INFORMATION FOR COMMUNICATING WITH FLORIPASAT-1

FloripaSat-1 communicates through VHF and UHF bands

Operation Parameters

COMMUNICATION: VHF

Beacon

The beacon is sent constantly and provide the satellite basic stats and data.

COMMUNICATION: UHF

Downlink and Uplink

Also constant, the downlink provide complete satellite packet. Uplink allows telecommands to be sent.

OPEN COMMANDS

Repeater

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

PROTOCOLS

NGHam e AX.25

FloripaSat-I uses two different protocols: NGHam and AX.25. Both for VHF and only NGHam for UHF.

DATA

Decoding

Using the FloripaSat-I custom-made software, it is possible to process and decode the collected data.

TRACKING

TLE

More current TLE for FloripaSat-1, if there is a new one updates will be made here:

1 44885U 19093G 20016.32880055 .00000212 00000-0 33465-4 0 9991

2 44885 97.9741 93.3222 0014762 179.9634 180.1610 14.81953583 4028

Orbit

Altitude: 628.6km;
Inclination: 97.9°;
Cycle Repetition: 31 days;
Orbit Period: 5835 seconds;
Ascending Node Local Time: 10:30 a.m.

  • Frequency: 145.9 MHz
  • Protocol: NGHam and AX.25
  • Modulation: GFSK
  • Deviation: 2,5 kHz
  • Baudrate: 1200 bps
  • Output Power: 30 dBm (1 W)

The Beacon of FloripaSat-I transmits packets periodically, with 5 possible periods (accordingly to the overall energy level of the satellite):

Energy LevelBeacon Period [s]
L1 (100% – 90% of total battery charge)10
L2 (92.5% – 80% of total battery charge)10
L3 (82.5% – 70% of total battery charge)20
L4 (72.5% – 60% of total battery charge)30
L5 (62.5% – 0% of total battery charge)30

In normal satellite operation, the beacon packets contains the following data:

FieldOffsetLength [bytes]Content
Satellite ID010“FLORIPASAT”
Batteries voltages104Variable
Batteries tempearatures146Variable
Total charge of batteries202Variable
Solar panels currents2212Variable
Solar panels voltages346Variable
Overall status of the satellite402Variable
Accelerometer and gyroscope4212Variable
Time since boot544Variable
Number of OBDH module resets since launch582Variable

If a fault on the OBDH module occurs (if the TTC module stops receiving data from it), only the EPS data are transmitted:

FieldOffsetLength [bytes]Content
Satellite ID010“FLORIPASAT”
Batteries voltages104Variable
Batteries tempearatures146Variable
Total charge of batteries202Variable
Solar panels currents2212Variable
Solar panels voltages346Variable
Energy level401Variable

If a fault occurs in the OBDH and EPS modules, only the satellite ID is transmitted:

FieldOffsetLength [bytes]Content
Satellite ID010“FLORIPASAT”
  • Frequency: 436.1 MHz
  • Modulation:2- GFSK
  • Protocol: NGHam
  • Deviation: 5 kHz
  • Baudrate: 2400 bps
  • Output Power: 30 dBm (1 W)

The Downlink of FloripaSat also transmits packets periodically (it contains a lot more data than the beacon packets), accordingly to the energy level of the satellite:

Energy LevelDownlink Period [s]
L1 (100% – 90% of total battery charge)60
L2 (92.5% – 80% of total battery charge)60
L3 (82.5% – 70% of total battery charge)120
L4 (72.5% – 60% of total battery charge)120
L5 (62.5% – 0% of total battery charge)none

The content of each periodic downlink packet is described in the table below:

FieldOffsetLength [bytes]Content
Flags02Variable
OBDH Status26Variable
IMU Accelerometer812Variable
IMU Gyroscope2012Variable
OBDH Misc.326Variable
OBDH Uptime384Variable
Solar Panel Sensors4212Variable
Main Radio5419Variable
Solar Panels Data7318Variable
EPS Misc.918Variable
Battery Monitor9921Variable
Temperatures12021Variable
Energy Level1411Variable
RUSH Data14240Variable
Payload X1827Variable

The downlink also transmits sporadic packets with the answers of the uplink telecommands.

