INFORMATION FOR COMMUNICATING WITH GOLDS-UFSC
GOLDS-UFSC communicates through VHF and UHF bands
GOLDS-UFSC
An educational mission where students will be involved with the design and operation of a cubesat system in a space environment. Students will also learn about radio communications, digital communications, radio electronics, antennas.
An amateur radio mission will be implemented where the satellite functions as a digital store-and-forward repeater where digital frames will be stored and be relayed by the satellite. The amateur mission will have global coverage and will be accessible to any radio amateur. All students involved with the satellite operations will be required to have an amateur radio license.
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
GOLDS-UFSC uses two different protocols: NGHam and SBCD. Both for VHF and only NGHam for UHF.
DATA
Decoding
Using the GOLDS 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:
| Command | Length [bytes] | Content |
|---|---|---|
| Data request | 8 | “dr” + flags |
| Ping | 8 | “pg” + requester callsign |
| Message broadcast | Up 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 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 |
| 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 |