INFORMATION FOR COMMUNICATING WITH catarina - a1

CATARINA – A1 communicates through VHF and UHF bands

CATARINA – A1

The Catarina Constellation encompasses a set of satellites with the goal to provide services, mainly, to the civil defence, contributing to the country’s sustainable socioeconomic development agenda. Some of the Catarina Constellation satellites will provide a global coverage amateur radio service. The provided service is a digital store-and-forward repeater where digital frames will be stored and relayed by the satellite. All people involved in the service operation will be required to have an amateur radio license. The constellation has institutional support from the Brazilian Space Agency.

 


Operation and communication Parameters

COMMUNICATION: VHF

Beacon

The beacon is sent periodically and it provides the satellite basic statistics and data.​

COMMUNICATION: UHF

Downlink and Uplink

The downlink provides complete satellite packets. The uplink allows telecommands to be received.

OPEN COMMANDS

Repeater

Open to the ham radio community, there are three open commands: ping, data request and message broadcast.

PROTOCOLS

NGHam and ARGOS-2

CATARINA – A1 uses two different protocols: NGHam and SBCD. Both for VHF and only NGHam for UHF.

DATA

Decoding

Using the CATARINA – A1 custom-made software, it is possible to process and decode the collected data.

TRACKING

Information for tracking

NORAR ID:

                     International Designator:

 

Orbit


Altitude: 550km;
Inclination: 97.9°;
Cycle Repetition: 31 days;
Orbit Period: 5878.8 seconds;

Ascending Node Local Time: 10:30 a.m.

Satellite Specifications:

Parameter Value
Frequency 468 MHz
Modulation GMSK
Protocol NGHam
Deviation 10 kHz
Baudrate 4800 bps
Output Power 30 dBm (1 W)

Content of Each Periodic Downlink Packet:

Field Offset Length [bytes] Content
Flags 0 2 Variable
OBDH Status 2 6 Variable
IMU Accelerometer 8 12 Variable
IMU Gyroscope 20 12 Variable
OBDH Misc. 32 6 Variable
OBDH Uptime 38 4 Variable
Solar Panel Sensors 42 12 Variable
Main Radio 54 19 Variable
Solar Panels Data 73 18 Variable
EPS Misc. 91 8 Variable
Battery Monitor 99 21 Variable
Temperatures 120 21 Variable
Energy Level 141 1 Variable
RUSH Data 142 40 Variable
Payload X 182 7 Variable
  • Frequency: 145.8 MHz
  • Modulation: GMSK
  • Protocol: NGHam
  • Deviation: 5 kHz
  • Baudrate: 1200 bps

There are three types of uplink packets: Data request, ping and message broadcast. Each one is described in the table below:

