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

Re: Satellite Tracking to Alaska



Special Satellite tracking event on AO27

Steve Willey, KD7GXO and Eric Horst, KA7OBN requested APRS assistance in
tracking their vehicle starting Friday from Seattle to north of the Arctic
circle, Prudoe Bay while participating in the ALCAN2000 Alaska Rally from
11 to 19 Feb.  THis is a grueling event in the dark cold of the Arctic
WInter.

In the short time available, the best idea we could come up with was
to suggest using their THD7 Kenwood APRS hand talkies via AO27.  Since
this is a timed event, they will not be able to use handheld beams while
moving in the -50 deg weather, so they will only be transmitting with 5w
into a 2m vehicle whip and probably only once every 30 seconds.

We ask all Satellite capable stations in the Pacific Northwest to listen
for them (and/or their packets) during the daytime AO27 passes from the
11th to the 19th.  Particularly, the Western passes.

RECOMMENDATIONS:  We are NOT asking for dedicated time on AO27.  It is a
popular bird.  All we ask is that if you do hear a packet burst, then set
your watch and try to announce exactly when the next 30 second packet
might be, and clear that 1 second time slot for their weak signal.

1)  NO ONE else should transmit packets AT ALL.  Any other packets will
totally confuse all the rest of us listening.

2) Set PASSALL ON, so that you will capture even garbled packets.  We can
try to post-process these packets later to figure out where they are and
how they are doing.  Post any packets received.  Remember they will look
like 9 bytes or so of gyberish which is the APRS Mic-E compressed mode.
so save ALL packets no matter what they look like.

3) After about the 13th, they will be so far north and west, that only the
last 2 passes of the morning for Seattle will have them in the footprint.
SO point your beam fixed to the northwest and listen.  Also, those
northwestern passes should see much less USA QRM.

The downlink of AO27 starts on 436.805 at the beginning of the pass and
moves down to 436.785 by the end.  A BEAM is required.  These will be
standard 1200 baud AX.25 FM packets.  We hope this test will give us
useful data on the viability of wilderness communications via amateur
satellite.  To learn more, see:

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

Here are some estimated pass ties for the first 5 days:

DATE  PST  UTC  Comments
----  ---- ---- --------
11th  0930 1730
      1105 1905 Best (further from the USA)

12th  1045 1845
      1220 2020 Best (Further from the USA)

13th  1015 1815
      1155 1955 Best (Further from teh USA)

14th  0950 1750
      1125 1925 Best Seattle users beam NW

15th  1058 1858 Best (half way between Fairbanks and Seattle)
      1235 2035      Seattle users beam NW

The western passes of the two are generally better, since they will have
fewer USA stations on the bird at the same time.  Towards the 15th, then I
selected passes over alaska and so Seattle users should just park their
beams toward the NW and only concentrate on listening to those western
passes...

de WB4APR, Bob





----
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