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Berman, A. L.

Publications and source records attributed to Berman, A. L..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Radio science requirements and the end-to-end ranging system

Radio science ranging requirements negotiated between past and present flight projects and the DSN have generally focused on just the DSS and spacecraft hardware. All elements in the end-to-end system are analyzed and considered in terms of the error hierarchy. The end-to-end system is defined and examined as it applies to the generation of radio science ranging requirements. The variability of the performance levels of the system elements is emphasized with respect to the radio science experiment being performed and the DSN-spacecraft frequency band configuration.

Berman, A. L.↗
NASA NTRS1978

Parametric modeling of low-frequency water-vapor-induced tropospheric path length fluctuations

Detailed wet tropospheric fluctuation information is presented in support of proposals to search for gravitational waves in ultra-precise Doppler data. The similarities between the solar wind and tropospheric effects on apparent signal path length are used to hypothesize a parametric model for low-frequency wet tropospheric path length fluctuation. Experimental observations of wet tropospheric signal delay fluctuations are interpreted as confirmation of this parametric form. The model is used to suggest the appropriate conditions for collection of experimental tropospheric fluctuation data.

Berman, A. L.↗
NASA NTRS1978

The gravitational wave detection experiment: Description and anticipated requirements

The experiment to detect gravitational waves in ultraprecise two-way Doppler data is described, as are the anticipated requirements for the Deep Space Network, the spacecraft, and the data processing system. The special feature which allows the usage of ultraprecise Doppler data for the possible detection of gravitational waves is a unique three-pulse signature which is a function of the spacecraft, earth, and gravitational wave propagation direction geometry. The pulses (fractional frequency shifts) result from effects which are conveniently described as follows: Clock speed-up (earth only effect) and buffeting (equal earth and spacecraft effect).

Berman, A. L.↗
NASA NTRS1978

Deep space telecommunications and the solar cycle: A reappraisal

Observations of density enhancement in the near corona at solar cycle (sunspot) maximum have rather uncritically been interpreted to apply equally well to the extended corona, thus generating concern about the quality of outer planet navigational data at solar cycle maximum. Spacecraft have been deployed almost continuously during the recently completed solar cycle 20, providing two powerful new coronal investigatory data sources: (1) in-situ spacecraft plasma measurements at approximately 1 AU, and (2) plasma effects on monochromatic spacecraft signals at all signal closest approach points. A comprehensive review of these (solar cycle 20) data lead to the somewhat surprising conclusions that for the region of interest of navigational data, the highest levels of charged particle corruption of navigational data can be expected to occur at solar cycle minimum, rather than solar cycle maximum, as previously believed.

Berman, A. L.↗
NASA NTRS1978

Ground tracking system phase fluctuation spectra

Spectral analysis of solar wind plasma fluctuation requires knowledge of the average ground tracking system phase fluctuation spectrum. Typical ground tracking system phase fluctuation spectra are presented as deduced from two-way S-band Doppler noise measured at large Sun-Earth-Probe angles.

Berman, A. L.↗
NASA NTRS1978

System performance testing of the DSN radio science system, Mark 3-78

System performance tests are required to evaluate system performance following initial system implementation and subsequent modification, and to validate system performance prior to actual operational usage. Non-real-time end-to-end Radio Science system performance tests are described that are based on the comparison of open-loop radio science data to equivalent closed-loop radio metric data, as well as an abbreviated Radio Science real-time system performance test that validates critical Radio Science System elements at the Deep Space Station prior to actual operational usage.

Berman, A. L.↗
NASA NTRS1977

Planetary atmosphere modeling and predictions

The capability to generate spacecraft frequency predictions which include the refractive bending effects induced during signal passage through a planetary atmosphere is a pivotal element of the DSN Radio Science System. This article describes the current implementation effort to develop planetary atmosphere modeling and prediction capability.

