The headfile

Hi,

Most of the sensors in a Nortek instrument have to be calibrated to keep the specified accuracy. This and the fact that we offer flexibility in probe geometry, deployment orientation and external output/inputs make it necessary to store a number of parameters to make the instrument perform as intended. This is stored in the headfile. It is actually misguiding to call it a headfile; it has parameters that are dependent of the instruments electronics as well. We make the file when producing the instrument, and it is saved in the respective instrument (we also keep a copy at Nortek).

So, what does it contain?
Here's a list of the calibration parameters that are stored in the headfile.
- Serial no.
- Pressure sensor calibration data
- Tilt sensor calibration data
- Beam to XYZ transformation matrix (conversion between the coordinate systems)
- The transducing frequency
- No. of beams
- Tilt sensor orientation
- Compass alignment data
- Temperature sensor calibration data
- Compass calibration data
The last two are dependent of the instruments electronics - not the probe head.

When e.g. replacing a probe head it is quite easy to download a new one by selecting Configuration -> Sensor Head in the instruments software.
We might ask you to do download the headfile from the instrument some time to provide you the best support. It is not that simple, but here is how to do it:
- Connect the instrument to the computer and start the instruments software.
- In the terminal emulator choose Log File and give the file a describing name.
- In the Command window type GH and press send. (GH is short for Get Headfile).
- Choose Stop logging to end the file.
You have now captured the data. To be able to download the file there are two more steps that rarely are necessary for other than Nortek staff to do:
- Remove the last two binary characters of the file (06 06 which is acknowledge).
- Save the file as *.bin.

Hopefully some of the mystery around the headfile is gone…..
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Best Regards
Jonas Røstad