Tone Power Research Articles

A 610-mW zero-overhead class-G full-rate ADSL-CO line driver

With the drive to increase the number of ports that can be incorporated onto a single linecard in an ADSL Central Office (CO), and the consequent power consumption and thermal management issues that this increased density raises, power dissipation is a key parameter in the design of an ADSL modem. This paper presents a full-rate ADSL CO line driver, consuming 610 mW through active termination and a zero-overhead class-G technique. The supply switching scheme used features very low overhead voltage, logic control, and controlled supply rail ramp rate, and requires analog signal peak prediction be done on the digital data stream. The process used features dielectrically isolated silicon-on-insulator 0.7-μm complementary BiCMOS with thin-film resistors. The MOSFET class-G transistors operate in two modes for power efficiency and distortion control. The power consumption is 610 mW and the downstream missing tone power ratio is 69 dBC with 16-dB peak-to-average ratio support.

Highly efficient xDSL line drivers in 0.35-μm CMOS using a self-oscillating power amplifier

The design of two highly efficient line drivers in a digital 0.35-μm, 3.3-V technology are presented. The self-oscillating power amplifier (SOPA) architecture has been developed in order to obtain a high efficiency for systems with a high crest factor like discrete multitone modulated xDSL modems. The SOPA architecture is an unclocked switching-type line driver. By using self-oscillation and noise-shaping, a high signal linearity can be obtained for low over-switching ratios. By coupling two SOPA line drivers with a signal transformer, the two limit cycle oscillations are pulled toward synchronization. This gives an important mean switching frequency suppression toward the line. The need for an extra filter dealing with the mean switching frequency is in that way heavily relaxed. A zeroth-order SOPA and a third-order SOPA are prototyped. The zeroth-order line driver meets ADSL-Lite specifications with a missing tone power ratio (MTPR) of 41 dB for an 800-kHz bandwidth. The maximum efficiency is 41%. The third-order version meets ADSL and VDSL specifications with an MTPR of 56 dB and an 8.6-MHz bandwidth. An efficiency of 47% was measured for an ADSL signal with a crest factor >5.

Quantifying memory effects in RF power amplifiers

This paper proposes a system-level behavioral model for RF power amplifiers (PAs), which exhibit memory effects, that is based on the parallel Wiener system. The model extraction is performed using two-tone intermodulation distortion (IMD) measurements with different tone frequency spacings and power levels. It is found that by using such a model, more accurate adjacent-channel power-ratio levels may be predicted for high PAS close to the carrier frequency. This is validated using IS-95B CDMA signals on a low-power (0.5 W) class-AB PA, and on a high-power (45 W) class-B PA. The model also provides a means to quantify memory effects in terms of a figure-of-merit that calculates the relative contribution to the IMD of the memoryless and memory portion of the PA nonlinearity. This figure-of-merit is useful in providing an estimate of the amount of correction that a memoryless predistortion system may have on PAS that exhibit memory effects.

Low-Speed Fan Noise Reduction with Trailing EDGE Blowing

An experimental proof-of-concept test was conducted to demonstrate rotor-stator interaction tone noise reduction through rotor trailing edge blowing. The velocity deficit from the viscous wake of the rotor blades was reduced by injecting air into the wake from a trailing edge slot. Composite hollow rotor blades with internal flow passages were designed based on Computational Fluid Dynamics codes modeling the internal flow. The hollow blade with interior guide vanes creates flow channels through which externally supplied air flows from the root of the blade to the trailing edge. The impact of the rotor wake-stator interaction on the acoustics was also predicted analytically. The Active Noise Control Fan, located at the NASA Glenn Research Center, was used as the proof-of-concept test bed. In-duct mode and farfield directivity acoustic data were acquired at blowing rates (defined as mass flow supplied to trailing edge blowing system divided by fan mass flow) ranging from 0.5% to 2.0%. The first three blade passing frequency harmonics at fan rotational speeds of 1700 to 1900 rpm were analyzed. The acoustic tone mode power levels (PWL) in the inlet and exhaust were reduced 11.5&–0.1, 7.2&11.4, 11.8&19.1 PWL dB, respectively. The farfield tone power levels at the first three harmonics were reduced 5.4, 10.6, & 12.4 dB PWL. At selected conditions, two-component hotwire and stator vane unsteady surface pressures were acquired. These measurements show the modification of the rotor wake due to trailing edge blowing and its effect on the stator vane to illustrate the physics behind the noise reduction.

