64Kbps, 3.1kHz audio transfer, 8kHz integrity
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In North American a T1 line carries signals at 1.544 Mbps (24 channels at 64Kbps). E1 is the European format for digital transmission. E1 carries signals at 2 Mbps (32 channels at 64Kbps, with 2 channels reserved for signaling and controlling). T1 and E1 lines may be interconnected for international use.
The standard sampling for digitized voice rate is 8000 times per second with 8 bits per sample providing for 64,000 bits per second or 64kbps.
As we know that voice signal is of frequency 3.3 Khz,and as per the Nyquist Rate or PCM quantization rate for transmission we required signal of >=2f(here 'f' is GIF [3.3]=4).and each sample of data is a byte. DS0: provides one 64kbps channel.E1: 32 DS0 or 32 channels with 64kbps Also we know that voice signal frame consisits of 32 bytes .Hence value of an E1 will be =2x4Khzx8bitsx32slots =2.048Mbps
when ou put the files in itunes it should automatically make them the right file if they arent already
SDH and PDH are two digital hierarchies in which different line speeds (e.g. E1, T1, STM1) are categorized.PDH (plesiosynchronous digital hierarchy) was replaced by SDH (synchronous digital hierarchy) due to its drawback in synchronisation where plesio refers to nearlysynchronous.E1, T1 and J1 are generally categorized under PDH. STM1, OC3, STM4, OC12 etc. are categorized under SDH.E1 is used worldwide nowadays in 2G technologies except North America and Japan (who are using T1 and J1 respectively). It is the line speed of 2Mbps. But how this speed comes along? The derivation is as follows.The audio signals were sampled and converted to digital signal at 64kbps, since 1960s for digital transmission of voice calls. When 32 channels (30 assigned for voice channels and 2 channels for framing and signaling), with each having speed of 64kbps are put together (or we call multiplexing), a line speed of E1, i.e. 2Mbps is produced by having 32 x 64kbps = 2.048Mbps.T1 line, which transmits at 1.544 Mbps can be interconnected with E1 for international use.Having 3 different speeds (E1, T1 and J1), PDH was later replaced by SDH in order to standardize the speed, making only 1 standard speed worldwide, which is STM1 having the speed of 155.52Mbps.
PCM technique is used to convert analog voice signals into digital. In PCM the analog frequency is first sampled and then converted into binary bits. Each samples are taken as 8bits long. Basic communication theory requires that a minimum sampling rate of twice the frequency of the signal to be sampled will result in an accurate representation of the original signal.Human voice can have max 4000hz frequency, therefore sampling rate should be 8000 samples/sec.Which implies required bit rate for transmitting voice is 8000*8 = 64000 bits/sec = 64kbps.
In 2G networks, data speeds are limited to 64 kbps due to the technology used for transmission, primarily circuit-switched systems like GSM. The architecture was designed primarily for voice communication, and the available bandwidth was constrained by the frequency allocation and modulation techniques. Additionally, the efficiency of data encoding and the limited processing power of devices at that time also contributed to the lower data rates. As a result, while 2G introduced mobile data services, it could not support high-speed internet access.
Advantages: Reasonable WAN speed (64kbps -- 1.5Mbps) When T1 or Fract. T1 is the transport Buy bandwidth only when you need it **** One serial port at the central site can support multiple incoming PVCs Telco is responsible for insuring connectivity
It depends on the quality of the recorded music, i.e. how many bits per second were used to record it. At CD quality, 192 thousand bits per second (192kbps), you can store (8Gbits/192k x 60) = 694 minutes (remember, 1Gbyte = 8Gbits). Decreasing the recording quality to 128kb, will bump that figure up to 1040mins, speech quality (64kbps) will double that.