DINO – Peer Review 4 December 2015 DINO Communication System Peer Review Zach Allen Chris Page

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium2 Purpose Establish two-way communication link between satellite and ground station. –Link must allow transfer of map files from satellite to ground. –Must allow transmission of health and status data from satellite to ground. –Must allow the satellite radios and flight computer to receive command lines transmitted by ground station.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium3 Requirements Imposed by other Subsystems Data Rate: must be high enough to accommodate all data –20 kbytes per topographical map –255 bytes per Health and Status Packet –5 kbytes per uploaded schedule Antennas –Must be deployable by structures –No deployable ground plane allowed

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium4 Requirements on Power –Transmitter (Radio1) Transmit mode: 12 V at 1.4 A (16.8 W) Idle mode: 12 V at 90 mA (450 mW) Must have capability to be activated/deactivated by flight computer. –Receiver (Radio2) 5 V at 90 mA (450 mW) Must be active concurrently with flight computer –External TNC (tentative): 12 V at 200 mA (2.4 W) Must always be active when flight computer is active

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium5 Requirements on C+DH Two RS-232 Serial Ports –1 serial port dedicated to external TNC 9600 baud, 8 data bits, no parity bit, 1 stop bit Must have hardware flow control (CTS, RTS) –1 serial port shared between radio1 and radio2 Must be able to switch at any time between the two radios 9600 baud, 8 data bits, no parity bit, 1 stop bit Software flow control only

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium6 Requirements on Software Set up Radio1 (Transmitter) Parameters –Switch the shared serial port to Radio1 immediately after Radio1 is powered on (every time!) –Must program the following parameters into Radio1: Transmit frequency (TBD, after FCC assigns the frequency) Transmit power (5 Watts)

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium7 Requirements on Software, Continued Set up Radio2 (Receiver) Parameters –Switch the shared serial port to Radio2 immediately after Radio2 is powered on (every time!) –Must program the following parameters into Radio2: Receive frequency (TBD, after FCC assigns the frequency) Squelch

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium8 Requirements on Structures Mass –Two Transceivers –170 grams each –2 x 170 grams = 340 grams total –External TNC –Still determining. Upper limit is 40g. –Bent Dipole Antenna (transmit antenna) –Duck Antenna (receive antenna) –Approximately 2 feet of coax to feed the antennas

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium9 Requirements on Structures, Continued Dimensions –Two Transceivers –4.9 x 2.3 x 1.2 inches each –Mounted together in one 3CS-sized box (7.25 x 4.75 x 1 inch) –External TNC –Model still being determined –Upper Limit 6.1 x 7.3 x 1.3 inch –Box arrangements TBD –Antennas –Deploy Bent Dipole –Deploy Duck Antenna

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium10 Subsystem Block Diagram All Data lines use RS-232 Serial Transmitter operates at 12 V Receiver operates at 5 V. External TNC: 12 V line, allows 9,600 bps link to ground. Internal TNC proven to be reliable at 1,200 bps. 12 V line voltage 1.4 A 16.8 W transmitting (450 mW idle) 5 V line voltage 90 mA 450 mW (constant) 12 V line voltage 400 mA, 4.8 W (constant) RS-232 Serial 9,600 bps (during setup only) RS-232 Serial 9,600 bps (during setup only) RS-232 Serial 9,600 bps (constant) Radio1 Transmitter Kenwood TH-D7 Radio2 Receiver Kenwood TH-D7 External Terminal Node Controller (TNC) Internal TNC Internal TNC Antenna Power Line Data Line Legend Antenna

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium11 Design Transceivers –Two Kenwood TH-D7 radios Radio1: Downlink, approximately 436 MHz Radio2: Uplink, approximately 145 MHz TNC still under consideration –Timewave PK-96 Requires removing many electrolytic capacitors –Kantronics KPC Requires removing many electrolytic caps –Paccomm UP-9600 Already surface mount Heritage with Citizen Explorer Mission

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium12 Analysis: Power Requirements Daytime Operation –Receiver: 0.45 W (5 V, 90 mA) always. –TNC: 2.4 W (12 V, 200 mA) always. –Transmitter: 16.8 W (12 V, 1.4 A) for approx. 8 minutes, otherwise same as Receiver (0.45 W). Nighttime Operation –Receiver: 0.45 W (5 V, 90 mA) always. –TNC: 2.4 W (12 V, 200 mA) always. –Transmitter: 16.8 W (12 V, 1.4 A) for approx. 4 seconds, otherwise same as Receiver (0.45 W). Safe Mode –Same as nighttime.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium13 Analysis: Calculating Transmission Time We need to find the transmission time in order to find the exact power requirements over the course of one day. Time needed to send one packet: –10 bits/byte * 256 bytes/packet  1200 bits/sec = sec/packet Total transmission time (assuming 25 kB per pass during daytime): –2.133 sec/packet * 25 kB/pass  256 bytes/packet = sec/pass = ~ 3.5 minutes (absolute minimum) –May be approx. twice the minimum (resending, errors, etc.) –This is a realizable amount of time.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium14 Antenna/Structure Considerations Fit on nadir plate without obstructing cameras Little room for placement inside satellite Deployment of antenna Antenna Structure –Cost –Weight –Material (no outgasing)

