Engineering Design NIDisk Podręcznik Użytkownika Pobierz pdf (Strona 11)

DartDisk User Guide

No. channels can be set to 1 or 2. Maximum sample rate is unaffected by the number of

channels selected.

Filename specifies the destination sound file. If the filename does not include a full path

(drive letter and directory), files are stored in the directory containing DartDisk. Embedded

spaces are allowed in the filename. DartDisk will append the ".wav" extension to Wave files

if not included.

For a one-channel acquisition, Filename simply specifies the name of the destination sound

file.

For a multi-channel acquisition, the Filename specification depends on the Channel format

setting. With "One file per channel" (the recommended setting), specify the File prefix and

DartDisk will store the data, one file per channel, in SIGNAL files prefix.1, prefix.2, etc. or

Wave files prefix.1.wav, prefix.2.wav, etc. File prefixes should not end with a period (.).

With "Multi-channel file", specify the Filename and DartDisk will store all acquisition

channels in this file (see Channel format). Note that multi-channel SIGNAL files require

SIGNAL 5, and Wave files with more than 2 channels may require special software.

File type may be SIGNAL or Wave. Sound data are written as 16-bit integers, coded as

follows. SIGNAL files are strongly recommended.

• SIGNAL files are written in the native 12-bit or 16-bit coding of the installed I/O

board, with offset removed from 16-bit data. A conversion factor is stored in the file

header that allows SIGNAL to reconstruct the original voltage range.

• Wave files are written in 16-bit coding (0 offset, ±32768 range), independent of the

installed I/O card. Offset is removed and 12-bit data are scaled to 16 bits. Files are

uncompressed, i.e., in the "PCM" or "type 1" standard

Wave file format.

• Note that Wave file amplitudes may not scale correctly in SIGNAL, since the

Wave header contains no conversion factor to indicate the original voltage range

of the data.

• Note also that Wave files with sample rates other than 44,100 Hz may not be

playable on all systems.

Channel format indicates how to store multi-channel acquisition data. One channel per file

stores each acquisition channel in a different file (see Filename above). Multi-channel file

stores all channels in one file, interleaved. For example, a 2-channel acquisition will store

point 1 of channel 1, point 1 of channel 2, point 2 of channel 1, point 2 of channel 2, etc.

Overwrite allows DartDisk to overwrite pre-existing data files of the same name without

warning the user. If Overwrite is not checked, DartDisk will request permission before

overwriting.

Dart model specifies the Dart model installed in the current system, according to its

maximum sample rate of 50, 48, or 44.1 kHz. See "Sample rate selection" below for a list of

the sample rates available for each model.

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 28 29

Brak uwag

Engineering Design NIDisk Podręcznik Użytkownika Strona 11