M-ary CPSK Detection with Noisy Reference and Interferences

A general expression of the error probability on an M-ary coherent phase-shift-keyed (MCPSK) signal purturbed by a noisy reference carrier, multiple interferences, and additive Gaussian noise is presented taking into account the frequencey divider in the carrier recovery circuit. First, a new expression for the probability density function (pdf) of the phase of a composite wave of signal, multiple interferences, and additive Gaussian noise is derived. Then this result and a pdf of the phase error modified from the Tikhonov distribution are used to obtain the erro probability of an MCPSK detector. In addition, the comparison between the error probabilities with and without the frequency divider is given, and it is found that the estimation is more pessimistic when the frequency divider is included.     

The waves observed in the ARAKS-East experiment

Experimental results of the Wave measurements over frequency range 0.1–5.0 MHz during the second launch of the ARAKS Experiment (15.02.75) are reported. The differences between the results of the first and the second launches are discussed.     

Development of 1000-mHz Distance Measuring Equipment

The major radio aids to air navigation are listed. Underlined are those whose signal format is standardized by the International Civil Aviation Organization (ICAO) and they have now all been the subject of the IEEE Aerospace and Electronic Systems Society Pioneer Award, as follows: airborne direction finder/nondirectional beacon (ADF/NDB), Busignies and Moseley, 1959; VHF omnidirectional range (VOR), Stuart, 1962; instrument landing system (ILS), Kramar 1964, Alford 1965; air traffic control radar beacon system (ATCRBS), Williams, Bowden, and Harris, 1973; distance measuring equipment (DME), Dodington, 1980. A brief history of the development of the distance measuring equipment, which also formed the basis for an IEEE National Aerospace Electronics Conference luncheon address, is given.     

Missile Electronic System Hardness Assurance Program

A hardness assurance program suitable for a retaliatory or deterrent missile system is discussed. The program consists of three phases: the establishment of suitable controls and screens to ensure piece part hardness, a supplier data monitoring program to measure hardness related parameters in a timely fashion to obtain advanced warning of potential problems, and a hardness assurance verification testing (HAVT) program to periodically measure the radiation response of parts, circuits, subsystems, and systems on a sample basis to ensure proper functioning in simulated radiation environments. All of the data relevant to hardness assurance is stored in computer memory and routinely interrogated with programs which compare current results with the engineering baseline data and other data from preceding lots. Other computer programs enable statistical estimation of system response to the radiation environment with confidence based on the expanding data base provided by the HAVT program.     

EXOSAT observations of the BL Lac object Mkn 421

The BL Lac object Mkn 421 was observed by EXOSAT four times over a period of six days in February 1984. Significant X-ray variability was apparent on a timescale of less than a day, but with no accompanying spectral change. The source exhibited a very soft power law X-ray spectrum with an extremely low intrinsic column density (N_H10²⁰ cm^–2). There was no evidence for an additional hard component attributable to synchrotron self-Compton emission. The observations when combined with other published data imply that significant changes occur in the form of the broad-band UV/X-ray continuum of this source.     

Performance Analysis of the Modulation Cancellation Altimeter

The performance of the modulation cancellation altimeter is investigated. Several sources of error are considered, specifically: 1) terrain averaging error; 2) output noise fluctuations; 3) errors due to phase shifts; and 4) acquisition ambiguities. The predominant parameters affecting these errors are investigated with a view towards optimizing the performance of the altimeter.     

Identification and characteristics of source flares emitting 3-He or Fe enriched cosmic rays in the period September to December 1977

During the observation of solar cosmic rays on the Prognoz 6 and Helios 1 and 2 spacecrafts, several events with anomalous composition of accelerated particles (higher abundance of 3-He or Fe nuclei) occurred. We found seven such events from the period September to December 1977 for which data from the Prognoz 6 solar X-ray photometer are available. This material together with published optical and radio data from terrestrial observatories enabled us to identify more reliably the source flares and describe their characteristics. It turned out that the character of X-ray emission accompanying the emission of accelerated particles with anomalous composition shows no pronounced difference from other flares. No correlation has been found among the ratio 3-He/4-He and the angular distance between the field lines connected with the source flare and the place of observation. If a solar flare with anomalous ratio 3-He/4-He appears in a given active region, this region will probably produce other anomalous events.     

Scientific results from the pioneer Saturn infrared radiometer

The Pioneer 11 Infrared Radiometer instrument made observations of Saturn and its rings in broadband channels centered at 20 and 45 μm and obtained whole-disk information on Titan. A planetary average effective temperature of 96.5±2.5 K implies a total emission 2.8 times the absorbed sunlight. Correlation with radio science results implies that the molar fraction of H₂ is 90±3% (assuming the rest is He). Temperatures at the 1 bar level are 137 to 140 K; regions appearing cooler may be overlain by a cloud acting as a 124 K blackbody surface. A minimum temperature averaging 87 K is reached near 0.06 bars. Ring boundaries and optical depths are consistent with those at optical wavelengths. Ring temperatures are 64–86 K on the south (illuminated) side, ～54 K on the north (unilluminated) side, and at least 67 K in Saturn's shadow. There is evidence for a south to north drop in ring temperatures. Titan's 45 μm brightness temperature is 75±5 K.