International Telemetering Conference Proceedings, Volume 03 (1967)
http://hdl.handle.net/10150/578454
2024-03-28T20:27:25ZInternational Telemetering Conference Proceedings, Volume 03 (1967)
http://hdl.handle.net/10150/666501
International Telemetering Conference Proceedings, Volume 03 (1967)
International Telemetering Conference Proceedings / October 02-04, 1967 / Marriott Motor Hotel, Washington, D.C.
1967-10-01T00:00:00ZA New Concept in Low Flutter High Environmental Recorders
http://hdl.handle.net/10150/606429
A New Concept in Low Flutter High Environmental Recorders
Hadady, R. E.; Bentley, R.
To improve the performance of tape recorders operating under severe vibration, acceleration, and shock environments, two new flutter reduction design concepts have been developed: 1. Capstan servoing during the recording process to servo out flutter before it is recorded. 2. A new reel drive system in which the reels are coupled together to minimize tape tension variations and eliminate the possibility of throwing a tape loop. Test data on a prototype spaceborne recorder has proven the validity of the concept. The prototype has shown a capability to reduce flutter by factors ranging from 3 to 10 over conventional high-environrnent recorders. Typical flutter performance figures on the prototype (which accommodates 600 feet of 0.25" wide tape and operates at 30 ips) are: 0.36% p/p to 5000 Hz - on the bench 1.8% p/p to 5000 Hz - under environment (20 g rms random vibration) Time displacement errors (TDE) are ± 3 microseconds - on the bench ± 6 microseconds - under environment (20 g rms random vibration)
International Telemetering Conference Proceedings / October 02-04, 1967 / Marriott Motor Hotel, Washington, D.C.
1967-10-01T00:00:00ZDelta-T Curves for Measuring Magnetic Tape Link Jitter
http://hdl.handle.net/10150/606410
Delta-T Curves for Measuring Magnetic Tape Link Jitter
Sos, J. Y.; Poland, W. B., Jr.; Cole, J. M.; Weiss, G.
Magnetic instrumentation tape recording links are usually required to be substantially transparent data channels. One of the most important deviations from this requirement, both in FM and direct recording modes, occurs in the area of time delay error. A method for measuring the root-mean-square time delay error (Δ) between points on a record vs their separation in playback time (T) has been described in the literature (Refs. 1 and 2), but the implications and interpretation of this technique have not been fully developed. This paper derives the theoretical relationships between the Δ-T curve and the autocorrelation function of a pure sine wave recorded on the tape, and uses this correspondence to establish a connection between jitter spectra and Δ-T curves. A simple instrument for measuring these curves with high accuracy is described, and results of measurements made on a number of intermediate-band tape units in use at the Goddard Space Flight Center are presented. These measurements show that a low-mass tape unit may be superior to high mass units by more than an order of magnitude. The utility of the Δ-T measurement technique is discussed on the basis of its direct relationship to PCM and coherent recording applications, and its value as a standard means for evaluating time delay error in magnetic tape links is described. It is also shown that the technique can be used to determine FM modulation index.
International Telemetering Conference Proceedings / October 02-04, 1967 / Marriott Motor Hotel, Washington, D.C.
1967-10-01T00:00:00ZAdaptive PCM Pattern Synchronization
http://hdl.handle.net/10150/606409
Adaptive PCM Pattern Synchronization
Van de Houten, R. S.
The trend toward more automated PCM decommutation systems demands less operator intervention in their operation. A weak link in this progression has been in the implementation of group synchronizer strategy. A new synchronizer has been developed based on the optimum properties of sequential probability ratio testing which requires only one program based on required worst case decision error probabilities and which is independent of the PCM format being synchronized. A mathematical model is formulated which accurately describes the operating characteristics of this technique. These operating characteristics are then compared to conventional synchronizer characteristics which demonstrate the superiority of this approach. The decision process described inherently adapts to signal conditions by making decisions faster and with less chance of error as bit error rate decreases. Only the Check Mode is discussed, but the same techniques apply to the Lock Mode.
International Telemetering Conference Proceedings / October 02-04, 1967 / Marriott Motor Hotel, Washington, D.C.
1967-10-01T00:00:00Z