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Analog Telephone Cores The early telephone networks had analog cores. Frequency division multiplexing (FDM) was used to transmit a number of voice signals over the single line. Twelve calls were multiplexed into a group. Five groups were multiplexed into a supergroup. Digital Telephone Cores The present telephone networks have digital cores. This requires that the analog signals in the local loops are converted to digital signals that are transmitted via the trunks. This is done by codec (coder decoder). Time division multiplexing (TDM) is used to multiplex digital signals in the trunks, since it can be entirely handled by digital ... Read More
The Universal Mobile Telecommunications System (UMTS) is a broadband, packet-based, 3G mobile cellular system based upon GSM standards. The specifications of UMTS covers the entire network system, including the radio access network, the core network and user authentication. Features UMTS is a component of IMT-2000 standard of the International Telecommunications Union (ITU), developed by 3GPP. It uses wideband code division multiple access (W-CDMA) air interface. It provides transmission of text, digitized voice, video and multimedia. It provides high bandwidth to mobile operators. It gives a high data rate of 2Mbps. For High-Speed Downlink Packet Access (HSDPA) handsets, the data-rate is as high ... Read More
Pulse code modulation (PCM) is a technique of digitally representing analog signals. It takes samples of the amplitude of the analog signal and changes it to binary data. PCM technique is used by codecs in telephone networks to convert analog signals in local loops to digital signals in the trunks, and reverse conversion at the receivers’ end. Operations in Pulse Code Modulation The operations in PCM technique involves operations at the transmitting end and the operations at the receiving end. Transmitting End − In the transmitting end, the analog signals are sampled, quantized and encoded. The codec samples the analog ... Read More
We can update another table with the help of inner join. Let us create two tables. Creating a table mysql> CREATE table tblFirst -> ( -> id int, -> name varchar(100) -> ); Query OK, 0 rows affected (0.48 sec) Inserting records mysql> INSERT into tblFirst values(1, 'John'); Query OK, 1 row affected (0.17 sec) mysql> INSERT into tblFirst values(2, 'Bob'); Query OK, 1 row affected (0.26 sec) mysql> INSERT into tblFirst values(3, 'David'); Query OK, 1 row affected (0.20 sec) Displaying ... Read More
Stored Procedure In MySQL, a stored procedure can be called with the help of call statement. A stored procedure returns more than one value. A stored procedure returns 0 by default. It cannot be used in SQL query and is based on precompile. Function A function can be called inside the statement. It can return a value with the help of return statement and it returns only one value. A function returns any single value, which can be a table. It can be used in SQL query and isn’t based on precompile.
Enhanced Data-rates for GSM Evolution (EDGE) is an improved version of GSM providing higher data transmission rate than GSM, while being compatible with the older systems. Features It was standardized by 3GPP as a part of GSM family and was deployed in GSM networks in 2003. The other names for EDGE are Enhanced GPRS (EGPRS) and IMT-Single Carrier (IMT-SC). It is compatible with any packet – switched application. It is also backward – compatible, i.e. compatible with existing or older versions. It enables data to be sent over a GSM TDMA systems at speeds of 384Kbps. GSM uses the ... Read More
CDMA2000 is a code division multiple access (CDMA) version of IMT-2000 specifications developed by International Telecommunication Union (ITU). It includes a group of standards for voice and data services − Voice − CDMA2000 1xRTT, 1X Advanced Data − CDMA2000 1xEV-DO (Evolution-Data Optimized) Features CDMA2000 is a family of technology for 3G mobile cellular communications for transmission of voice, data and signals. It supports mobile communications at speeds between 144Kbps and 2Mbps. It has packet core network (PCN) for high speed secured delivery of data packets. It applies multicarrier modulation techniques to 3G networks. This gives higher ... Read More
It is very difficult to say whether to prefer one large table or multiple small tables. It depends − On the application we are using. On database normalization However, there are many key points, through which we can say that multiple small tables are good in that situation. Suppose many developers are going to develop multiple tables, then there is a need to split them into multiple small tables. A situation when you are giving authority to many developers. This authority is for different parts of data. In this case, a need arise to split into multiple small ... Read More
Let us now see the following methods to calculate the time difference between two timestamps in seconds. Method The following is the query to calculate the difference between two timestamps. mysql> SELECT TIMESTAMPDIFF(SECOND, '2018-10-17 11:51:55', '2018-10-17 11:51:58'); The following is the output in seconds. +---------------------------------------------------------------------+ | TIMESTAMPDIFF(SECOND, '2018-10-17 11:51:55', '2018-10-17 11:51:58') | +---------------------------------------------------------------------+ | ... Read More
The garbage collector (GC) manages the allocation and release of memory. The garbage collector serves as an automatic memory manager. You do not need to know how to allocate and release memory or manage the lifetime of the objects that use that memory. An allocation is made any time you declare an object with a “new” keyword or a value type is boxed. Allocations are typically very fast. When there is not enough memory to allocate an object, the GC must collect and dispose of garbage memory to make memory available for new allocations. This process is known as ... Read More