ADDITIONS TO STP PAYLOAD REQUIREMENTS DOCUMENT FOR PCSAT-FOLLOW-ON ------------------------------------------------------------------ Bruninga 16 July 2002 The following items are the suggested additions to the STP Payload Requirements Document for ANDE to support the addition of the active PCsat telemetry/comm system. These listed additions only represent first order additions and not necessarily second order effects that might impact existing wording... 2.1 MISSION OBJECTIVES 2.1.2 Key Mission Objectives * Secondary objective to extend the PCsat educational communications and telemetry mission... 2.2.1 Major Component Descriptions MOCK ANDE ACTIVE SPHERE: 10 kg of primary batteries (2 kg absolute minimum) 1 kg telemetry/comm module 2.2.4 Electrical Interfaces The telemetry/comm system activation mechanism will consist of dual-dual redundant magnetic proximity switches to activate the active payload on separation. 2.3.1 Hardware Subsystems 2.3.1.1 The telemetry/Comm module is a 6"x6"x2" module with three external electrical connectors: * Antenna coax connector * DB-9 Nine pin Battery power connector * DB-15 Fifteen pin telemetry connector 2.3.1.2 Antenna interface circuit board 2"x1"x1" which serves as the matching circuit to couple the XMTR/RCVR to the split-shell of the sphere. 2.3.1.3 Battery box of size 6"x6"x6" full of primary batteries of type (TBD). 2.3.1.4 Telemetry sensors and wiring. There will be six sun sensors and six thermisters attached to the spaceframe sphere and connected to the telemetry module with small wiring. 2.3.2 Software Subsystems. The telemetry/commmand/control and communications subsystem consists of a 68HC11 commercial grade processor operating from ROM. On every power-up, the processor cold boots and executes from factory defaults. Any SEU or other anomolies that cause abnormal operations will be reset on the next 3 minute hardware power cycle. 2.4.1 Operations description 2.4.1 The Telemetry/Command/comm system's primary function is to provide a once every 3 minute worldwide telemetry and to also support command and communications while over a command or user ground station. 2.4.2 Operations Modes. The Telemetry/Command/Comm system will operate in three modes for telemetry, command and control, and user communications support (if available). 2.4.2.1 TELMETRY: Telemetry will consist of a one second telemetry burst once every 3 minutes worldwide. This 0.5% duty cycle is what minimizes primary power drain. All the rest of the time, all electronics including the command receiver will be off except for a master hardware timer which only draws microwatts. 2.4.2.2 COMMAND/CONTROL: There is a 1 second receive window after each telemety packet, when a command station may send a wake up command to activate the system and keep it active for 30 seconds after the last command. During this time any commanding or high rate telemetry may be enabled. 2.4.2.3 COMM SUPPORT: Also during this COMMAND/COMM window, the PCsat style active transponder may be enabled to allow PCsat style packet relay in support of users and other educational or experimental comm needs. 2.4.3 Mission Profile/Timeline Activation: The master hardware timer will be activated by dual-dual redundant magnetic proximity switches on the spacecraft held normally OPEN by magnets embedded in the CAPE foam system. Normal Operations: Normal telemetry will continue throughout the life of the battery system. Commanding will be performed as needed from the primary (USNA) and alternate command sites. User Communications may be enabled over the USA, Europe, Australia, Japan and possible other countries as power budget permits. 2.4.5 Minimum Mission Success Criteria The success criteria for the followon PCsat Telemetry system is the receipt of nominal temperature and spin rate data for ANDE for a minimum of one day after separation. 3.2 Power Requirements 3.2.1 Standby power 0.0 watts 3.2.1 Normal operations. MODE POWER SOURCE PEAK DUTYCYCLE --------------------- ------ ------- ------ --------- Hardware Master Timer .005W 9 Volt .005W 100% Telemetry .025W 9 volt 5W 0.5% Commanding 5/week .005W 9 volt 5W 0.1% MaxUser Load .100W 9 volt 5W 2% Total Average .135W 9 volt 5W 2.7% 3.4.3 Command Requirements Other than those necessary to deploy and sepparate ANDE there are no shuttle/ISS services required by the payload for commanding. But since the Amateur Radio Packet system on the ISS (ARISS)is compatible with the PCsat telemetry command and control system on ANDE, it may be used to monitor the telemetry and or give commands after activation.. 3.4.3.1 Command Interface is RF only at 145.825 MHz. Protocol is 1200 baud AX.25 AFSK tones on a 3 KHz deviation FM carrier. 3.4.3.2 Command data rate is 1200 baud 3.4.3.3 The commmand system can support a serial data stream and 3 or more optional ON/OFF switch closures. Applications of these switches are TBD. 3.4.4 Telemetry Requirements use the same RF channel and protocol as the command system. Telemetry is transmitted once every 3 minutes in a one-second data burst. This telemetry is receivable with any omni antenna ground station within the footprint. 3.6 Orientation and Stabilization Note that the PCsat Command/Control system could be capable of doing some minimum torquing if torquing coils are added to the system. 4.4 Electrmagentic Compatibility 4.4.1 Sensitivity to Radiated emissions. The PCsat follow-on system should not be exposed to RF levels greater than 5 volts per meter in the 140 to 150 MHz band or 20 volts per meter elsewhere. 4.4.2 Sensitivity to Conducted Emissions. Th ePCsat follow-on system should not be exposed to conducted currents between the lower and upper hemispheres of greater than 10 amps average or 100 amps peak. 4.4.3 Sensitivity to magnetic fields. PCsat follow-on system has no restrictions on magnetc fields. 4.9 Radio Frequency Emissions 4.9.1 The PCsat follow-on telemetry/command/control system operates on only one internationally allocated frequency (used by PCsat) of 145.825 MHz. This frequency is pre-approved by the ITU for amateur satellite operations. 4.9.2 Transmit power is 5 watts with a field strength of 32 volts per meter. 4.9.3 Operations are dual-dual inhibited while PCsat is captive within the CAPE system. The first one second transmission will occur within 5 seconds of separation. 7. GROUND OPERATIONS SUPPORT 7.3 Experiment Ground Support Equipment. During all test and integration phases, the PCsat follow-on telemetry/command and communications system may be supported by a single suitcase portable command system and laptop PC. 7.5 Ground Support Facilities. The US Naval Academy Satellite Ground station will be the primary command and telemetry station. Additional telemetry ground station receivers are currently active in several countries providing live downlink data via the internet. As a follow-on PCsat style teleletry system, these stations are in place and will remain active and continue to provide worldwide telemetry data. Additionally, Amateur Satellite Users worldwide will be able to use the bent-pipe AX.25 transponder when power budget permits. Such users and ground support equipment are in place.