Remark: this wiki page is mostly outdated - find informations on special ratescans on https://trac.fact-project.org/wiki/SpecialRatescans
Here I want to explain a little bit, how to perform a ratescan with a closed lid and bias switched on. In case you find something not explained precise enough, you are of course welcome to edit this page...
The process might take a couple of hours to complete.
In order to be able to operate during daytime with bias voltage enabled. Max Knoetig (who is currently at La Palma) has put a cloth over the camera, in order to shield the lid from direct sun light. In case this ratescan is done during dark time (e.g. in case of bad weather), no cloth is needed of course.
I assured myself visually, that the cloth is currently draped over the camera, before starting. I used VLC to look at it, using this URL: rtsp://cam2:554/h264
In order to conduct the ratescan I first make sure we have a bias current calibration. (RECONNECT bias, and CALIBRATE feedback)
Since the rates are expected to be fairly low, the internal countdown in ratescan would stop the ratescan too soon in some cases. Therefore I will set the countdown to 600 (instead of 150, which is the default). countdown=600 corresponds to 600seconds, if the FTM prescaler is set to 1Hz (which is the default). Also in order to save some time, I will set the minimum requested precision to 10% instead of 5% (which is the default)
Both settings can currently only be changed by shutting down the program "ratescan" and restart it with different settings, so I did that. Shutting down a FACT++ program can be done, either via the command line, by entering "quit" or hitting "Ctrl+D" or by sending the EXIT dim-command from any dim client, which is capable of sending dim commands to servers, such as the old GUI, or the dimctrl cmd line interface.
The command I use to restart ratescan is equivalent to this:
$HOME/FACT++/ratescan --max-wait=600 --resolution=0.1
(in case you just quit ratescan, you'll find yourself in a shell in $HOME/operation, in which you can simply type:
./ratescan --max-wait=600 --resolution=0.1
)
In order to initialise the ratescan, Gareth prepared a nice js-script, which can be found here: https://trac.fact-project.org/browser/trunk/FACT%2B%2B/scripts/closed_lid_ratescan.js
As one can see in the "main" section of the script, the ratescan will be from 100 to 900 in steps of 10.
