Measured Power Levels Research Articles

An improved calibration technique for on-wafer large-signal transistor characterization

The on-wafer measurement of complex quantities and absolute power levels of active devices is truly significant for nonlinear device characterization and modeling. An original procedure, which allows one to perform both the vector and the power calibrations at the RF wafer probe tips used for on-wafer measurement of two-port devices, is presented. The measurement system is based on an automatic vector network analyzer with coaxial directional couplers and RF coplanar wafer probes. A new error model of the dual directional coupler, which samples the power waves traveling at device output, allows one to take advantage of the coaxial section at the output of the measuring system for calibrating the power level up to the on-wafer probe tips. >

Electricity use in Information Technologies

At present, there are no definitive, measured data on electricity loads and operating profiles for computers and other electronic office equipment, based on a statistically meaningful sample of US commercial buildings. In this paper, the authors review fragmentary data available to us and analyze measured power levels for computers and peripherals. The authors then discuss options for improved efficiency in electronic equipment hardware, software, and operations. Finally, the authors outline future trends in electricity loads due to information technologies, to illustrate the influence of component efficiency and market saturation.

The scatter of data caused by interference of tire noise in sound power level measurement of running road vehicles

The scatter of data caused by interference of tire noise in sound power level measurement of running road vehicles

A diffuse field sonar tank for measurement of projector sound power level and directivity index

Though widely used in air acoustics, the diffuse field technique has not been extensively used in underwater acoustics. This paper describes a small (2 m3) diffuse field sonar tank facility intended for production testing of the steady-state sound-power level and directivity index of wideband sonar projectors. When evaluated by standards used in air acoustics to ensure adequate diffuse field measurement accuracy, this compact and inexpensive facility appears to be qualified for the determination of band-averaged sound-power level over a frequency range exceeding five octaves (from about 4 to 160 kHz). When compared with a free-field measurement facility, the practical advantages of this approach include large savings in cost and space. Long transducer rise times are permitted since measurements are steady state. Moreover, the implicit spatial integration of radiation patterns makes results of diffuse field testing more appropriate than free-field testing for some applications.

Improved Error-Correction Technique for Large-Signal Load-Pull Measurements (Short Paper)

This article presents an improved vector error-corrected calibration technique for the well-known system used for large-signal characterization of oscillator and power amplifier transistors. The calibration procedure is very similar to conventional automatic network analyzer calibration procedures, and all its measurements, except for one power measurement, are performed by the system itself. Therefore, reflection coefficient and power level measurement accuracies of the system at both the input and output ports of the DUT are excellent, and are of the same order of magnitude as those of the automatic network analyzer.

Measurement of Sound Power Level by Sound Intensity Method

Measurement of Sound Power Level by Sound Intensity Method

Radiation from NB3Ge Nanobridges: Experiments and Comparison with Theory

High-κ nanobridges were structured from Nb3Ge thin-films and their radiation was measured at 10.5 GHz. The measured power levels and linewidths are about 10-13 W and 300 MHz, respectively. Series connected bridges show a much smaller linewidth. This indicates a coherent behaviour which can be observed in the de-characteristics, too. The experimental results are compared with a theoretical model and characteristical times are extracted.

On the draft of Japanese Industrial Standard "Precision Methods for the Measurement of Sound power Level in Reverberation Rooms."

On the draft of Japanese Industrial Standard "Precision Methods for the Measurement of Sound power Level in Reverberation Rooms."

Results of the round robin tests for sound power level measurements

Results of the round robin tests for sound power level measurements

Definition and measurement of sound energy level of a transient sound source.

Concerning stationary sound sources, sound power level which describes the sound power radiated by a sound source is clearly defined. For its measuring methods, the sound pressure methods using free field, hemi-free field and diffuse field have been established, and they have been standardized in the international and national standards. Further, the method of sound power measurement using the sound intensity technique has become popular. On the other hand, concerning transient sound sources such as impulsive and intermittent sound sources, the way of describing and measuring their acoustic outputs has not been established. In this paper, therefore, “sound energy level” which represents the total sound energy radiated by a single event of a transient sound source is first defined as contrasted with the sound power level. Subsequently, its measuring methods by two kinds of sound pressure method and sound intensity method are investigated theoretically and experimentally on referring to the methods of sound power level measurement.

