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New TTC Requirements
1.1.1 TTC should use a RF Module embedded with amplifier and LNA circuit to increase the output power up to 31 dBm to control beacon and transceiver.
1.1.2 The sensitivity should have up to -126 dBm.
1.1.3 The maximum output power shall be +30 dBm.
1.1.4 Operating Range Temperature shall have -40 ~ +85 °C.
1.1.5 Should have a working voltage range of 3.3 to 6.5 V and typical is 5 V.
1.1.6 The Radio Modules shall have GFSK Modulation of feature.
1.1.7 The antenna output of the radio module should be connected to the respective connector over a 50 Ω coupled trace.
1.2.1 Radio Modules shall be capable to have a Baudrate of 1,2 Kbps to beacon.
1.2.2 Radio Modules shall have 145,9 Mhz to operate the beacon.
1.3.1 Radio Modules shall be capable to have a Baudrate of 2,4 kbps to transceiver.
1.x.2 Radio Modules shall have 437,9 Mhz to eperate the Transceiver.
2.1 The Microcontroller should follow this requirements.
3.1 The telemetry module should operate at 5V and 500 mA.
3.2 The beacon radio module should operate at 5V and 500 mA.
3.3 TTC should be connected to EPS and anothers modules using PC104 and follow this requirement.
4.1 The main software structure of the TT&C, shall initialize and configure the drivers to be used.
4.2 After the initialization the main program must enter in a infinite loop, and all the tasks must be performed through a hardware interrupt.
5.1 The watchdog timer shall reset the MCU every 16 seconds.
5.3 The timer interrupt must be set to generate an interrupt every second, and count to be the system time reference.
5.3.1 This time must be store in a non-volatile memory, for the system redeem this information when a reset occurs, and continue the counting of the time.
5.4 The TT&C must ensure that have a communication with the EPS board.
5.4.1 This communication must be through the UART bus.
5.4.2 Must be configured at a transfer rate of 4800 bps.
5.5 The TT&C must ensure that have a communication with the OBDH board.
5.5.1 This communication must be through the SPI bus
5.5.2 Must be configured at a transfer rate of 2400 bps.
5.6 The antenna must be inicialized
5.7 The radio modules must be inicialized.
6.1 The beacon should deployed the antenna and configure to operate of a 145 Mhz band.
6.2 TT&C Should receive data from OBDH, whenever requested.
6.3 TT&C Should receive data from EPS, whenever requested.
6.4 TT&C Should be responsible to transmitted to GRS the beacon packet of data, containing the data from the EPS and the OBDH module.
6.4.1 This beacon packet should be transmitted periodically, and the frequency that is transmitted should vary with energy level:
| Level | BTI |
|---|---|
| L1 | 10s |
| L2 | 10s |
| L3 | 20s |
| L4 | 30s |
| L5 | 30s |
- (BTI) Beacon signal Transmission Interval.
6.4.2 The beacon packet shoud have the following structure:
| Information | Length (Bytes) |
|---|---|
| Satellite ID: "FLORIPASAT" | 10 |
| Batteries voltages | 4 |
| Batteries tempearatures | 6 |
| Total charge of batteries | 2 |
| Solar panels currents | 12 |
| Solar panels voltages | 6 |
| Overall status of the satellite | 2 |
| Accelerometer and gyroscope | 12 |
| Time since boot | 4 |
| Number of OBDH module resets since launch | 2 |
6.5 The beacon radio should reset every 10 minutes.
6.6 The beacon System should reset every 12 hours.
6.7 When the OBDH send a command, the Beacon should execute the command:
- "Shutdown"
- "Request antenna mutex"
6.8 The beacon Radio should activates the reception of data, if the OBDH have a critical failure.