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  • 1
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    A 2.5-K GM/J-T cooler for maser low-noise amplifiers (2001)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: This paper describes a 2.5 K cooler intended for microwave Maser low noise amplifier cooling applications.
    Keywords: Engineering (General)
    Type: Cryogenic Engineering Conference; Madison, WI; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    X/Ka Celestial Frame Improvements: Vision to Reality (2010)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: In order to extend the International Celestial Reference Frame from its S/X-band (2.3/8.4 GHz) basis to a complementary frame at X/Ka-band (8.4/32 GHz), we began in mid-2005 an ongoing series of X/Ka observations using NASA s Deep Space Network (DSN) radio telescopes. Over the course of 47 sessions, we have detected 351 extra-galactic radio sources covering the full 24 hours of right ascension and declinations down to -45 degrees. Angular source position accuracy is at the part-per-billion level. We developed an error budget which shows that the main errors arise from limited sensitivity, mismodeling of the troposphere, uncalibrated instrumental effects, and the lack of a southern baseline. Recent work has improved sensitivity by improving pointing calibrations and by increasing the data rate four-fold. Troposphere calibration has been demonstrated at the mm-level. Construction of instrumental phase calibrators and new digital baseband filtering electronics began in recent months. We will discuss the expected effect of these improvements on the X/Ka frame.
    Keywords: Geophysics
    Type: Proceedings of the Sixth General Meeting of the International VLBI Service for Geodesy and Astrometry; 285-289; NASA/CP-2010-215864
    Format: application/pdf
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  • 3
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    The efficiency calibration of the DSS-24 34-meter beam-waveguide antenna (1995)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Microwave performance testing of the new Deep Space Station (DSS)-24 34-m-diameter antenna was carried out during the summer of 1994. Efficiency measurements were made at the 8.45 GHz (X-band) and 32-GHz (ka-band) frequencies both at the antenna Cassegrian (f1) and beam-waveguide (f3) focal points. In addition, the antenna f3 efficiencies were measured on the DSS-24 operational 2.295-GHz (S-band) and 8.45-Ghz feeds. This article presents the efficiency determinations as a function of elevation angle along with a corresponding error analysis of the measurements. Peak measured gains and efficiencies are tabulated for all frequencies.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommunications and Data Acquisition Report; p 174-187
    Format: application/pdf
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  • 4
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    Efficiency calibration of the DSS 13 34-meter diameter beam waveguide antenna at 8.45 and 32 GHz (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Efficiency measurements at 8.45 and 32 GHz (X and Ka bands, respectively) were carried out on the new 34 m diameter beam waveguide antenna now in use at the NASA Goldstone Deep Space Communications Complex. The use of portable test packages enabled measurements at both the Cassegrain and beam waveguide focal points. Radio sources (quasars and Venus) were used as calibrators, and updated determinations of flux and source size correction were made during the period of the measurements. Gain and efficiency determinations as a function of elevation angle are presented, and the effects of the beam waveguide system and antenna structure are clearly seen. At the beam waveguide focus, an 8.45 GHz peak efficiency of 72.38 pct. was measured; at 32 GHz, 44.89 pct. was measured.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommunications and Data Acquisition Report; p 283-297
    Format: text
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  • 5
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    Platinum-Resistor Differential Temperature Sensor (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Platinum resistance elements used in bridge circuit for measuring temperature difference between two flowing liquids. Temperature errors with circuit are less than 0.01 degrees C over range of 100 degrees C.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: NPO-15666 , NASA Tech Briefs (ISSN 0145-319X); 8; 4; P. 464
    Format: text
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  • 6
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    Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station (2001)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.
    Keywords: Optics
    Type: JPL-TMO-PR-42-145
    Format: application/pdf
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  • 7
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    Spring-Loaded Joule-Thomson Valve (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Improved design reduces clogging and maintains constant pressure drop as flow rate varies. Spring-Loaded Joule-Thomson Valve pressure drop regulated by spring pushing stainless-steel ball against soft brass seat. Pressure drop remains nearly constant, regardless of helium flow rate and of any gas contaminants frozen on valve seat. Because springloaded J-T valve maintains constant pressure drop, upstream roomtemperature throttle valve adjusts flow rate precisely for any given upstream pressure. In addition, new valve relatively invulnerable to frozen gas contaminants, which clog fixed-orifice J-T valves.
    Keywords: MECHANICS
    Type: NPO-16546 , NASA Tech Briefs (ISSN 0145-319X); 10; 3; P. 101
    Format: text
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