National Instruments 5411 - page 61

Appendix B Waveform Sampling and Interpolation

DAQArb 5411 User Manual B-2

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National Instruments Corporation

To ease the requirements of the analog filter and to get more outpu t

bandwidth, the DAQArb 5411 uses a half-band digital filter to

interpolate a sample between every two samples at twice the update

frequency, 2fc. Also, the DAC operates at twice the sample frequency.

This increase pushes the images from fc to 2fc and the analog filter

roll-off easily rejects any images from the output spectrum. This

behavior can be seen in the frequency domain representation from

Figure B-2 and in the time domain representation from Figure B-3.

Figure B-2. Digital Filter, Analog Filter, and Signal Images with Digital Filteri ng

Figure B-3. Waveform Updates

Note: The digital filter will be operational only for sample rates of 40 MHz and

20 MHz. For other sample rates, the digital filter will not be of any use.

fc

02fc

0.5fc

Images

f0

Analog Filter

Digital Filter

Signal

Power

(Interpolation Frequency)

4fc

Without Interpolation With Interpolation After Analog Filtering

Contents

Main Page Important Information Warranty Copyright Trademarks WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS Page Chapter 4 Arb Operation Page Tables About This Manual Organization of This Manual Conventions Used in This Manual Customer Communication Introduction About Your DAQArb 5411 What You Need to Get Started Software Programming Choices National Instruments Application Software NI-DAQ Driver Software Optional Equipment Cabling Unpacking Installation and Configuration Installation Hardware Configuration Installing the Optional Memory Module Signal Connections I/O Connector ARB Connector = x 10 V V R + R SYNC Connector PLL Ref Connector Page Chapter 3 Signal Connections National Instruments Corporation 3-5 DAQArb 5411 Use r Manual Figure 3-4. DAQArb 5411 50-Pin Digital Output Connector Pin Assignments Signal Descriptions SHC50-68 50-Pin Cable Connector Chapter 3 Signal Connections National Instruments Corporation 3-7 DAQArb 5411 Use r Manual Figure 3-5. SHC50-68 68-Pin Connector Pin Assignments Power-Up and Reset Conditions National Instruments Corporation 4-1 DAQArb 5411 Use r Manual Arb Operation This chapter describes how to use your DAQArb 5411. Figure 4-1 shows the DAQArb 5411 block diagram. Figure 4-1. DAQArb 5411 Block Diagram Waveform Generation Update Rate Arb Mode Waveform Size and Resolution Waveform Memory Minimum Buffer Size and Resolution Waveform Linking and Looping Chapter 4 Arb Operation National Instruments Corporation DAQArb 5411 User Manual 4-6 Waveform Staging Page Direct Digital Synthesis (DDS) Mode Page Frequency Resolution and Lookup Memory Frequency Hopping and Sweeping Triggering Trigger Sources Modes of Operation Single Trigger Mode Continuous Trigger Mode Stepped Trigger Mode Burst Trigger Mode Marker Output Signal Page Analog Output SYNC Output and Duty Cycle Output Attenuation Output Impedance Output Enable Pre-attenuation Offset Phase-Locked Loops ! Master/Slave Operation a. RTSI Bus Master/Slave Configuration Device b. External Master Analog Filter Correction Digital Pattern Generation Page RTSI Trigger Lines Calibration A Specifications Analog Output Voltage Output Sine Spectral Purity Filter Characteristics Waveform Specifications Timing I/O Page Marker Output Digital Pattern Output External Clock Reference Input Internal clock Mechanical B Waveform Sampling and Interpolation Page C Customer Communication FTP Support Electronic Services Bulletin Board Support Telephone and Fax Support Telephone Fax Fax-on-Demand Support E-Mail Support (currently U.S. only ) Technical Support Form DAQArb 5411 Hardware and Software Configuration Form National Instruments Products Other Products Documentation Comment Form Title: Edition Date: Part Number: Mail to: Technical Publications Fax to: Technical Publications Glossary Numbers/Symbols A B C D Page E F G H I K L M N O P R S T U V W Index Numbers A B C D E F H I L N O P R S T U V W