Time Code Generator Research Articles

FPGA based Time Code Generation and Dissemination in a Distributed Control Systems

This paper discusses the development of a FPGA based standard time IRIG-B DC (unmodulated) and AC (modulated) code generation cum dissemination system over serial and Ethernet (unicast and multicast mode) network using verilog HDL which in turn trigger all sequential control actions occurring across the entire sensor network based on precise time stamping. Design of external signal conditioning circuitry for IRIG-B AC code is also described. The total development is based on modular approach in a single FPGA board for generation, dissemination, modulation and monitoring facility in case of flight vehicle control.

Loop-Strap Type Does Not Affect Facemask Removal Using an Anvil Pruner

Purpose: To compare time and movement characteristics of four different brands of football facemask loop straps during a cutting task. Methods: Ten certified athletic trainers, age 24.8 ± 3.4, years of experience 2.4 ± 2.5, cut four different brands of football helmet loop straps (ShockblockerTM, ASI (Athletic Specialty), SchuttTM AG (Armourguard) Elite, and RiddellTM) with an anvil pruner. Task completion time was measured with a time code generator. Helmet movement was measured in the lateral flexion plane using 2-dimensional motion analysis. Results:Measureable but non-significant differences were observed between loop strap types (P < 0.05) for dependent variables (time, range movement, and mean movement). Conclusions: Emergency personnel can effectively cut through various brands of football helmet loop straps using an anvil pruner and do not need brand-specific tools for facemask removal. Similar movement characteristics were observed while cutting all four brands of loop straps. Movement occurring during facemask removal may increase cervical displacement and increase injury severity. Measureable differences in cutting time warrant further investigation.

Using Real Time Workshop for rapid and reliable control implementation in the Frascati Tokamak Upgrade Feedback Control System running under RTAI-GNU/Linux

The Feedback Control System running at FTU has been recently ported from a commercial platform (based on LynxOS) to an open-source GNU/Linux-based RTAI-LXRT platform, thereby, obtaining significant performance and cost improvements. Based on the new open-source platform, it is now possible to experiment novel control strategies aimed at improving the robustness and accuracy of the feedback control. Nevertheless, the implementation of control ideas still requires a great deal of coding of the control algorithms that, if carried out manually, may be prone to coding errors, therefore time consuming both in the development phase and in the subsequent validation tests consisting of dedicated experiments carried out on FTU. In this paper, we report on recent developments based on Mathworks’ Simulink and Real Time Workshop (RTW) packages to obtain a user-friendly environment where the real time code implementing novel control algorithms can be easily generated, tested and validated. Thanks to this new tool, the control designer only needs to specify the block diagram of the control task (namely, a high level and functional description of the new algorithm under consideration) and the corresponding real time code generation and testing is completely automated without any need of dedicated experiments. In the paper, the necessary work carried out to adapt the Real Time Workshop to our RTAI-LXRT context will be illustrated. A necessary re-organization of the previous real time software, aimed at incorporating the code coming from the adapted RTW, will also be discussed. Moreover, we will report on a performance comparison between the code obtained using the automated RTW-based procedure and the hand-written C code, appropriately optimised; at the moment, a preliminary performance comparison consisting of dummy algorithms has shown that the code automatically generated from RTW is faster (about 30% up) than the manually written one. This preliminary result combined with the fact that the use of RTW eliminates the coding workload leads to the conclusion that this approach to control implementation grants significant advantages. According to the FTU experiment program, the actual deployment of the new tool is scheduled for the next experimental campaign.

HMS Scott ring laser gyro navigator integration

HMS SCOTT is a United Kingdom ocean survey vessel that hosts a state-of-the-art deep ocean mapping system which was designed, developed, and is currently maintained and periodically updated by the Space and Naval Warfare Systems Center, San Diego, (SSC San Diego). A recent update of this system consisted of the replacement of an obsolete and very costly to maintain inertial navigation system. Another reason for updating the ship's inertial system was to provide higher accuracy attitude data, than was previously available with the old inertial system, to the high resolution multi-beam sonar system in order to produce improved bathymetric charts. After conducting a market survey of suitable inertial navigator systems, the Kearfott SEANAV ring laser gyro navigator (RLGN) system, using a monolithic T-24 gyro, was selected to replace the old inertial system. The selection of the SEANAV RLGN was based on its relatively low cost, high reliability, and, particularly, the roll and pitch data accuracies of typically less than 1-arc-minute. This attitude data accuracy was key to enable a significant improvement in the bathymetry data accuracy. Two SEANAV systems were integrated with GPS receivers, a system master time code generator, and electro magnetic (EM) log and Doppler sonar speed sensors to provide the navigation portion of the mapping data. Operational testing of this updated system aboard HMS SCOTT, in November, 2003, showed a marked improvement in the quality of the map product due, in part, to the improved attitude data provided by the SEANAV RLGN system.

