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DP5 Enhanced Digital Processor

Product Migration Information

Amptek Inc is introducing a family of enhanced X-ray spectroscopy products, based on a new generation digital pulse processor, the DP5. The DP5 will provide better performance, new signal processing features, improved data processing algorithms, faster data transfers, and a simpler interface. Amptek has also developed an enhanced power supply board for use with Amptek detectors and preamplifiers, the PC5. Products now available using the DP5 and PC5 include:

1. The X-123SDD, a significantly enhanced X-123 which uses the new silicon drift detector (SDD), the DP5 digital processor, and a new PC5 power supply module.
2. The DP5/PC5 combination, used primarily by OEMs with Amptek’s detectors and preamplifiers.
3. The DP5 as a standalone unit.

The DP5 implements all of the features and performance of the DP4 with many enhancements. Communication protocols and software are generally compatible with the DP4. Specifically, accessing new features of the DP5 requires software changes but software written for the DP4 will work with the DP5 with minor changes, providing the capabilities of the DP4.

This first part of this page contains a FAQ that describes how users of the existing products can migrate to the new family of products. The second section of the page is the DP5 full specification.

Frequently Asked Questions

How Long will the DP4 be Available?

The DP4 has been replaced by the DP5. There are no more DP4 units left. If you are an existing OEM please migrate to the DP5. This includes users of the X-123 (Si-PIN or CdTe) since there is a DP4 inside of the unit. The X-123SDD with the silicon drift detector (SDD) is not affected as it already contains a DP5. If you have written custom software using the DPP API, RS232, or USB you will have to make some small changes to your code to be compatible with the DP5. Please contact Amptek with any questions.

What Enhancements Will Be Found in the DP5 vs. the DP4?

Performance enhancements

• Faster peaking time available, allowing higher input count rates. Shortest peaking time is 0.2 µsec (equivalent to 80 nsec shaping time).
• Additional peaking times are available, with over 350 settings covering 0.2 µsec to 102 µsec.
• 4,000,000 cps periodic
• Reduced dead time allowing higher throughput. Dead time is typically 10% shorter than in the DP4.
• Dead time due to USB & RS232 transfers is significantly reduced.
• Improved dead time measurement for more accurate corrections at high rate.
• Fast channel peaking time as short as 0.1 µsec (40 nsec shaping time). This improves pile-up rejection, measurement of incoming count rate, and risetime discrimination.
• Larger gain range, with all ranges overlapping. (16 analog gains, from 1x to 100x.)
• Lower noise analog prefilter. This improves resolution with the lowest noise detectors.
• Input offset and input polarity under software control.
• Software control of the offset channel in the output spectrum, permitting zero offset.

Interface enhancements

• Ethernet (10-base T) (will be available summer 09)
• USB upgraded to 2.0 full speed (12 Mbps).
• RS232 upgraded to 115 kbaud (57.6 kbaud selectable).
• No daughter boards (PC4-2, etc) required for DP5 operation.
  • Power supplies are now on the DP5 board, so it only requires +5V input.
  • DP5 can be powered from USB (but not when connected to PC5 for Amptek detectors).
  • Communication connectors on the DP5 board.
• Power supply board for Amptek’s XR100 detectors (new PC5) is under software control, to set temperature and high voltage bias.
• Firmware, both in FPGA and microcontroller, can be upgraded via standard serial interfaces by the user.
• New “List Mode” will be available in the next release. Instead of a spectrum, each event generates an amplitude and a time tag, which are stored and can be downloaded.
• New “Setup” spectrum can be acquired, showing the noise Gaussian, events rejected by pile-up rejection and risetime discrimination, by gating logic, etc. Useful for optimizing parameters.
• A “board interconnect” has been added to simply interface to daughter boards with other capabilities, or to systems containing multiple digital processors.
• A 512kB low-power SRAM was added to the DP5, adding buffering flexibility. For example, sequential spectra can be buffered for later transmission to the PC.

Is the DP5 Backward Compatible with the DP4?

As close as feasible but some changes are inevitable.

