Communications ICD

Change Log

Communications ICD Change Log

Introduction

This page outlines the mechanical, electrical, thermal, and data interfaces of the Communication subsystem.

Overview

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

Interface Connectors [outdated]

The connectors in Figure 1 above are described in the table below.


Table 1: Interface connectors

ManitobaSat Connector Identifier Registry

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will be mounted on a PCB, then mounted inside the COMMS/CDH module as shown in Figure 2 [Note: the diagram below is outdated, awaiting for a new engineering drawing from the structural lead].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


Radio Transceiver

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

  • 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

  • CAD file for transceiver

Figure 4: Mechanical Drawings of the AX100 transceiver

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

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

Table 3: Telemetry and Commands List for AX100

Communications Interface Control Document

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

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

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)

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

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

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

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