Embedded Files
Introduction
Introduction
This page outlines the mechanical, electrical, thermal, and data interfaces of the Communication subsystem.
Overview
Overview
Block Diagram
Block Diagram
This diagram illustrates the interface connections between the communications subsystem and the satellite CAN bus, and between the different components of the communications subsystem. The subsystem interface has a power and ground connection, and a CAN line (differential) for data. The system has an interior and exterior components, which are connected through a coaxial cable via the U-loop. The U-loop is a MCX to SMA right angle adapter.
Figure 1: Communications Subsystem Interface Block Diagram
Module Layout
Module Layout
The interior components of the communications subsystem will be mounted on a PCB, then mounted inside the COMMS/CDH module as shown in Figure 2 [Note: the diagram below is outdated, awaiting for a new engineering drawing from the structural lead]. The exterior components will be mounted to the top of the module with access to the antenna door.
Figure 2: COMS Module Antenna Assembly
Figure 2: COMS Module Antenna Assembly
Radio Transceiver
Radio Transceiver
Electrical
Electrical
Through J1 connector
Input Voltage: 3.3 V
Input Current
RX: 55 mA (typ) 120 mA (max)
TX: 800 mA (typ) 850 mA (max)
Power Consumption
RX: 0.18W (typ) 0.40W (max)
TX: 2.64 (typ) 2.81W (max)
Radiated power output to J4 = 1 Watt
Connectors (Figure 3):
J1 - FSI Main Connector, 20-pin (needs connector SAMTEC-FSI-110-D)
J2 - Picoblade JTAG interface for factory software upload only
J3 - Picoblade USART (debug) connector for configuration
J4 - 50 Ω MCX RF Connector for edge mounting (coaxial cable)
Note: J2 and J3 will not be used in flight.
Table 2: Pinout for J1 connector
Figure 3: Electrical hardware connectors of the AX100 transceiver
Mechanical
Mechanical
Mass: 24.5 grams
Radio Dimensions: 65mm x 40mm x 6.5mm (Figure 4)
Stacking height of P1 connector: 3mm
Total tallest component height (+Z): ~10mm
Transceivers will be mounted on the PCB via fasteners on the 4 corners (with 3mm spacers)
Bill of Materials / Outgassing: TBC
Figure 4: Mechanical Drawings of the AX100 transceiver
Thermal
Thermal
Black-anodized aluminum heat sink / EMI shield
Overall temperature range: -30 °C to +85 °C (datasheet)
Assumed heat output = (power in - RF power out)
Receive: 0.1815W (no radiated power)
Transmit: 2.64W - 1W = 1.64W
Built-in sensor for over-temperature protection. Temperature data available upon command from CDH
Special milling around the power amplifier that provides a thermal contact with the heat sink using a thin 110 μm piece of Kapton
Figure 5: Aluminum heat sink / EMI shield
Software
Software
The AX100 uses the CubeSat Space Protocol (CSP) to transfer data to and from CSP nodes on-board the main system bus. The CSP network layer protocol supports multiple data-link layer protocols, such as KISS, I2C and Can Fragmentation Protocol (CFP). For the current system design, comms uses CAN Bus for communication with CDH. For more information on software interfacing with the AX100, see the user manual.
Processes that occur in the communications transceiver include the following
Input:
Shut down command
Comms Parameter Configuration
Commands from CDH
Receive data from CDH
Packetization and Depacketization (AX.25)
Modulation and Demodulation (FSK)
Phase Locked Loop (PLL)
Error Correction
Output:
Relay all ground station commands
Telemetry (temperature, data counters, bootcounter, etc.
see Table 3
COMMS Control PWB
COMMS Control PWB
Mechanical Interface
Board mass: ~20g
Connectors mass: ~4g
Dimensions: 90mm x 90mm x 1.57mm
Materials: FR-4, copper
Mounted in the COMMS/CDH module via fasteners on the 4 corners and 1 in the center (Figure 6)[Note: the diagram below is outdated, awaiting for a new engineering drawing from the structural lead]
Electrical Interface
J8 connector that connects the CAN Bus lines with OBC
SAMTEC-FSI-110-D (P1) main connector to interface with the radio transceiver
J9 connector for power (Vbatt & GND)
Thermal Interface
Temp range: -30 °C to +85 °C (same as transceiver)
Data Interface
Twisted pairs jumper wires relay between CDH and transceiver
Figure 6: Mechanical drawing of communications PCB
Antenna
Antenna
Mechanical Interface
Mass: ~2g
Length: 175 mm
Materials: Springsteel
Antenna is fastened to antenna door using epoxy
Electrical Interface
Power input to the antenna: approximately 1W plus cable loss
SMA connector to coaxial cable
Thermal Interface
Temp range: -30 °C to +85 °C (same as transceiver)
Data Interface
N/A
Antenna Deployment
Antenna Deployment
The antenna deployment mechanism is shown here.
Mechanical Interface
Mass: TBD
Dimensions: 90mm x 90mm
Materials: Delrin
Requires antenna mounting collar and ultra high molecular weight polyethylene line
Electrical Interface
Input Voltage: 6.4 V (Vbatt)
Input Current: ~2 A
Operational Power Consumption: ~5.12 W @ 792 mW
Controlled by PCU load switch
Burn resistor
Thermal Interface
Temp Range: -50°C to +80°C
Data Interface
Limit switch sensor input to detect antenna deployment status
U-Loop (Right Angle MCX to SMA Adapter)
U-Loop (Right Angle MCX to SMA Adapter)
Mechanical Interface
Mass: ~3 g
Right angle Adapter
MCX & SMA screw-in connectors
Electrical Interface
1 Watt power at the RF output of the radio
MCX connectors (J5/P5, J6/P6)
50 Ohm impedance
Thermal Interface
Temp Range: -50°C to +80°C
Data Interface
N/A
Buck Converter
Buck Converter
Mechanical Interface
Mass: ~1g
Dimensions: 3mm x 3mm x 1mm
Materials: Space approved Plastic
Located on COMMS control PWB
Electrical Interface
TPS62111MRSAREP buck converter
Max input voltage: 17V
Min input voltage: 3V
Output Voltage: 3.3 V
Max current output: 1.5A
Soldered on the COMMS control PWB for electrical connectors
Thermal Interface
Temperature Range: -40°C to +85°C
Data Interface
N/A
Copper Ground Plane
Copper Ground Plane
Mechanical Interface
Mass: ~90g
Dimensions: 49mm x 202mm x 1mm
Materials: 101 Copper
Located on the outside of the shells.
Electrical Interface
Connected through a jumper cable to the coaxial cable as per NASA-STD 8739.4A
Thermal Interface
Temperature Range: -40°C to +85°C
Data Interface
N/A
Coaxial Cable
Coaxial Cable
Mechanical Interface
Mass: ~10g
Dimensions: ~10 cm long
Materials: Brass, FET, PTFE
Electrical Interface
Screw in to the MCX to SMA right angle Adapter
Thermal Interface
Temperature Range: -40°C to +85°C
Data Interface
N/A
References
References
Page updated
Google Sites
Report abuse