PCsat2 TELEMETRY/COMMAND/COMMUNICATIONS PROJECT BACKGROUND      18 Nov 02
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Students:           	Midn 1/C Otero, Silver, Jones, Evans, and Henry
Faculty and Staff:	Bob Bruninga (WB4APR), LTCOL Billy Smith
     
MISSION:  The Comm payload for PCsat2 is an opportunity to provide a 
Communications payload in the Amateur Satellite Service that is compatible 
with the objectives of the ARISS Program. 
   
The packet portion of this mission will augment the constellation of other 
similar amateur satellites (PCsat, ISS, MIR, OPAL, Sapphire and SUNSAT)
which have served the amateur community as worldwide packet relays for 
user communications and position/status reporting for educational outreach 
and for remote travelers.  The packet formats permit dozens 
of users per pass to relay individual packets via the satellite.  This 
constellation of satellites, can also augment the existing worldwide 
terrestrial APRS tracking system by providing links from the 90% of the 
earths surface not covered by the terrestrial network.

The PSK-31 COMM transponder similarly provides multi-user access to augment
the ARISS outreach potential.  It uses very narrowband PSK-31 linear uplinks 
on the 10 meter band and an FM downlink on UHF that can be received by
any FM receiver and sound card software on any PC.

BACKGROUND:  Today, most of the US urban amateur population is covered by 
the terrestrial APRS network, BUT the other 80% of the area in most countries
and all of the oceans, third-world and polar regions (95% of the earth's
surface) are void of any digital connectivity.   Schools, distant travelers,
boats at sea, and stations in the rest of the world are presently unable to
use the APRS system as a digital reporting system.  The launch of PCsat in
September 2001 extended this capability worldwide.  The joint ISS/ARISS/PCsat
communications experiments in October 2002 extended this capability and
demonstrated the viability of having more than one satellite suporting
this mission.  Multiple UI digipeaters on the same frequency, will give the 
program reliability and continuity and connectivity more often than a single 
satellite can provide.

FREQUENCY CONSIDERATIONS:  The frequency of 145.825 is already established
for digipeating by the precedence of SUNSAT and PCsat.  Although the
desired downlink is also 145.825, this would cause interference to other
ARISS missions on the ISS and so the primary downlink will need to be on 
the UHF band.  For times when no ARISS voice activity is planned, then
the 145.825 downlink can be activated for dual constellation operations
with PCsat and ANDE.

INTERNET LINKED GROUND STATIONS:  APRS is unique in the way it combines all
packets heard everywhere in the world into a single common internet feed 
channel.   Existing downlink sites need only add a UHF receiver to continue
to bring in downlink data from PECsat.  THus the infrastructure for 
distributing APRS traffic no matter where its source into all other 
stations already exists. 

TECHNICAL INVESTIGATION OF RADIATION EFFECTS ON SOLAR CELLS:  The power
system for PCsat2 on the PEC system consists of a number of high-tech solar
cells.   The space environment effects of radiation on these cells will
be included in the housekeeping telemetry and such investigations are in 
accordance with the objectives of the Amateur Satellite Service.

WB4APR, Bob