Regarding BitSat uplink rate

[Jacob D]

I've read through the BitSat Architecture v0.1 document and a few questions.

It seems the minimal uplink speed suggested was 20kbps. A look at some the information available shows typical uplinks for cubesats are 9600 bps. What are some proposed ways to overcome this? A cursory search on the internet reveals a couple presentations on how to approach the problem.

A couple of finds after my cursory search:

http://www.nanosat.jp/images/report/pdf/NSS-05-0602.pdf

https://www.youtube.com/watch?v=mNI0Tdju3Y4

[Alek Lidtke]

OK, there are two ways to boost the downlink/uplink bit rate if you want to keep the bit error rate (BER) under a certain threshold, i.e.

• use a higher-gain antenna (which is normally larger and hence its deployment is more cumbersome and risk)
  
• use a higher power transmitter. This obviously requires more DC input power, which requires more solar array area which requires a larger cubesat and deployment of additional solar array panels.
  

Or you combine the two approaches. I can't see any other option if you want to be transmitting at any time (if you could schedule the communications to some fixed times you could use batteries or somesuch to gather enough power to enable downlink).

BTW guess why GEO comsats are so huge - they transmit a lot of data, hence need large antennae and solar arrays to power the RF equipment ;)