Special Coverage

Home

Photodiode-Based, Passive Ultraviolet Dosimeters

Outputs of photodiodes are fed to coulometers.Simple, passive instruments have been developed for measuring the exposure of material specimens to vacuum ultraviolet (VUV) radiation from the Sun. Each instrument contains a silicon photodiode and a coulometer. The photocharge generated in the photodiode is stored in the coulometer. The accumulated electric charge measured by use of the coulometer is assumed to be proportional to the cumulative dose of VUV radiation expressed in such convenient units as equivalent Sun hours (ESH) [defined as the number of hours of exposure to sunlight at normal incidence]. Intended originally for use aboard spacecraft, these instruments could also be adapted to such terrestrial uses as monitoring the curing of ultraviolet-curable epoxies.

Posted in: Test & Measurement, Briefs

Read More >>

Portable Electromyograph

Signals from 16 differential EMG electrodes can be recorded for 8 hours.A portable electronic apparatus records electromyographic (EMG) signals in as many as 16 channels at a sampling rate of 1,024 Hz in each channel. The apparatus (see figure) includes 16 differential EMG electrodes (each electrode corresponding to one channel) with cables and attachment hardware, reference electrodes, an input/output-and-power-adapter unit, a 16-bit analog-to-digital converter, and a hand-held computer that contains a removable 256-MB flash memory card. When all 16 EMG electrodes are in use, full-bandwidth data can be recorded in each channel for as long as 8 hours. The apparatus is powered by a battery and is small enough that it can be carried in a waist pouch.

Posted in: Test & Measurement, Briefs

Read More >>

Small Active Radiation Monitor

This is a significant advancement over the passive dosimeters that presently monitor astronaut exposure to radiation.A device, named small active radiation monitor, allows on-orbit evaluations during periods of increased radiation, after extravehicular activities, or at predesignated times for crews on such long-duration space missions as on the International Space Station. It also permits direct evaluation of biological doses, a task now performed using a combination of measurements and potentially inaccurate simulations. Indeed the new monitor can measure a full array of radiation levels, from “soft” x-rays to “hard” galactic cosmic-ray particles. With refinement, it will benefit commercial (nuclear power-plant workers, airline pilots, medical technicians, physicians/dentists, and others) and military personnel as well as the astronauts for whom thermoluminescent dosimeters are inadequate.

Posted in: Test & Measurement, Briefs

Read More >>

13-bit magnetic sensor

Renishaw, Hoffman Estates, IL, has introduced a 13-bit magnetic sensor for rotary and angular positioning control. Providing 8,192 counts per revolution, the sensors are available in chip, chip-on-board, and ready-to-mount packaged versions. The solid-state, non-contact design features an integrated circuit chip that senses the position of a separate two-pole permanent magnet. Suited for difficult environmental requirements, the sensors provide -40°C to 125°C operational temperature range, and shock and vibration resistance. Friction-less, low-inertia operation enables 0.3° positioning accuracy at speeds to 30,000 rpm. They are available in models providing absolute, incremental, analog, or digital outputs, as well as simultaneous SSI and incremental output. Chip and chip-on-board models allow the sensors to be integrated into machinery and equipment designs. Packaged versions enclose the chip and electronics in metal cases. Enclosed units are used in rugged applications and environments; fully encapsulated versions are waterproof.

Posted in: Products

Read More >>

p1411A RF vector signal generator

PrecisionWave Corp., Colorado Springs, CO, has introduced the p1411A RF vector signal generator that includes a spectrum analyzer display and an internal IQ waveform generator. It is available in both benchtop and ATE configurations. User-created IQ waveforms can generate other signal types, specify data content, or create worst-case signal scenarios for development and test of ICs, sub-assemblies, or completed products. The display continuously shows the instrument's output, and can be used to preview waveforms prior to selecting them for output. The 7" TFT display includes a touch panel for instrument control without an external mouse, keyboard, or stylus - all of which can be connected if required. The instrument features LAN programming, and may be controlled and monitored from Web applications. It includes a low-phase-noise 10-MHz internal frequency reference, and can accept an external 10-MHz reference signal for synchronization with other devices and test equipment. For Free Info Visit http://info.hotims.com/10958-120

Posted in: Products

Read More >>

Apparatus Characterizes Transient Voltages in Real Time

Only the most relevant data are recorded. The figure shows a prototype of a relatively inexpensive electronic monitoring apparatus that measures and records selected parameters of lightning induced transient voltages on communication and power cables. The selected parameters, listed below, are those most relevant to the ability of lightning induced transients to damage electronic equipment.

Posted in: Test & Measurement, Briefs

Read More >>

Measuring Humidity in Sealed Glass Encasements

This noninvasive technique helps in the preservation of valuable documents.

Posted in: Test & Measurement, Briefs, TSP

Read More >>