This paper presents a wireless fault detection system for industrial motors that combines vibration, motor current and temperature analysis, thus improving the detection of mechanical faults. The design also considers the time of detection and further possible actions, which are also important for the early detection of possible malfunctions, and thus for avoiding irreversible damage to the motor. The remote motor condition monitoring is implemented through a wireless sensor network (WSN) based on the IEEE 802.15.4 standard. The deployed network uses the beacon-enabled mode to synchronize several sensor nodes with the coordinator node, and the guaranteed time slot mechanism provides data monitoring with a predetermined latency. A graphic user interface offers remote access to motor conditions and real-time monitoring of several parameters. The developed wireless sensor node exhibits very low power consumption since it has been optimized both in terms of hardware and software. The result is a low cost, highly reliable and compact design, achieving a high degree of autonomy of more than two years with just one 3.3 V/2600 mAh battery. Laboratory and field tests confirm the feasibility of the wireless system.

This paper presents the design of a wireless flood sensor to detect the presence of water on home floors, providing early warning of water leaks. A wireless sensor network has been deployed to gather the measurements from the sensor nodes. A control central coordinates the network and processes the data. Users can remotely inquire for the presence of water, status of the batteries for a specific node, the type of liquid and information about its functionality and alarms, thanks to a proprietary software application. The alerts are also communicated to the user within the home through an audible siren. The designed device is optimized in terms of costs, ease of deployment and maintenance, thus making it widely acceptable to end users.

A CMOS variable gain amplifier (VGA) based on a novel linear and tunable triode transconductor is presented. The proposed transconductor employs local negative feedback for linearisation controlling the drain voltage of the input transistors biased in the triode region. The new design is able to operate at low supply voltage and the stability is guaranteed. The transconductor features a 47.75 dB dc gain and a 4.23 MHz unity gain frequency with a power consumption of only 91 µA. To show the feasibility of the proposed transconductor, a VGA has been fabricated. Measurement results for a 0.13 µm CMOS design show a −3 dB bandwidth above 2.8 MHz and a third-order harmonic distortion at 500 kHz below −46 dB over the whole gain range. The VGA exhibits a maximum power consumption of only 395 µW from a single 1.2 V supply.

This work presents the design, construction and testing of a new embedded sensor system for monitoring concrete curing. A specific mote has been implemented to withstand the aggressive environment without affecting the measured variables. The system also includes a real-time monitoring application operating from a remote computer placed in a central location. The testing was done in two phases: the first in the laboratory, to validate the functional requirements of the developed devices; and the second on civil works to evaluate the functional features of the devices, such as range, robustness and flexibility. The devices were successfully implemented resulting in a low cost, highly reliable, compact and non-destructive solution.

No abstract

A third-order Gm-C Chebyshev low-pass filter with high linearity and automatic frequency programmability has been designed. The filter is intended to be used as a channel-select filter for a zero-IF Bluetooth receiver. The frequency tuning scheme is simpler and has more relaxed specifications than conventional ones. The filter bandwidth is 0.5 MHz and the overall scheme dissipates 1.1 mA from a 1.8-V supply. The third-order intermodulation (IM3) distortion of the filter for a 1Vpp two-tone signal centered at 350 kHz is −67dB.

A Gm-C third-order Chebyshev low-pass filter with a novel switched capacitor frequency tuning technique for a zero-IF Bluetooth receiver has been designed. The frequency tuning scheme is simpler and has more relaxed specifications than conventional ones. Furthermore, a highly linear pseudo-differential transconductor with a compact feedback loop able to operate with low supply voltage has been used. This control loop holds the input transistors in triode region and provides high output resistance, keeping high linearity in a wide range of transconductance. The filter bandwidth is 0.5 MHz and the overall scheme consumes 1.1 mA from a 1.8-V supply. The measured third-order intermodulation (IM3) distortion of the filter for a 1 Vpp two-tone signal centered at 300 kHz is 65 dB.

No abstract