Engineering PapersSearch

Engineering topics

Graf, E.

Publications and source records attributed to Graf, E..

New features of different frequency generating systems due to the use of electrodeless rigidly mounted VBA quartz crystal resonator

The BVA 5 MHz crystal equipped frequency sources exhibit a new blend of performances such as 10 to 11 daily stability, 5x10-13 short term stability (1 to 30 s time intervals) and close to the carrier low phase noise (1 Hz : -120 dBc, 10 Hz : -140 dBc), whereby retaining the customary crystal oscillator benefits of small volume, high reliability and low price, as opposed to more sophisticated frequency generators which would be required to achieve comparable performances. Examples illustrating the impact of the Oscilloquartz BVA oven-controlled crystal oscillator in different frequency generating systems are presented: cesium frequency standards; hydrogen frequency standard; a precision distribution sub-system for satellite ground stations; and high hierarchy exchanges of digital networks, synchronized by the master-slave method are discussed.

Jendly, A.

Prospects for augmenting Spacelab capability

Extensions and improvements projected for the baseline Spacelab system are with emphasis on near-term improvements currently being investigated by the ESA. This ESA Phase B study is primarily concerned with resources augmentation and mission duration extensions. Attention is also given to such long-term Spacelab applications as its use as an element of a larger space platform structure, constituting a permanently manned facility for the 1987/1990 period. Near-term improvements include the incorporation of radiator panels that cover the upper surface of the Spacelab module or extend outward from its pallets, pallet size variations for greater payload accommodation flexibility, and the accommodation of crews in the Spacelab interior.

Wienss, W.