Engineering topics

Turko, B.

Publications and source records attributed to Turko, B..

3 records

NASA NTRS1980

Space Borne Event Timer

The Space Borne Event Timer is a part of the NASA laser ranging system that is intended to operate aboard the Space Shuttle orbiting over California. The object is to measure, by laser ranging, the earth movement along the San Andreas fault and possibly forecast future earthquakes. A number of cube reflector targets will be placed along both sides of the fault. The ranging system aboard the Space Shuttle will fire a burst of laser pulses at each target and detect the reflected light. Time differences between pulses from the two sides of the fault will indicate earth displacements. The Space Borne Event Timer is a CAMAC compatible system that provides extremely accurate timing data and controls the operation of the ranging system. For each event the time is given in 19.53 increments from the instant of firing the laser to the instant the reflected light is received back, within a range of 130 days.

Turko, B.↗

NASA NTRS1978

A picosecond resolution Time Digitizer for laser ranging

The Time Digitizer capable of covering a range of 0.34 sec in 9.76 psec increments is described. The time interval between a pair of start-stop pulses is digitized coarsely in 20 nsec periods by a very accurate 50 MHz reference clock. The residual fractions of a clock period at the start and the stop end of the measured interval are stretched in two interpolators and digitized in 9.76 psec increments. An equivalent digitizing frequency of 102.4 GHz is thus achieved. The digitizer is built in a minicrate and communicates via a standard crate controller. It is intended for use in the laser ranging between ground stations and the Laser Geodetic Satellite (LAGEOS). It is shown that the distribution in any two adjacent 9.76 psec channels of a small number of identical test time intervals is essentially binomial. The performance of the digitizer and test results are given.

Turko, B.↗

NASA NTRS1977

Optical timing receiver for the NASA laser ranging system. Part 2: High precision time interval digitizer

The development of a high precision time interval digitizer is described. The time digitizer is a 10 psec resolution stop watch covering a range of up to 340 msec. The measured time interval is determined as a separation between leading edges of a pair of pulses applied externally to the start input and the stop input of the digitizer. Employing an interpolation techniques and a 50 MHz high precision master oscillator, the equivalent of a 100 GHz clock frequency standard is achieved. Absolute accuracy and stability of the digitizer are determined by the external 50 MHz master oscillator, which serves as a standard time marker. The start and stop pulses are fast 1 nsec rise time signals, according to the Nuclear Instrument means of tunnel diode discriminators. Firing level of the discriminator define start and stop points between which the time interval is digitized.

Leskovar, B.↗