iDSC 1816

Data Acquisition, Spectral Analysis, and Aliasing

Data acquisition digitizes an analog signal by sampling it at discrete times, several times in each cycle, to produce a stream of numbers. Spectral analysis does the math on these numbers, mostly using the fast Fourier transform, that breaks out the frequency components of the signal. And aliasing – high-frequency results folded into otherwise accurate data – corrupts the results.

The iDSC 1816 removes all aliasing from data acquisition. Guaranteed. Using the latest analog and digital components and proprietary algorithms, it implements onboard brick-wall filters. And that makes spectral analysis reliable.

Microstar Laboratories has produced a unique new board for the PC. And it has applied its trademark onboard intelligence to make the board a must-have product for anyone doing serious data acquisition. The filters in the iDSC 1816 have variable cutoff frequencies – up to 61.44 kHz – and linear phase response. Each channel can have a different filter. And the board requires no user programming.

Sometimes you have to get serious about aliasing. And when you do, contact us.

iDSC 1816: When you need the ultimate in signal quality

The iDSC 1816 board combines 16-bit resolution on eight simultaneous channels of data acquisition with brick-wall anti-alias filters on each channel. The iDSC 1816 samples analog inputs at a throughput of 1.2M samples per second, with the sampling rate on each channel ranging from 8 samples per second to 153.6k samples per second. The data stream optionally includes an additional 300k samples per second: information from one or two external timing channels. Software can parse the data stream to correlate the analog data with events on one or both of the timing channels, to a resolution of 51 nanoseconds.

The iDSC 1816 comes with DSCview included, and drivers for DASYLab, Agilent/HP VEE, LabVIEW, LabWindows/CVI, and MATLAB. The iDSC 1816 also includes programming support for Visual Basic, Visual C++, and other Windows programming environments through the DSCIO.DLL, a standard Windows DLL interface. It supports development environments like Delphi and C++Builder through a native DSC Component. It also supports Linux development environments like Kylix and GC++. With the DSCview software on your PC, you can customize the filter characteristics for each channel, and download them to the iDSC board. Download DSCview and check it out.

If you need signal conditioning for your iDSC 1816 system, Microstar Laboratories has the solution. Microstar Laboratories has developed an 8-channel sensor signal-conditioning system, the SCS, that complements the 8-channel iDSC 1816 board to provide a continuous path in a single package: starting with raw measurements at the sensor and ending with conditioned anti-aliased data logged to disk on a PC.

Features

High-Speed Input

The iDSC 1816 provides continuous, gap-free input, and allows a different cutoff frequency on each channel.

Software Selectable Acquisition Front End

Menu choices configure which physical inputs to sample. The iDSC 1816 provides up to 8 inputs each with its own separate software-selected filter.

PRODUCTS

Data Acquisition
Measurement Computing
Microstar Laboratories
Vibration
The Modal Shop
Benstone Instrument
Vibrant Technology
Test Products Intl (Vibration Meter)
Digital Multimeters
Test Products International
Data Communications
Advantech B+B Smartworx
(f.k.a. B&B Electronics)

PC Interface

The iDSC can transfer to PC memory continuously at the 1.2M samples per second required for 8 simultaneous channels sampling at its maximum rate per channel of 153.6k samples per second.

Synchronizing Several Boards

Onboard circuitry and special synchronization connectors can support several Microstar Laboratories boards, in any combination of iDSC and DAP models, running in the same PC. A master DAP provides a sampling or an update clock to software-selectable slave DAPs. A software-selectable master iDSC provides a sampling clock to software-selectable slave iDSC boards. The iDSC sampling clock signal, when applied to the external clock input of the master DAP, synchronizes both groups of boards. Each DAP then may sample up to 153.6k samples per second. Microstar Laboratories also provides for synchronization of boards installed in different PCs. Contact us for details.

Sampling Rate

Onboard fourth-order analog anti-alias filters pass signals to decimation filters in the eight Sigma-Delta A/D converters. This hardware converts signals to simultaneous filtered data at 153.6k samples per second on each channel. Configurable symmetric FIR filters implemented on two DSP chips allow any of these sampling rates:

                     153600
102400                76800
 51200                38400              
 25600                19200         15360
 12800         10240   9600          7680
  6400          5120   4800          3840
  3200   3072   2560   2400   2048   1920
  1600   1536   1280   1200   1024    960
   800    768    640    600    512    480
   400    384    320    300    256    240
   200    192    160    150    128    120
   100     96     80     75     64     60
    50     48     40            32     30
    25     24     20            16     15
           12     10             8

Cutoff Frequency

Valid cutoff frequencies fall in the range 2% to 80% of Nyquist; in other words: 100 to 2.5 samples per cycle. So cutoff frequencies range from 61.44 kHz on down. Above 50% of Nyquist, resulting filters roll off at better than 96 dB per quarter-octave.

Timing Signal Inputs

Software can instruct the iDSC 1816 to enable either or both of the two external timing channels. The board then samples TTL signal inputs at 128 times the maximum data sampling rate to provide a resolution below 51 nanoseconds. It uses this information to time the sample on each data channel closest to an event on a timing channel. Contact Microstar Laboratories before working with this feature at data rates above 78.6k samples per second.

iDSC 1816 Specifications

General Specifications
Dimensions	13.33 inches x 4.80 inches
Power requirements	+5V, 3.0 Amps
Operating temperature	0-50 degrees Celsius
Type of A/D converter	Sigma-Delta
Number of A/D converters	8
Input
Number of analog channels	8
Expandable to	112 simultaneous analog inputs (w/ multiple iDSC 1816 boards)
Input voltage range	+/-5 V, +/-10 V
Max. input voltage (fault-protected inputs)	-40 V, +55 V
Max. analog sampling rate per channel	153.6k samples/second
Max. aggregate analog sampling rate over 8 channels	1229k samples/second
ADC Resolution (bits)	16
Number of external timing channels	2
Microprocessor
CPU type	Intel 80486 DX4
CPU clock speed	96 MHz
Onboard operating system	DAPL (modified version)
CPU DRAM	16 Mbytes
DSP
Type of DSPs	Motorola 100 MHz DSP56303
Number of DSPs	2
PC INTERFACE ¹
Bus support	PCI
Samples transferred per second ²	1229k samples/second
Samples logged per second	1229k samples/second

¹ Benchmark rates vary with PC platform.
² Maximum disk logging and data transfer rates vary with PC platform.

* All specifications are applicable from DC through the entire frequency range unless otherwise noted.

Learn about the software side of filtering with DSCview or learn about the wide range of Data Acquisition Processor boards available from Microstar Laboratories. If you need signal conditioning for your iDSC 1816 system, Microstar Laboratories has the solution.