Akurasi Waktu Jam Masjid di Kota Lhokseumawe

Accuracy of time is very closely related to Islamic law, a lot of worship related to time, such as prayer times, breaking fast and ruling. Without a standard time accuracy, worship can not be done perfectly. The clock is a marker of time that makes it easy for Muslims to carry out worship and social activities. Until now there has been no clock that can survive accuracy with a long time, meaning that all clocks must be calibrated within a certain time span. The time standard for clock calibration is the Atomic Clock time that is on the GPS or on the link ntp.bmkg.go.id controlled by Badan Meteorologi Klimatologi dan Geofisika (BMKG). This study tries to find the accuracy of mosque hours and the type of clock used in mosques in Lhokseumawe City by using the method of observation and documentation of 20 mosques selected as samples in the study. The results of observation and documentation show that all mosques (100%) in Kota Lhokseumawe have used the clock as a timemarker, 12 mosques, or 60% of the mosque has been using a digital clock with accuracy of 50% in accordance with the standard and 35% analog clock in accordance with a clock standard observer BMKG.

High Precision Clock Bias Prediction Model in Clock Synchronization System

Time synchronization is a fundamental requirement for many services provided by a distributed system. Clock calibration through the time signal is the usual way to realize the synchronization among the clocks used in the distributed system. The interference to time signal transmission or equipment failures may bring about failure to synchronize the time. To solve this problem, a clock bias prediction module is paralleled in the clock calibration system. And for improving the precision of clock bias prediction, the first-order grey model with one variable (GM(1,1)) model is proposed. In the traditional GM(1,1) model, the combination of parameters determined by least squares criterion is not optimal; therefore, the particle swarm optimization (PSO) is used to optimize GM(1,1) model. At the same time, in order to avoid PSO getting stuck at local optimization and improve its efficiency, the mechanisms that double subgroups and nonlinear decreasing inertia weight are proposed. In order to test the precision of the improved model, we design clock calibration experiments, where time signal is transferred via radio and wired channel, respectively. The improved model is built on the basis of clock bias acquired in the experiments. The results show that the improved model is superior to other models both in precision and in stability. The precision of improved model increased by 66.4%~76.7%.