ARISSat-1 Critical Design Review Orlando, Feb 15, 2010 SDX Module Anthony Monteiro

Feb 15, 2010ARISSat-1 CDR2 Introduction Software Defined Transponder Provides radio signal modulation services Scope –Requirements –Design –Safety Considerations –Verification –Operations –Status

Feb 15, 2010ARISSat-1 CDR3 Requirements Creates radio signals –CW Beacon –FM Audio –BPSK Telemetry (2 formats) –Linear Transponder Sets signal levels Input and Output at 10.7 MHz

ARISSat-1 Band Plan W5DID AA2TX 4-NOV-2009 CW Upper Band Edge FM BPSK FM Transponder Transponder CW Lower Band Edge m Downlink Upper Band Edge Lower Band Edge Transponder Transponder Input cm Uplink FM: Voice announcements, SSTV, Telemetry. CW: Morse code beacon CW1 active with BPSK-400 CW2 active with BPSK-1000 BPSK: Telemetry, Experiment data Transponder: linear, inverting

Feb 15, 2010ARISSat-1 CDR5 Signal Levels SignalIF LevelRF Output CW-16 dBm 0 25 mW FM-6 dBm mW BPSK-10 dBm mW Transponder-9 dBm mW

Feb 15, 2010ARISSat-1 CDR6 ARISSat-1 Radio Architecture 70 cm Receiver 2 m Transmitter SDX 70cm Input 10.7 MHz IF 10.7 MHz IF 2 m Output

Feb 15, 2010ARISSat-1 CDR7 SDX Hardware Architecture I/Q Demodulator A/D I/Q Modulator D/A Digital Processor 10.7 MHz Input 10.7 MHz Output II QQ SPI to IHU

Feb 15, 2010ARISSat-1 CDR8 I/Q Demodulator 10.7 MHz Input 10.7 MHz Quadrature Oscillator A/D 00 90  Double Balanced Mixer Double Balanced Mixer Splitter I Q

Feb 15, 2010ARISSat-1 CDR9 I/Q Modulator 10.7 MHz Output 10.7 MHz Quadrature Oscillator D/A 00 90  Double Balanced Mixer Double Balanced Mixer Combiner I Q

Feb 15, 2010ARISSat-1 CDR10 Digital Processor Microchip PIC32 (MIPS core) 80 MHz clock 512k Program memory 32k RAM On-chip peripherals

Feb 15, 2010ARISSat-1 CDR11 Main Software Loop Wait for CODEC Ready Get Filled Rx Buffer from CODEC Get Empty Tx Buffer from CODEC Get data from IHU Do Digital Signal Processing Put Filled Tx Buffer to CODEC Return Rx Buffer to CODEC

Feb 15, 2010ARISSat-1 CDR12 DSP - CW Beacon 5 ms Exponential Shaper +1/-19 kHz Quadrature Oscillator CW I - Output Q - Output 00 90  Double Balanced Mixer Double Balanced Mixer

Feb 15, 2010ARISSat-1 CDR13 DSP - FM Audio Q-Output 12 kHz Quadrature Oscillator Audio I-Output Phase Modulator Phase Modulator 90  00 3 kHz Low-pass Filter

Feb 15, 2010ARISSat-1 CDR14 DSP - BPSK Bipolar Converter -18 kHz Quadrature Oscillator BPSK Data I - Output Q - Output 00 90  Double Balanced Mixer Double Balanced Mixer Pulse Shaping Filter

Feb 15, 2010ARISSat-1 CDR15 DSP - Linear Transponder 90 degree Phase Shift Delay Equalizer Combiner I Q 16 kHz Low-pass Filter I - Output Q - Output 90 degree Phase Shift Delay Equalizer

Feb 15, 2010ARISSat-1 CDR16 Safety Considerations Part of IHU stack inside IHU enclosure All electronics operate at low voltages and low power Software is mission critical but is not a safety consideration

Feb 15, 2010ARISSat-1 CDR17 Verification IHU+SDX paired testing (10.7 MHz) –Output levels tested –Power Modes tested –Signal generation tested System Tested with RF XCVR (2m / 70 cm) –Signal levels verified at 2m transmitter output –Signal quality checked via outboard receivers –BPSK modulation tested via external demodulator (both formats) –Pass-band checked on Spectrum analyzer –Transponder tested with CW/SSB/FM signals

Feb 15, 2010ARISSat-1 CDR18 Verification (cont.) Flat-Sat Integration Testing –Signal generation verified (2m output) –Still need to test transponder (70cm input) Environmental Testing – not done –Temperature –Vacuum –Vibration

Feb 15, 2010ARISSat-1 CDR19 Operations High power mode; generates CW, BPSK, FM and transponder signals. Low power mode; power cycled by IHU to conserve power. CW, FM, BPSK only. Emergency power mode; power cycled by IHU to conserve power. CW, FM, BPSK only. Ground control can select BPSK-400 or BPSK-1000 modulation.

Feb 15, 2010ARISSat-1 CDR20 Status SDX module design completed Environmental testing not done Need to construct and test flight boards