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DACS App Note

What is a 'Custom Model?' (#28)

The Digital Audio Communication System is a flexible, digital, DSP-based platform that can be configured to accomplish a variety of synthesis and switching tasks. These could range from a pair of operators connected with a single channel intercom, to a large group of operators, each with a variety of radios, each in a different vehicle, with different vehicle sounds. Then you add radar warning and jamming effects, complex intercom busses and sidetone effects and you soon find that no two applications are quite the same.

This configuration of the DACS to provide the specific connectivity and aural cue environment is called a "Custom Model."

Model Builder Software and Custom Model Overview

The ASTi Digital Audio Communication System (DACS) is designed as a general purpose tool for creating sound and radio/communications simulation solutions. It is intended to allow the engineer to translate his understanding of the simulation and training task into a completed physical implementation without learning abtruse code or digital hardware techniques. He interacts with the platform at a high level of abstraction, on a command-line data entry level. Typical applications include flight simulators where the DACS is used to provide aural cue simulation (i.e., simulation of engine sounds, gear noises, landing/takeoff sounds, hydraulic, electrical, and environmental system sounds, etc.) as well as radio/communications simulation (i.e., warning sounds, radio tuning tones and background noise, communications mixing and volume control, press-to-talk logic, navigational beacon sounds, etc.). A very important feature of the DACS/Model Builder is that changes are effective in real time and can be heard instantaneously. It is not necessary to compile and re-link.

What is a Custom Model?

Since the Model Builder software package included with the DACS hardware is a generic tool, it must be configured to specific simulation requirements by entering parameter values and connecting the software object "building blocks" together. The application software provides "lists" of general-purpose software objects such as Engine, Rotor/propeller, Radio, Jammer, EW Source, Counter, Logic Table, Sawtooth, DIS Transmitter, Intercom, PlaySound, Balancer, etc. which the user then selects and connects together as necessary to create the desired sound simulation model. It is the conceptual equivalent of a spreadsheet, which the user tailors to their specific application by entry of the pertinent data. And just like the spreadsheet, the complexity of the final product is virtually unlimited, bounded only by the complexity of the application and the source data. When the Model Builder tool has been configured to provide the features and interconnections pertinent to the specific simulator application, this set of data is saved (just like a spreadsheet data configuration) as a "Custom Model." A virtually unlimited set of different variations of Custom Model can be created and saved on the DACS, and the specific model required can then be specified on power-up.

Model Builder Traininh

The analogy with a spreadsheet is also applicable to the user learning process. No matter how "user-friendly" the user interface is, if a software program is designed to provide solutions in a very complex problem domain, then it will require a certain level of training to function effectively with, and make full use of, its capabilities. The Model Builder tool allows a user to create solutions to a very diverse and, in some cases, very complex set of problems. We offer a three day training course that gives the customer an overview of all the different feathers, and which is usually tailored to the customer's specific application. A variation on the standard training course requires the customer to arrive with a preliminary definition of the model requirements (such as logic/block diagram of the vehicle communication system interconnections, and for the entire course to be an On-The-Job session in which an initial Custom Model is created specific to the particular application.

Turnkey Custom Models

In most instances, Custom Models are configured by the user to meet their particular requirements. The advantage of this approach is that adjustments, tuning, or updates can be made in a few moments by the customer without recourse to ASTi. In some instances, however, the user will elect to subcontract with ASTi to configure the Custom Model based on data provided by the user. In these cases, ASTi receives data from the user, usually in the form of audio tapes and equipment description (such as VHF radio, UHF radio, VOR receiver, etc.) for the simulated device and constructs the sound model for the user based on this information.

Aural Cue Source Data

ASTi has a library of aural cue sounds which can be applied to the customer vehicle configuration in most cases, and then tuned in response to comments from a subject-matter expert, such as a pilot. However, this is a fall back mode and, wherever possible, we prefer to create a customer model against customer-furnished source data, as this makes the acceptance process more straightforward. Tapes provide a basis for the engine sounds, gear sounds, hydraulic and other equipment sounds as well as any other special sound effects from the device which the user wishes to replicate. Both audio tape analysis and equipment description define which sound objects from the standard Model Builder lists are inserted in the sound model using the same Model Builder software tool provided with the DACS. In effect, the user is simply subcontracting the labor to build the sound models.