Intermodulation distortion in high dynamic range microwave fiber-optic links with linearized modulators

Linearization of integrated optic intensity modulators significantly reduces the two-tone intermodulation distortion. The resulting intermodulation distortion produced by these modulators then varies as the input power to the fifth-order link system, the overall intermodulation product is a combination of third-order and higher-order terms. The authors determine the dynamic range of a cascaded microwave network consisting of a preamplifier, a high-dynamic-range fiber-optic link with a highly linear modulator, and a postamplifier. An expression is found that relates the intermodulation power at the output to the relative suppression from the signal level. As an example, a hypothetical 10-GHz low-distortion fiber-optic link that has a dynamic range of 125 dB in a bandwidth of 1 Hz is cascaded with various preamplifiers, and it is shown that the dynamic range of the system is reduced by as much as 20 dB, depending on the third-order intercept of the amplifier

Comparison of Analog R-F Photonic Links Using a Variety of Linearized Electro-Optic Modulators

The potential applications of high dynamic range analog r-f photonic links include antenna remoting, photonic-coupled phased-array antennas, and cable-television transmission. This paper compares the results obtained with a number of different modulator types and link configurations and gives recent experimental results. Further details on the analysis and results for some of the schemes can be found in a review paper that will appear later this year

Distortion in linearized electrooptic modulators

Intermodulation and harmonic distortion are calculated for a simple fiber-optic link with a representative set of link parameters and a variety of electrooptic modulators: simple Mach-Zehnder, linearized dual and triple Mach-Zehnder, simple directional coupler (two operating points), and linearized directional coupler with one and two dc electrodes. The resulting dynamic ranges, gains, and noise figures are compared for these modulators. A new definition of dynamic range is proposed to accommodate the more complicated variation of intermodulation with input power exhibited by linearized modulators. The effects of noise bandwidth, preamplifier distortion, and errors in modulator operating conditions are described

Bayesian Nonparametric Shrinkage Applied to Cepheid Star Oscillations

Bayesian nonparametric regression with dependent wavelets has dual shrinkage properties: there is shrinkage through a dependent prior put on functional differences, and shrinkage through the setting of most of the wavelet coefficients to zero through Bayesian variable selection methods. The methodology can deal with unequally spaced data and is efficient because of the existence of fast moves in model space for the MCMC computation. The methodology is illustrated on the problem of modeling the oscillations of Cepheid variable stars; these are a class of pulsating variable stars with the useful property that their periods of variability are strongly correlated with their absolute luminosity. Once this relationship has been calibrated, knowledge of the period gives knowledge of the luminosity. This makes these stars useful as "standard candles" for estimating distances in the universe.Comment: Published in at http://dx.doi.org/10.1214/11-STS384 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

The Real Exchange Rate and Employment in U.S. Manufacturing: State and Regional Results

In a series of earlier papers we have examined the impact of exchange rate movements on employment and output in the manufacturing sector, disaggregated by industry sector and by production and non-production workers. In this paper we examine the impact of exchange rate movements on manufacturing employment, disaggregated geographically, using census divisions, regions, states and SMSA's as the unit of analysis. Empirical estimates of employment changes are first presented for the four census regions, the nine census divisions, and the fifty states plus the District of Columbia. For the country as a whole, we estimate that movements in the real exchange rate led to the loss of about 1 million manufacturing jobs over this period. We go on to examine in greater detail manufacturing employment in New York State, and report that exchange rate movements had a much larger impact in the areas outside of New York City than in the metropolitan area. This result is consistent with earlier work that found that employment in management or research is not as sensitive to exchange rate movements as employment in production processes. The New York results are followed by an examination of manufacturing employment in five southern states with large rural populations. Some policy makers have expressed a concern that manufacturing employment in rural areas suffered more than in urban areas during the period of the dollar appreciation. We find that within these five states, the impact of the exchange rate on manufacturing employment in the non-SMSA areas was the same or less than was the case for employment within SMSA areas. Finally, we use a multivariate model to explore why manufacturing employment is more sensitive to exchange rate movements in some states than in others. Factors which are associated with greater sensitivity of manufacturing employment to exchange rate movements are: the percent of the population living outside of SMSA areas, the level of production worker wages, and crude oil production. Factors that are associated with less sensitivity of manufacturing employment to exchange rate movements include the percent of the population with 4 years or more of college or per-capita expenditures on public secondary schools.

