Townshend Computer Tools DAT-Link - 10.4 Downloading DSP32 C Programs; 10.5 Checking the DAT-Links Filters

92 Utilities
TxFSync: The digital audio transmitter's sample-rate clo ck is connected to
the DSP32C's serial input with clocks generated by the DSP32C. This
mode can be used to measure the sampling frequency of output when
locked to an external clo ck.
TxFSync: The digital audio receiver's sample-rate clo ck is connected to the
DSP32C's serial input with clocks generated by the DSP32C. This mode
can b e used to measure the sampling frequency of a digital audio inputs.
The naset program can also b e used to reset the parameters to the default state,
by specifying the -c option. The manual page for naset in Appendix G discusses
these and other options.
10.4 Downloading DSP32C Programs
The naloaddsp program provides a facility for users to download their own DSP
programs to the DAT-Link 's DSP32C pro cessor. The DSP32C program must be
compiled and linked using AT&T's DSP32C Development System to create a COFF
executable le. Section 11.2.1 describes the interface to AT&T's software. To
download an executable named foo , use:
naloaddsp -c foo
This will force the NetAudio server to use foo during all transfers to or from the
DAT-Link . Note that this will aect subsequent use of the NetAudio software in-
cluding naplay , narecord , and rctrain .To return DAT-Link to normal op eration,
use naloaddsp with no arguments.
The name of the currently loaded DSP program can also be checked using the -q
option to naloaddsp :
naloaddsp -q
10.5 Checking the DAT-Link's Filters
When the DAT-Link is used for sample-rate conversion, it must p erform some low-
pass digital ltering to eliminating aliasing during the conversion process. Also,
custom lter responses can be specied for equalization, notch ltering, and other
special applications. If it is necessary to obtain the exact specications of the lter
being used by the DAT-Link , the following procedure can b e used:
1. Perform the operation for whichyou want to examine the lter. For exam-
ple, to examine the lter used for recording with conversion to 8000 sam-
ples/second, run the command: