Digital Pulser/Receivers

A Pulser is a device used to generate the burst of energy that excites the ultrasonic transducer and causes it to generate sound. The Receiver captures the resulting echos and converts them back into an electronic signal. The two are commonly combined into an instrument called a Pulser/Receiver (P/R).

Digital P/Rs

Instrument settings tab in Basic Mode, showing common P/R settings.

ODIS will work a number of P/Rs that are controlled via the computer. in Basic Mode, a common subset of the available controls is visible on the Controls form. In Advanced Mode, P/Rs have individual windows with the full set of controls.

Any P/R that is not controlled directly by the computer can be used with ODIS: however, the user is responsible for ensuring that the settings are correct for a particular scan setup.

For a full list of supported DPRs, see here.

Common P/R Settings

The lists below describe some common Pulser/Reciever settings and their function. Not all pulsers will have the same features.

Pulser Settings

Echo/Through

Whether or not the P/R is in Pulse-Echo mode (also known as Pitch-Catch) or Through Transmission mode. In Pulse-Echo, the signal will be sent and received on the same transducer; in Through Transmission, there is usually one connection for the triggering transducer, and another for the receiving transducer.

Trigger Mode

Usually Internal or External. If in Internal triggering mode, the P/R generates triggers at a rate set by the Pulse Repetition Frequency (see below). If in External triggering mode, and external source (such as an A/D board) is responsible for telling when the P/R to trigger.

Pulse Repetition Frequency (PRF)

The rate at which the pulser generates triggers. If the pulser is in External trigger mode, this value does nothing. In Internal mode, the pulser will trigger at the rate specified in Hertz (Hz).

Damping or Pulse Width

Sets the duration of the trigger pulse. More damping will decrease the amount of time that the pulse is applied to the transducer. The value is set in Ohms (Ω) if using Damping, or Hertz (Hz) if using a fixed Pulse Width. Allowed values vary among different pulsers.

Energy

The Energy value for the trigger pulse, measured in microJoules (μJ). Many pulsers have a number of energy settings that can be configured.

Voltage

The Voltage value for the trigger pulse, measured in Volts (V). Voltage ranges vary widely among pulsers.

Receiver Settings

Filters

Most pulsers have a number of frequency filters that can be run on the incoming signal in order to remove unwanted data. High Pass Filters (HPF) remove frequencies below the specified value; Low Pass Filters (LPF) remove frequencies above the specified value. Filters are specified in Hertz (Hz).

Gain or Attenuation

Gain and/or Attenuation settings allow the user to increase or decrease the amplitude of the incoming signal. The methods for increasing or decreasing gain vary widely. Gain and Attenuation settings are specified in Decibels (dB).

Phase

Sets the amount of shift on the input signal. Some pulsers allow the user to set shift signal 180^o out of phase, thus inverting the waveform.

P/R Rep Rates and Scanning

Pulsers have a maximum repetition rate (i.e. "Rep Rate") at which they can be triggered; beyond this rate, the pulser does not have a chance to fully renergize, resulting in a reduction in signal power. This can drop the amplitude of the resulting waveform and alter the results of a scan.

Because the actual Rep Rate will depend on the velocity and resolution of a scan, it is important to take this into consideration when selecting the pulser and transducer to be used.

The tables below show the maximum Rep Rate of some common pulsers, and an example of the effective rep rate of scans.

P/R Name	Remote Pulser	Max Rep Rate (kHz)	Minimum Voltage (V)	Max Freqency (MHz)	Recommended Transducer Frequencies
DPR500
	RP-L2	5	155	90	1-65 MHz
	RP-L4	50	170	260	40-165 MHz
	RP-H2	20	185	260	40-165 MHz
	RP-U2	20	-230*	295	> 100 MHz
	RP-U4	50	-220*	295	> 100 MHz
	RP-U5	50	-40*	375	> 100 MHz

• Fixed voltage values

Repetition rate chart, assuming a scan velocity of 400 mm/second
Resolution (microns)	Resolution (mm)	Rep. Rate (triggers/sec)	Rep. Rate (KHz)	Comments
200	0.2	2000	2	Calculated Rep Rate must be 80% of the Max Rep Rate of the pulsers for best results. For example, a 20 micron resolution will not work with an RP-L2.
100	0.1	4000	4
50	0.05	8000	8
20	0.02	20000	20

Multi-Channel Considerations

Multi-Channel P/R Settings

Pulsers that contain two or more channels can set one channel as a slave: this allows the slave channel to trigger in sync with the master channel. Other settings (Gain, Filter, etc.) will remain separate among the channels. Consult the P/R manual for details.

Systems with Multiple P/Rs

Multiple JSR pulsers can be used in the same system if using DPR300, DPR500, or DPR35G devices, daisy-chained to the same serial port. Specific settings in *.exe.config must be set to ensure that all pulsers are detected.

To use the daisy-chain properly, each JSR pulser must have a unique ID. Use the JSR Control panel program to make sure that the Pulser IDs are set properly.

Additionaly, multiple instances of PureView and DPR650 DPRs can also be used. The system will automatically detect each device on the USB ports.

To run on a system with DPRS from different manufacturers or between the groups listed above, additional configuration tags must be added in *.exe.config: see the link for details.