Berman, A. L.↗
NASA NTRS1977

An empirical model for the solar wind velocity

An analytic expression for the average radial component of the Solar Wind velocity between 1 solar radius and 1 AU is developed. The model is constructed by assuming the conservation of particle flow in the Solar Wind and application of a twelve-year average measured value of the Solar Wind radial velocity at 1 AU.

Berman, A. L.↗
NASA NTRS1977

RMS electron density fluctuation at 1 AU

Analytic expressions at 1 AU for the average RMS Electron Density Fluctuation and the ratio of RMS Electron Density Fluctuation to Electron Density, both as functions of the observational time scale, are constructed from average spacecraft in situ density measurements at approximately 1 AU and columnar phase fluctuation measurements over a wide variety of signal closet approach points. Additionally, the (one-dimensional) Electron Density Fluctuation spectrum and the Doppler phase fluctuation scale are derived, and various extrapolations to the region interior to 1 AU are made.

Berman, A. L.↗
NASA NTRS1977

Phase fluctuation spectra: New radio science information to become available in the DSN tracking system Mark III-77

An algorithm was developed for the continuous and automatic computation of Doppler noise concurrently at four sample rate intervals, evenly spanning three orders of magnitude. Average temporal Doppler phase fluctuation spectra will be routinely available in the DSN tracking system Mark III-77 and require little additional processing. The basic (noise) data will be extracted from the archival tracking data file (ATDF) of the tracking data management system.

Berman, A. L.↗
NASA NTRS1977

DSN radio science system Mark III-78 real-time display capability

The current plane to provide radio science real-time display capability in response to multimission radio science requirements is described. Topics discussed include the display of Doppler frequency and high-resolution graphical display of all closed-loop radio metric parameters, and spectrum displays of open-loop receiver output.

Berman, A. L.↗
NASA NTRS1977

Viking S-band Doppler RMS phase fluctuations used to calibrate the mean 1976 equatorial corona

Viking S-band Doppler RMS phase fluctuations (noise) and comparisons of Viking Doppler noise to Viking differenced S-X range measurements are used to construct a mean equatorial electron density model for 1976. Using Pioneer Doppler noise results (at high heliographic latitudes, also from 1976), an equivalent nonequatorial electron density model is approximated.

Berman, A. L.↗
NASA NTRS1977

Proportionality between Doppler noise and integrated signal path electron density validated by differenced S-X range

Observations of Viking differenced S-band/X-band (S-X) range are shown to correlate strongly with Viking Doppler noise. A ratio of proportionality between downlink S-band plasma-induced range error and two-way Doppler noise is calculated. A new parameter (similar to the parameter epsilon which defines the ratio of local electron density fluctuations to mean electron density) is defined as a function of observed data sample interval (Tau) where the time-scale of the observations is 15 Tau. This parameter is interpreted to yield the ratio of net observed phase (or electron density) fluctuations to integrated electron density (in RMS meters/meter). Using this parameter and the thin phase-changing screen approximation, a value for the scale size L is calculated. To be consistent with Doppler noise observations, it is seen necessary for L to be proportional to closest approach distance a, and a strong function of the observed data sample interval, and hence the time-scale of the observations.

Berman, A. L.↗
NASA NTRS1977

Modification of the DSN radio frequency angular tropospheric refraction model

The previously derived DSN Radio Frequency Angular Tropospheric Refraction Model contained an assumption which was subsequently seen to be at a variance with the theoretical basis of angular refraction. The modification necessary to correct the model is minor in that the value of a constant is changed.

Berman, A. L.↗
NASA NTRS1977

A comprehensive two-way Doppler noise model for near-real-time validation of Doppler data

Doppler noise generated within the tracking system is modeled as a function of the dominant variable-Doppler sample interval. Additionally, the relationship between media noise and Doppler samples interval is empirically determined, and the ratio of media noise for S- and X-band downlinks is solved for. These functional relationships are incorporated into the previous media noise modeling to obtain a comprehensive two-way Doppler noise model.

Berman, A. L.↗