TURKSAT and Istanbul Technical University

CubeBug-1 is the first technology demonstration mission for a new CubeSat platform design (mechanics, hardware and software) intended to be released as Open Source and Open Hardware for its use in Amateur projects, University projects and research labs.

NASA-Catalog: 39153

Downlink

437.445 MHz FM 1k2 AFSK AX.25 1W

Call

CUBEB

Status

INACTIVE

Orbital Parameter

NORAD                   39153
COSPAR designator       2013-018-D  
Inclination             98.035
RA of A. Node           352.361
Eccentricity            0.0018381
Argument of Perigee     18.264
Revs per day            14.77975548
Period                  1h 37m 25s (97.42 min)
Semi-major axis         7 014 km
Perigee x Apogee        623 x 649 km
BStar (drag term)       0.000267390 1/ER
Mean anomaly            341.924

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Telemetry

The source of the AX.25 packet is labeled as “CUBEB” and destination “UI”. The data portion contains a binary blob. There are mainly two beacon formats. Packets starting with FF FF F0 are the complete beacon, packets starting with FF FF F3 are a short beacon, with basic information, and a different encoding. All numbers in the packets are stored in network byte ordering (Big Endinan). Most values require a conversion formula, provided in the next table.

The short beacon is encoded a bit different. For every bit the satellite wants to transmit it actually transmits 4. So, for example, the 8 bits 0xA5 become F0F00F0F in the air (a nibble per bit). As this encoding transmits more energy with each bit, it will give us a chance to decode some basic telemetry in a worse scenario. The first three bytes (FF FF F3) identify the packet as a short telemetry beacon, the rest must be “decoded” before interpretation.

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