National Instruments NI 5102 Active and Current Probes

Chapter3 DigitizerBasics

©NationalInstruments Corporation 3-11 NI5102 User Manual

Figure3-8. ProbeCompensation Comparison

Active and Current Probes

You can also useactive probes and current probes with digitizers

andDSOs.

Activeprobes, such as differential and field-effect transistor (FET) probes,

contain activecircuitry in the probe itself to reject noise and amplify the

signal. FET probes are useful for low-voltagemeasurements at high

frequenciesan d differentialprobes are noted for theirhigh common mode

rejection ration (CMRR) and nongrounded reference.

Instead of using a series resistance in the loop to measure current, current

probesmagnetically measure AC and/or DC current flowing in a conductor.

This lack of seriesresistance causes very little interference in the circuit

being tested.

ProbeAdjustment Signal ProbeAdjustment Signal Probe Adjustment Signal

ProperAmplitude of a

1MHz Test Signal

ReducedAmplitude of a

1MHz Test Signal

IncreasedAmplitude of a

1MHz Test Signal

a.Compensated Correctly b. Undercompensated c.Overcompensated

Contents

Main Page Important Information Warranty Copyright Trademarks WARNINGREGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS Compliance FCC/Canada Radio Frequency Interference Compliance* Determining FCC Class FCC/DOC Warnings Class A Compliance to EU Directives Contents Page About This Manual Conventions Used in This Manual Related Documentation Introduction About Your NI 5102 Acquiring Data with Your NI 5102 Figure1-1. TheRelationship Between the Programming Environment, NI-DAQ,and Your Hardware x/ Interactively Controlling your NI 5102 with the Scope Soft Front Panel Help. Note Press F1withthe Soft Front Panel running to access the Scope Soft Fron t Panel NI-SCOPE Driver NI-DAQ API NI Application Software Using PXI with CompactPCI Optional Equipment Installation and Configuration What You Need to Get Started Unpacking Installing the NI 5102 Hardware Configuration Digitizer Basics Understanding Digitizers Nyquist Theorem Analog Bandwidth Sample Rate Vertical Sensitivity ADC Resolution Record Length TriggeringOptions Making Accurate Measurements Page Page Understanding the Probe and Its Effects on Your Waveform Passive Probe How to Compensate Your Probe Page Active and Current Probes NationalInstruments Corporation 4-1 NI5102 User Manual Hardware Overview Figure4-1. NI 5102 (PCI, PXI, ISA) Block Diagram Chapter4 HardwareOverview NI5102 User Manual 4-2 ni.com Figure 4-2 showsa block diagram of the NI 5102 (PCMCIA, USB). I/O Connector Page Page Signal Connections Serial Communications Port (AUX) Analog Input Page ADC Pipeline Delay Acquisition Modes Posttrigger Acquisition Page Page Pretrigger Acquisition Page Page TriggerSources Figure4-10. ScanClock, Start Trigger, and Stop TriggerSignal Sources Analog TriggerCircuit TriggerHold-off Page Random Interleaved Sampling Calibration RTSI Bus Triggerand Clock Lines Figure4-12. RTSIBus Trigger Lines PFI Lines PFI Lines as Inputs PFI Lines as Outputs Page Master/Slave Operation Restrictions Connecting Devices Page A Specifications Input Characteristics Timebase System TransferCharacteristics Dynamic Characteristics S/H Characteristics Stability Triggers Analog Digital (PFI1 and PFI2) RTSI (NI 5102 for PCI, PXI, ISA Only) Power Consumption Physical Maximum Working Voltage Environmental Safety Electromagnetic Compatibility Calibration B Technical Support Resources Web Support NI Developer Zone Customer Education System Integration Worldwide Support Glossary Numbers/Symbols A B C Page D Page E F G H I Page K L M N O P Page R S Page T U V W Z Index A B C D E F H I J L M N O P R S T U V W