[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Mobile Satellite Packet Operations made Easy



Satellite Tracking Made Easy.  You can work SUNSAT during about a 3 hour
window Mornings and evenings.  Just visualize its orbit as a north-south
train track in the sky that your QTH passes under about 0350 and 1640
daily local sun time because of the rotation of the earth to the East..*

When the earth brings you within range, you could see 2 or 3 passes
depending on where SUNSAT is in its orbit.  If you see an early LOW pass
to the East, then 100 minutes later, the next pass could be very high
overhead followed by the last one low to the West.  Or you could get the
first one relatively high to the East and then there is only time for one
more 100 minutes later relatively high to your West.  THis graphic
attempts to help you visualize the geometry as if you were facing North.

                                  * <= orbit
MORN          0500           0400 *         0300           0200
EVES         1800           1700  *        1600           1500

ELEV ............................90...................................
     .....................45............45............................
ANGLE..........20..................................20.................
     10....................................................10.........

THREE    o <======100 min======> o <======100 min======> o    PASSES
TWO                  o <=======100 min======> o               PASSES

===> Earth's Rotation to the East ====>

If your mobile uses a 19" whip that has about 8 dBi gain above 30 deg on
the 436.250 MHz downlink, then you will expect to hear SUNSAT once or
maybe twice between about 1550 to 1730.  But since the same antenna gives
you a good 2m uplink above about 10 deg, then you should be able to report
your STATUS/POSIT maybe 2 or three times between about 1500 to 1800

Uplink at 1200 baud on 145.900 or at 9600 baud on 145.825 and check
FINDU.COM to see if you made it in.  SUNSAT dumps all POSITS/STATUS heard
4 times a day to FINDU.COM

NOTES:
1) This graphic only makes sense if you use a FIXED SPACED FONT.
2) TIMES are shown right-to-left due to the rotation of the earth
3) This graphic is drawn for about 40 deg Lat.  The offset between
   MORN and EVES will be less, closer to the Equator
4) The times are correct for about the middle of your time zone.
   Your offset from the center of your zone can change this +/- 30 mins
5) This pattern is moving earlier about 20 minutes a month.

UO-22 is similar.  It's crossings are centered about 0730 and 1830 daily.

de WB4APR@amsat.org, Bob

See APRS SATELLITES       http://web.usna.navy.mil/~bruninga/astars.html







----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home