Peak Phase Deviation Research Articles

In-Service BER Based Estimation of OFDM PAPR and CFO-induced Peak Phase Deviation

High Peak-to-Average Power Ratio (PAPR) of the transmitted OFDM signal is a well-known major drawback of the Orthogonal Frequency-Division Multiplexing (OFDM), so the High-Power Amplifier (HPA) is therefore necessary to operate in its linear region, i.e. with large back-off between the operating input power and its saturation region, so introducing not only in-band distortion, but also the adjacent channel interference. Specifically with the Long-Term Evolution (LTE) systems downlink, some sort of PAPR reduction, such as e.g. clipping, must be utilized. Considering that in many practical situations, determining PAPR demands complex test equipment, such as e.g. Vector Signal Analyzer (VSA), which might not be available, in this paper, we develop a simple Bit-Error-Rate (BER) based model for the (residual) PAPR estimation, by applying link abstraction, i.e. considering the easy measurable BER degradation due to HPA non-linearity, as if it were the consequence of the according level of additive white Gaussian noise (AWGN) abstracting the HPA distortion, while considering high Signal-to-Noise Ratio (SNR) and long enough cyclic prefix (CP), thus neglecting (real) additive noise and time dispersion (i.e. multipath fading). Moreover, the out-of-service BER testing, which requires network operator to interrupt its revenue-generating traffic, can be substituted by in-service BER estimation from in-phase and quadrature-phase eye diagram closures, measured on live traffic, by means of a simple oscilloscope. The analytical model is verified by the appropriate Monte-Carlo simulations.

A Two-Point Modulation Spread-Spectrum Clock Generator With FIR-Embedded Binary Phase Detection and 1-Bit High-Order ΔΣ Modulation

This paper describes a spread-spectrum clock generation method by utilizing a Δ∑ digital PLL (DPLL) which is solely based on binary phase detection and does not require a linear time-to-digital converter (TDC) or other linear digital-to-time converter (DTC) circuitry. A 1-bit high-order Δ∑ modulator and a hybrid finite-impulse response (FIR) filter are employed to mitigate the phase-folding problem caused by the nonlinearity of the bang-bang phase detector (BBPD). The Δ∑ DPLL employs a two-point modulation technique to further enhance linearity at the turning point of a triangular modulation profile. We also show that the two-point modulation is useful for the BBPLL to improve the spread-spectrum performance by suppressing the frequency deviation at the input of the BBPD, thus reducing the peak phase deviation. Based on the proposed architecture, a 3.2 ㎓ spread-spectrum clock generator (SSCG) is implemented in 65 ㎚ CMOS. Experimental results show that the proposed SSCG achieves peak power reductions of 18.5 ㏈ and 11 ㏈ with 10 ㎑ and 100 ㎑ resolution bandwidths respectively, consuming 6.34 ㎽ from a 1 V supply.

Radio Signatures of November 1998 Leonid Meteor on Transionospheric VHF Satellite Signal

This letter presents, to our knowledge for the first time, two cases of scintillations of the 244 MHz satellite beacon signal recorded from the geostationary satellite FLEETSATCOM (FSC) (Long: 73°E) at the Haringhata Field Station (HFS) (Lat: 22.97°N Long: 88.50°E Dip: 32°N) of the University of Calcutta on the night of November 16/17, 1998, which corresponds to the peak period of the Leonid meteor shower in terms of its rate and visual magnitude. Scintillations produced by the sporadic-E layer (E s) generated by meteoric ionization are transient and quasi-periodic in nature. This type of scintillations have much shorter durations (∼30–100 s) than those normally observed at night in the equatorial latitudes (∼5 min to couple of hours). It is characterized by a primary deep fade out in field strength, associated with regular ringing patterns before and after it. Generation of quasi-periodic scintillations is believed to be due to a small-scale (scale size ∼100–1000 m) density enhancement or blob which acts as a radio lens in the path of the transionospheric signal. Assuming one-dimensional density irregularities, the peak phase deviation introduced in the radio wave passing through is estimated. The observed scintillation patterns have been simulated considering a series of isolated ionospheric irregularities of different strengths and scale sizes. Critical frequency of the E s layer (f 0E s) measured by the Ahmedabad ionosonde (Lat: 23.03 0N Long: 72.40 0E Dip: 34°N) for the same night shows two isolated spikes which may be due to a sudden increase in plasma density caused by meteoric ionization. In addition, the meteor visual magnitude and cumulative mean flux have been calculated using the meteor intensity data available on the Internet.

