Frequently Asked Questions (FAQs)

SimPhonics, Simulation Audio Systems

My UDP/IP device is not reviving data correctly from my host, but the custom socket I/O device does. Why?

Non-Intel machines use big-endian format. That is, for a given multi-byte numeric representation, the most significant byte has lowest address, which is also referred as network byte order and is the standard for network byte ordering for internet and network data transfers. This means that the Intel machines must rearrange the bytes.

The Custom Socket I/O Device performs byte ordering automatically by calling the appropriate byte ordering routines.

The UDP/IP device, however does not perform automatic bye ordering. Therefore, when using the UDP/IP device, remember to use little endian format for the data on the wire.

What is a simulation audio system?

Simulation audio systems are used in flight simulation and other similar training systems where a virtual audio environment must be simulated. For example, a flight simulator requires sound simulation to re-create the audio environment inside the cockpit for the conditions that the crew of the simulator is experiencing. Examples of sound simulation audio are engine sounds, sounds of aerodynamics, weapon sounds, malfunctions, etc. These systems are not limited to sound simulation. Other types of audio are also present, such as radio receiver simulation, intercom, navigational audio, etc. Other simulator systems also require sound systems such as driving simulators, tank simulators, etc.

What is the FAA Level D Sound Certification?
How Does SimPhonics Meet These Requirements?

Download a PDF document that describes this process.

How do I Specify an Audio System for My Device?

Good question, and one not easily answered since this depends on the desired fidelity of your system. The FAA has roughly established the level of fidelity for civil flight simulation audio devices. SimPhonics has some guidelines for specifying systems. Other than this, we suggest you look at some previous systems.

How does the audio system interface to my host computer?

SimPhonics digital audio systems can interface to a wide variety of common interfaces. Since our systems are based on the V+ visual development system, the interfaces (I/O Devices) that V+ supports is the list of interfaces that is supported by our audio systems.

See this link for a current list.

How many sounds can the SimPhonics System Play Simultaneously?

This number is virtually unlimited, especially for typical flight simulation devices. The actual theoretical number depends on the type, duration, and dynamic effects that are selected for each sound. SimPhonics systems are modular so that adding new sounds is a matter of adding additional resources to the system. Also, most of the sounds are dynamically simulated, and are actually modes, rather than sound libraries. Sounds therefore are not downloaded, and are always available when the command calls for them.

Typical limits are:

FXDirect on a typically delivered Pentium 200 MMX without any DSP cards is roughly 45.
FX-30 Systems at typical sample rates are 20 per DSP. Up to eight DSP’s may be added to a single chassis, yielding 160 dynamic sounds per chassis.

A typical system may combine both FX-30 cards and utilize FXDirect in the same chassis.

How do I Verify Compliance/Operation of a Audio System Before/After Delivery?

SimPhonics provides a comprehensive Acceptance Test Procedure for this purpose.  A web page explains this in more detail and provides an actual ATP for download.

Why does my system seem to shut down periodically?

Ensure BIOS power management features are disabled!  Typically BIOS power management begins to shut down the system if no user input is detected over a period of time.  This will obviously cause problems with embedded systems. 

Why does the audio sound scratchy when using FXDirect?

Ensure that the bits/sample is set to 16 and the sample rate is adequate for your purposes. Good quality audio is 16 Bits/Sample and 44,1000Hz sample rate. Note that when using networked audio objects with FXDirect objects ON THE SAME AUDIO DEVICE, the sample rate is forced to 8000Hz and the bits/sample is forced to 8 for that device.

It seems like Windows is constantly accessing my hard disk, which causes problems in the real-time portion of V+ FXDirect.  How can I remedy the problem?

If the virtual memory of Windows 95 is configured too small Windows may often exchange data with the hard disk to dynamically resize the swap file located on the drive. This can cause audio interruptions when playing back or recording audio in Samplitude.

To remedy the problem, the virtual memory in Windows 95 should be configured to reflect a large minimum size to reduce the resizing activity. Here are steps to change the virtual memory settings:

1. Open the System dialog in Control Panel.

2. In the System Properties dialog select the Performance tab.

3. Next, select Virtual Memory.

4. In the Virtual Memory dialog select ‘Let me specify my own virtual settings.’

5. Set the Minimum size to at least 40 MB size. Windows 95 determines the Maximum size if you don’t reduce it.

6. Click on OK. Windows 95 may ask you to reboot your system at this point.

When I try to update my .vne file, the file no longer works.

Here is a work-around:

1. Open V+ Run-time System

2. Configure the I/O Devices.

3. Save the new .vne file.

4. Close all windows.

5. Open the .vne file created in Step 3.

6. Update the V+ worksheets.

7. Run the design(s).

8. Save the .vne file

9. Close all V+ windows.

Open/launch the .vne file. At this point the V+ design automatically starts running and the application starts successfully.

Tech-Notes,   List of Documents, On-Line