Daqarta for DOS Contents
expanded waveform display.
This is also the number of samples that will be processed by the FFT if that mode is active, but note that although the raw output of the FFT will contain this many points, it takes two output values to make one frequency line in the spectrum display, which shows the resultant magnitude of both the Cosine (Real) and Sine (Imaginary) outputs of the FFT. So there will only be half as many spectral lines in the (unexpanded) display as shown by N.
In general, if you double the number of lines in a spectrum by doubling N, any random noise will be spread over twice as many spectral lines. Each line will thus have half the noise power (3 dB lower). Note that this is exactly the result obtained by waveform averaging twice as many sweeps at the smaller N, such that the total number of samples considered is the same.
status will change to Pause. The Pause option will also be highlighted. If the current trace was already Paused, then Live operation will be restored.
In addition to this explicit manual operation, Daqarta will also enter Pause mode at the completion of an average. The Pause option will also be highlighted, but the status will be shown as Done.
When Daqarta is in Pause mode, all data collection is halted unless you are recording in DDisk mode. In that case, the DDisk recording continues and only the trace is frozen. You may want to do this to better examine some detail of the trace, without disrupting the actual recording. If you want to stop the recording, use the spacebar DDisk Skip or the Remote Control, if activated.
Whenever MemSv or MemRd is used to save to or read from trace memory, Pause is also activated. MemSv just results in the normal Pause status display, but MemRd shows the status as 'Mem n' where n is the memory trace number.
Similarly, if a file is loaded from disk, the status will show 'FILE'.
Pause mode is also entered automatically after a Single Sweep (Singl) operation.
DQA.CFG file. In addition to modules provided with Daqarta, like the STIM3A Advanced Stimulus Signal Generator, other modules may be provided by third-party programmers or may be written by advanced users for custom applications.
Daqarta allows these modules to access internal variables and functions, and to replace functions with those provided by the module. Modules may access functions and data in other modules, enabling standard libraries to be built and shared. Note, however, that a library module should usually be loaded before modules that will use it, so that it will be found when those modules are initialized at load time. Load order is determined simply by order of appearance in DQA.CFG.
Due to the complexity of interfacing plug-in modules with main Daqarta modes and functions, this is best left to experienced developers. All code is in assembly language, and great attention to detail is required. A plug-in developer's kit is being planned to make this easier, with source code for typical working modules and a Help compiler for use with the CTRL-Help system. Serious developers should contact Interstellar Research for more information.
Interstellar Research requests no royalties from developers who sell plug-in modules, as long as they make it clear to their customers that the sale does not include Daqarta itself, which is shareware.
key macros, you will instead be asked if you want to save them:
'Save changed Key Macros? (Y default/N):'If you hit the N-key (shifted or unshifted), Daqarta will quit immediately. If you hit anything else, you will be prompted for the file name to save the macros as, with the default being the normal DQA.MAC macro file. You might want to choose another name if you will be using different macro files for different users or different experiments, in which case you can have a batch file that selects the proper macro file and renames it to DQA.MAC before invoking Daqarta.
Note that there is no prompt to save changed palettes to a file.
Averager or DDisk operation can be rigged up at the end of a long cable. A plasic 35mm film cannister makes a handy switch holder: Drill or punch one hole in the lid and one in the bottom of the can. Mount a miniature toggle or pushbutton switch in the lid. Thread the cable through the can bottom and solder to the switch. Snap the lid on and you're set. If you can get a can with a light grey lid instead of black, you can label the On and Off positions of the toggle switch with an indelible marker, then cover the lettering with clear tape. Trim any excess tape that overhangs the edge of the lid with a sharp utility knife.
Shielded coaxial cable is the best choice if the remote cable must pass into an electrically shielded room.
The switch setup must be able to provide an acceptable TTL level to the I/O port on the acquisition board. Many boards provide +5 Volts at their connectors, but if yours does not you will have to find it somewhere. Many serial ports provide +5 Volts... check yours with a voltmeter. If all else fails, you can always find +5 Volts inside the case of any regular (non-portable) computer at the disk drive connectors, etc, so you might be able to tap into that if you feel competent.
TTL devices require that zero be a short circuit, not an open circuit, so you should wire your switch like this:
.---- +5 Volts | | R = 1K to 10K | Cable center | .---------------------------^---- Digital Input | \ Switch | `-------------------------------- Digital Ground Cable Shield
When the switch is open, the digital input receives +5 Volts through the resistor, whose value is not critical. When the switch is closed, the digital input is shorted to ground and a small current flows through the resistor and switch.
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