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.
|TX Power||4.8 W / 6.8 dBW / 36.8 dBm|
|TX Ant Gain||5 dBi|
|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/N0||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|
- Attenuation due to rain, ionosphere and atmospheric gasses set to 2 dB
- TX power is 4.8 watts/antenna.
- TX antenna is microstrip patch, linear, assuming 5 dBi gain.
- 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
- 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.