CommandLength [bytes]Content
Data request8“dr” + flags
Ping8“pg” + requester callsign
Message broadcastUp to 28“br” + requester callsign + message
  • Data request: To request data of the satellite use this command. Selecting the flags, the user can download a set of past data of sensors or modules.
  • Ping: This command can be used to test the communication with satellite. When received, the satellite transmits back a ping packet.
  • Message broadcast: When received, the satellite transmits back the same content (an string with up to 20 characters) with the callsign of the source of command. This command can be used for communication between two or more ground stations.
  • Nominal mode This is the default operational state of the satellite. In the Nominal Operation Mode, the satellite will perform all its intended functions, including receiving data from the DCP stations, transmitting data to the ground segment, evaluating the effects of radiation on COTS electronic devices, and providing relay services for the amateur radio community. The Nominal Operation Mode also involves maintaining satellite attitude and managing power consumption, ensuring that all systems operate optimally. The satellite will remain in this mode as long as all functions are operating as expected.
  • Nominal operation mode – EDC activated This is the default operational state of the satellite when it is flying over Brazilian territory. During this period, the EDC is activated to receive and store data from the Data Collection Platforms (DCPs). Additionally, the satellite performs attitude maintenance and power consumption management tasks. The EDC payload, crucial for receiving data from the DCP stations, is a critical part of the mission. However, to optimize power usage and maximize operational efficiency, the EDC will only be activated when the satellite is passing over Brazilian territory. This will allow the EDC to collect data from the DCPs more effectively and transmit them to the ground segment while conserving energy when data collection is not possible. The decision of when to activate and deactivate the EDC will be based on the satellite’s orbit propagation, which will be calculated using regularly updated Two-Line Elements (TLEs). TLEs are widely used format for describing a satellite’s orbit. It consists of two lines of textual data that contain information about the orbital element epoch, inclination, right ascension of the ascending node, eccentricity, argument of perigee, mean anomaly, and mean motion of the satellite. The satellite’s TLEs will be received periodically from the ground segment. The mission control team will calculate the satellite’s future position based on the TLEs and determine the period when the satellite will be over Brazil. During this period, the EDC will be activated and begin collecting data from the DCPs. Once the satellite exits the coverage area, the EDC will be deactivated until the next pass over Brazil. This approach of operating the EDC based on orbit propagation allows for efficient utilization of satellite resources while maximizing the amount of data collected and transmitted to the ground segment. In addition to data collection, the satellite continues to provide relay services for the amateur radio community. However, priority is given to the operation of the EDC and data collection from the DCPs during this period. The average consumption of the satellite in this mode is described in the table below:
Module Duty Cycle (100%) Power (mW)
OBDH 100 115
TTC (radio 1 RX) 95 65
TTC (radio 1 TX) 5 3250
TTC (radio 2 RX) 95 65
TTC (radio 2 TX) 5 3250
EPS 100 320
BAT (idle) 90 0
BAT (heater full) 10 5000
Antenna (deployment) 0 1800
Antenna (deployed) 100 35
Payload EDC 0 1250
Radiation instrument 100 1000
Average 1762 mW
    • Nominal operation mode – EDC deactivated
When the satellite is out of reach of Brazil, the EDC is deactivated to save energy. During this period, the focus is on the operation of the radiation measurement instrument, which assesses the effects of radiation on COTS electronic devices. While the EDC is deactivated, the radiation measurement instrument is activated and begins collecting data. This data is essential for evaluating the effectiveness of COTS electronic devices in radiation environments, providing valuable insights for the future development of satellites. Additionally, the satellite continues to maintain its attitude and manage its power consumption. It also continues to provide relay services for the amateur radio community, although these may be limited to prioritize radiation data collection. In both modes, the health and performance of the satellite are continuously monitored by the mission control team to ensure that all operations are being executed as planned. If any issues arise, the satellite can be put into an alternative operational mode for diagnosis and troubleshooting. The average consumption of the satellite in this mode is described in the table above.
Module Duty Cycle (100%) Power (mW)
OBDH 100 115
TTC (radio 1 RX) 95 65
TTC (radio 1 TX) 5 3250
TTC (radio 2 RX) 95 65
TTC (radio 2 TX) 5 3250
EPS 100 320
BAT (idle) 90 0
BAT (heater full) 10 5000
Antenna (deployment) 0 1800
Antenna (deployed) 100 35
Payload EDC 0 1250
Radiation instrument 100 1000
Average 2387 mW
  • Emergency mode
The emergency mode is automatically activated in case of subsystem failure, when the satellite’s power is very low, or manually through telecommands. In this mode, all payloads are turned off, and the satellite operates only with the essential modules for its functioning. The average consumption of the satellite in this mode is described in the table below:
Module Duty Cycle (100%) Power (mW)
OBDH 100 115
TTC (radio 1 RX) 95 65
TTC (radio 1 TX) 5 3250
TTC (radio 2 RX) 95 65
TTC (radio 2 TX) 5 3250
EPS 100 320
BAT (idle) 90 0
BAT (heater full) 10 5000
Antenna (deployment) 0 1800
Antenna (deployed) 100 35
Payload EDC 0 1250
Radiation instrument 0 1000
Average 1387 mW
  • Power Budget
Power Budget is the avarage consuption of the satellite, in this table we can see this consuption in the period of one orbit witch the total is 3.95W. In the tabble bellow we can see the avarage consumption in the deferent modes of opperation:
Operating mode Power Budget
Nominal operation mode – EDC activated 2.188 W
Nominal operation mode – EDC deactivated 1.563 W
Emergency mode 2.563 W