Here's an update on what's been achieved since we last reported in.
Our hardware manifest for the whole project is complete: we have all parts in hand. We obtained a 1600gm balloon envelope, which means that we no longer need to use hydrogen - with all the electrostatic distcharge risk management that that implies - instead of helium. Using helium means that we can invite people to the launch, and have a team near the launch package, without a great deal of Health and Safety load.
Programming of the Instrument Co-Processor (ICP) - an Android phone - has progressed very well indeed. We have a mechanism to control the ICP using SMS messages, and an SMS mechanism for sending back telemetry. The phone only activates its radio interface below an operational ceiling set at the height of the highest mountain in the UK, but will use that to send back tracking information during the descent phase. It records instrumentation to its MicroSD card throughout the flight. Once it's below its radio ceiling, it will also attempt to send as much of its instrumentation capture as possible to a server.
The Command and Control Processor (CCP) development was delayed a bit pending building the hardware around the CCP. We now have the first prototype CCP motherboard, including the balloon cutaway pyro circuit, complete, and it's being tested at the moment. We'll be posting up details of the circuits soon. CCP programming has resumed, now that we have the full hardware platform ready. We're getting good data from the CCP's GPS unit. The main remaning task is to integrate the licence-exempt downlink transmitter into the software stack.bu
We've abandoned the concept of heaters for now. We may yet create some kind of low-energy warming blanket for the main power supply unit, to maximise the amount of available power, whilst using as little as possible for warming. Of course, any heater has to be in direct contact with what it's warming, as air at 10mbar doesn't really convect all that well.
Talking about power, we have a backup power source, in the shape of a second Scosche GoBat II, available now.
We've encountered some problems with our cameras. We'd like to be able to run - or at least support - these from the main power source via USB, but they don't seem very happy with staying operational, even with a dumb power supply (with the D+ and D- lines tied together). We're trying to find either alternative imaging devices with sufficiently high resolution and the ability to continue to run whilst on USB power, or a way of botchering the cameras to ast as we need, perhaps by replacing their battery packs with dummy packs supplying power from the GoBat II.