Accuracy and reliability of temporal gait measurement

Abstract This study compared measurements of the temporal gait parameters obtained from videotape using a field counting technique with those obtained from footswitches and force plates. Five subjects traversed a walkway 3 times for each of the 3 conditions, barefoot, in outdoor shoes and in training shoes. Each of the 4 footswitches was connected to a Light Emitting Diode (LED) and these were placed in view of one video camera, a second camera was used to obtain a sagittal plane view of the subject crossing the force plates. The video system had a playback rate of 50 fields/s. The signals from the two cameras were mixed and recorded as a split screen image. The signal from a time code generator was later added to this tape providing information on time to 1/100 s. From the videorecording, 4 individual raters determined the times of heel contact and toe-off for both feet as they crossed the force plates. Inter-rater reliability of detection of the temporal phases of walking was investigated using IntraClass Correlation analysis (ICC) and description of percentage of agreement between raters. Footwear, particularly the training shoes, was found to attenuate the signals from the footswitches leading to differences typically of the order of 0.04 s between the durations of the temporal gait phases calculated from the forceplate data. The technique for visually detecting the time of the key events of make and break of foot/floor contact from videotape was found to be highly reliable with, for example, the barefoot condition demonstrating 95% rater agreement values to within 5% of the time of total support.

A Time Source for a Data Acquisition System Designed for Phase Propagation Study of Magnetic Pulsations.

A time source for a data acquisition system was designed to use the fluxgate magnetometer for the measurement of long-distance phase propagation of magnetic pulsations at very low latitudes. The time source consists of a very low frequency (VLF) signal receiver, antenna, time code generator with crystal oscillator, and microcomputer chip. Omega navigation signals received by the VLF receiver are utilized for the time base. The computer-aided system can choose the Omega station with the greatest signal strength at the observation site and can decode the transmitted signals to utilize them as the time source of the internal clock. The prominent feature of this system is software-aided fully automatic operation at any location in the world. The overall accuracy of the clock is expected to be ±30 ms.

Integrating behavior and cardiovascular responses: posture and locomotion. I. Static analysis

Heart rate, arterial blood pressure, and renal and mesenteric or femoral blood flow were telemetered from 11 Papio hamadryas in an untethered free-ranging situation. The animals' behavior was recorded on videotape, and the cardiovascular (CV) data were recorded on the audio channels of the tape. The behavior was coded, and the codes were linked to the CV data via a time-code generator and computer control. The CV data were digitized into 1-s intervals, and the static relations between CV measures and the postures/locomotions (P/Ls) associated with the behavior were analyzed. The total frequency distributions for heart rate, blood pressure, and renal conductance approximated Gaussian distributions, whereas femoral conductance was positively skewed. The distribution for renal conductance suggested that during normal waking conditions the kidney is not maximally dilated and may increase or decrease its blood flow. All distributions were highly influenced by the Sit category, which occupied 80% of the total time. The CV measures for all P/Ls had wide ranges, and the CV values associated with each P/L overlapped those for the other P/Ls. The heart rate and renal conductance associated with the various P/Ls showed the largest deviations from the grand means and therefore contributed the most to the ability to discriminate one P/L from another. Blood pressure varied little from one P/L to another. The patterns of CV variables served to distinguish particular P/Ls very effectively. The frequency distributions were separated best when they were parceled on the basis of the intensity of behavior associated with a particular P/L. These variations in intensity were the major cause of the overlaps in the frequency distributions associated with P/Ls.

A microprocessor controlled time code generator for an OBS system.

A very compact time code generator is designed for an OBS system and portable observing system with battery power supply. By use of a microprocessor it is constructed without any hardware counter or any shift register. All the process of a time code generator is realized by software, and the CPU clock is the sole timing unit. The program is stored in 256 byte memory.

Time, date, and event code generator to identify physiologic events simultaneously recorded on magnetic tape and oscillographic paper.

This instrument will generate upon command any one of three serial code sequences in a binary coded decimal (BCD) format representing either 1) time of day, 2) time and date, or 3) event number. Either a single code sequence or continuously repeating sequences can be generated. The instrument is intended to be used in a biomedical data acquisition system to permanently identify, index, and synchronize analog or digital data recorded on magnetic tape or oscillographic paper. Three-digit event codes, consecutively numbered 1 through 999 in successive frames, are particularly valuable for indexing experimental maneuvers or deliberate changes in experimental variables. Individual digits in the code format are easier to interpret visually than are corresponding digits in recognized time code formats.

Electronic Journalism Editing at NBC

At the heart of electronic journalism (EJ) at NBC is a small, battery-powered, portable VTR — the Sony U-Matic® VO-3800, which uses 20-min 3/4-in cassettes. Whether the stories on these cassettes are beamed to the studio by microwave or carried there by courier or by the News team, they are soon ready for editing on Sony VO-2850 VTRs prior to airing. The EJ edit rooms at NBC's Radio City studios are described in detail and a number of useful modifications of standard equipment are discussed. Such modifications have made a time-code reader more versatile, provided a new edit-preview capability, allowed the VTRs to be used in a fast-search “Videola” mode, and — by using the video signal for control purposes — permitted camera-trigger operation of the portable VTR and (optionally) a time-code generator. Block diagrams of the audio, video, and monitoring systems are discussed. Finally, a new tri-color VTR system is revealed for obtaining full-fidelity NTSC color signals with low-cost helical-scan VTRs. The system records white, red, and blue signals with separate portable VTRs; a time code on a soundtrack and three separate time-base correctors are used to assure proper registration. The resulting improvement in picture quality may extend the use of portable EJ VTR equipment into new programming areas.

Time code generator and event marker for correlating chart and magnetic tape records.

The b.d.c. trace proved easy to read from chart. It was particularly useful in correlating sections of chart records with the corresponding magnetic-tape record using the leading edge of the first bit of the time code as a reference point.