What is DFAT?

MSI-DFAT® provides DFAT® Services for acoustic testing of spacecraft. Direct field acoustic testing is a technique that can be used for acoustic testing aerospace structures and components. The methodology uses electro-dynamic loudspeakers, arranged uniformly around the test article, to generate a diffuse and well-controlled direct sound field at the surface of the unit under test.

The system employs speaker cabinets with high-capability drivers combined with extremely high output amplifiers. System control is effected by a narrow-band Multiple-Input-Multiple-Output (MIMO) controller deriving real-time input from a matrix of precision laboratory microphones. This system can be used to produce an acoustic environment that can simulate helicopter, aircraft, jet engine, or launch vehicle sound pressure fields. The system is capable of producing levels from ambient to over 150 dB Overall Sound Pressure Levels for more than one minute over a frequency range from 25 Hz to 10 kHz.

  • Portability: can be set up almost anywhere

  • Modularity: adapts to multiple configurations

  • Controllability: safe, repeatable, real-time control system

  • Narrow-band control: can provide control to a spec defined at 3 Hz increments from 25 to 10kHz

  • Response limiting: control on SPL, acceleration, force or stress

  • Over-test protection: abort on peak or rms response values

Portable Spacecraft Testing

A key feature of the MSI-DFAT® system is its portability, which allows testing at the customers or any other facility. The equipment is set up, tuned, calibrated, used to perform a Direct Field High-Intensity Acoustic Test (HIAT), and then dismantled and removed from the test site. The entire process from load-in to load-out takes about 4 days for a large satellite or similar aerospace structure.

The MSI test system uses a “building block” approach to form combinations of equipment to satisfy our client’s specific needs. Systems typically include 700 plus speakers, 2 million-plus watts of amplification, at least 12 to 16 control microphones, and a proprietary Spectral Dynamics Jaguar closed-loop MIMO Acoustic Control and Data Acquisition System. The mobility and flexibility of the system allow this method to be tailored for each application, providing a timely and cost-effective test solution as well as adapting to changes in schedule and/or requirements. DFAT® Systems can also be scaled to meet the requirements of small, individual component tests, or the requirements of test articles that are too large to fit inside a traditional acoustic reverberant chamber.

Along with supplying equipment, MSI-DFAT® provides experienced and qualified audio and aerospace engineers to ensure the accuracy, repeatability, consistency, and reliability of your test program. MSI-DFAT® provides well defined and documented procedures and can also provide extensive pre-test consultation to support our client’s specific test requirements.

Process

The process requires the assembly of a speaker circle around the test article. The size of the circle is dependent on the size of the test article. Generally, a circle 12 feet in diameter larger and 4 feet taller than the test article is required. This is a turnkey system where the speakers are driven by a series of audio amplifiers that are powered by a system that protects the customer’s electrical power. The system is safely and accurately controlled by a closed-loop feedback control system that can be used to limit and/or abort if an over-test condition is detected. The entire operation is usually completed in four days, of which only requires the test article for one day. All equipment is brought to the test article, assembled, pre-tested, and performance checked prior to testing the flight article. The flight article is generally required for only one day of testing depending on the complexity of the test plan. Upon completion of the flight test, the article is removed and all equipment is disassembled and transported from the site. MSI-DFAT® provides all Operating and Safety procedures for use of their equipment and integrates their system with each customer’s requirements. Test data reduction, analysis, and reporting are also available on an as-needed basis.

Cost

The cost of a DFAT® is calculated on a per-test basis, although multiple discounts and long-term agreements are available. The cost is fixed and usually billed directly to a project. No maintenance, repair, facility, storage, or other overhead costs are involved. MSI-DFAT® also manufactures and assembles custom DFAT® components, up to and including complete turnkey systems. Equipment purchase, as well as service for maintenance, repair and project support, are also offered.

Schedule

The entire operation is usually completed in about four days and only requires the test article for one day. System checkout and a pre-test to verify performance are done on the second day. The flight article test takes place on day three. The system is disassembled and shipped out on the fourth day. Additional test time can be scheduled if required.

Risk

This process minimizes the risk to the flight hardware. No packing or transport of flight and/or support equipment is necessary. No operations at an offsite facility are required.

Call MSI-DFAT Today at (410)448-1400 or Send Us a Request for more information on how we can assist on your next Direct Field Acoustic Test.

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