Go inertial time was: November 21, 2013 at 07:10:10.147 UTC (launch was 5 years, 10 months, 22 days, 15 hours, 48 minutes ago)

Satellite name: ZACUBE-1 (TshepisoSat)
Satellite TX frequency: 437.355 MHz (Downlink)
Satellite HF payload beacon transmitter frequency: 14.099 MHz
Modulation and data rates: UHF AX.25 1200 bps AFSK and 9600 bps GMSK. HF payload in CW.
Satellite antenna polarization: Linear
Satellite transceiver manufacturer: CPUT/F’SATI

HF payload beacon activation will happen after satellite checkout and commissioning and will be announced on this page (Details to follow).

Orbital Elements

Up-to-date TLEs can be found at the link below, under “ZACUBE-1 (TSHEPISOSAT)”:

CelesTrak – cubesat

Below are old elements that were accurate for a few days after launch:
Preliminary two-line element set
Preliminary two-line element set

Online resources


The South African National Space Agency (SANSA) has made available an easy to use web app to determine ZACUBE-1’s real-time position and predict upcoming passes.

The SATVIEW website can also be used to keep an eye on ZACUBE-1.


Beacon decoding

The satellite is usually configured to transmit a beacon message on its UHF transmitter every few minutes, if the battery charge state is good. After launch a beacon message was transmitted containing an ASCII encoded text message, timestamp, battery voltage, OBC temperature and uplinked command counter. Another two beacon messages were later added, which includes information on OBC status and battery voltage. The initial message, updated messages and beacon decoder application is discussed below.

Initial beacon message

One of the first TLM messages received

An example of the status beacon message transmitted after separation from the launch vehicle can be seen below in its SLIP encoded raw hexadecimal format. The message contains a header, text string, time, battery potential, temperature and command counter.

c0 0c 16 7a 61 63 75 62 65 30 31 2e 00 00 19 6d 2c 0b 0e 2c 06 ad 2c 00 2e c0

For easy tracking and identification after launch of ZACUBE-1 the ASCII text string should be easily identifiable from your TNC/modem output. In RAW HEX it has the following format 7a 61 63 75 62 65 30 31 which is decoded to zacube01. This ASCII message is configurable and might be changed after launch. The equations to convert TLM manually is given below. The message above will be used as an example.
0C - header
16 - message payload length
7A 61 63 75 62 65 30 31 2E - ASCII Text message
00 00 19 6d 2C - Timestamp (ticks)
0B 0e 2C - Battery bus voltage (volt)
06 ad 2C - OBC temperature (°C)
00 2E - Command counter

Temperature = 0.1728239*value – 277.746 (°C)
Battery voltage = 0.0029*value + 0.023 (volt)

The 2E and 2C values indicate the end of the field.

Updated beacon message

Two additional beacon messages were added with information on the OBC status and battery voltage. These two additional message are transmitted periodically and might not always be broadcasted during a satellite over pass.
Info on new messages here and the decoding

Message: Battery voltage – c0 0d 06 0e 0c 02 0a 8a c0

0d 06 0e 0c - header
02 - message payload length
0a 8a - Battery bus voltage (volt = 0.0029*value + 0.023)


Message: OBC status – c0 0d 06 24 0c 0b 1d 01 03 03 00 34 00 12 01 41 06 c0

0d 06 24 0c - header
0b - message payload length
1d - event counter
01 - scheduler power state - good(1) / low(0)
03 - scheduler state - running(3)/stopped(0)
03 - beacon state - running(3)/stopped(0)
00 - UHF beacon type - UHF msg+TLM(0) / HF msg+TLM(25)
34 - LEOP state - deployed1(0x34) / deployed2(0x3c)
00 - logger state - running(1) / stop(0)
12 - command counter
01 - LEOP flag stop - run normal(1) / stop flag(0)
41 - payload power bus state - bit-field - on(1) / off(0) - Beacon3v3(bit2), Beacon5v(bit4), ADCS3v3(bit5), ADCS5v(bit8)
06 - i2c state - bit-field - OK(1) / warning(0) - SDA(bit2), SCL(bit3)

Beacon decoder

A decoder application is available to decode and log the telemetry beacon message received by TNC/modem. Submitting log files generated by the provided app is preferred when submitting received telemetry beacons. The app will also be updated if new telemetry is added. Logfiles can be submitted to the address below.

Decoder application

The application receives KISS encoded messages from a TNC and decodes the messages to understandable values. Configure the application by using the drop down boxes to select the serial port that your TNC is connected to and set the baud rate for your TNC and click connect. MixW and a virtual serial port emulator can also be used with the decoder application.

Download ZACUBE-1 status beacon decoder updated 2014-05-28

It would be greatly appreciated if any received TLM be sent to:
For further up-to-date information follow us on Twitter



We would like to thank the following people for submitting received beacon messages!

Craig Francis (Cal Poly – California – USA)
Dave Williams (G7GQW, Amsat UK member – UK)
Jan v Gils (PE0SAT – NL)
Mario Fazio (LU4EOU – Bahia Blanca – Argentina)
Roland Zurmely (PY4ZBZ – Sete Lagoas – Brazil)
Tetsurou Satou (JA0CAW – Niigata-City – Japan)
Toshio Kasei (JA1GDE – Tokyo – Japan)
Bob Mattaliano (N6RFM – Bristol – Rhode Island – USA)
Mike Rupprecht (DK3WN) – Germany

If you have submitted messages but are not listed above let us know (