coms transceiver – rf datatech lrt470 frequency: 432-442mhz operation: half-duplex max. rf...
TRANSCRIPT
COMS
Transceiver – RF DataTech LRT470
Frequency: 432-442MHz
Operation: Half-Duplex
Max. RF Transmit Power: 750mW
Typical Power Draw at 750mW RF: 3.5W
Bandwidth: ≤ 25kHz
Modem – PIC 16C711 from RF DataTech
Modulation: 4800bps GMSK
Summer Review6th Aug. 2008
SRCSPACE ACADEMY
Architecture
Link Budget
Tx Power (mW) Rx Antenna Gain (dB) Bit Rate (bits/s) Ebno (dB)750 20.00 9600 41.47
Down-Link
Ebno required = 9.6 dB for a bit error rate of 10-5
[Jan_King_Calculator.xls; http://cubesat.wikidot.com/local--files/amsat-colloquium-2007/Jan_King_Calculator.xls]
Tx Power (mW) Rx Antenna Gain (dB) Bit Rate (bits/s) Ebno (dB)10000 0.00 9600 58.89
Modem chip from RF DataTech is a Microchip PIC. A board will be built to interface it to the transceiver and MCU. A circuit diagram has been supplied by RF DataTech.
Summer Review6th Aug. 2008
SRCSPACE ACADEMY
Up-Link
Concept
Variable voltage dual output power supply – zero to 800V
Preamp Shapingamp Discriminator Buffer
HV Powersupply
Powercontroller
V/I Statusmonitor To MCU
To MCU
FromMCU
MCP
Incident dust particles cause plasma-induced electron cascade in singlemicrochannel plate (MCP) with single terminal anode.
Charge pulse from anode goes through electronics chain, which producesa pulse-height signal to be read by the MCU
PAYLOAD
Summer Review6th Aug. 2008
SRCSPACE ACADEMY
1st July 8th July17th July
14th July21st
22nd July
24th July25th 1st August 6th August
Lab work
Gain calculations
Electronicstesting
MCAsetup
Detectorassembly
Vacuumpumpdown
HV supplysetup
Electronicsredesign
FirstPower-up
Detector repairand reassembly
Secondpower-up?
Test plate voltage 700VGap voltage 100VMaximum safe plate voltage 850V
Summer Review6th Aug. 2008
SRCSPACE ACADEMY
Flight design
Detector body height = 4.3mm
Mass (assuming density is similar to aluminium) = 14g
Approximate specifications:
Power consumption: Plate supply = 70mW Support electronics = 50mW
Detector area (assuming 46mm diameter disk) = 16.6cm2
Open area = 10.5cm2
Summer Review6th Aug. 2008
SRCSPACE ACADEMY
Budget
Summer Review6th Aug. 2008
SRCSPACE ACADEMY
Subsystem Total Cost Cost to Date
MECH/OBDH £2992 £3819.79
ADCS £70 £70
PSU £12000 £1761.28
COMSCAMPAY
£850£184£3,400
LaunchTesting and development
£20,000 £5,000 (excluding Heidelberg)
Contingency (30%) £13,242
TOTAL COST £57,738 £5351.07
Remaining Cost to Completion £32157to Orbit £52157
Mass BudgetInternal Configuration
Slot No. Spacing (mm) Subsystem Mass (kg) Connector Masses (kg) Area (mm squared)
Bottom - 0 4.5 OBDH 0.074 ? 8645.95
0 -1 25.0 COMS 0.115 0.016 4056
1 – 2 15.0 PSU + BATTERY 0.15296 0.00098 9216
2 – 3 15.0 ADCS + MODEM + PAY 0.1 0.00098 4704 so far
3 – 4 15.0 PAY undefined 0.00098 undefined
4 - Top 12.9 DETECTOR + ANTENNA 0.07 0.00117 undefined
Structure Mech 0.17 0.01856
External Solar Panels 0.03375 0.009
Total 87.4 0.71571 0.04767
Reserve 0.0 0.23662
Summer Review6th Aug. 2008
SRCSPACE ACADEMY
Next Steps
Summer Review6th Aug. 2008
SRC
PSU• Fix BCR1• Go through battery charge / discharge cycles • Select and purchase Solar Cells • Test PSU with the solar cells
OBDH
• Flight board needs to be tested
• MCU needs to be programmed
• Subsystems need to be physically interfaced
• Subsystems need to be run from MCU
ADCS• Power consumption test whilst
connected to the Flight Control Board• Axes sensitivity deviation test• Refining of electrical components on
ADCS board
PAY• Laboratory Calibrations• Heidelberg accelerator testing• Support Electronics construction• Detector body prototyping and
construction
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