EPOCH 1000 Series ProcedurePhased Array DAC/TVG

PA DAC/TVG Feature OverviewThe EPOCH 1000i offers a combined DAC/TVG sizing feature standard

for phased array mode:

Includes ASME, ASME-3, JIS and Custom features

Quick setup using modified GAIN calibration tool

Edit features allows individual point edits for increased accuracy at critical angles

Designed for intuitive compatibility with conventional DAC/TVG procedures

Required Items

Test Block– EP1000-PABLOCK-1

Couplant– D-12

Transducer and Wedge– 5L16-9.6X10-A10P-P-2.5-OM probe– SA10P-N55S wedge

Feature Activation Proper calibration is required prior to activation of the DAC/TVG feature for precise

measurements

The DAC/TVG activation is located in the SIZING OPTION menu group under [P1] (DAC/TVG)

Under the DAC/TVG menu, select the desired curve method

– In this example, use ASME-3

NOTE: If GAIN calibration has already been performed, the message belowwill appear. Select NO for thisdemonstration

Acquiring DAC Points As with the conventional DAC/TVG feature, the user must capture individual

points using the DAC function.

Use the PA Demo Block’s side drilled holes (SDH) to build a demonstration DAC curve

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.) After exiting the DAC/TVG activation menu, the instrument will default

to the PA CAL group, with the Calibration type DAC active

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 AUTO-80% may be used for each reflector to bring the initial reflection

to 80% and allow proper amplitude measurement across angle range

Range adjustment is valid during DAC acquisition

Angle adjustment is valid to view any live A-scan individually

Gate adjustment is valid during DAC acquisition

[P3] (ERASE) key erases the ENTIRE curve

[P4] (Delete) key deletes the last point of the curve for re-entry

Gate Positioning During DAC Acquisition It is critical to avoid collecting amplitude information from other sources during

DAC setup.

This is especially true for the deepest SDH in the PA Demo Block.

Use Gate adjustment during amplitude measurement acquisition to avoid incorrect readings

Completed DAC from PA Demo Block

DAC/TVG Menu 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 For conventional procedure

compliance, it is critical to have accurate curves represented at 45, 60 and 70 degrees

The EDIT function allows the user to edit the TOF and Gain of any individual DAC point acquired during setup

EDIT uses a TVG Table format for simplicity

Edit Feature Utility The EDIT feature is especially important

to make the overall DAC acquisition process faster

Allows user some basic inaccuracies of the initial setup that can be removed later

High angles (such as 70 degrees) often require editing for precision

– See 70 degree amplitude acquisition as an example!

Editing DAC PointsTo edit individual DAC points: Enter the EDIT mode from the DAC menu

Use the Angle/Cursor button to select the desired angle

Press [P1] (Edit) to enter the TVG Table

Editing DAC Points (cont.) Use the arrow keys to navigate to cells within the table

A purple square (top) and red crosshair (bottom) on the live A-scan indicates the TOF position of the selected row in the table

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 It is important to note that the EPOCH 1000i handles some aspects of

DAC/TVG differently than other PA instruments

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

This means that there could be a different Ref dB for every focal law

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!