ANDE COMMAND AND CONTROL SYSTEM WB4APR --------------------------------------------------------------------- 24 Mar 2004 This Naval Academy command and control system for ANDE has been flight proven on PCsat and PCSAT2 and will provide the following capabilities on orbit with the minimum power requirements suitable for this mission: 1) Routine telemetry every 1 minute when in view of command station 2) Telemetry of 20 analog parameters (4 blocks of 5 each) 3) Three on/off command channels and bidirectional RS-232 channel 4) AX.25 1200 baud compatibilitiy with all existing packet systems and the worldwide internet linked APRS gnd stations on 145.825. 5) PCsat style communications worldwide at low duty cycle 6) Text-to-speech experiment for low-tech communications 7) Reception by student stations with only a whip antenna. 8) Average power requirement of only 0.4W The average power requirement of 0.3 Watts for a mission life of one year can easily be met with the 112 Lithium Primary cells in 28 banks of 4 cells each. The extremely low power budget is met with the following operations plan which does not sacrifice any significant operational functions of the PCsat type mission but achieves a 20 to one power savings. 1) Except for a milliwatt timer, all electronics are off 2) Once every 15 secs for 1.5 secs, the primary TNC and receiver power up. 3) If no packets are heard, the TNC then powers back off. 4) If packets are heard, a 1 min timer holds the system ON. 5) While the TNC and RX are on, the system is fully usable like PCsat. It will send once a minute telemetry, it will respond to a sysop loggon and the ON/OFF BIT commands, and it is also available to users to use as a packet relay. POWER BUDGET: To determine the power budget, the Satellite is assumed to be in view of each command station on 4 passes a day. There are about 6 full time commmand station areas, East USA, West USA, East Europe, West Europe, east Australia and Japan. The satellite may be used in other locations, but the duty cycle will be insignificant to these six. Each such pass is assumed to last 8 minutes. Thus the total access times average to about 120 minutes a day for an 10% dutycycle. All the rest of the time, the TNC/Receiver are only waking up for 1.5 seconds out of every 15 for another 10% duty cycle. The transmitter is assumed to transmit 10 Telemetry packets, 10 overhead packets, and 10 user packets per pass for a total of 30 in 8 minutes. Peak rates for packet are typically 20% transmit dutycycle when in use. Receiver - 35mA @ 12 volts @ 20% = .08 W TNC - 20mA @ 12 volts @ 20% = .04 W XMTR - 500mA @ 12 volts @ 20% of 10% = .12 W Bkup Sys - 55mA @ 12 volts @ 3% = .02 W Timers etc- 5mA @ 12 volts @ 100% = .06 W --------------------------------------------------- Total AVERAGE Power = .32 W This power can be met with 112 Lithium Ion Primary cells an last more than one year. de WB4APR, Bob Bruninga