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Symbol Rate, Bandwidth and Bit Rate Definition and Conversion of Each Others
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4/21/2015 Symbol rate, Bandwidth and Bit rate definition and conversion of each others. | broadcastinfo
https://broadcastinfo.wordpress.com/2012/03/10/symbolratebandwidthandbitratedefinitionandconversionofeachothers/ 1/3
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Symbol rate, Bandwidth and Bit rate definition andconversion of each others.
Posted by Broadcast Information on March 10, 2012 in UncategorizedSymbol rate:
In digital communications, symbol rate is the number of symbol changes (waveform changes orsignaling events) made to the transmission medium per second using a digitally modulated signalor a line code.
The Symbol rate is measured in baud (Bd) or symbols/second.
Bandwidth:
Bandwidth is often used as a synonym for data transfer rate – the amount of data that can becarried from one point to another in a given time period (usually a second).
This kind of bandwidth is usually expressed in bits (of data) per second (bps).
Bit rate:
In telecommunications and computing, bit rate (sometimes written bit rate, data rate) is thenumber of bits that are conveyed or processed per unit of time.
The bit rate is quantified using the bits per second (bit/s or bps) unit.
Symbol Rate = Bandwidth / 1.35(For QPSK and 8PSK modulation, Roll Off = 35%)
Or,
Symbol Rate = Bandwidth / 1.25(For 8PSK modulation, Roll Off = 25%)
4/21/2015 Symbol rate, Bandwidth and Bit rate definition and conversion of each others. | broadcastinfo
https://broadcastinfo.wordpress.com/2012/03/10/symbolratebandwidthandbitratedefinitionandconversionofeachothers/ 2/3
Bit Rate = Symbol Rate * Modulation * Framing * FECWhere,
Modulation:
MSK ——– 1 bit/sec/Hz
BPSK 2^1 = 1 bit/sec/Hz
QPSK 2^2 = 2 bit/sec/Hz
8PSK 2^3 = 3 bit/sec/Hz
16QAM 2^4 = 4 bit/sec/Hz
32QAM 2^5 = 5 bit/sec/Hz
64QAM 2^6 = 6 bit/sec/Hz
256QAM 2^8 = 8 bit/sec/HzFraming = 188/204
Here,
Packet Length =188
Frame Size=204 bits= X * Y * Color Depth
X= Scaning Line (Ho)
Y=Scaning Line (Ve)
FEC = 1/2, 2/3, 3/4, 5/6, 7/8
Example:
If the bandwidth is 5MHz, DVB, PAL, FEC=3/4, QPSK Modulation. What is the symbol rate and bit rate?
Solution:
Symbol Rate = Bandwidth / 1.35
=5 (MHz) / 1.3
= 5* 1000 / 1.35
= 3703.7
≈3704
Maximum Symbol Rate is 3704 Hz. Now, we assume the symbol rate 3600 and the rest of it forside band.
4/21/2015 Symbol rate, Bandwidth and Bit rate definition and conversion of each others. | broadcastinfo
https://broadcastinfo.wordpress.com/2012/03/10/symbolratebandwidthandbitratedefinitionandconversionofeachothers/ 3/3
Bit Rate = Symbol Rate * Modulation * Framing * FEC
= 3600*2*(188/204)*(3/4)
= 4976.47 bit/sec
=4.97647 Mbit/sec
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