Wednesday, June 26, 2013

Unattended running

The Rocketometer has been running unattended now for several hours. For instance, last I checked it was just over 7 hours, and had generated 77 files of 4MiB each. This represents a data rate of about 12kiB/second. At this rate, the device will fill up in about 350 hours, or 14 straight days.

So, I asked about which direction would be vertical when the Rocketometer is installed in the rocket. It is vertical when accelerometer reads most strongly in the  +Z direction. Coincidentally, this means that the interface is on the bottom, and the lights will be hidden.

I put in a piece of code which detects when the Z axis is stronger than the others. Mindful of the Genesis reentry failure, I put in code such that if the board is either +Z or -Z, it will decide that it is vertical. I can't test that Z is correct, but I can observe the board in place in the control section and visually confirm that Z is correct.

Now this piece of code will just reduce the rate of readout from once every 3 ms to once every 30ms, still quite quick, but only 1/10 the data rate. Even if it is wrong, we will still get some data.

I will need a log of when the CCD board is powered in order to match up non-flight measurements with anything, but the flight should be either the last or second-to-last record on the board.

For the unattended run, the system will be set to chunk its data into 1GiB pieces, and use only the last digit of the 4-digit number for chunks in a run, reserving 3 digits for runs. I do not expect the Rocketometer to be power-cycled more than 1000 times.

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