National Instruments SCXI-1142 Lowpass Filter Input Module

The NI SCXI-1142 (Part Number: 776572-42) module is suitable for antialiasing applications and can also be used for general-purpose signal amplification and filtering. This module has a Bessel filter response, eight channels, and works with National Instruments E/M Series DAQ instruments. Multiplexed and parallel modes are the two modes of operation available on this module.

The 8^th-order Bessel filters on the SCXI-1142 preserve signal phase integrity and are well-suited for applications that entail simultaneous sampling. The filters are a combination of SCFs and continuous-time filters (CTFs). SCF technology allows the cutoff frequency to be configured via software with ease. Although, SCFs are sampling systems and are therefore subject to the same aliasing effects as digitizers. The hybrid design utilizes a CTF prefilter to stop aliasing in the SCF and CTF postfilter to recreate the sampled waveform.

The SCXI 1142 Lowpass Filter Input Module has calibration hardware to get rid of error sources. Software-programmable analog switches can ground the inputs of the instrumentation amplifiers for offset error calibration with the use of automatic input zeroing. With the use of an external reference voltage, the user can calibrate the module to their specific operating environment. Also, DC compensation circuits eradicate the offset errors of the filters. This ensures great DC preciseness, despite whether lowpass filtering is activated. An onboard EEPROM saves the calibration constants in the permanent memory, which cannot be altered by the user. NI-DAQ transparently utilizes the calibration constants to adjust for gain mistakes.

SCXI-1142 Obsolete Status has been announced by National Instruments, but the module will still be available for purchase and repairs by Apex Waves.