We need a GNSS (also known colloquially as GPS) module to allow FINCH to know it’s the exact location. In addition, this needs to be a co-com unlocked module, which basically means that it won’t shut down during missile-like behaviour (i.e. orbit conditions)
Getting cocom unlocked is difficult and expensive. It’s difficult because there are a lot of hoops to jump through to convince u-blox that we aren’t a terrorist group, and aren’t building a missile. And it’s expensive because they know we have no other option, and it takes time for them to verify our non-terrorist status.
While we don’t have exact costs and timelines for getting a cocom unlocked device, we know that the locked one is around $225USD, and Mingde says that in his experience an unlocked one will run you 10-20x the locked cost. A quick Google corroborates this — the cheapest one I could find was $5000USD.
Even once we have the thing, we need to find and validate a GPS antenna, and find a way to mount it on the top of the ADCS module — the GPS antenna must be on the Z axis facing away from the Earth to receive signal.
According to Tensor Tech 22/12/22 they charge $1200 for a GNSS package (once you account for discounts). See the Slack thread:
Here is the email:
In summary, for $1200, we get the GNSS module, antenna, and it comes already mounted and software already integrated.
Buy the Tensor Tech GNSS package. It’s cheaper, involves (way) less work on our end, and is better tested.