What is Signal Conditioning?

Key Technologies

 

Amplification
Amplifiers boost input signal level to better match the analog-to-digital converter (ADC) range, thus increasing the measurement resolution and sensitivity. In addition, using external signal conditioners located closer to the signal source, or transducer, improves the measurement signal-to-noise ratio by boosting the signal level before it is affected by environmental noise.

 

Attenuation
Attenuation, the opposite of amplification, is necessary when voltages to be digitized are beyond the digitizer input range. This form of signal conditioning decreases the input signal amplitude so that the conditioned signal is within ADC range. Attenuation is necessary for measuring high voltages.

 

Isolation
Isolated signal conditioning devices pass the signal from its source to the measurement device without a physical connection by using transformer, optical, or capacitive coupling techniques. In addition to breaking ground loops, isolation blocks high-voltage surges and rejects high common-mode voltage and thus protects both the operators and expensive measurement equipment.

 

Multiplexing
By multiplexing, a measurement system can sequentially route multiple signals into a single digitizer, thus providing a cost-effective way to greatly expand the system channel count. Multiplexing is necessary for any high-channel-count application.

 

Filtering
Filters reject unwanted noise within a certain frequency range. Nearly all data acquisition applications are subject to some level of 50 or 60 Hz noise picked up from power lines or machinery. Most signal conditioners include lowpass filters specifically designed to provide maximum rejection of 50 to 60 Hz noise.

 

Excitation
Excitation is required for some transducers. For example, strain gages, thermistors, and RTDs require external voltage or current excitation signals. RTD and thermistor measurements usually are made with a current source that converts the variation in resistance to a measurable voltage. Strain gages, which are very-low-resistance devices, typically are used in a Wheatstone bridge configuration with a voltage excitation source.

 

Cold-Junction Compensation
Cold-junction compensation is a technology required for accurate thermocouple measurements. Any time a thermocouple is connected to a data acquisition system, you must know the temperature at the connection point (as this junction represents another "thermocouple" in the measurement path and typically injects an offset in your measurement) to calculate the true temperature your thermocouple is measuring.

What Is Signal Conditioning?

Signal conditioning turns your data acquisition device into a complete data acquisition system by helping you directly connect to a broad range of sensor and signal types, from thermocouples to high-voltage signals. Key signal conditioning technologies improve overall data acquisition system performance and accuracy by up to 10X.

Feature Resources

Signal Conditioning Fundamentals
Learn about signal conditioning fundamentals for computer-based data acquisition systems.

Critical Signal Conditioning System Technologies
Learn how signal conditioning can improve your data acquisition system performance and accuracy by up to 10X.

Sensors Plug&Play
See how you can use NI signal conditioning products with IEEE 1451.4 TEDS-enabled sensors.

Measuring Temperature with an RTD or Thermistor
Learn how to measure temperature with NI data acquisition systems.

Measuring Temperature with Thermocouples
Learn how to measure temperature with NI data acquisition systems.

Measuring Strain with Strain Gages
Learn how to measure strain with NI signal data acquisition systems.

Measuring Pressure with Pressure Sensors
Learn how to measure pressure with NI data acquisition systems.

Featured Products

The NI signal conditioning product families support connectivity to many different sensor and signal types. Each family is designed to satisfy specific sensor/signal type, form factor, and budget-related signal conditioning needs.

SCXI
These modular, high-performance, USB data acquisition systems offer sensor and signal-specific conditioning for virtually any measurement type.

SCC
These portable, low-cost, modular front-end signal conditioning systems are designed to work with M Series and E Series DAQ devices and feature per-channel custom direct connectivity.

SC Series
These PXI data acquisition devices have built-in, measurement-specific conditioning.

Sensors Plug&Play (TEDS) Measurement Devices
This modular signal conditioning hardware helps you use IEEE 1451.4 smart TEDS sensors to simplify your system setup.

5B Series
These front-end analog signal conditioning modules are for low-channel-count applications requiring very high isolation.

Signal Conditioning Accessories
NI offers these low-cost analog and digital signal conditioning accessories for plug-in data acquisition devices.