Software

• A new release of Amptek’s ADMCA software incorporates the DP5 interface over USB. With ADMCA one can access all of the DP5’s features in the same manner as the DP4 or PX4.
• The DP5 uses FLASH memory to store its power-up configuration and some parameters which are unsupported by the legacy DP4 & PX4 protocols (for example, switching to 80MHz operation to access the fastest peaking times, selecting 115k/57.6k RS232 operation, etc.). These options can be selected via the standard serial interfaces.
• For users who have written or are writing their own software, there are a few options.
  • To use the new functions and features of the DP5, new data packets and communications libraries are required. This implies some software changes, for either USB or RS232.
  • With RS232, the DP5 recognizes the same data packets used with the DP4 and PX4. There are some parameters which must be specified with the DP5 which were not used in the DP4, e.g. input offset. These can be set once, during initial product configuration, and are then stored in the DP5’s EEPROM. A stand-alone application is provided by Amptek to set the new features and store them. With this legacy DP4 software can be used unchanged.
  • With USB, the DP5 recognizes the same packets for commanding and for readout of spectra and status packets. Readout of configuration and of oscilloscope packets requires minor software changes. (The DP5 microcontroller supports fewer USB ‘endpoints’ or ‘pipes’ than the DP4 microcontroller, so a few required remapping.)
  • An updated Windows API interface (DPP API) is available on the software download page that is also backwards compatible with the DP4 and PX4.

Physical

• DP5 Standalone
  • The DP5 has the same physical size and mounting holes as the DP4.
  • The preamp input connector and DAC output connector are different, but in the same location.
  • Additional interface connectors have been added, eliminating the need for daughter boards and reducing the number of supply voltages required. The backplane (JP6) and auxiliary (JP9) connectors have been changed and moved. Standard USB, serial, Ethernet, and power supply connectors are now on the DP5.
• X-123SDD and DP5/PC5
  • The X-123SDD USB and serial connectors have been moved slightly. A different power connector is now used. An Ethernet connector has been added, although it is not yet supported in software.
  • With the PC5, the 8 pin power & serial header used previously is still available. The same USB and serial connectors are still available, moved from the PC4-2 and PC4-3 to the DP5.
• The power dissipation will increase to 0.9 W for a 20 MHz clock. To use faster peaking times, an 80 MHz clock is required, with dissipation of 1 W typical.

How Were These Enhancements Achieved?

• The DP4’s ADC and digital processor operated at a 20 MHz clock rate. The DP5 can be clocked at 20 or 80 MHz. The higher clock rates permit the faster peaking times in both the main and fast channels but the unit dissipates more power in this mode. For systems not requiring the fastest peaking times or operating at the higher rates, the 20 MHz clock can be used to reduce power.
• A number of improvements were made to the digital signal processing algorithms and to the analog prefilter. Amptek has conducted significant in-house research and development on digital signal processors since the release of initial DP4 and has tailored the design to meet the unique needs of many customers. These developments were folded into the new DP5.
• The constantly shrinking physical sizes of many components permitted us to move the power supplies and connectors from daughter boards, used with the DP4, onto the DP5. This significantly simplifies system integration.

Transition Documentation

For complete information on the changes between the DP5 and the DP4, please download the zip file below.

DP5 Documentation (3MB)

Specifications

Pulse Processing Performance

MCA Performance

Hardware

Communications

Auxiliary Inputs and Outputs

The primary purpose of this connector is to bring out logic signals which are not required for the primary use of the DP5: acquiring spectra and transmitting then over the serial interface. These are generally “low level” logic signal associated with each pulse processed by the DP5. They are primarily used for synchronizing the DP5 data acquisition to external hardware and for direct counter/timer outputs from the DP5. The signals are described below. The connector is a 2x8 right angle Samtec part number ASP-135096-01.

Auxiliary Connector Pin Assignments

Connections

Power

Physical

General and Environmental

DP5 Architecture

The DP5 is a component in the complete signal processing chain of a nuclear instrumentation system. The input to the DP5 is the preamplifier output. The DP5 digitizes the preamplifier output, applies real-time digital processing to the signal, detects the peak amplitude (digitally), and bins this value in its histogramming memory, generating an energy spectrum. The spectrum is then transmitted over the DP5’s serial interface to the user’s computer. Clearly, the DP5 must be used with other components, including a detector, preamplifier, and computer.