On the draft of Japanese Industrial Standard "Engineering and Survey Methods for the Measurement of Sound Power Level in General Sound Fields"

On the draft of Japanese Industrial Standard "Engineering and Survey Methods for the Measurement of Sound Power Level in General Sound Fields"

Standardization for the method of measurement of sound power level

Standardization for the method of measurement of sound power level

On the draft of Japanese Industrial Standard "Precision methods for the measurement of sound power level in anechoic and hemi-anechoic rooms

On the draft of Japanese Industrial Standard "Precision methods for the measurement of sound power level in anechoic and hemi-anechoic rooms

The National Voluntary Laboratory Accreditation Program for acoustical laboratories

The National Voluntary Laboratory Accreditation Program (NVLAP) administered by the National Bureau of Standards (NBS) established a program in September 1982 to accredit laboratories that provide acoustical testing services. The Acoustics Laboratory Accreditation Program (Acoustics LAP) covers 50 national and international test methods for which laboratories can apply for accreditation. The test methods cover procedures for measuring the properties of acoustical materials, sound power and sound pressure level measurements, and field measurements of noise produced by products. Applicant laboratories are evaluated through on‐site visits by experienced assessors and by participation in proficiency testing programs administered by NVLAP. Proficiency testing programs are currently in operation for test methods ASTM C423 and ASTM E90. Seven laboratories are currently accredited for various test methods and additional laboratories are in the process of being evaluated for accreditation.

Measurement of low power levels of pulsed laser radiation

Measurement of low power levels of pulsed laser radiation

An improved method for determination of radiated sound power and sound transmission from large sources

The proposed method is an improvement of the methods for measurement of sound power level, in which the real sound source is represented by an equivalent monopole. It is based on a new concept, the equivalent acoustical centre, which is introduced and defined in the paper. The main assets of the method in comparison with the existing monopole-methods are a higher accuracy, a possibility of measuring at considerably shorter distances from the noise source, and a certain freedom in the choise of the measuring points around the source. Moreover, since the position of the equivalent monopole is obtained, it can be used for more accurate calculations of the sound transmission to the surroundings of the source. The method is particularly suitable for determination of sound power levels and sound transmission of noise radiated from large areas, such as industrial complexes, installations of petrochemical industries and the like. It can be especially useful in disputable cases of industrial plants that produce noise close to the legally permissible limit. The new method was first reported at the meeting of the Dutch Acoustical Society which took place in Utrecht on 22 November 1978.

Sound power levels of road vehicles measured by a new method using a reverberant tunnel.

For the measurement of sound power level of vehicle noise in constant speed run, a new method using a reverberant tunnel is investigated. This measuring method is a kind of sound source substitution method in a reverberant sound field, which makes the measurement easier and more accurate, compared with the ordinary method. By making a field measurement on road vehicles in actual use using this new method, 179 data of passenger cars and 490 data of heavy vehicles were obtained. Concerning these results, the correlations between A-weighted sound power level and such vehicle properties as running speed, total weight, and type of tires are investigated.

Intermodulation generation by electron tunneling through aluminum-oxide films

The generation of intermodulation (IM) interference by nonlinear conduction mechanisms in normally passive hardware components can lead to severe degradation in the performance of multi-carrier communication systems in satellites, space probes, and ship-board systems. This paper describes an investigation of the generation of IM due to nonlinear conduction by electron tunneling through aluminum-oxide films. Details are presented regarding the fabrication of Al-Al 2 O 3 -Al junctions, the current-voltage and capacitance characteristics, and the measurement of IM power levels. The IM is correlated with the junction circuit parameters and with tunneling theory. Results are also presented on preliminary experiments to beneficially modify such nonlinear conduction by implantation of metallic ions in the oxide film.

