4 General Description
4.1 Description
The DPR300 is a general-purpose ultrasonic pulser/receiver that can be configured for a wide range
of uses. In addition to describing available DPR300 features and options, this manual indicates the
differences between the available DPR300 configurations.
The DPR300 can be configured during manufacture as a pulser/receiver with manual-only control,
PC control, or simultaneous manual and PC control. For DPR300 units populated with both front
panel and remote PC controls, the instrument responds to both sets of controls, and each instrument
function will be set to the value most recently received from the front panel or remote command.
The DPR300 receiver is available in 35MHz and 50MHz bandwidths, and the DPR300 pulser is
available in 475V and 900V amplitude ranges. Users should familiarize themselves with the
operational limits of DPR300 pulsers that have the 900V option installed by reading about the PRF
command in Section 6 of this manual.
In a typical DPR300 application, the DPR300 pulser produces a high voltage electrical excitation
pulse and applies this pulse to the instrument’s T/R connector. An ultrasonic transducer connected
to the T/R connector via a length of 50 Ωcoaxial cable is then employed to convert the electrical
energy of the excitation pulse into an ultrasonic pulse that is propagated into a test material or
medium. Four energy levels, sixteen amplitude levels, and two pulser-impedance values offered by
the DPR300 enable the user to adjust the characteristics of the excitation pulse to the specific
transducer employed. Sixteen discrete damping levels in the DPR300 allow the transducer response
to be adjusted over a wide damping range.
With the DPR300 configured for pulse-echo mode operation, acoustic echoes reflected from
interfaces or defects within the test material are converted by the transducer into electrical signals
that are presented to the T/R connector of the DPR300. The low-noise DPR300 receiver amplifies
these electrical signals, and the signals then pass through adjustable high pass and low pass filters.
The DPR300 receiver gain is adjustable between -13 dB and 66 dB, and there are six high pass and
six low pass filter settings for band-limiting the receiver frequency response. The amplified and
filtered signals are available on the instrument’s Receiver Output connector.
The DPR300 may also be used in transmission mode operation wherein a separate receiving
transducer is used to detect acoustic pulses that have propagated through a test material or medium.
This second transducer is connected to the DPR300 receiver Through connector, and the received
signals are processed as described above for pulse-echo mode operation.
The DPR300 allows external equipment such as A/D digitizer boards or oscilloscopes to be
synchronized to the pulser operation. To facilitate this, a synchronization pulse applied to the
Trig/Sync connector can be employed to trigger the pulser when the instrument is in external trigger
mode. Alternatively, when the DPR300 is configured for internal-trigger mode, a short pulse is
output on the Trig/Sync connector simultaneous with the generation of the excitation pulse. All
connectors on the DPR300 are BNC-type with the exception of the computer interface connectors.
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