1. MnSGC Ballooning Team Techniques: HOBO temp/solar panel data analysis James Flaten Summer 2010

2. HOBO data usually looks about like this when originally stored (depending on what units are selected during export step). Here the 4 channels are internal temperature, internal relative humidity, external temperature, and voltage (from a solar panel).

3. Improve the labeling, widening the columns as need be. Add “Time T (raw)” and “Time T (min)” and “Flight time t (min)” columns. In the Time T (raw) column copy the TIME, GMT information, formatting the cells to “General” to expose the raw timing values.

4. Next generate values for the Time T (min) column by subtracting the first raw value from each one, then dividing by 0.0006945 which is the amount of raw time per actual minute. In the spreadsheet above, the first raw value is in cell C5 (in blue) and the time per actual minute is in cell E1 (in yellow), so the required code for box D5 is “=(C5-$C$5)/$E$1” (where the dollar signs indicate absolute referencing rather than relative referencing).

5. A quick look at the External Temperature versus Time T suggests that Release was at about T = 131.5 min, so use an offset of -131.5 minute to generate Flight Time t (min) values – note the use of absolute referencing.

6. Final data-versus-time graphs will use the Flight Time t (min) column. The time axis may be truncated on graphs so as not to show too much pre-flight nor post-flight data. Here is an example of solar panel data, with Launch at t = 0 (always), Burst at t = 76 min, and Touchdown at t = 117 min. The noise in the data is due to rotation of the stack so that the solar panel is sometimes in the sunlight and sometimes in the shadow.