Baud is a unit of measurement for symbol rate in data communication. Specifically, in telecommunications and electronics, baud (symbol: Bd) is a common unit for measuring the symbol rate, which is a key component determining the communication speed over a data channel.
Understanding Baud Rate
To fully grasp the concept of baud, let's break it down:
- Symbol: A symbol can represent one or more bits of data. For example, a symbol could represent a single bit (0 or 1), or it could represent multiple bits encoded together.
- Symbol Rate: This refers to the number of symbols transmitted per second. A higher symbol rate generally means a faster data transmission rate, assuming the same number of bits are encoded per symbol. Baud is the unit used to express this rate. 1 baud means 1 symbol per second.
Baud vs. Bits per Second (bps)
It's important to distinguish baud from bits per second (bps). While often used interchangeably, they are not always the same:
| Feature | Baud (Symbol Rate) | Bits per Second (bps) |
|---|---|---|
| Definition | Number of symbols transmitted per second. | Number of bits transmitted per second. |
| Relationship | Bd = Symbols/second | bps = Bits/second |
| Equivalence | Baud = bps when each symbol represents 1 bit | Can differ if one symbol encodes multiple bits |
| Example | 1200 baud means 1200 symbols per second. | 1200 bps means 1200 bits per second. |
- When Baud = bps: If each symbol represents only one bit, then the baud rate is equal to the bits per second. For example, if using Frequency-shift keying (FSK), where one frequency represents '0' and another represents '1'.
- When Baud != bps: If each symbol represents more than one bit (using more advanced modulation techniques), then the bits per second will be higher than the baud rate. For example, Quadrature Amplitude Modulation (QAM) can encode multiple bits in a single symbol, resulting in a higher data rate (bps) than baud rate.
Practical Implications
Understanding baud rate is crucial for:
- Modem Technology: Older modems often used lower baud rates. As modulation techniques improved, modems could transmit more bits per symbol, achieving higher data rates without necessarily increasing the baud rate.
- Serial Communication: Baud rate is a critical setting in serial communication protocols like RS-232. The transmitting and receiving devices must be configured with the same baud rate to communicate correctly.
- Data Throughput Calculation: Baud rate, along with the number of bits encoded per symbol, helps determine the overall data throughput of a communication channel.
