FSpace laboratory


For radio operators

Telemetry and beacon data from F-1 contain critical information about the satellite’s health (battery & solar cell voltages, temperature readings) and they are very important to us. This is our first space mission so we would like to ask the amateur radio community to help in tracking and receiving data from F-1 CubeSat. You will receive the verification card from us!

Here is a quick summary on F-1’ frequencies:

145.980 MHz: main channel, 1W RF output, FM, AFSK 1200bps, one telemetry packet every 30 seconds, operates in the dark by default (but can be commanded later to operate in sunlight as well)

437.485 MHz: backup channel, 0.2W RF output, FM, PWM CW beacon, each beacon transmission lasts about 20 seconds then 90 seconds delay, only operates in sunlight

1. Latest TLE of F-1 (updated Sep 24, 2012)

We will try to provide TLE as soon as possible but initially you can use the ISS’s because F-1′s orbit will be very much similar to that of the ISS.

1 25544U 98067A   12268.26025190  .00017277  00000-0  30696-3 0  3551
2 25544  51.6496 348.9327 0018454  95.4346 318.9373 15.50115148793411

2. Satellite pass prediction

You can use any program to predict satellite passes based on TLE. We suggest Orbitron v3.71 as it is quite simple and easy to use http://www.stoff.pl/downloads.php
Note that you should synchronize your PC’s time by using Windows’s built-in feature or by a 3rd party tool such as Dimension 4 v5.0 http://www.thinkman.com/dimension4/download.htm

3. F-1 Telemetry Decoder

– F-1 Telemetry decoder requires Microsoft .Net framework 4.0 to run, if you haven’t installed the framework, you can download it from here .Net framework 4.0 
– F-1 Telemetry Decoder v2.1.2 update 04/October/2012  (please uninstall earlier version first, if any)
– F-1 Telemetry Decoder User Manual (detailed instructions)
Sample audio
– Sample audio F-1 PWM CW beacon
– Sample audio F-1 packet beacon (this audio file contains a burst of 3 similar telemetry packets from F-1, please use it to verify that F-1 Telemetry Decoder is running correctly on your computer and ready to decode received packets from F-1)

If your software modem only support TCP/IP port:
-Please visit: http://www.mixw.net/index.php?j=related and download, then installation “serial port emulation driver”.
-Download and Installation TCP2COM
-Run your software modem.
-Run and config TCP2COM software.
-Run F-1 Telemetry Decoder.
4. F-1 beacon data format

4.1. VX-3R1
– Frequency: 437.485MHz, FM Narrow
– Power supply : directly from solar cells, only operates in sunlight
– Output power: average 0.2W, half-wave dipole antenna
– Modulation scheme: Morse code beacon (10 chars) using PWM CW
– Beacon interval: every 90 seconds (configurable), each beacon transmission lasts about 20 seconds
– Beacon prefix: there are 2 “z” characters sent before the beacon message, just ignore them
Beacon format:
No1 Data Description Size (bits) Size (chars)
1 F-1’s callsign “XV1VN” 5
2 OBC1 reset count Number of OBC1 reset 8
3 Temp. 1 Temperature inside F-1, OBC board, oC 8  5
4 Temp. 2 Temperature outside Y- side, oC 8
5 Checksum bit 0 if sum of items #2 to #4 is even, 1 if it is odd 1
Total 10
– The beacon data containing 25 (8+8+8+1) bits stream is encoded into 5 Morse characters using the following mapping:
0 = 00000
1 = 00001
9 = 01001
A = 01010
B = 01011
V = 11111
– Since the UHF beacon only has 0.2W output power so it maybe difficult to receive and decode the signal. High gain Yagi antenna (preferably an array of yagis) is recommended.

4.2 VX-3R2

– Frequency: 145.980MHz , FM Narrow
– Power supply: rechargeable battery, operates in the dark by default but can be commanded to operate in sunlight as well
– Output power: max 1.0W, half-wave dipole antenna
– Modulation scheme: AFSK 1200bps
– Telemetry interval: one burst of 3 telemetry packets in KISS format every 30 seconds (configurable)
Telemetry data format:
No Data Description Size (bit)
1 Date time Date: dd/mm/y: 5/4/3=12 bits
Time: hh/mm/ss: 5/6/6=17 bits
2 Battery voltage Battery voltage multiplied by 100 (divide by 100 to get actual value) 11
3 Solar cells voltage Solar cells voltage multiplied by 10 (divide by 10 to get actual value) 8
4 Temp. 1 oC (outside Y+) 8
5 Temp. 2 oC (outside Y-) 8
6 Temp. 3 oC (outside X-) 8
7 Temp. 4 oC (outside Z+) 8
8 Temp. 5 oC (outside Z-) 8
9 Temp. 6 oC (outside X+) 8
10 Temp. 7 oC (inside Z-) 8
11 Temp. 8 oC (inside, under VX-3R1) 8
Total 112 bits = 14 bytes


  • F-1 periodically sends a burst of 3 telemetry packets with the same content to avoid loss of packet
  • Time in UTC, 24 hours format
  • Year count starting from 2012 (2012 equals 0, 2013 equals 1 and so on…)
  • Battery voltage reading is accurate to 0.01V, values are multiplied by 100. Divide by 100 to get actual value
  • Solar cells voltage reading is accurate to 0.1V, values are multiplied by 10. Divide by 10 to get actual value
  • Temperature reading from sensors, will be added with 100 before transmission to ensure a positive number so please subtract 100 to get actual value
  • 112 bits, divide to 14 chunks of 8 bits, each chunk becomes one byte

5. Decoding data from F-1

For PWM CW beacon, you can use your ear or any CW decoding tools you like, we suggest using CW Get (download from here http://www.dxsoft.com/en/products/cwget/)
For telemetry packets, please use F-1 Telemetry Decoder to decode, the software requires a COM port that is connected to the TNC modem (a soft-modem such as MixW/virtual COM ports can also be used). You can use the client software to submit decoded data to us or by sending directly to me (via thuvt@fpt.edu.vn), audio records are highly appreciated. You will receive the verification card from us!

Please feel free to ask if there is any question. We would really appreciate your kind support!


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