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RF Communications Jonathan Parkhurst Space Sciences Laboratory University of California, Berkeley. RF Communications Agenda. AGENDA Requirements Communications Overview UHF (Low-Rate) System S-Band (High-Rate) System Patch Antenna Issues. RF Communications Requirements.
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RF Communications Jonathan Parkhurst Space Sciences Laboratory University of California, Berkeley
RF Communications Agenda AGENDA • Requirements • Communications Overview • UHF (Low-Rate) System • S-Band (High-Rate) System • Patch Antenna Issues
RF Communications Requirements UHF Communications (low rate) • uplink telemetry commands • 1.2 kbps • S-Band Communications (high rate) • downlink science and telemetry data • 1Mbps Circular Polarization
RF Communications Overview Low-rate Command Link UHF, 450 MHz, FM, 1.2 kbps, No coding High-rate Telemetry and Science Data Link S-band, 2200-2290 MHz FM, 1 Mbps, Reed-Solomon coding CINEMA BGS Helix Antenna BGS 11m Antenna MOC at UCB/SSL
Low-Rate UHF Uplink AstroDev He-100 radio Operating Frequency: 450 MHz Data Rate: 1200 bps(max) Power Usage (RCVR) < 200 mW Receiver Sensitivity: -104.7dBm, for a bit error rate of 10E-3
UHF Antennas on the Satellite ~16.7 cm (1/4 wavelength) deployed after the sat is in orbit
High-Rate S-Band Downlink Emhiser Digital Transmitter Model Number EDTC -09E1A502-00
High-Rate S-Band Downlink (cont) Emhiser Digital Transmitter Model Number EDTC -09E1A502-00 Frequency Range: 2200.5 - 2299.5 MHz Input Voltage: +12 VDC Temperature Operating Range: -20 C - +70 C Size: 3.5” x 2.5” x 1.0” Output Power: 5 W Bit Rate: 1 Mbps
S-Band Patch Antennas Solar Patch Panel Antennas • PC board material separating • two copper plates • Dimensions a, b, x’, y’ adjusted • to give antenna characteristics
Antenna Development Plan • Analytical estimations to determine directivity, • input impedance, degree of polarization, and • resonant frequency (iterative process) • Network Analyzer • Anechoic Box / Anechoic Chamber (UCSF) • Far-field testing using 11m dish