Reliability of measurements of muscle tone and muscle power in stroke patients.

to establish the reliability of the modified Ashworth scale for measuring muscle tone in a range of muscle groups (elbow, wrist, knee and ankle; flexors and extensors) and of the Medical Research Council scale for measuring muscle power in the same muscle groups and their direct antagonists. a cross-sectional study involving repeated measures by two raters. We estimated reliability using the kappa statistic with quadratic weights (Kw). an acute stroke ward, a stroke rehabilitation unit and a continuing care facility. people admitted to hospital with an acute stroke-35 patients, median age 73 (interquartile range 65-80), 20 men and 15 women. inter- and intra-rater agreement for the measurement of power was good to very good for all tested muscle groups (Kw = 0.84-0.96, Kw = 0.70-0.96). Inter- and intra-rater agreement for the measurement of tone in the elbow, wrist and knee flexors was good to very good (Kw = 0.73-0.96, Kw = 0.77-0.94). Inter- and intra-rater agreement for the measurement of tone in the ankle plantarflexors was moderate to good (Kw = 0.45-0.51, Kw = 0.59-0.64). the Medical Research Council scale was reliable in the tested muscle groups. The modified Ashworth scale demonstrated reliability in all tested muscle groups except the ankle plantarflexors. If reliable measurement of tone at the ankle is required for a specific purpose (e.g. to measure the effect of therapeutic intervention), further work will be necessary.

An exact performance analysis of the clipped diversity combining receiver for FH/MFSK systems against a band multitone jammer

This paper applies the clipper receiver with diversity combining techniques to the frequency hopping (FH) M-ary frequency shift keying (MFSK) systems against a destructive band multitone jammer, and presents an exact error probability performance evaluation with further discussions. A noise free channel is first assumed for analysis, and this assumption is then verified by computer simulation. Both optimal jamming tone power from the jammer's view and the choice of the clipping level from the communicator's view are investigated. The worst case performance of the FH/MFSK system against an optimum jammer is discussed in detail with extensive numerical results. It is also found that the clipper receiver provides the most attractive performance as compared to several other diversity combining receivers previously proposed. >

Scheme for phase-locking a local oscillator in submillimetre-wave receiver

A technique for phase-locking a low-power fundamental local oscillator in a superconductor-insulator-superconductor (SIS) junction submillimetre-wave receiver is described. The arrangement uses the low-noise SIS mixer itself to downconvert the local oscillator signal from a Josephson junction or quantum well oscillator. A high-frequency phase-locked reference tone is required but for a typical SIS receiver the tone power is less than 10 nW. Even at terahertz frequencies this could easily be generated using a simple multiplier. >

Clock-aided carrier recovery in trellis-coded PSK

The effects of imperfect carrier phase recovery on uncoded and trellis-encoded PSK (phase-shift keying) are compared. A recently proposed clock-aided carrier recovery scheme is analyzed and compared to the standard frequency multiplication circuit. Results obtained through a combination of analysis and computer simulation compare uncoded 4-PSK with trellis-encoded 8-PSK carrying two bits per channel symbol. The quality of the recovered carrier phase is evaluated using the ratio of tone power to background. The system error probability is evaluated and used to determine how accurate the time clock recovery must be in a clock-aided carrier recovery circuit in order to outperform classical recovery systems. It is shown that if the clock recovery system is accurate enough, clock-aided carrier recovery used with coded 8-PSK can compensate for the increased sensitivity of the latter to phase errors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Radio Channel Characterization by Three Tones

Three radio pilot tones, available on in-service AR6A single sideband radios, have been used to characterize the dispersive nature of radio fading. The paper presents new results on how three tones can be used to determine the delay and amplitude of the second ray and the notch frequency in a two-ray fading model. The model chosen is justified on physical and practical grounds. Measurements on radio hops yield histograms of second ray delay and amplitude. It is found that most of the fading events can be described by the two-ray model. The measurements are compared to distributions, assumed or measured, given in the literature. The experimental technique used lends itself easily to the measurement of other propagation characteristics like the cumulative statistics of single and average tone power and the in-band power difference.

Error Performance of Binary NCFSK in the Presence of Multiple Tone Interference and System Noise

This paper presents a general solution to the problem of calculating the error performance of binary NCFSK systems in the presence of multiple tone interference and system noise. The development uses the concepts of circularly symmetric signals and expresses the results in terms of a Bessel integral. This integral is then evaluated using a rapidly converging Fourier-Bessel series. The error in this approximation to the integral is controlled by two parameters which may be adjusted so that the desired accuracy is attained. It is determined that, in the useful probability-of-error range and when the total tone power is constrained, the error rate increases for an increase in the number of interfering tones. In addition, for equal amplitude tones, the performance is independent of the distribution of the tones within the channel. The technique used is also applicable to other detection problems where the threshold is a random variable.