Figure 3. Block diagram of the DP5 in a complete system.

Analog Prefilter

The input to the DP5 is the output of a charge sensitive preamplifier. The analog prefilter circuit prepares this signal for accurate digitization. The main functions of this circuit are (1) applying appropriate gain and offset to utilize the dynamic range of the ADC, and (2) carrying out some filtering and pulse shaping functions to optimize the digitization.
NOTE: The DP5 can be ordered with a charge sensitive preamplifier on the board for use with PMTs.

ADC

The ADC digitizes the output of the analog prefilter at a 20 or 80 MHz rate. The digitized values are sent, in real time, into the digital pulse shaper. 12 bit ADC is used.

Digital Pulse Shaper

The ADC output is processed continuously using a pipeline architecture to generate a real time shaped pulse. This carries out pulse shaping as in any other shaping amplifier. The shaped pulse is a purely digital entity. Its output can be routed to a DAC, for diagnostic purposes, but this is not necessary.

There are two are two parallel signal processing paths inside the DPP, the “fast” and “slow” channels, optimized to obtain different data about the incoming pulse train. The “slow” channel, which has a long shaping time constant, is optimized to obtain accurate pulse heights. The peak value for each pulse in the slow channel, a single digital quantity, is the primary output of the pulse shaper. The “fast” channel is optimized to obtain timing information: detecting pulses which overlap in the slow channel, measuring the incoming count rate, measuring pulse risetimes, etc. and to obtain

The DP5 uses trapezoidal pulse shaping, which offers high energy resolution, reduces ballistic deficit, and provides excellent baseline stability at high count rates.

Pulse Selection Logic

The pulse selection logic rejects pulses for which an accurate measurement cannot be made. It includes pile-up rejection, risetime discrimination, logic for an external gating signal, etc. At high count rates, the DP5 has both better pile-up rejection and higher throughput than a traditional, analog shaping amp.

Histogramming Memory

The histogram memory operates as in a traditional MCA. When a pulse occurs with a particular peak value, a counter in a corresponding memory location is incremented. The result is a histogram, an array containing, in each cell, the number of events with the corresponding peak value. This is the energy spectrum and is the primary output of the DP5. The unit also includes several counters, counting the total number of selected pulses but also counting input pulses, rejected events, etc. Auxiliary outputs include eight different single channel analyzers, and both a DAC output and a digital output showing pulse shapes from several points in the signal processing chain.

Interface

The DP5 includes hardware and software to interface between these various functions and the user’s computer. A primary function of the interface is to transmit the spectrum to the user. The interface also controls data acquisition, by starting and stopping the processing and by clearing the histogram memory. It also controls certain aspects of the analog and digital shaping, for example setting the analog gain or the pulse shaping time.

The interface includes a microcontroller and serial interface hardware. RS232 and USB are currently implemented with Ethernet available in the summer of '09.

PC5 Power and Interface Board

Amptek’s DP5 Digital Pulse Processor is a component in the complete signal processing chain of a nuclear instrumentation system. It must be used with other components, including (at a minimum) a detector and preamplifier, and computer with a serial interface and software to communicate. The DP5 itself has its own power supplied so only needs a +5 V DC input. When using the DP5 with Amptek detectors, additional power supplies are needed for the detector and preamp. Amptek provides the PC5 board that mates with the DP5 and provides power to Amptek detectors.

The PC5 provides power to Amptek XR-100 detectors from a +5 VDC source. This board is intended for those using Amptek detectors and preamps. The USB interface cannot supply enough current to operate the XR100, so an external DC supply is required, which must be between 2.5 and 5.5 V.
Dimensions: 3.5 in. x 2.5 in.

Figure 7. DP5 (top) mated with the PC5 (bottom).

Figure 8. DP5 (top) mated with the PC5 (bottom), back connector view.

Software

The A250 Connected to a DP5 Digital Pulse Processor and MCA

Figure 12. The A250 charge sensitive preamplifier connected to the DP5 digital pulse processor and MCA.

DP5 Specifications in PDF (500k)

DP5 Transition Documentation (3MB)
Digital Pulse Processor FAQ
Glossary

Revised December 8, 2009