What is STM-1?
Synchronous Transport Module Level-1 (STM-1) is the designation of the second to lowest level in the synchronous digital hierarchy (SDH). The STM-1 line is 155.520 megabites per second (MBPS), while the actual payload is 150.336 Mbps. The STM-0 is at the lowest SDH level and the STM-0 line is 51.840 Mbps. Other SDH rates are STM-4, STM-16 and STM-64 with 4, 16 and 64 times higher than the STM-1 measure. The American SDH counterpart is a synchronous optical network (Sonet), a standard for optical fiber transmission, while the International Telecommunications Union (ITU) of the telecommunications standard (ITU-T) is controlled by SDH. This is analogous to send the package and is used for the packaging material. The actual payload is an item that is actually sent, while the total weight of the package is equal to the payload plus overhead. The actual level of useful load is important for services that will support SDH. Instead of setting a measure of a line of line is aimed at custom -consumer loadSTM-1 due to the complexity of STM-1 as a whole.
A typical basic suborn of the useful load is one voice channel. An ordinary voice channel is sampled 8,000 times per second. The rate is a standard rate derived from the rule that if the maximum voice frequency is of 4,000 cycles per second, the sampling speed should be 8,000 times per second.
The voice channel level uses 8 bits for satisfactory reproduction. Eight digital bits will be able to encode a total of 256 levels or 128 positive levels and 128 negative levels. There will be more samples at lower voice levels than at higher levels. The latter is referred to as a combination algorithm.
The resulting rate for one voice channel is 64,000 bits of Zadruhý (BPS). The STM-1 is therefore able to carry 2,349 voice channels and 2,349 is the payload rate of 150,336 kilobytes per second (KBPS)/64 kbps. Using multiplexers and demultIpplexers are able to use small clusters of subtle channels as needed.
For example, if the mobile phone service provider should connect to other networks with a channel of 1,000 x 64 kbps for a voice and another 1,000 x 64 kbps for data, one StM-1 link would be enough. This results in a replacement of 349 x 64 kbps channels. There are many ways to implement the same connection depending on the anticipated future needs and existing channel investigation, called transcoders.