  • Frequency: 436.1 MHz
  • Modulation: 2-GFSK
  • Protocol: NGHam
  • Deviation: 5 kHz
  • Baudrate: 2400 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.

The two callsigns are showed below:

  • 0PY0EFS
NameID Code [1 byte]Data [up to 220 bytes]Data Size [bytes]Total Size [bytes]Acess Level
OBDH Data0x00OBDH/EPS data5090Public
EPS Data0x01EPS data3190Public
TTC Data0x02“FLORIPASAT”1058Public
OBDH Data0x03OBDH/EPS data5070Public
EPS Data0x04EPS data3151Public
TTC Data0x05“FLORIPASAT”1030Public
Telemetry0x10Flags (16 bits) + OBDH/EPS data212266Public
Ping answer0x11Requester callsign (ASCII)758Public
Data request answer0x12Requester callsign (ASCII – 7 bytes) + Data (140 bytes)7 to 14758 to 202Public
Hibernation feedback0x13Requester callsign (7 bytes) + Hibernation duration in hours (16 bits, MSB first)958Public
Charge reset feedback0x14Requester callsign (7 bytes)758Public
Message broadcast0x15Resquester callsign (7 bytes) + Destination callsign (7 byes) + Message (up to 38 chars)14 to 5290Public
  • 00PP5UF or any callsign
    NameID Code [1 byte]Data [up to 220 bytes]Data Size [bytes]Total Size [bytes]Acess Level
    Ping request0x20None058Public
    Data request0x21Data flags (16 bits) + Count (1 byte) + Origin (1 byte) + Offset (4 bytes)858Public
    Broadcast message0x25Destination callsign (7 bytes) + Message (ASCII, up to 38 characters)7 to 3890Public

NGHam

The figure below describes the NGHam protocol fields of each packet.

The only customized parameters from the protocol changed in FloripaSat-I, are the preamble and the sync. word, which are applied for both frequency communications:

  • Preamble: 0xAA, 0xAA, 0xAA, 0xAA
  • Sync. Word: 0x5D, 0xE6, 0x2A, 0x7E

More information about the NGHam protocol can be found here.

AX.25

The beacon packets are also transmitted using the AX.25 protocol (the same packet with both protocols).

FieldLength [bytes]Content
Preamble40xAA, 0xAA, 0xAA, 0xAA
Sync. word40x5D, 0xE6, 0x2A, 0x7E
Flag10x7E
Destination Address7Ground Station Callsign and SSID
Source Address7Satellite Callsign and SSID
Control10x03
Protocol Identifier10xF0
Data60, 41 or 10“FLORIPASAT” + Data
Frame Check Sequence2Variable
Flag10x7E

NOTE: The callsign and SSID of both satellite and ground station, will be defined accordingly to the obtained licenses.

More information about the AX.25 protocol can be found here.

To decode the packets, there is a custom made sofware developed by the group. This software is capable of handling SDR devices, receive/transmit the signals and code/decode packets.

More information about this software can be found here. To obtain the program, go to this page and download the latest release.

Also, see our tutorials on youtube.

video tutorials

Some steps are documented through tutorial videos, intending to turn the process more simple and clear.

If you do not have access to the software or are unsuccessful in decoding send us the signal audio via email (contact@spacelab.ufsc.br) and we will try to decode it. 

Any questions we will be pleased to answer, send via email or make a new “issue” in our GitHub page.

Could you capture a signal from FloripaSat-1? Email us and get your QSL card

To receive your QSL card send an email to contact@spacelab.ufsc.br containing the following information:

  • Full name with identifier number
  • Date containing day, month, year and time UTC of signal reception
  • Grid locator
  • Frequency used
  • Signal audio received in the format. wav

If you want to describe the equipment that was used to capture the signal we will be happy know!

The FloripaSat-1 mission has finished its development and integration phase, but our work is not over yet.

Follow the SpaceLab lab to see recent activities from future space missions and group-led projects.

Contact us if you wish to join!

@ 2019 SpaceLab UFSC – Space Technology Research Laboratory, Federal University of Santa Catarina