Below you will find the link budget summary calculated for a few distances during the interplanetary cruise of UNITEC-1. The link budget calculator sheet containing all the details is available here.

Parameter |
Value |
||||

Frequency | 5840 MHz | ||||

TX Power | 4.8 W / 6.8 dBW / 36.8 dBm | ||||

TX Ant Gain | 5 dBi | ||||

EIRP | 11.8 dBW | ||||

Distance (km) | 20.000 | 200.000 | 2.000.000 | 15.000.000 | 20.000.000 |

Distance (AU) | 0.0001337 | 0.0013369 | 0.0133692 | 0.1002687 | 0.1336916 |

Free Space Loss | 194 dB | 214 dB | 234 dB | 251 dB | 254 dB |

Atm. losses | 2 dB | ||||

Signal at RX ant | -184 dBW | -204 dBW | -224 dBW | -242 dBW | -244 dBW |

Pointing loss | 0.4 dB | ||||

Receiver G/T | 23 dB/K | ||||

S/N_{0} |
67 dBHz |
47 dBHz |
27 dBHz |
10 dBHz |
7 dBHz |

SNR @ 500 Hz BW | 40 dB |
20 dB |
0 dB | -17 dB | -20 dB |

SNR @ 100 Hz BW | 47 dB |
27 dB |
7 dB | -10 dB | -13 dB |

## Assumptions

- Attenuation due to rain, ionosphere and atmospheric gasses set to 2 dB
^{[2]} - TX power is 4.8 watts/antenna
^{[3]}. - TX antenna is microstrip patch, linear, assuming 5 dBi gain
^{[3]}. - Our beam width is 0.5° and I assumed a pointing error no greater than 0.1° (very optimistic) giving a 0.4 dB pointing loss.

## TBDs and TBCs

- Measure the receiver noise floor, i.e. local interference contribution to sky temperature (important)
- Re-assess sky noise taking expected solar noise, etc. into account
^{[2]}

## Conclusions

- An optimistic estimate suggests that we should be able to receive UNITEC-1 up to 10-15 million km distance.
- There is plenty of margin in the beginning and we can use a low gain antenna for initial acquisition. The IKEA dish has ~25 dBi gain and it could be used up to 1 million km where after the trajectory is hopefully well known.