Crossfield® provides instrumentation systems based on IEEE 802.15.4 ZigBee, Bluetooth Low Energy (BLE), and IEEE 802.11 (WiFi) wireless technologies. The choice of a particular wireless technology is based upon the required data rate, communications range and battery life.

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IEEE 802.15.4 Wireless USB Dongle

Crossfield has developed small, custom IEEE 802.15.4 Wireless USB dongles to provide a full-speed USB 2.0 interface into IEEE 802.15.4, RF4CE or ZigBee® networks. The dongle was made to fit into a small enclosure and communicate with remote wireless devices, such as a wireless instrumentation gateway, in an industrial environment.

Instrumentation

Instrumentation encompasses a wide variety of sensor types: temperature, pressure, strain, acceleration, orientation (gyroscope), rotation, and many others. The analog domain spans the signal chain from sensor to analog-to-digital converter, and typically includes a programmable gain instrumentation amplifier, a DAC for offset removal, calibration and anti-alias filtering. The digital domain spans data capture and buffering, digital signal processing, event detection, non-volatile storage, and packet processing.

State-of-the-art systems have excellent common-mode noise rejection, power supply noise rejection, and high resolution/accuracy.
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RF SYSTEMS

Crossfield has the expertise to develop custom receivers, transmitters and synthesizers for commercial and defense applications. Our experience base includes zero-IF and near-zero-IF receivers and direct modulation. Our team has developed baseband modulators/demodulators using a variety of waveforms.

Crossfield has in-house test equipment supporting designs up to 20 GHz.

Crossfield uses AWR/Microwave Office for design of RF and microwave circuits, including RF printed circuits boards and integrated microwave assemblies.

Embedded Firmware Design

Wireless sensor applications are typically written in the “C” programming language to support real-time data acquisition, power management and communications. Vendor-supplied communications software, such as Freescale’s Simple MAC, is typically written in “C”.

Crossfield can provide a LabVIEW™ driver and application to configure and read-out data from the wireless systems.
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Power Efficiency

Wireless systems require efficient energy management. The goal is for the sensor to “sleep” in a zero-power state and periodically wake, or wake on an event, to sense the environment and then promptly go back to sleep to conserve energy. However, sensors typically require a short period of wake time to stabilize prior to making an accurate measurement. Also, it is sometimes important that digital circuitry be inactive during the sense period to minimize noise in the measurement.

An efficient power supply is required to maximize the lifetime of the battery. Crossfield uses high-efficiency, low quiescent current, low noise power supplies that extract the maximum energy from the battery.

Antenna Design

The antenna is a key component of a wireless system design. Linear or circular polarized patch antennas provide robust performance in difficult environments with significant multipath interference and fading. For low cost applications, the antenna can be patterned onto the printed circuit board.
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Packaging & Regulatory Compliance

The enclosure should be designed to a specific NEMA/IP rating for the intended environment. The product must be RoHS/WEEE and UL/CE/FCC/CSA compliant to be sold in the North American and European markets. Crossfield has experience working with local compliance test labs to ensure that the product meets these standards and to obtain the documentation required to enable the product to be marked with appropriate compliance marks.

Compact, Rugged Wireless Modules

Crossfield has experience developing shock-hardened wireless Instrumentation Gateways for data logging using non-volatile memory for data storage. USB and IEEE 802.15.4 wireless interfaces provide configuration and data readout. The module shown here supports a wide range of single-ended and differential-ended sensor types, including ¼-, ½-, and full-bridge sensors in an ultra-compact form factor. It was tested for survivability up to 10,000 G.
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