What is Symbol rate? 

Hi Tejas

Symbol Rate is the Modulation rate in bauds. This rate may be higher than the transmitted bit rate as in the case of coded pulses or lower as in the case of multilevel transmission. It specifies the Size of the digital package transmission.

Regards

Answered by Suparna at 12:43 AM on October 30, 2008

The symbol rate is the rate of state changes on a communications circuit.

If a circuit can carry two tones per second, the circuit has a symbol rate of two.

Circuits then use different modulation techniques to carry multiple bits per symbol.

If the circuit is limited to two different tones, the first tone can represent a 0 and the second tone can represent a 1. In this circuit, the symbol rate is the same as the bit rate.

If the circuit can carry four different tones, then the tones can be used to encode twice as many bits per symbol. In this circuit, the bit rate is now twice the symbol rate.

Using more tones allows more bits per second (bps) to be squeezed out of every symbol, but this also requires higher quality circuits. If the circuit is not high enough quality, the number of retransmissions will cause the circuit to be slower than with a lower number of tones.

The choice of how many tones to use is determined by the modulation algorithm chosen. QPSK uses four tones, 8PSK uses eight tones.

The use of 4 tones is standard in the satellite world. In the cable television world, the higher quality transmission medium enables 64QAM modulation to be the standard.

Symbol Rate is abbreviated as SR.

The symbol rate is also known as the baud rate.
http://www.tech-faq.com /symbol-rate.shtml

Answered by Nishu's at 9:59 PM on October 29, 2008

Well Tejas! In digital communications, symbol rate, also known as baud or modulation rate; is the number of symbol changes (signalling events) made to the transmission medium per second using a digitally modulated signal or a line code. The Symbol rate is measured in baud (Bd) or symbols/second. In the case of a line code, the symbol rate is the pulse rate in pulses/second. Each symbol can represent or convey one or several bit of data. The symbol rate is related to but should not be confused with gross bitrate expressed in bit/s.

A symbol is a state or significant condition of the communication channel that persists for a fixed period of time. A sending device places symbols on the channel at a fixed and known symbol rate,and the receiving device has the job of detecting the sequence of symbols in order to reconstruct the transmitted data. There may be a direct correspondence between a symbol and a small unit of data (for example, each symbol may encode one or several binary bits) or the data may be represented by the transitions between symbols or even by a sequence of many symbols.

The symbol duration time, also known as unit interval, can be directly measured as the time between transitions by looking into an eye diagram of an oscilloscope. The symbol duration time Ts can be calculated as:


where fs is the symbol rate.

A simple example: A baud rate of 1 kBd = 1,000 Bd is synonymous to a symbol rate of 1,000 symbols per second. In case of a modem, this corresponds to 1,000 tones per second, and in case of a line code, this corresponds to 1,000 pulses per second. The symbol duration time is 1/1,000 second = 1 millisecond.

http://en.wikipedia.org/wiki/Ba ud_rate

Answered by Kumaar at 4:47 PM on October 29, 2008

The symbol rate is the rate of state changes on a communications circuit.
If a circuit can carry two tones per second, the circuit has a symbol rate of two.
Circuits then use different modulation techniques to carry multiple bits per symbol.
If the circuit is limited to two different tones, the first tone can represent a 0 and the second tone can represent a 1. In this circuit, the symbol rate is the same as the bit rate.
source-http://www.tech-faq.c om/symbol-rate.shtml

Answered by Satyakam at 2:48 PM on October 29, 2008

The symbol rate is the rate of state changes on a communications circuit.

If a circuit can carry two tones per second, the circuit has a symbol rate of two.
Circuits then use different modulation techniques to carry multiple bits per symbol.
If the circuit is limited to two different tones, the first tone can represent a 0 and the second tone can represent a 1. In this circuit, the symbol rate is the same as the bit rate.
If the circuit can carry four different tones, then the tones can be used to encode twice as many bits per symbol. In this circuit, the bit rate is now twice the symbol rate.
Using more tones allows more bits per second (bps) to be squeezed out of every symbol, but this also requires higher quality circuits. If the circuit is not high enough quality, the number of retransmissions will cause the circuit to be slower than with a lower number of tones.
The choice of how many tones to use is determined by the modulation algorithm chosen. QPSK uses four tones, 8PSK uses eight tones.
The use of 4 tones is standard in the satellite world. In the cable television world, the higher quality transmission medium enables 64QAM modulation to be the standard.
Symbol Rate is abbreviated as SR.
The symbol rate is also known as the baud rate.

Answered by raj u at 2:44 PM on October 29, 2008

The symbol rate is the rate of state changes on a communications circuit.


If a circuit can carry two tones per second, the circuit has a symbol rate of two.

Circuits then use different modulation techniques to carry multiple bits per symbol.

If the circuit is limited to two different tones, the first tone can represent a 0 and the second tone can represent a 1. In this circuit, the symbol rate is the same as the bit rate.

If the circuit can carry four different tones, then the tones can be used to encode twice as many bits per symbol. In this circuit, the bit rate is now twice the symbol rate.

Using more tones allows more bits per second (bps) to be squeezed out of every symbol, but this also requires higher quality circuits. If the circuit is not high enough quality, the number of retransmissions will cause the circuit to be slower than with a lower number of tones.

The choice of how many tones to use is determined by the modulation algorithm chosen. QPSK uses four tones, 8PSK uses eight tones.

The use of 4 tones is standard in the satellite world. In the cable television world, the higher quality transmission medium enables 64QAM modulation to be the standard.

Symbol Rate is abbreviated as SR.

The symbol rate is also known as the baud rate.

Answered by Hem@nt .... at 2:44 PM on October 29, 2008

In digital communications, symbol rate, also known as baud or modulation rate; is the number of symbol changes (signalling events) made to the transmission medium per second using a digitally modulated signal or a line code. The Symbol rate is measured in baud (Bd) or symbols/second. In the case of a line code, the symbol rate is the pulse rate in pulses/second. Each symbol can represent or convey one or several bit of data. The symbol rate is related to but should not be confused with gross bitrate expressed in bit/s.

A symbol is a state or significant condition of the communication channel that persists for a fixed period of time. A sending device places symbols on the channel at a fixed and known symbol rate,and the receiving device has the job of detecting the sequence of symbols in order to reconstruct the transmitted data. There may be a direct correspondence between a symbol and a small unit of data (for example, each symbol may encode one or several binary bits) or the data may be represented by the transitions between symbols or even by a sequence of many symbols.

The symbol duration time, also known as unit interval, can be directly measured as the time between transitions by looking into an eye diagram of an oscilloscope. The symbol duration time Ts can be calculated as:

T_s = {1 \over f_s},

where fs is the symbol rate.

A simple example: A baud rate of 1 kBd = 1,000 Bd is synonymous to a symbol rate of 1,000 symbols per second. In case of a modem, this corresponds to 1,000 tones per second, and in case of a line code, this corresponds to 1,000 pulses per second. The symbol duration time is 1/1,000 second = 1 millisecond.

Answered by NIVEDITA at 2:44 PM on October 29, 2008