SAS Satellite Avoidance System

The major functions to be provided by the SAS software module are:
  1. Load and parse the PAMs (Predictive Avoidance Approval Messages) provided by the LCH (Laser Clearinghouse). There are two types of PAMs: one for Alt/Az targets and one for RA/Dec targets.
  2. Generate a list of targets and their respective open and closed time windows.
  3. Generate an interlock signal to the main ARGOS HW (go / no go) based on:
  4. Telescope is pointing to an approved target.
  5. Time is inside an \x93open window\x94 for that target.
  6. Provide a visual indication to inform the operator of upcoming time windows for the selected target.
  7. Keep an activity log for reporting and troubleshooting.

Pam files

The following is an unclassified example of a PAM with OPEN windows and Fixed Field of View targets: /trunk/misc/sas/pam/sample.pam

Setting the SAS to manual mode

This procedure is not recommended but it may be that the laser operator needs to turn on or off the interlock signal manually instead of using the PAM files. In order to do this, the SAS configuration file, located in $INSROOT/etc/argos_satavoidd.cfg, has to be changes as follow:
manual_mode        true

After that, the user must go to the advanced tab of the Satellite avoidance GUI (see screenshot below) and reload the SAS configuration file. At this point, the interlock signals can manually be turned on or off.


Interlock signals

The SAS, when activated, sends periodically pulses to the SAS/AAS WebIO switch. When there is an open window, the system activates the Inner circle port to allow for Laser firing. The period of the pulses among other parameters of the WebIO switch are defined in the repository. Additionally, the heart beat port of the WebIO switch must be set in Pulse mode, shown in the following screenshot:


Additional documentation

The document describing the SAS can be found here: ARGOS_FDR_007
Topic revision: r4 - 08 Aug 2018, AndrewColson
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