Krishna

I have modified the C# code in BRS Beckhoff computers used for the angle readout. The code is used to fit the cross-correlation of the patterns in the CCD to infer the position change (=angle) of the patterns. The code used to have a manually adjusted fit parameter. This was unsatisfactory and produced errors in the fit as the beam-balance position changed over time or it's amplitude grew. The noise level in the angle would vary from ~0.2 nrad/rt(Hz) to ~0.4 nrad/rt(Hz). We came up with a better routine than can extract this parameter from the data and use it to correct the fit producing superior results as shown in the attachment. The noise level should now stay below 0.2 nrad/rt(Hz).

The code for both BRS' has been updated.

This should allow us to set higher thresholds for BRSX damper, which will help with the problem in 33028. However, it would still be a good idea for the operator or anyone else to keep the BRSX amplitude small by damping it, whenever we are not observing.

Other updates

I cleared the encoder_value_save.txt file for BRSX, by deleting all characters inside. I suspect the large number of ascii values there were caused by interruption of the ethercat communication to the Beckhoff Motor Controller, likely due to lose wires. The evidence for this is the two drops in the BRSX_BOXBIT in November. It hasn't happened since, but it would be good to investigate it when convenient. After clearing the file, I restarted the computer, restarted the PLC and zeroed the encoder position. After modifying the C# code and restarting it, the damper seemed fine. We'll keep an eye on this.

For BRSY, I noticed a couple of problems with the Diagnostic C# code, which we use when we have to change the centering of the beam-balance. First was that Visual Studio asked me to log in with a Microsoft account id. I created a new one, since I couldn't remember what the old one was. This info will be added to the BRS troubleshooting guide on the DCC to prevent this problem in the future. Second, the C# code would freeze after 11 seconds for no obvious reason. I restarted the Beckhoff computer, after which it worked fine. I wanted to make a note of this here to prevent future surprises.

After consulting with John W. and Bubba G., Jim W. and I decided to postpone the spare seismometer test at BRSY due to the poor road conditions. I'll leave the table with Jim and he will install it at the next available opportunity