Grafidy 3 Gradient Calibration

Grafidy 3 utilizes Grafidy PSD (pulse sequence) and Grafidy coil fixture, and has an improved user interface to allow more flexibility and ease of use. Grafidy 3 will adjust and compensate for short, long and very long time constants eddy currents, both linear and B0 terms. It is expected that the FE will start the calibration process by running Grafidy 3 in Auto Mode and then switch to Manual Mode only if Grafidy 3 cannot bring a term into specification. This should not often have to be done.

Refer to Table 1 for the suggested Grafidy 3 flow.

Table 1. Grafidy 3 Flow
Always perform L-Coil Calibration before starting either DC Offset Adjustment or Grafidy 3 Procedure. From the Calibration menu, select L-Coil Calibration. Click on the selection to start the tool. The calibration runs automatically. Always perform DC Offset Adjustment before starting Grafidy 3. Configure the system to run Grafidy 3. Things that will be accomplished here are: Set up the standard two-coil Grafidy kit. The 6-coil Grafidy fixture is not supported. Place a rotary attenuator set for 20dB of attenuation between exciter output and RFI. Manual Prescan and get “enough signal” to make sure the setup is good and the coils are good. Then Auto Prescan. Perform the Auto Grafidy 3 Procedure. Start Grafidy3 tool. Select components that are going to be calibrated and zero out their calibration values. Auto Mode is the mode from which Grafidy3 should normally be run. One coil axis is run at a time. Make sure the physical coil axis and the axis selected on the tool’s user interface are the same, and then scan. Perform Manual Mode if auto mode does not make all components under spec (still in “red” in User Interface’s result area/table), go to manual mode to do “touch up.”

Additional information can be found for GE Service Pull-Down and Aborting/Exiting the Grafidy 3 tool.