補聴器装用時域値をもとにした補聴器のフィッティング法（ＤＲＦ‐ＳＳＭ法）の開発

“DRF-SSM fitting” is a program of a “hearing aided threshold” to speech range.In subject with normal hearing high tone is emphasized by resonance in the external ear canal, and speech discrimination in advantageous in almost any listening environment. Therefore. this program is to match the “hearing aided threshold” to speech range like that in subject with normal hearing, and to limit a maximum out-put under the UCL. As the result hearing aid's out-put is suitably fitted to the user's dynamic range of hearing. In addition, these procedures have an “insertion gain” and an “ear -mold's influence” and the others. Therefore, this fitting provides clear and comfortable hearing.Actually, only three regulations (gain, tone, and maximum power out put) were given to hearing aided users for several times, and the fitting time was very short.From experience over 200 examples this program was proved as effective to almost all types of hearing loss.

Computational experiments on the effects of inlet turbulence and inflow distortion on fan noise

Existing solutions to the problem of sound production by an axial-flow fan interacting with inlet turbulence and inflow distortion (Marvin E. Goldstein et al., NASA TN D-7676, May 1974 and NASA TN D-7667, June 1974) were evaluated over a range of inflow parameters. Sound power in the fan fundamental and second harmonic tones was computed and the modal power distributions contributing to the total tone power were identified. Comparisons and contrasts between the relations of input parameters to sound power produced were made for the two forms of inflow disturbance. It was found that the bulk of the modal power was carried by modes near cutoff for both forms of inflow disturbance when described by parameter values typical of those expected in practical fan test situations. The implications of the numerical results for the design of passive inlet flow control devices proposed to simulate flight conditions during static fan tests are discussed.

Fan Stage Redesigned to Decrease Stator Lift Fluctuation Noise

An existing fan stage, redesigned to reduce stator lift fluctuations, was tested acoustically for reduced noise generation. The lift fluctuations on the stator were reduced by increasing the stator chord, adjusting incidence angles, and by adjusting the rotor velocity diagrams. The experiments showed significantly reduced broadband noise levels in the middle to high frequencies. Blade passage tone power was not reduced, but decreases in the harmonics were observed. Aerodynamic improvements in both performance and efficiency were obtained.

Physical Examination and Clinical Investigation of the Handicapped Child

In the examination of the handicapped child, as in any physical examination, the primary goals are the elucidation of possible causes for the disorder and a search for signs and symptoms that will differentiate a static from a progressive lesion. In this review, considerable attention is given to examination of the cranium and cranial nerves, and evaluation of movement disorders and abnormalities of tone and muscle power.

Experimental studies of discrete tone noise from an axial flow fan

Some measurements of discrete tone radiation from an axial flow fan are presented here in the form of tone directivity. These are explained from the established theory relating them. The effect of cut-off is explained. The measured discrete tone power at blade passing frequency and harmonics are presented. These are compared with the radiation efficiency of corresponding modes.

NERVE ANASTOMOSIS IN THE TREATMENT OF FACIAL PARALYSIS

Results obtained in the treatment of facial paralysis and clonic facial spasm by means of the operation of hypoglossal-facial anastomosis are described. Recovery of tone and voluntary power was satisfactory in eighteen patients, unsatisfactory in one. One patient has not been reviewed. Recovery was very satisfactory in two cases in which there was a delay of nine and a half months between the date of onset of facial paralysis and that of the reparative operation, and also in one other in which the delay was twenty-six months. These observations would seem to demonstrate that degeneration of muscle fibres and end plates is not of such importance as is generally believed.

NERVE ANASTOMOSIS IN THE TREATMENT OF FACIAL PARALYSIS

Summary Results obtained in the treatment of facial paralysis and clonic facial spasm by means of the operation of hypoglossal-facial anastomosis are described. Recovery of tone and voluntary power was satisfactory in eighteen patients, unsatisfactory in one. One patient has not been reviewed. Recovery was very satisfactory in two cases in which there was a delay of nine and a half months between the date of onset of facial paralysis and that of the reparative operation, and also in one other in which the delay was twenty-six months. These observations would seem to demonstrate that degeneration of muscle fibres and end plates is not of such importance as is generally believed.