The Powerbase: So let’s say a user has one of your ground station units, but (like most people) they don’t have the necessary license to actually transmit and can only receive. What could they do with the system in that case? Could they receive a downlink of news and information?
hadez: Assuming we’ve arrived at the point where this is technically possible the answer would be “most likely”. But we haven’t really looked into the specifics since there’s also huge differences internationally once you get into legal stuff.
The Powerbase: If everything works out as planned, the capability for anyone possessing a receiver to be able to get news and updates directly from the satellites could really help in situations such as a natural disaster. Is this an area you think the HGG could really do some good?
hadez: Yes, this would definitely be one of the possible use-cases. At first you would also not be able to transmit much data anyway since the downlink using possibly an omni-directional antenna will not allow for high bandwidth links. It should be enough to broadcast the most basic information required in such a scenario though.
The Powerbase: In regards to the satellites themselves, there are a number of satellites which amateur radio operators have been using for years. Could HGG use those? Or is there a concern about relying on satellites under someone else’s control?
hadez: Who has control over a satellite is of secondary importance at this point. We’re trying to improve upon the present situation and would love to see existing satellites be used more effectively using our distributed ground station. A distributed ground station network could for instance be used to increase the communication window one has with any given satellite. Since HAM satellites in low earth orbit usually take around 90 minutes to go around our little blue sphere the communication window a single receiver has isn’t that long and in the range of a few minutes. If we could implement a hand-off between ground stations this could be improved dramatically.
The Powerbase: Many people may not realize it, but there are a few highly successful amateur satellites that show a long-term reliable satellite and ground communication system doesn’t take millions to construct, such as the Delfi-C3. Do you use those projects as a reference when working on the HGG?
hadez: There’s nothing speaking against implementing support for these satellites. We’re actually already loosely affiliated with people working on such a system (not yet launched) from Stuttgart University via the Constellation project who’s planning to do the actual software implementation of the satellite tracking task.
The Powerbase: You mention on your site that the FUNcube satellite receiver isn’t suitable for the HGG. But it seems like the FUNcube project is very similar to HGG: allowing anyone with a computer to easily and cheaply receive transmissions from orbiting satellites. What makes HGG incompatible with it?
hadez: Yes and no, the FUNcube dongle is a great tool and we would strongly recommend that everyone interested in it should get one.
What it is no use for though is our prototyping target: ADS-B. ADS-B, or Automatic Dependent Surveillance, is what commercial aircraft use to transmit their position once every second. The signal is transmitted at roughly 1 GHz and the bandwidth proofed too high for the 96 kBit audio interface the FUNcube is using to connect to the host computer.
The Powerbase: So going back to the idea of the ground stations being an expandable platform, devices like the FUNcube radio are something that could be used in conjunction with the HGG in the future; but just something that isn’t necessary at this stage of development?
hadez: Yes, if you can come up with a measurement, receiver, sender module that would benefit from high accuracy timing, and if you can think of a way to build a module around it to plug it into the ground station, that would be a possibility.
With the FUNcube dongle specifically that might be a little hacked because of its USB Audio interface, but that should not keep you from exploring any ideas you come up with!
The Powerbase: Is it safe to say the extent of your current goals is simply to build the ground network? In other words, are you going to leave the design and construction of the satellites themselves up to another group?
hadez: Yes, definitely. We want to gain insight into the technology required to build satellite communication systems and simply build such a system so others don’t have to start from scratch. And who knows, once that’s done, we’ll pick another task. If that turns out to be satellites, I ensure you it’s only by pure chance and accident.
Helping The Cause
The Powerbase: Thanks for taking the time to answer a few questions. On a personal note, I really admire what groups such as yours and the Copenhagen Suborbitals are doing to push the limits of civilian achievement in space; especially at a time when it seems even NASA is scaling back it’s operations. What can readers do to support the HGG and continue pushing on with ambitious goals such as the “Hacker Space Program” proposed at Chaos Communication Camp 2011?
hadez: Thanks a lot to you as well.
At the moment HGG is at a very early prototyping stage and we have so far not felt comfortable with asking for donations even though we’ve had plenty of offers already and I’m sure that we get to a point where this would become an option in the future. For instance once we have a prototype ready and would need to manufacture and distribute a few. So if you want to stay in touch, follow us on Twitter and subscribe to the Constellation/HGG mailing list.
What’s even better would be sharing your expertise and simply join up with us or one of the other teams to actively work on HGG.
There’s also many more things to do before the ultimate goal of the “Hacker Space Program” can be achieved, so start a group at your local hackerspace and pick something, anything to work on this. If there’s not a hackerspace near your yet, start one!
All of the Staff here at “The Powerbase” would like to thank hadez and the HGG team for taking the time to answer our questions. Be sure to check back for our continuing coverage of this project as it evolves.