Synchronized Analog Clock System
In the present scenario, a demand for the highly reliable and synchronous Analog Clock systems is seen. As a result, there has been a gradual shift to distributed systems from the centralized systems. There are few disadvantages for this system too. The most important one is that in a distributed system like Analog Clock, the different nodes maintain their own time using local clocks and their time values may not be same for the different nodes. I.e. there is no global clock within the system so that that the various activities in the distributed environment can be synchronized. The various clocks in the system even if set to a common time value at an instant, drift apart due to unavoidable reasons. Hence some kind of continuous mechanism for synchronization is needed so that they can coordinate and work together to achieve the objectives of the distributed system. Two types of synchronization are possible- external synchronization and internal synchronization. In a real time scenario, it is important for the system to be synchronous with each other and with a common external reference time. This is called external synchronization. But in certain systems, it is only necessary for the nodes in the system to be synchronized with each other. This is called internal synchronization. In many applications, the relative ordering of events is more important than actual physical time. Here event ordering is done without clock time values. Hence, depending on the area and type of application, clock synchronization techniques used differs.
Clock synchronization is a topic in computer science and engineering that aims to coordinate otherwise independent clocks. Even when initially set accurately, real clocks will differ after some amount of time due to clock drift, caused by clocks counting time at slightly different rates. There are several problems that occur as a result of clock rate differences and several solutions, some being more appropriate than others in certain contexts.
In serial communication, clock synchronization can refer to clock recovery which achieves frequency synchronization, as opposed to full phase synchronization. Such Analog Clock Clock Singapore synchronization is used in synchronization in telecommunications and automatic baud rate detection. Plesiochronous or Isochronous operation refers to a system with frequency synchronization and loose constraints on phase synchronization. Synchronous operation implies a tighter synchronization based on time perhaps in addition to frequency.
In a system with a central server, the synchronization solution is trivial; the server will dictate the system time. Cristian's algorithm and the Berkeley algorithm are potential solutions to the clock synchronization problem in this environment. In a distributed system the problem takes on more complexity because a global time is not easily known. The most used Analog Clock synchronization solution on the Internet is the Network Time Protocol (NTP) which is a layered client-server architecture based on UDP message passing. Lamport timestamps and vector clocks are concepts of the logical clock in distributed systems. In a wireless network, the problem becomes even more challenging due to the possibility of collision of the synchronization packets on the wireless medium and the higher drift rate of Analog Clock on the low-cost wireless devices.
Analog Clock Synchronization is achieved in ad-hoc wireless networks through sending synchronization messages in a multi-hop manner and each node progressively synchronizing with the node that is the immediate sender of a synchronization message. A prominent example is the Flooding Time Synchronization Protocol (FTSP), which achieves highly accurate synchronization in the order of a few microseconds. Another protocol, Harmonia, is able to achieve synchronization even when the device firmware cannot be modified and is the fastest known synchronization protocol in ad-hoc wireless networks.