Telecommunication Subsystem Design for Small Satellites Haider Ali
Telecommunication Subsystem Design for Small Satellites Haider Ali Final Ph. D Presentation Tutor: Prof. Claudio Sansoé
Problem Statement n S-band OBRF Subsystem on Single Tile Cube. Sat dimension panel (98× 98 mm 2) q Low cost, compact & LEO compliant q Power efficient subsystems q Satisfy link budget requirement for Ara. Mi. S C-1 q q n Reusable Design for future missions (cutting recurring engineering/testing costs) Design of 2. 43 GHz Antenna q n RF Front End (Choice of PA, LNA and RF chain) Antenna (Gain, RL) Compact, light weight, small size, acceptable performance Telecommunication Protocol Design Compatible with other (GENSO) ground stations q Error Handling/Detection Capability q 27 October 2021 2
Outline n Ara. Mi. S C-1 n Telecommunication Protocol n Telecommunication Tile (Cube. TCT) n Patch & Array Antenna n Conclusion 27 October 2021 3
Ara. Mi. S-C 1 q q q q Cube. Sat compatible standard based on Ara. Mi. S Architecture Consists of Tiles Four Cube. PMT: solar panels , power management, attitude control & Determination subsystem Cube. TCT: S-band/ UHF Tx. Rx, S-band Antenna, UHF deployable antenna Dimension: 100 x 100 mm 3 Mass: 1. 3 kg Room for batteries & payload boards 27 October 2021 4
Telecommunication Protocol
GENSO (Global Educational Network for Satellite Operations) n Purpose: • • Extended Mission Controller access to satellite even if not visible Possible Through Network of ground stations & remote amateur radio via internet n GENSO System Main Components: • Mission Control Client Ground Station Server Authentication Server • • 27 October 2021 6
Other Amateur Protocol n n n 1962 Oscar 1 & Oscar 2 (Beacon CW) 1962 Oscar 3 (Linear Transponder) 1974 Amsat-Oscar 7 (AFSK RTTY) 1983 Amsat-Oscar 10 (computer-to-computer BPSK to 400 bps) 1986 F 0 -12 (BBS PSK) Since 1990: statement of AX. 25 modulation at 1200 bps AFSK first then FSK 9600 bps + Transceiver TNC (Terminal Node Controller) 27 October 2021 7
AX. 25 Protocol Allows: transfer of data packets encapsulated into frames connectionless for the transmission and reception of individual frames (one error detection on the frame) connected (fragmentation and error recovery) Frame I: N(S) / N(R) (2 B) Flag 1 B Dest. Add 7 B 27 October 2021 Source Add 7 B Ctrl 1 B PID 1 B Packet CMD/DAT/MSG (256 B max) Info 1 -256 B AX. 25 Frames FCS 2 B Flag (1 B) 8
System Architecture (Layered Protocol Model) Radio Channel (2. 4 GHz) 27 October 2021 9
Overall System Architecture Cube. TCT I 2 C/SPI C-1 27 October 2021 10
Developed Protocol at Higher Level Uplink commands generate data in downlink that needs to be received on Ground REQUIREMENT: Control the start of data transmission in downlink specifically when at that moment there is a GENSO Ground station that can receive it. Command Categories : n Controls at run-time short (SHORT) n Controls at run-time long (LONG) SHORT: n Already available in OBC memory n Automatically transmit Data after receiving this command LONG: n Data is first generated and then retained in memory. n Transmitted after subsequent request command (get. Data). 27 October 2021 11