A method of measuring sound power levels of vehicles using a reverberant field in tunnel

For the measurement of sound power levels of freely running vehicles, a new method using a reverberant field in a tunnel and a reference sound source was tested. In this test, a microphone was set on the wall at the center of the testing area (121 m, in this case) in a straight tunnel that is 1 km in length, and sounds generated by freely running vehicles were recorded on a tape recorder for each period within which they were in the testing area. The tape recordings were replayed through 1‐octave bandpass filters (63 ∼ 4 kHz) onto a square integrator. Then, comparing these integrated values with the value for the reference sound source that had been measured previously in much the same way as mentioned above, and with consideration of the differences in the integration times, 1‐octave band power levels for each vehicle were obtained. With these values, A‐weighted power levels were calculated. By this method, the sound power levels of 133 passenger cars and 141 trucks were measured.

One Stage and Two Stage Vibration Isolators as Applied to High Speed Textile Spindles to Achieve Noise Reduction

The operation of ring spinning frames in textile mills can create spinning room noise levels of 90 to 95 dBA. The spindle bobbin mechanisms (generally 300 to 400 per machine) which are operated at spindle speeds of 6,000 to 14,000 rpm are major sources of noise in this type of machinery. The rotating unbalance force in the spindle-bobbin mechanism creates high frequency vibrations in the spindle blade and in the spindle bolster which contains the bearings on which the blade rotates. The vibrations generated by the spindle bobbin mechanism and the bearings are transmitted through the spindle bolster to the rail structure of the spinning frame where they cause sand energy to be radiated. This paper describes the use of two types of elastomeric vibration isolators located between the spindle bolster and the rail to achieve reductions of vibration and noise levels associated with the spindle-bobbin-rail subsystem of spinning frames. The two types of elastomeric isolators employed are: (1) a single-stage isolator where a bonded elastomeric mounting of annular design is placed between the bolster and the rail, and (2) a two-stage isolator which incorporates an annular intermediate mass element between two annular elastomeric sections that provide the interfaces to the spindle and to the rail. The two stage isolator is a novel design for rotating spindle type applications and employs the classical two stage isolator principle to achieve greater attenuation of vibrations. While it has been known for some time that single stage elastomeric isolators provide an effective means of reducing vibrations and noise in textile spinning and twisting machines, recent emphasis on reducing machine noise levels has motivated increased effort to better describe and apply elastomeric isolators. The two-stage isolator concept has been employed in an attempt to achieve higher operating speeds and, therefore, higher productivity while keeping noise levels within acceptable limits. In order to demonstrate the degrees of noise and vibration reductions that can be attained using the two types of isolators in comparison with the non-isolated or hard-mounted spindle, tests were performed using a single oil base type spinning spindle with a full bobbin. The spindle-bobbin mechanism was mounted to a representative rail by the three mounting methods described previously and operated at speeds of 11,000 rpm and 14,000 rpm in a reverberation room. Octave band sound power level measurements and one-tenth octave band sound pressure measurements were made to compare the performance of the mounting methods. These measurements were made using six microphones at different locations and sampling their output signals at a high rate over an extended interval of time. One-tenth octave horizontal and vertical rail acceleration responses were obtained concurrently with the noise responses. These noise and vibration responses are presented and discussed in the paper. The results show that the elastomeric isolators provide significant reductions in rail vibration response levels in the spindle bearing vibration frequency range of 500 to 2000 Hz. The corresponding overall sound power levels for the two operating speeds when using one stage isolators were 8 to 18 dBA below the hard-mounted spindle condition. When using the two-stage isolator, the overall sound power levels for the two operating speeds were 9 and 20 dBA below the hard mounted spindle condition. The results demonstrate the importance of properly designing the mounting to tune the system for low noise responses while minimizing the impact on other operatonal criteria such as spindle static deflection and dynamic motion. A discussion of the isolator design parameter trade-offs is presented along with comments regarding the limitations of the testing and the constraints involved in predicting the noise level reduction to be expected for a whole spinning frame.