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium15 Antenna Considerations Noise Factor and Loss Maximum transmission distance Radiation Pattern –Gain –Beam width –Efficiency Link Budget –Carrier – to – Noise Ratio –Energy per bit – to – Noise Ratio (Available to Required) –Margin

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium16 Noise Factor and Loss The receivers will determine the noise factor based on criteria like –Bandwidth –Sensitivity Losses –Free space loss –Polarization loss –Pointing, component, and implementation losses –Atmospheric loss

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium17 Maximum Transmission Distance Calculations Low orbit height from earth = 425km Maximum distance from base station antenna (horizon) = (with  =5 o, slant angle) 1.84x10 6 m –For  =10 o  1.39x10 6 m –For  =15 o  0.99x10 6 m These distances play into our free space loss and ultimately our link budget Diagram Reference: Vincent L. Pisacane and Robert C. Moore, Eds., Fundamentals of Space Systems. New York: Oxford University Press, 1994.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium18 Up-link (Rubber Duck Antenna) Targeted Frequency of 145 MHz –Wavelength of approx. 2.1m Why chosen? –Ability to transmit high power and gain from base station –Heritage Antenna Radiation Patterns –Gain –Beam Width Link Budget

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium19 Up-Link (Rubber Duck Antenna): Radiation Patterns Gain –To be on the safe side, gain was projected to be 0dB Beam Width –Minimal beam width expected.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium20 Up-Link (Rubber Duck Antenna): Link Budget Link Budget Form courtesy of Dr. Stephen Horan, New Mexico State University.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium21 Down Link Targeted Frequency of 436 MHz –Wavelength of approx. 0.7m Primary consideration –Bent Dipole Helix design still in simulation Next consideration is phased, 4 element antenna array

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium22 Down-Link (Bent Dipole Antenna) Antenna Radiation Patterns –Gain –Beam Width Link Budget Simulations (NEC) –Design –Radiation Pattern –3D view of Radiation Pattern

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium23 Down-Link (Bent Dipole Antenna): Radiation Patterns Gain –6.58 dB (NEC Simulation 12-8) Transmitted Power –36.9 dBm (5W) Beam Width –120 o –Filled requirement of 90 o

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium24 Down-Link (Bent Dipole Antenna): Link Budget Link Budget Form courtesy of Dr. Stephen Horan, New Mexico State University.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium25 Down-Link (Bent Dipole Antenna): Simulation Design

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium26 Down-Link (Bent Dipole Antenna): Simulation Radiation Pattern

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium27 Down-Link (Bent Dipole Antenna): 3D View of Radiation Pattern

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium28 Antenna Deployment Before Deployment After Deployment Note: placement of monopole will need to be simulated and tested for best results Bent Dipole Monopole

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium29 Commands – After Antenna Deployment Radio2 power activated Software switches serial port to Radio2 Software programs Radio2 Radio1 power activated Software switches serial port to Radio1 Software programs Radio1 TNC power activated System Ready

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium30 Antenna Test Plan Testing to be done either at Ball Aerospace or CU Antenna Lab –Test for resonant frequency By measuring reflection S parameters –Antenna Radiation Pattern Measurements Gain Beam width Efficiency –Power transmitted to power received –Transfer files to and from spacecraft CDH system

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium31 Radio/TNC Test Plan Incremental Testing is important to track bugs –Test TNC on bench first, connected directly to another TNC –Connect TNC to flight radios. Make transmissions of ASCII character strings. Verify proper operation. –Test to make sure that received packets get properly decoded and sent out of TNC serial port. –Install Radios and flight antenna prototypes into metal DINO model –Connect a computer running the flight software to the TNC in the DINO model –Attempt communication link between ground station and DINO flight model.

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium32 Parts list and Cost Rubber duck –Bought through distributor –Cost of between $20-$50 Bent dipole –Metal selections considered Copper: ~0.68 pounds Aluminum: ~0.2 pounds –Estimated cost of $30 for each prototype All design and manufacturing will be done by Space Grant

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium33 Parts List and Cost Transmitter (Radio1): $ Receiver (Radio2): $ External TNC Initial cost: $ Custom Firmware: $80

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium34 Issues and Concerns Link Budget Issues –Need to verify noise figure and thermal noise for link budgets. –Need to verify link range Bent Dipole Issues –Gain and beam width only simulated, prototype must be built and tested. –What will be the margin of error between angle needed to angle achieved when deployed

DINO – Peer Review 4 December 2015 Colorado Space Grant Consortium35 Issues and Concerns External 9600 baud TNC interface still in question –Fall-back is 1200 baud