Package Definition Uplink Packet: 1. backdoor. Command 2. ordinary. Command (SHORT / LONG) SHORT: get. Data, get. Frag, basic. Telemetry, . . . LONG: orientation, image, . . . Downlink Packet: 1. pure. NACK 2. ordinary. Downlink (DATA, MESSAGE) DATA: beacon, ack_data, ack_frag Message: DATA_NRDY, BAD_CMD, UN_CMD_NUM. . . 27 October 2021 12
Managing SHORT Command N(S) + cmd. Short_code verify CRC Frame AX. 25 MCC GSS RF Channel OBRF timer polling TCP verify N(S) MEM ACK_DATA 27 October 2021 13
Managing LONG Command (I) verify CRC timer N(S) + cmd. Long_code + app. Num + params Frame AX. 25 polling MCC GSS RF Channel OBRF TCP verify N(S) Start exec TILE n CMD_RECEIVED 27 October 2021 14
Managing LONG Command (II) timer MCC GSS RF Channel OBRF TCP Checking TILE n DATA/NULL MEM 27 October 2021 15
Managing LONG Command (Ill) timer N(S) + get. Data_code + appl. Num MCC GSS RF Channel OBRF TCP MEM DATA_NRDY/ ACK_DATA 27 October 2021 16
Error Handling n Error handling based on "positive acknowledgment or retransmission" n Loss in uplink/downlink: MCC NOT Receive ACK_DATA /CMD_RECEIVED within timeout Retransmit N(S) + cmd. Short_code MCC n GSS timer RF Channel OBRF TCP MEM Loss in downlink: Satellite receives command for second time. (a) SHORT: N(S) + cmd. Short_code (b) LONG: N(S) + cmd. Long_code + app. Num + params MCC 27 October 2021 GSS RF Channel OBRF timer TCP MEM (a) SHORT: ACK_DATA (b) LONG: CMD_DUPLICATED 17
Performance Analysis (I) SHORT command We define: Request-Delivery Time (RDT): time that elapses between the start of transmission of the command the end of the receipt of the response. TInternet_up MCC GSS TInternet_down 27 October 2021 (Ttx+Tp)up RF Channel (Ttx+Tp)down Tpoll+Tread OBRF Tsend timer TCP MEM 18
Performance Analysis (l. I) Rb_int = 100 kbps TTimer = 0. 06 s (TTimer > 0. 04 s) TInternet_up = TInternet_down =50 ms DCom = 255 B = DMSG TSync+ LHeader+ LPayload = 293 B RDT (s) d = 800 km → RDT = 0. 656 s Rb'= LPayload /RDT = 3. 1 kbps By using S-band (@100 kbps in Downlink) → RDT = 0. 426 s Rb'= LPayload /RDT = 27 kbps Rb_int (x 1 0 5 bps) T er Tim (s) Rb_int= 70 ÷ 150 kbps TTimer= 0. 06 ÷ 0. 11 s Fragmented Data Rb‘ improves significantly! 27 October 2021 19
Fragmentation Performance Analysis 27 October 2021 20
Telecommunication Tile (Cube. TCT)
Spacecraft Design Configuration n Physical Module Based Configuration n Reusable Design Configuration n Satellite on Demand Configuration Cube. TCT
Cube. TCT 2. 4 GHz OBRF UML Class diagram 27 October 2021 23
Cube. TCT 2. 4 GHz OBRF n Cube. TCT is Cube. Sat standard Telecommunication Tile • • n Cube. TCT Subsystems • • • n Cube. TCT Transceiver (Tx/Rx) RF Front End Switching & Linear Regulators Current, Voltage & Temperature Sensors Anti Latchup Protection, Load Switch. Goals • • • n Dimensions 98 x 1. 55 mm 3 4 -layered PCB (1 st Traces & Components, 3 rd Digital Traces, 2 nd & 4 th Ground) Outer/Exterior side: S-Band 2. 43 GHz Patch Antenna Inner/Interior side: Electronic subsystems Implement these subsystems as single module Compact, Rigid & Power efficient Reduction in overall Cost, Weight & Dimension COTS • • Convenient Availability Selection criteria: Low Price, Performance, Size 27 October 2021 24
