRS Japanese Frequency and keep everyone on same frequency without confusion.

Bob, WB4APR




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