EPOCH 1000 Series Procedure Phased Array DAC/TVG

PA DAC/TVG Feature Overview The EPOCH 1000i offers a combined DAC/TVG sizing feature standard for phased array mode: u Includes ASME, ASME-3, JIS and Custom features u Quick setup using modified GAIN calibration tool u Edit features allows individual point edits for increased accuracy at critical angles u Designed for intuitive compatibility with conventional DAC/TVG procedures

Required Items u Test Block –EP1000-PABLOCK-1 u Couplant –D-12 u Transducer and Wedge –5L16-9.6X10-A10P-P-2.5-OM probe –SA10P-N55S wedge

Feature Activation u Proper calibration is required prior to activation of the DAC/TVG feature for precise measurements u The DAC/TVG activation is located in the SIZING OPTION menu group under [P1] (DAC/TVG) u Under the DAC/TVG menu, select the desired curve method –In this example, use ASME-3 u NOTE: If GAIN calibration has already been performed, the message below will appear. Select NO for this demonstration

Acquiring DAC Points u As with the conventional DAC/TVG feature, the user must capture individual points using the DAC function. u Use the PA Demo Block’s side drilled holes (SDH) to build a demonstration DAC curve u Place the 5L16 probe on top of the demo block, over the most shallow SDH, and facing the closest side of the block

Acquiring DAC Points (cont.) u After exiting the DAC/TVG activation menu, the instrument will default to the PA CAL group, with the Calibration type DAC active u Use the same procedure as GAIN calibration to acquire each individual SDH as a point on the DAC curve: –Set reference cursor to 45 degrees –Position Gate 1 to capture an amplitude measurement from the SDH across all angles –Use AUTO 80% to bring the SDH reflection to 80% at 45 degrees –Press [P1] (ADD) to begin point calibration –Press [P2] (DONE) after successful acquisition of each point

DAC Point Acquisition Screens

Functions During DAC Acquisition u AUTO-80% may be used for each reflector to bring the initial reflection to 80% and allow proper amplitude measurement across angle range u Range adjustment is valid during DAC acquisition u Angle adjustment is valid to view any live A-scan individually u Gate adjustment is valid during DAC acquisition u [P3] (ERASE) key erases the ENTIRE curve u [P4] (Delete) key deletes the last point of the curve for re-entry

Gate Positioning During DAC Acquisition u It is critical to avoid collecting amplitude information from other sources during DAC setup. u This is especially true for the deepest SDH in the PA Demo Block. u Use Gate adjustment during amplitude measurement acquisition to avoid incorrect readings

Completed DAC from PA Demo Block

DAC/TVG Menu u Once DAC points have been acquired, the DAC group menu appears beside [F2] (DAC) in group 4/5 –P1 – Toggles between DAC and TVG view on the active A-scan –P2 – Adjusts DAC Curve Gain to properly size in the far field –P3 – Adjusts the gain step for Curve Gain –P4 – Selects visible curve for live A-scan measurement comparison –P5 – Allows individual DAC point edit –P7 – Turns DAC function OFF without entering a setup menu

Point Edit Function u For conventional procedure compliance, it is critical to have accurate curves represented at 45, 60 and 70 degrees u The EDIT function allows the user to edit the TOF and Gain of any individual DAC point acquired during setup u EDIT uses a TVG Table format for simplicity

Edit Feature Utility u The EDIT feature is especially important to make the overall DAC acquisition process faster u Allows user some basic inaccuracies of the initial setup that can be removed later u High angles (such as 70 degrees) often require editing for precision –See 70 degree amplitude acquisition as an example!

Editing DAC Points To edit individual DAC points: u Enter the EDIT mode from the DAC menu u Use the Angle/Cursor button to select the desired angle u Press [P1] (Edit) to enter the TVG Table

Editing DAC Points (cont.) u Use the arrow keys to navigate to cells within the table u A purple square (top) and red crosshair (bottom) on the live A-scan indicates the TOF position of the selected row in the table u Use the knob to increase/decrease the gain of each point at critical angles to meet 80% exactly MOST COMMON ADJUSTMENT

Phased Array DAC/TVG and the EPOCH 1000i u It is important to note that the EPOCH 1000i handles some aspects of DAC/TVG differently than other PA instruments u To standardize to conventional DAC/TVG usage, the displayed Reference Gain for each focal law represents the gain required to bring the first DAC point at that focal law to 80% full screen height u This means that there could be a different Ref dB for every focal law u This is true of conventional UT at varying angles, as well –Advantage of PA: One DAC calibration file handles all critical angles instead of multiple DAC curve setups that require recall and verification!