RITECMEDARS

MULTIPLE EMAT DRIVER AND RECEIVER SYSTEM

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Drive Phased

Arrays of EMATs at

high powers

MEDARS Overview

Drive up to 8 Electromagnetic Acoustic Transducers (EMATs) with precise control of phasing between transmitters

Very High Power (up to 10 KW) Unique Bipolar Square Wave Pulse Low Noise Broadband Receiver Adjust phase delay with sub nanosecond

resolution

MEDARS Overview

FrequencySynthesizer

Logic &Timing Circuitry

High PowerBipolar Square Wave

Pulser

Impedance Match

EMAT

EMAT

Receiver

Device Under Test

Frequency & PhaseControl

Delay & WidthControl

Output Level

Gain, Input Selection,& Bandwidth

Control

Control

RF Output To OscilloscopeOr Data Acquisition System

MEDARS Features & Benefits

Unique Bipolar Square Wave Burst

Trigger

Positive Pulse Driver

Negative Pulse Driver

Bipolar Square Wave Output

Adjustable up to 800 VPP~ 5 Ohm Output Impedance

The frequency is adjustable using a separatedirect digital synthesizer as a clock.

Pulse width adjustable from one to 250 cycles

MEDARS Features & Benefits

Precise control of Phasing and delays between transmitter pulses

Synthesizer N

Synthesizer 1 (Frequency Resolution .006 Hz)

Phase Shift (12 bit or .088 degree control)

Delay Resolution = 0.24 nsec at 1 MHz

Delay Range = 0 - 20 microseconds

MEDARS Features & Benefits

Adjust phase delays for constructive interference between transmitters

improves signal-to-noise adjust for beam focusing or direction control

MEDARS Features & Benefits

120.0 130.0 140.0Time (microseconds)

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

-1.8

-1.3

-0.8

-0.3

0.3

0.8

1.3

1.8M

ultip

lexe

r O

utpu

t (V

)Receiver Output

Transm itter 1-5 onlyTransmitters 1 onlyTransmitters 1 & 2Transmitters 1,2 &3Transm itters 1-4

Arbitrary delay for transmitters 2-5

MEDARS Features & Benefits High Efficiency, Low Output Impedance

0.0 5.0 10.0 15.0 20.0Time (microseconds)

-200.0

-100.0

0.0

100.0

200.0

-150.0

-50.0

50.0

150.0

Vol

tage

Out

put f

rom

Pul

ser

(V)

Output from Pulser

420V DC supply, into 2.7 Ohm Resistive load

MEDARS Features & Benefits

Generate High Currents in EMAT

0.0 5.0 10.0 15.0 20.0Time (microseconds)

-100.0

-50.0

0.0

50.0

100.0

150.0

-125.0

-75.0

-25.0

25.0

75.0

125.0

Cu

rre

nt in

EM

AT

(A

)800V peak to peak drive

into impedance matched EMAT

MEDARS Applications

Provides high power outputs (~9KW) into impedance matched EMATs

Efficient transmitter allows smaller size and permits up to 8 transmitters and receivers in a single instrument

Ideal for industrial applications such as flaw detection, weld evaluation

0.0 100.0 200.0 300.0 400.0Time (microseconds)

-0.5

-0.3

-0.1

0.1

0.3

-0.4

-0.2

0.0

0.2

0.4

Rec

eive

r O

utpu

t (V

)

Received Signal100V DC supply on transmitter, 77 dB gain in receiver

MEDARS Applications

Ideal for industrial applications such as flaw detection, weld evaluation

1mm hole

30 cm

MEDARS Transmitter Specifications Frequency Range: 250 kHz to 5 MHz Output Amplitude: 0 V to 800 V peak to peak

into 50 Ohms with 12 bit range of adjustment; 440 V peak to peak into 5 Ohm load.

High Power: up to 9.7 KW into 5 Ohms Burst Width: adjustable to 250 cycles Independent control of pulse amplitude and

delay for 8 transmitters

MEDARS Receiver Specifications Up to eight high Gain (95 dB) broadband

receivers with low noise preamplifiers Two receiver inputs for through transmission

and pulse/echo with a single EMAT Adjustable high pass and low pass filters Frequency range: 250 kHz to 5 MHz Output linear to 2V peak to peak Multiplexed and summed outputs available