Block View of Cube. TCT 2. 4 GHz OBRF § Telecom link S-band (500 kbps) § Rx sensitivity upto -100 d. Bm § Tx Power upto 33 d. Bm § Monitoring: Sensors/Devices § Control: RF, SW, PA , Regulators § Anti Latchup Protection 27 October 2021 25
Cube. TCT (Physical PCB Layout) SPI Connector 3. 3 V REG CC 2510 Rx PDB Connector CC 2510 Tx PA Latchup Protection Chip LNA DEBUG Connector RF Switches DEBUG Connector 6 V PA REG UHF Tx. Rx 27 October 2021 26
Cube. TCT Tx / Rx n 2 TI’s CC 2510 configured as Rx & Tx n Decapsulate Commands Packets Rec. from GS n Encapsulate MSG/DATA Packets & Trans. to GS n Perform error detection (CRC) n Rx Communicates with OBC via SPI n Rx & Tx Communicate via UART (Null Modem) n Monitoring & Housekeeping sensors/devices n Controls: Regulators, Load Switch, PA & RF SW n Separate Tx and Rx Debug Interface 27 October 2021 27
RF Front End Main Components: n PA (SZM-2166 Z) • • Operates on 6 V Supply (TPS 5450) Power Output 33 d. Bm Gain 37 d. B n LNA (MAX-2644) • • Noise Figure : 2 d. B Gain: 17 d. B (IIP 3 : -3 d. Bm) n RF Switches (TQP 4 M) • 2 x Absorptive RF Switches Tx & Rx chain isolation : 90 d. B Low insertion loss : -0. 9 d. B • • • 27 October 2021 28
Regulators n n Cube. TCT Input Power: PDB (12 -18 V) 3. 3 V, 3 V Ref & 6 V Enabled/Disabled by Cube. TCT Transceiver (except 3. 3 V) 3. 3 V Mixed Two Stage (Switched & Linear) Regulator: ¨ ¨ n 3. 0 V Reference (Linear) Regulator: ¨ ¨ ¨ n Switching Stage: Down converts PDB into 5 V, High Efficiency Linear Stage: Down converts 5 V into 3. 3 V, Stable Output, Less EMI Output Current Rating: 100 m. A @ 3. 3 V Supply’s for Tx, Rx, LNA, RF Switches Down converts 5 V (1 st 3. 3 V mixed Reg. stage) into 3. 0 V Ref Signal Stable output, Less EMI, Small Size Supply’s Temperature Sensor 6. 0 V (Switched) Regulator: ¨ ¨ Down converts PDB into 6. 0 V for Power Amplifier, High Efficiency Output Current Rating: 2. 5 A @ 6 V 27 October 2021 29
Sensors n n Monitor functional health of Cube. TCT 3 different Voltage Sensors: ¨ ¨ ¨ n Temperature Sensor: ¨ ¨ n 20 V: PDB voltage level 10 V: 6 V PA supply voltage level 5 V: 3. 3 V supply voltage level Monitors temperature level of Cube. TCT Temperature Range (0 -103°C) Current Sensor: Monitors total current consumed at PDB ¨ Max Current Rating: 5. 682 A ¨ 27 October 2021 30
Anti Latchup & Load Switch n Anti Latchup ¨ 1 B 127 Anti Latchup Chip Protection against SEL ¨ Disables Tile Power ¨ Timing is critical ¨ n Load Switch Enable/Disable PDB to PA (6 V power supply) ¨ Control Power Consumption ¨ 27 October 2021 31
1 B 9_Cube. TCT Testing (I) n RF communication testing (@ 2. 43 GHz) ¨ ¨ RF Receiver Testing n Tx. Rx Testing via Smart RF Studio tool n Using 20 d. B Attenuator with CC 2510 Reference Module as Tx (antenna G~1 d. Bi) n Tx Power = -20 d. Bm n Min. Measured RSSI = -75 d. Bm n 0% PER 100 packets @ 500 kbps n Distance = 3 m (Free Space Path loss = -49. 7 d. B) n Cube. TCT Patch Antenna Gain= 4. 5 d. Bi RF Transmitter Testing n Max Tx Power = 32 d. Bm (Carrier) n Distance = 3 m (Free Space Path loss = -49. 7 d. B) n Cube. TCT Patch Antenna Gain = 4. 5 d. Bi n Measured RSSI (using Spectrum analyzer)= - 14. 5 d. Bm 27 October 2021 32
