Delta-T Devices AP4, User Manual

Page: 40 / 64

HOW MANY READINGS TO TAKE
Page 40
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Contact a statistician, or get a good statistics book, for advice on how
to ensure your results are statistically significant.
HOW MANY READINGS TO TAKE
You can take nearly 1600 readings with no annotations added.
This reduces to 632 if you add a 30-character note to each.
Most users will take readings for 2-3 days before filling memory.
MEMORY USAGE
The memory size is 32,000 bytes.
Each reading uses 20 bytes, with an optional 0 to 30 bytes overhead for any annotation
you add (1 keyboard character = 1 byte).
Readings are kept in groups, each with its own optional name of up to 16 characters.
There is a fixed overhead of 44 bytes per group.
The main title can also be up to 16 characters long.
Each group is identified by a number, as is each plant and each leaf.
EXAMPLE PLAN
Title: My first attempt
Number of groups = 4
Group names will be: Treatment 1, Treatment 2, Treatment 3, Treatment 4
Number of plants in each group = 5
Number of leaves per plant = 5
So, total number of readings = 4 x 5 x 5 = 100
At one reading per minute expect to take about 2 hours.
Battery life = 20% (say)
[ 100% ≈ 20 hours ]
[This is a bit low - better recharge battery]
Free memory = 20% (say)
[Should be OK for 126 readings at least, more if I keep down the annotation to a
reasonable level. Someone must have left in a lot of data from last time. Do they want it
or can I delete it now?]
Check desiccant.
Check Calibration Kit - see
CHECKS above.
Is the calibration plate fresh, i.e. recently made up with damp filter paper?
Are the plants ready?
OK? ACTION! LET'S GO AND DO SOME SCIENCE!