ARRL Satellite Bulletin ARLS002 (2005)

ARLS002 ISS, PC-sat set up for joint packet tests

QST de W1AW  
Space Bulletin 002  ARLS002
From ARRL Headquarters  
Newington, CT  February 3, 2005
To all radio amateurs

ARLS002 ISS, PC-sat set up for joint packet tests

ISS Ham Radio Project Engineer Kenneth Ransom, N5VHO, says the
Amateur Radio on the International Space Station (ARISS) transceiver
has been switched to the PCsat frequency of 145.825 MHz for a few
days to conduct some joint packet operational tests.

''ISS will have several extended periods when the satellites will be
in view of each other,'' he said. ''This will be a temporary move to
take advantage of PCsat being operational due to full sun and the
favorable alignment of orbits between the two spacecraft.''

Ransom says the challenge for Earth stations is to try to relay a
signal through both spacecraft--a double hop. ''Trying to do this via
two space-based satellites is a bit trickier, since they are only in
view of each other for a short time,'' he said. ''The fact that these
satellites also have to deal with Doppler relative to each other
increases the difficulty.''

PCsat controller Bob Bruninga, WB4APR, says both spacecraft will
operate as conventional APRS digipeaters using the alias of WIDE.
''This should double the opportunities for QSOs for the next eight
days and also allow some potential double hops,'' Bruninga commented.

He and Ransom emphasized that Earth stations should only undertake
attended operations and not transmit any beacon any more often than
once a minute. In addition, stations should avoid jamming the
uplink, not conduct any operations after dark and not digipeat via
W3ADO-1. ''If that call sign appears, it means PCsat has reset, and
we only have one orbit to recover or we may lose her.''

Ransom says the ISS should remain on 145.825 MHz until February 10.
''Bottom line,'' he added, ''try to get your packet signal to go
through ISS and then PCSAT--or the other way around--and see if you
can work folks outside of the footprint you are currently in.''