Hi everyone, apologies if this post is in the wrong category.
I am part of a group of amateur astronomers and (very) amateur satellite enthusiasts located in Port Macquarie, Australia.
We want to build our own Cubesat to house a telescope. The plan is to utilise the satellite for star gazing when local conditions prevent us using our telescope.
What I am hoping for is someone to point me in the right direction for advice on communication systems. We’ll need TTC and data at a rate decent enough for reasonable quality images. Then of course we need to receive the data, regardless of where the satellite is and display it at our observatory.
There is so much information out there that I’m finding it a challenge to determine what is relevant and what is not. My background is in pre-hospital emergency care, so this is all very new ground for me. Any assistance will be enormously helpful to us.
Thanks in advance,
Derek.
Hi Derek,
my recommendation is to first define what quality (image data size) and image capture rate you are looking for. Usually a well defined mission helps a lot to make such choices.
For TTC VHF and UHF are most common but both wont offer you the data rate for a telescope. So a common choice (without knowing anything about your constraints) would be to use an additional S-Band Downlink for the images. Take a look at SatNOGS COMMS for example. A teleskop and S-Band transmitter are uncommon for anything below 2 or 3U because of power/space constraints.
If you give us a little more information we can help you better.
Cheers,
Milenko
Hi Milenko,
thanks for your reply. I apologise for taking my time in getting back to you - we had a long weekend here.
We are very much at the concept formulating stage at present, however I can tell you that we plan a 3U cubesat in order to accommodate the telescope, comms, gimble, etc.
Our desire is for reasonably high quality images so your suggestion of an S-Band transmitter sounds feasible. As for the data rate, we still have no idea of the resolution our images will use. Sorry for the lack of info, but we’re just looking to be pointed in a positive direction at present. You’ve already helped enormously with the point about the S-Band transmitter.
Cheers,
Derek.
No worries when something new comes up feel free to ask, always happy to help 
Hi Milenko,
here’s a bit more information about our organisation and if you or anyone else has any advice they can give, as usual it will be greatly appreciated.
As previously mentioned, we are part of the Port Macquarie Astronomical Society. We are a group of volunteers who are responsible for the running and manning of the Port Macquarie Observatory. We’re a community based organisation that is funded by memberships and small government grants.
Our plan is to build a 3U Cubesat to house a 90mm mirror scope and high quality imager, with adequate battery storage, solar panels and an appropriate software suite to enable star mapping.
Ideally, we want to control the unit with a laptop or mobile phone to point the unit at the celestial body of our choice, take an image and then download that image for display at our observatory for when the weather prohibits the use of our ground based scope and for public interest.
My part of the project is understanding the comms requirements as I mentioned in my earlier post. As I understand it we can utilise the amateur radio network for VHF and UHF TTC (pending approval) and for image download an S-band transmitter.
Am I correct in assuming that if we join SatNOGS we can access the network of ground stations and use that network to access our S-band transmitter and retrieve our images that way, without having to build our own ground station?
If you (or anyone else) can confirm my assumptions, that would help us a lot.
I apologise again for taking my time in communicating, my workload here has been very demanding, but my time is a lot more flexible now so I’ll be able to reply quickly to any responses from now on.
Thank you in advance, stay safe.
Derek.
If you haven’t already, read the Satellite Operator Guide
This part is probably relevant:
In order to use an Amateur Radio band, your mission needs to be Amateur Radio related. Broadly speaking this includes and Amateur Radio service (like a transponder) or Amateur Radio experiment (new modulations, propagation experiments etc).
Most existing Satnogs ground stations are VHF or UHF. Not many can receive S-band. But maybe the few that exist can be sufficient for your needs.
Hi,
Thank you for the additional information!
You will need your own GS or buy in a commercial operator to have command ability on VHF/UHF. SatNOGS does not (yet) provide uplink capability. Even if it is not a hard requirement, it is desirable for satellite operators that use SatNOGS to contribute a station.
Cheers,
Milenko
Btw, here is the number of antennas (stations) per band, according to the data currently available through the API:
1 HF
3 HF, VHF
101 HF, VHF, UHF
86 HF, VHF, UHF, L
55 L
1 LF
1 LF, MF, HF, VHF
6 L, S
30 S
1078 UHF
5 UHF, L
1 UHF, L, S
1 UHF, L, S, C, X
2 ULF
1 ULF, VLF, LF, MF, HF, VHF, UHF, L
1 ULF, VLF, LF, MF, HF, VHF, UHF, L, S, C, X, Ku, K, Ka
1341 VHF
24 VHF, UHF
7 VHF, UHF, L
1 VHF, UHF, L, S
Note that the vast majority of the registered stations are not online. Statistics:
1616 Offline
261 Online
147 Testing
Here is the number of antennas (stations) per band with status=Online:
3 HF, VHF, UHF
4 HF, VHF, UHF, L
3 L
2 S
148 UHF
3 UHF, L
184 VHF
6 VHF, UHF
1 VHF, UHF, L
Can you add to those the Testing ones?
Sure. This is with Online and Testing:
8 HF, VHF, UHF
9 HF, VHF, UHF, L
7 L
2 L, S
4 S
249 UHF
3 UHF, L
1 ULF
1 ULF, VLF, LF, MF, HF, VHF, UHF, L
278 VHF
7 VHF, UHF
1 VHF, UHF, L
Here is how anyone can do it:
- Download the full station list from the API using this script. Downloading will take a while.
- Use jq to filter. Example:
jq -r '.[][]| select(.status=="Online",.status=="Testing") | .antenna | .[].band' stations.json | sort | uniq -c