National Instruments

About: National Instruments is a company organization based out in Dublin, Ireland. It is known for research contribution in the topics: Signal & Interface (computing). The organization has 1135 authors who have published 1719 publications receiving 35682 citations. The organization is also known as: NI & National Instruments Corporation.

Adjustable time constant integrator

Abstract: A variable time constant integrator includes an amplifier configured to generate an output signal, a capacitor coupled to provide feedback to the amplifier, and a variable gain element coupled to the output of the amplifier and to the capacitor. The variable gain element is configured to provide the product of a gain and the output signal to the capacitor. The variable gain element is also configured to receive an indication of a new value of the gain and to responsively set the gain equal to the new value of the gain. Adjusting the gain of the variable gain element adjusts the integrator's time constant.

High-speed cosine generator

Abstract: An 8-bit high-speed cosine generator circuit was designed and simulated. Speed and area estimates were made for 16-, 24-, 32-, 40-, 48-, 56-, and 64-bit designs. The basis of the cosine generator design is stages of a half-angle cosine function preceded by a low order Taylor series approximation of cos (/spl theta//2/sup N/). This turns out to be a decent approximation. The big difference between this and most other methods is that a lookup ROM for the first order approximations is avoided. >

Method for correcting analog-to-digital converter (ADC) errors, and apparatus embodying same

Abstract: A method for correcting output codes produced by an analog-to-digital converter (ADC), and an apparatus embodying the method. The method includes receiving a digital output code i produced by the ADC, and randomly selecting a new digital output code within a range of code values dependent upon a difference between an actual code edge transition of the digital output code i and an ideal code edge transition of the digital output code i. An n-bit ADC produces digital output codes 0 through (2 n −1). Digital output codes 1 through (2 n −1) have actual and ideal code edge transitions. The actual code edge transition of the digital output code i, where 1≦i≦(2 n −1), is a transition between a digital output code i−1 and the digital output code i within an actual transfer function of the ADC, and the ideal code edge transition of the digital output code i is a transition between a digital output code i−1 and code i within an ideal transfer function of the ADC. When the ADC is an n-bit ADC, both the digital output code i and the new digital output code are n-bit values. Producing n-bit values, the method, employing a probabilistic approach to ADC code correction, is easily incorporated into measurement and control systems designed to receive n bits from an n-bit ADC. The method corrects ADC output code errors resulting from a number of error sources, including offset error, gain error, and linearity error, or any combination thereof.

Buffer object for performing buffered data transfers in a data acquisition system

Abstract: A buffer object for performing intelligent buffering functions in a data acquisition (DAQ) system. The buffer object stores information regarding data to be transferred and includes one or more iterators for performing burst transfers. When a DAQ user application generates a call to perform data transfer operations in the DAQ system, the driver level software creates or instantiates a buffer object. The buffer object includes data format information specifying a format of the data being transferred, including the size of the data, the number of samples per scan, and number of scans of the data. The driver level software also creates a foreground iterator which is executable to transfer data between a client portion of system memory and a buffer portion of system memory. The driver level software also creates a background iterator which is executable to transfer data between a buffer portion of system memory and the on-board memory comprised on the DAQ device. The foreground iterator and the background iterator execute in response to the DAQ user application to perform data transfers to/from the DAQ device. The foreground and background iterators also use information in the buffer object to perform the data transfer. In the preferred embodiment, the foreground iterator executes in user mode of the CPU, and the background iterator executes in kernel mode of the CPU.

Integrated Data Viewer

Abstract: System and method for recording and displaying data associated with a program executing a program Data associated with the program is displayed in a first instance of a graphical user interface (GUI) element The data are saved one or more times during or after execution of the program in response to input, including saving information regarding the GUI element The saved data are then displayed in a second instance of the GUI element in response to user input invoking display of the saved data, based on the saved information regarding the GUI element