1 B 9_Cube. TCT Testing (II) n Regulators/Sensors Testing: ¨ Manual Measurement: DMM ¨ Debug interface: (Smart RF 04 EB + IAR EWB) ¨ Results in close agreement 27 October 2021 Regulators 1 B 1254 A Mixed Regulator 3 V 3 (1 st Stage) 1 B 1254 A Mixed Regulator 3 V 3 (2 nd Stage) 1 B 132 F Reference Regulator 3 V 0 1 B 1255 A Switching Regulator 6 V Rated Input (V) 4. 5~45 Applied Input (V) 10 -16 Applied Enable (V) PDB Measured Input (V) 4. 98 3. 8~20 4. 98 PDB 3. 28 4. 5~5 4. 98 CC 2510 3. 12 10~30 10 -16 CC 2510 5. 98 Housekeeping Sensor Calculated Measured 1 B 131 C_Voltage_Sensor_V 1 1 B 131 B_Voltage_Sensor_V 1 1 B 132 F_Current_Sensor_V 1 1 B 133 B_Temperature_Sensor 1. 79 V 1. 06 V - 1. 78 V 1. 02 V 10. 2 m. V 820 m. V (27°C) ADC Acquired 1. 82 V 1. 02 V 11. 6 m. V 837 m. V (27°C) 33
Patch & Array Antenna
Introduction n Antenna Design in S-band (2. 43 GHz) n Two design solutions: i. Single Patch (Cube. Sat) Low Gain (LP) Wide HPBW ii. Patch Array (Ara. Mi. S) High Gains (RHCP) Low HPBW 27 October 2021 35
Patch Antenna • • • Microstrip technology εr= 1 -5 (typically) Compact structure Small size Considerable Gain (3 -9 d. B) Inexpensive to build Easy manufacturing Narrow Band Poor efficiency (improved by low εr & thicker substrate use) 27 October 2021 36
Patch Array n S-Band Antenna Design @ 2. 43 GHz n Rectangular single patch (LP) n Single Patch has lower Gain (~5 d. B) n Generate CP using LP elements by particular orientation & phase shifted BFN n (2 x 2 grid) 4 Patches at ψ = 90° phase shifted to adjacent element. n Mathematically: 27 October 2021 37
10 25. 2 m m • Improved design compactness • Suitable for 2 x 2 array grid on (150 x 150 mm 2) • Small Dimension (@ 2. 43 GHz) • Butterfly shape more compact • Provides better AF GAIN • Reduced inter-element coupling m m Patch Design Choice (Pros & Cons) • Suitable for Single Patch Design (100 x 100 mm 2) • Designed with Rogers 6002 (εr = 2. 94 & t=0. 762 mm) 27 October 2021 38
Physical Design of Patch Array • Designed in RT/Duroid 6006 (εr = 6. 15 & t=3. 8 mm) • 2 x 2 patch elements array • fed with phase shift of 0°, 90°, 180° and 270° • Diagonal elements placed inverted on array grid • Compact patch shape ensure proper arrangement on limited tile face (150 mmx 150 mm) • Angular orientation suppress inter-element coupling 27 October 2021 39
Design Layout : Patch & Array Patch 27 October 2021 40
Simulation Results (Antenna Gain) 27 October 2021 41
3 D Gain Pattern Single Patch 27 October 2021 Array 42
RL (Measured v. Simulated) 18 MHz 45 MHz 27 October 2021 43
Gain Comparison : Patch v. Array 27 October 2021 44
Prototyped Patch Array & Patch Antenna Type Gain HPBW RL -15 d. B BW Max. (Deg) (d. B) (MHz) (d. Bi) Single Patch Cube. Sat (LP) Patch Array Ara. Mi. S (RHCP) Sim. 6. 8 76 -28. 5 20 Meas. 6. 2 74 -26 18 Sim. 8. 5 42 -20. 5 50 Meas. 7. 6 40 -18 45 Parameters measured at design frequency (f. C = 2. 43 GHz) 27 October 2021 45