Commodity Prices as a Leading Indicator of Inflation

This paper studies the value of broad commodity price indexes as predictors of consumer price inflation in the G-7 industrial countries. After an introduction, the paper discusses the theoretical relationship between commodity and consumer prices and the conditions under which, in general, one would expect commodity prices to be a leading indicator of inflation. It then presents tests of the relationships between conventional broad indexes of commodity prices and consumer prices, and uses the data on individual commodities to generate the optimum weights in a commodity price index for forecasting G-7 inflation. We find that commodity and consumer prices are not co-integrated; the hypothesis that there is a reliable long-run relationship between the level of commodity prices and the level of consumer prices may be rejected. There is a tendency for changes in commodity prices to lead those in consumer prices, at least when the data are denominated in a broad index of major-country currencies. However, although the inclusion of commodity prices significantly improves the in-sample fit of regressions of an aggregate (multi-country) consumer price index, the results may not be sufficiently stable to improve post-sample forecasts. Estimated alternative commodity price indexes, in which the weights are chosen so as to minimize the residual variance in aggregate inflation regressions, track the behavior of the aggregate CPI reasonably well in-sample. However, the estimated indexes work only moderately well in post-sample predictions, and they do not appear to offer significant advantages over the conventional export weighted index. Perhaps the most important result is that turning points in commodity-price inflation frequently precede turning points in consumer-price inflation for the large industrial countries as a group.

The Real Exchange Rate, Employment, and Output in Manufacturing in the U.S. and Japan

In the spring of 1981 the U.S. dollar began a four-year period of real appreciation that took it to a peak of more than 50 percent by first quarter 1985. Since then, the dollar has depreciated substantially, but remains above its 1980 level. During the same period, the Japanese yen first depreciated by 12 percent in real terms from 1981 to 1982, and then appreciated by some 30 percent to 1986. These swings in real exchange rates effects on the relative competitiveness of U.S. and Japanese industry, and have effects on employment and output in sectors producing tradeable goods. This paper presents estimates of these effects. Using time series data for the period 1970 to 1986, we use a simple model of supply and demand to estimate the impact of swings in the effective real exchange rate of the dollar and the yen on manufacturing employment and output in the U.S. and Japan, disaggregated by industry sectors, and by production and non-production workers in the case of the U.S. employment. These results are part of a larger research project to estimate the effects of the movements in the real exchange rate on world manufacturing industries. We find significant and substantial effects of the dollar appreciation on employment and output in U.S. manufacturing. In particular, we find that exchange rate movements have had important effects on the durable goods sectors, including primary metals, fabricated metal products, and non-electrical machinery. Other sectors that suffer large employment and output losses when the dollar appreciates are stone, clay and glass products, transportation, instruments, and chemicals. Estimates are also presented for non-production and production workers in the U.S. employment of the latter is more sensitive to the real exchange rate, especially in the durable goods sectors. This suggests the possibility of hysteresis in trade. For Japan, we find significant effects of movements in the yen on employment and output in the durable goods sectors, especially those producing machinery. In particular, yen appreciation causes substantial losses in employment and output in fabricated metal products, general machinery, and electrical machinery. The results for Japan are not as clear as for the U.S., perhaps because we have only annual data for Japan, but quarterly data for the U.S.. Nevertheless, the importance of movements in the real exchange rate for employment and output in manufacturing is evident in both cases.

Basements

Discusses recommendataions for basement design, construction, and maintenance