High-speed polarization scrambler with adjustable phase chirp

We report on the operation and performance of a novel electrooptic polarization scrambler that is capable of generating any desired combination of optical phase and polarization modulation. The scrambler comprises a dual-drive Mach-Zehnder-type intensity modulator on lithium niobate and an external microoptic polarization splitter which combines the two complementary outputs of the integrated-optic intensity modulator in orthogonal polarization states. The modulation indexes of the sinusoidal phase and polarization modulation in the output light can be varied independently of each other via the amplitudes and phases of the two drive voltages to the Mach-Zehnder modulator. The scrambler has a 3-dB modulation bandwidth of 14 GHz and operates in the 1.5-1.6-/spl mu/m wavelength range with an overall fiber-to-fiber insertion loss of less than 5 dB. At 5 GHz modulation frequency and electric drive powers between 390-2030 mW, we demonstrate phase-chirped and chirp-free depolarization with a residual degree of polarization of less than 0.02 and continuously variable phase modulation to 2.3-rad peak phase deviation.

An analog MMIC phase modulator for X-band satellite transponder applications

The design and measured performance of a GaAs MMIC (monolithic microwave integrated circuit) analog linear phase modulator for the next-generation space-borne communications systems are presented. The analog phase shifter is based on the reflection-type hybrid coupled approach and uses a novel lumped quadrature hybrid and MESFET varactors as a building block. Three cascaded sections (with tapered varactor sizes) of this building block along with two high-isolation amplifiers have been realized in a single chip (96 mils*36 mils). This MMIC provides an X-band (8415+or-50-MHz) phase modulation with +or-2.6 radians (300 degrees ) of peak phase deviation, +or-2% of phase deviation linearity, 1.5-dB insertion loss, and better than 12-dB input and output return loss performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optical phase and amplitude measurement by single sideband homodyne detection

The amplitude and phase of optical signals are linearly transferred into a low frequency amplitude and phase by phase modulated single sideband homodyne detection with an arbitrary, odd phase modulation of appropriate peak phase deviation. When introducing an additional amplitude modulation or by employing double phase modulation or a single sideband detector, absolute amplitude and phase errors less than 1 percent and 1°, respectively, are achieved for a large range of the peak phase deviation. Test measurements with integrated Mach-Zehnder interferometers on LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> are in excellent agreement with the theoretical results.

Phase modulated axial modes in a passive cavity

The fm laser consists of a laser with a phase modulator in the cavity, driven at a frequency of approximately the axial mode spacing. A passive two-mirror cavity and a passive ring cavity containing such a modulator are analysed using travelling plane waves. The axial modes of the cavities are shown to be phase modulated and their centre frequencies and peak phase deviation are determined in each case.

Measurement of Nonlinear Phase Distortion in Microwave Limiters under Dynamic Conditions

Nonlinear phase distortion (amplitude-modulation to phase-modulation conversion) in microwave limiters can be different under static and dynamic conditions. A technique for measurement of dynamic phase distortion is described in which a two-tone test signal is used to simulate amplitude modulation with modulating frequencies of the order of megahertz. The two-tone test signal is generated by linearly summing two equal-amplitude sine waves. The result is a constant-frequency amplitude-modulated signal whose envelope varies as a rectified cosine wave at the beat frequency of the two sine waves. There is no phase deviation except at the envelope zeros, where the phase jumps 180°. Measurements are made by splitting the output signal from the limiter into two identical signals and delaying one relative to the other by approximately an odd multiple of one-half the envelope period. The two signals, when displayed on an X-Y cathode-ray tube, produce a pair of filled-in ellipses with major axes at 45° and and 135°. Peak phase deviation is obtained by direct measurement of either ellipse. Measurement data in E band are given for two tunnel-diode amplifier-limiters, a balanced mixer-limiter, and a traveling-wave-tube amplifier followed by a balanced mixer-limiter.

Degradation effects of arbitrary phase errors on high-resolution radar performance

It is well known that phase errors introduced during the formation of synthetic antenna apertures and in the data-processing stages of pulse-compression radars degrade system performance. Expressions are presented from which the upper bounds of the degradation effects of small arbitrary phase errors on the azimuth resolution of synthetic apertures and the range resolution of pulse-compression radars can be calculated. It is not necessary to know the exact phase-error function; only the peak phase deviation need be given or estimated. These expressions allow the use of amplitude weighting factors for sidelobe reduction, and the effect of these factors on resolution degradation in the presence of phase errors is exhibited.

Effect of arbitrary phase errors on the gain and beamwidth characteristics of radiation pattern

Simple expressions have been obtained for predicting the maximum loss in antenna gain when the peak value of the aperture phase deviation is known. It is not necessary to know the exact amplitude or phase distribution function as long as the phase errors are relatively small; and the same expressions may be used for both rectangular and circular aperture cases. Relations have also been established such that the maximum change in the main-lobe beamwidth can be predicted from the knowledge of the amplitude distribution function and the peak phase deviation.