- The UTxx electronic ultrasonic test system developed by NUKEM is a channel-oriented digital electronic test system. It is parallel, multi-channel and modular oriented and achieves high test throughputs at low cost in automated inspection systems. The UTxx replaces the previous generation of electronic systems, the NIM and the System 20.00. Its capabilities and versatility exceed all preceding system generations. Even the name of the system indicates its decisive advantage: xx signifies that this system is not restricted to a single range of operations but is instead designed for applications that match needs. The variable characters xx become a dimension checking (DIM) function or a defect detection (FDU) function only at the stage of practical application. Since this function can be programmed at any time, with no modifications to the electronic system - the UTxx is genuinely a system which can be configured to meet the user's needs. In short: It is the user who specifies the meaning of xx.

- As a subrack/cassette, the UTxx is indeed related in terms of conception to NUKEM's original NIM system but is at the same time, as a digital system based on the VXI bus, a further refinement of System 20.00, which was based on the VME bus. It has thus been possible to incorporate tried and proven cassette technology into digital systems. The UTxx therefore provides the answer not only for users of the NIM cassette system but also users who prefer purely digital solutions.

- The use of highly integrated digital modules in the UTxx made it possible to further reduce the number of analog circuits requiring intensive adjustment and calibration. The system thus minimizes adjustment and calibration work, achieves higher long-term stability and thus cuts overall costs significantly - both for manufacturing and for servicing and repair.

- A mathematical procedure in measured-data processing, for which a patent has now been filed, also made it possible to significantly improve resolution and measuring accuracy. The UTxx can therefore be used both for crack detection and for high-resolution measurement of echo-time.

- Each cassette provides a complete ultrasonic channel. For applications requiring long cable distances between the probe and cassette or work in highly EMC-contaminated environments, the transmitter and receiver pre-amplifier can be removed and installed in a housing close to the probe mountings. All facilities for connection of the probes and other instruments are located easily accessible on the front panel. The standardized 19'' withdrawable module system incorporating the VXI bus accommodates thirteen cassettes, with one slot for the computer cassette and twelve vacant slots for UTxx cassettes or other VXI function cassettes. This arrangement guarantees maximum flexibility; the system can be augmented and upgraded with other measured-data evaluation systems at any time. The configuration can be expanded by means of additional subracks with a bus link with no difficulty if the twelve slots are not sufficient for any particular application. The computer cassettes available for the UTxx are based on standard PCs or, alternatively, standard work-stations. This standardization makes it possible to operate the UTxx under a Windows user interface.

- And this produces yet another advantage: The widespread familiarity with the Windows user interface not only means significantly lower staff training costs, but also fewer operating errors.


Principal layout of a UTxx module

Technical data for one channel, UTxx electronics system

Transmitter
Transmitter location	for probes with a 0.4-25 MHz frequency range internal, optionally removable for local deployment
No-load voltage	approx. 300 Vss (negative square-wave pulse); bipolar transmitter with no-load voltage approx. 650 Vss, external, can be connected for ultrasonic testing 150 V - 170 V to 50 Ohm (negative square-wave pulse)
Initial pulse width at 50 %	15 ns - 1.5 µs
Initial pulse adjustment (increment)	1 ns
Initial pulse activation	serial, digital
Initial pulse triggering	internal, external
Synchronization of initial pulses	automatic, between all channels
Initial pulse delay	adjustable until next initial pulse (max. 16 ms)
Initial pulse delay (increment)	1 µs, additional interference compensation for use of VIP transducer (VIP = multi-channel/parallel system)
Maximum pulse repetition frequency	20 kHz (for standard defect detection)
per channel	> 5 kHz (for standard dimension checking)
Transmitter output impedance	15 Ohm - 650 Ohm or switchable (for ultrasonic testing)
Receiver
Receiver location	internal pre-amplifier and main amplifier, pre-amplifier can be removed for local deployment (optional)
Maximum input voltage for echo signal	500 Vss
Processable input voltage range	< 10 Vss - 2 1 mVss at 100 % indication
Adjustable dynamics	80 dB
Programmable distance amplitude correction	30 dB with 1024 sampling points in 1 dB increments
Sampling point width for amplitude correction	60 ns ^ approx. 0,04 mm in steel for longitudinal waves
Frequency response	150 kHz to 25 Mhz (-3 dB)
Input impedance	15 Ohm - 650 Ohm or switchable (parallel to pre-- amplifier impedance)
Input impedance adjustment(increment)	15 Ohm
High-pass filter, passive, first order	0,2; 0,5, 1; 2; 5 Mhz + 10 % (-3 dB); Filter OFF
Low-pass filters, passive, first order	1; 2; 5; 10; 20 Mhz + 10 % (-3 dB); Filter OFF
Digital data processing
Evaluation	by means of DSP (Digital Signal Processor) and PLDs (programmable logic devices) for amplitude and time-- of-flight measurement, slope or peak evaluation in freely selectable gates, accuracy enhancement by means of mathematical procedure (patent pending), statistical noise suppression, data compression, A-scan presentation
Parameter and measured-data output	by computer, via standard interfaces
Noise suppression	adjustable, 0-50 % indication
Gates (standard version)	4 defect/measuring gates
Thresholds	2 thresholds per measuring gate, programmable
Aperture trigger mode	Occurrence dependent, on (for instance) initial pulse, surface echo, back-wall echo, etc.
Amplitude measuring accuracy of electronic channel for defect detection	< +- 1 % referred to a 10 MHz signal
Time-of-flight measuring accuracy of electronic channel for dimension measurement	+- 1 um referred to velocity of sound in steel with a frequency 2 15 MHz
Standard assignments and functions of on-line signals
4 on-line INPUT signals	parallel, optocoupler, 3 V - 24 V
Crack detection and dimension checking:	External trigger Start/Stop measurement Millimeter trigger Revolution trigger
8 on-line OUTPUT signals	parallel, optocoupler, < 50 mA /< 35 V but < 150 mW
Crack detection	initial pulse monitoring (function checking) probe monitoring (echo checking) 6 alarm signals for threshold overshoot (3 gates, two thresholds per gate)
or Dimension checking: Wall thickness	initial pulse monitoring (function checking) Probe monitoring (echo checking) Measuring gate monitoring (probe coupling wall) Lamination Wall-thickness change + tolerance for wall thickness exceeded - tolerance for wall thickness exceeded special function (e.g. variation in wall thickness)
or Dimension checking, external diameter (reference channel) Probe monitoring (echo checking)	Initial pulse monitoring (function checking) + tolerance for external diameter exceeded - tolerance for external diameter exceeded + tolerance for internal diameter exceeded - tolerance for internal diameter exceeded -2 special functions (e.g. variation of external diameter, variation of internal diameter)

SPECIAL MAY '98 EXHIBITION
Ultrasonic Flaw Detectors