When comparing audio and comms solutions for training and simulation, it's easy to be misled. On the surface, the best-value solution appears to be the standard PC with a sound card and ethernet adapter. Top it off with the latest version of Windows, and throw in a few third-party, sound-processing software bundles and you're all set, right?

Well... not if you think any of these are important:

• Actual bottom-line price
• Product support responsibility
• Life cycle maintainability
• Features and performance

ASTi wants you to be able to make a direct and fair comparison. So, here are the key questions that must be answered to ensure that you have found the best solution for your audio and comms application.

Is the solution a self-contained product, integrating digital signal processing and communications networking hardware and software, developed and produced by a single vendor?

If it's not a truly integrated product, then who is the overall responsible party for all of the individual bits and pieces that comprise the system? Where do you go for support?

Does the vendor have a dedicated service department with the capability to provide service to several different customers at the same time? Or, will you have to wait patiently for "your turn" when critical support is needed?

Demand proof of performance: Ask for references and contact previous customers.

What is the product support lifespan of your program?

The makers of commercial sound cards have no concern for long-term support. They design products to be consumable, "throw-away" elements. For example, no sound card available today was available 18 months ago.

Any replacement product is almost certain to have different driver software, and may have operational differences (read: headaches).

The operating system baseline is crucial in ensuring continuing support. Any system based on a domestic OS (such as any Windows release) will find an amazing lack of support for previous OS releases once a newer version hits the market. What would Microsoft say if you asked them to fix a bug in Windows98 today? Can you even buy Windows98 today?

Does your system require more than 2 operators?

Using more than 1 sound card in a system often causes compatibility issues.

Multi-channel sound cards are rare. In the commercial market, we have only identified two, and both have critical limitations:

• The Gadget Labs card does not work with networking software.
• The Echo Corporation Layla appears to prevent mixing of odd channels with even channels. It functions as two independent four-by-four mixers.

What types of audio hardware do you need to connect?

Commercial sound card products are designed to work with consumer-grade audio devices (mics/speakers), and, hence, have limited interface capability. Sound cards cannot directly connect to most military or industrial communications devices, such as:

• low-impedance aviation headsets
• O2 masks
• active (powered) noise-canceling mics
• live radio interfaces

Sound cards use consumer-grade connectors, which are non-rugged and non-locking.

Is a networked communication environment (DIS or HLA) required?

If the supplier of the networking software is NOT the same as that providing the core audio environment, significant issues of problem ownership will arise.

Commercial sound card solutions may not provide sample rates that are compatible with the accepted, standard rates of 8kHz and 16kHz. This will result in additional sample-rate conversion processing.

Network compatibility is also a big issue. Who is the encumbent supplier of DIS/HLA systems in this industry?

It is easy for a vendor to claim HLA capability, but check to see whether they are currently shipping an off-the-shelf HLA solution. If not, who is going to pay for the engineering effort? You will!

Ask the vendor about what limitations are placed on the system by running HLA software on the same platform as that providing all other audio processing.

How do you produce environmental cue sounds?

A commercial sound card has good ability to replay sampled sounds. But, how easy (or difficult) is it to apply this ability to a tightly-integrated vehicle environment such as an aircraft, where a vast number of distinct sounds are all mixed with each other?

A commercial sound card usually has no synthesis capability, and many sounds are much better suited to synthesis than sampling. Consider rotors, propellers, and jet engines; all have significant wave-shape behavior changes through the typical operating range. Are you going to sample everything?

What is the level of detail in the communications environment simulation?

What are the details of the radio propagation model?

Is a tactical data link feature available to allow data messages to be propagated through the simulated radio environment?

Is it possible to integrate the radio environment with that of a terrain database to provide accurate terrain interaction?

Can the system accurately handle multiple signal reception when radios are operating in AM modes to realistically simulate real-world radio traffic, while mixing received signals?

Can frequency hopping be simulated?

Are secure modes of operation simulated, and are simple hooks provided for the various audio effects created by this type of operation?

Can the communications environment be directly interfaced to off-the-shelf user control devices? If so, are the user interfaces developed and produced by the vendor?

After all of the separate components and engineering tasks are accounted for, what is the actual bottom-line price?