Link Budget Calculation
Polito Ground Station 27 October 2021 47
Uplink BUDGET Ara. Mi. S - C 1 (Polito GS) Ground Station Radio Link Path Satellite Transmitter Power Output Transmission Line/ Sw Losses Antenna Gain EIRP Antenna Pointing Loss Path Loss (Elevation angle =10°) Ionospheric Loss Atmospheric Loss Isotropic Signal Level Antenna Pointing Loss Antenna Polarization Loss Antenna Gain Transmission Line Losses LNA Noise Temperature Transmission Line Temp Sky Temperature Transmission Line Coefficient Effective Noise Temperature Figure of Merit (G/T) S/No Power Density System Desired Data Rate Telemetry Sys. Eb/No(~Spectral efficiency 1 bps/Hz) Required BER(Assume G 3 RUH FSK; No Coding; 1 d. B Implementation Loss) Required Eb/No System Link Margin 27 October 2021 44 d. Bm -2. 0 d. B 35 d. Bi 45. 0 d. BW -2. 0 d. B -167. 7 d. B -0. 2 d. B -0. 3 d. B -129. 2 d. BW -1. 0 d. B -3. 0 d. B 6. 0 d. Bi -2. 0 d. B 500 K 270 K 290 K 0. 8943 788 K -24. 0 d. B/K 77. 4 d. BHz 500 Kbps 57. 0 d. BHz 17. 2 d. B El El. Angle (Deg) Path Loss (d. B) Link Margins (d. B) 20 -165. 2 6. 3 30 -163. 1 8. 4 45 -160. 8 10. 7 60 -159. 4 12. 1 90 -158. 3 13. 2 Ground St. Antenna Gain 20 d. Bi 1. 00 E-05 13. 4 d. B 25 d. Bi Link Margin (d. B) Data Rate (Kbps) El= 45° El= 90° 128 2. 1 4. 1 100 3. 2 5. 2 128 7. 1 9. 1 100 8. 2 10. 2 7. 1 d. B 48
Downlink BUDGET Ara. Mi. S - C 1 (Polito GS) Transmitter Power Output Transmission Line Losses Antenna Gain Satellite EIRP Antenna Pointing Loss Antenna Polarization Loss Path Loss (Elevation angle =10°) Radio Atmospheric Loss Link Path Ionospheric Loss Ground Station Isotropic Signal Level Antenna Pointing Loss Antenna Gain Transmission Line Losses LNA Noise Temperature Transmission Line Temp Sky Temperature Ground St. Transmission Line Coefficient Effective Noise Temperature Figure of Merit (G/T) S/No Power Density System Desired Data Rate Telemetry Sys. Eb/No(~Spectral efficiency 1 bps/Hz) Required BER(Assume G 3 RUH FSK; No Coding; 1 d. B Implementation Loss) Required Eb/No System Link Margin 27 October 2021 32 d. Bm -2. 0 d. B 6. 2 d. Bi 8. 7 d. BW -1. 0 d. B -3. 0 d. B -167. 7 d. B -0. 3 d. B -0. 2 d. B -163. 5 d. BW -2. 0 d. B 35. 0 d. Bi -1 d. B 125 K 290 K 200 K 0. 7943 344 K 8. 6 d. B/K 71. 8 d. BHz 500 Kbps 57. 0 d. BHz 14. 8 d. B El El. Angle (Deg) Path Loss (d. B) Link Margins (d. B) 20 -165. 2 3. 9 30 -163. 1 6. 0 45 -160. 8 8. 3 60 -159. 4 9. 7 90 -158. 3 10. 8 Ground St. Antenna Gain 20 d. Bi 1. 00 E-05 13. 35 d. B 1. 4 d. B 25 d. Bi Data Rate (Kbps) Link Margin (d. B) El=50° El=90° 128 0. 2 1. 8 100 0. 8 2. 8 128 4. 8 6. 8 100 5. 8 7. 8 49
Conclusion n n n n Subsytems integration on a single PCB Low design/manufacturing cost (~ 250 euros) Weight: 180 g (Cube. TCT+ patch antenna) Compact & occupy no extra space on the spacecraft Selected RF components satisfy link budget criteria LEO orbit environment Low cost antenna design for 2. 43 GHz with acceptable results Ara. Mi. S Protocol design compatible with GENSO 27 October 2021 50
Thank You For Your Attention!
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