Designing High-Speed Digital Tests for Military Defense Systems

Author(s):
Rabah Derradji - EDA Industries SRL
F. Arcangeli - EDA Industries SRL
F. Magnino - EDA Industries SRL
L. Magni - EDA Industries SRL

Industry:
Aerospace/Avionics, Semiconductor, Government/Defense, Electronics

Products:
Digital I/O, LabVIEW, PXI/CompactPCI, High-Speed Digital I/O

The Challenge:
Developing a high-channel-count digital test system with an open architecture that can leverage existing digital test patterns created for traditional digital instruments.

The Solution:
Creating a flexible digital test system with LASAR import capabilities using National Instruments PXI hardware, high-speed digital I/O hardware, and LabVIEW software.

Militaries have a growing need for maintainable test systems with guaranteed support and reliable operation. Budget reductions, increasing distances between a system’s manufacturer and the user, and the long life expectancies of these systems are all factors driving the need for improvements. Manufacturers recognize these challenges and provide specially designed systems capable of debugging and repairing systems in the field. These repairing machines have become a critical component of many defense systems.

SELEX Sistemi Integrati, formerly known as Alenia Marconi Systems (AMS), asked EDA Industries to create a low-cost digital test system to assist in the repair and debugging of existing radar systems in the field. Our system was designed to meet the needs of the user (in this case, radar operators) as well as the manufacturer (SELEX Sistemi Integrati).

The radar operators required repair autonomy; an open, commercial off-the-shelf hardware platform; a reduction in repair costs; and less reliance on third parties. The manufacturer requested that our systems have low maintenance costs and the ability to use existing test patterns, such as LASAR tap files, from digital simulator tools.

NI LabVIEW and PXI Hardware

We selected the PXI platform from National Instruments as the foundation for our digital test solution and created custom application software using NI LabVIEW to meet all of SELEX Sistemi Integrati’s requirements. With the virtual instrumentation capabilities of LabVIEW, we were able to use low-cost, open hardware to design a system that met immediate needs and offered the flexibility to expand the software and hardware in the future.

We used PXI hardware, including an NI PXI-8176 embedded controller, 15 NI PXI-655x high-speed digital waveform generator/analyzers (300-channel capacity), and a programmable power supply unit controlled via GPIB, for the solution. In addition to this hardware, we created the necessary mechanical fixture and unit under test (UUT) adapter board to interface with the 15 high-speed digital modules. With the built-in timing and synchronization features of PXI, we easily used multiple digital modules to achieve the high-channel count.

Software Modules for Existing Test Pattern Needs

We created three powerful software modules (virtual instruments) to meet our demands for functionality and compatibility with existing test patterns. The first was a LASAR translator module, which automatically translates output files from the LASAR simulation environment into the HWS standard, a format compatible with NI tools. The next module was the Go/No Go functional test module that can dynamically or step-by-step execute test procedures for the UUT. Finally, the reverse probing module we created guides the operation through the fault search and repair process when a failure occurs.

The LASAR translator module automatically converts existing test information (simulator outputs) used on other digital automated test equipment to a format suitable for our DTS-LASET system. The main objective of this module is to provide the manufacturer and user with the ability to reuse the existing functionality of their traditional testers, particularly the reverse probing section, to minimize the cost of changing to a new digital test system.

The translation procedure contains the following key pieces:

• Source file selection from the LASAR environment (*.tap file)
• Generation of the translator configuration files
• Generation of the test pattern (stimulus pattern and expected pattern) in HWS format
• Generation of the DUT database

Go/No Go Functional Test Module

The Go/No Go functional test component controls the core digital test procedures, the generation of the stimulus pattern, and acquisition of the response data using NI PXI-655x digital waveform generator/analyzers. This module is also responsible for comparing the acquired response data to the expected data. The stimulus data and expected response patterns are derived from the outputs of the translator module.

The Go/No Go sequence follows these basic steps:

• Select the unit under test (UUT)
• Test the UUT
• Execute the test procedure
• Display acquired response pattern and compare it to the expected response

Reverse Probing Module

When a failure is registered by the Go/No Go module, the reverse probing module guides the user through the fault search and repair process. The module identifies the faulty component or wiring on the UUT.

Using information from the board database and the pattern data of the internal nodes (provided by the translator module), the algorithm implemented in this module guides the user through the fault search procedure. An iterative algorithm is implemented that traverses the electrical network of the UUT to identify the component or wiring that generated the failure.

The Reverse Probing steps are:

• Select the desired test options
• Select the faulty line to debug and repair (if more than one)
• Display probe instruction to guide the user
• Test the current internal node

Digital Test System and LASAR Importer Solution

We created a high-performance, low-cost digital test solution for SELEX Sistemi Integrati, a key European defense contractor, with NI software and hardware. We created the system without relying on custom hardware or incurring the high cost of a general-purpose tester. NI offered the necessary tools to create a digital test system competitive with the traditional suppliers of automated digital test equipment. Our solution resulted in a 30 percent time savings and a significantly better performance-to-cost ratio.

For more information, contact:

Rabah Derradji

EDA Industries SRL

02015 Cittaducale (RI) Italy

Tel: +39 0746 694044

Fax: +39 0746 694089

E-mail: rabah.derradji@eda-industries.com

 

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