Uploaded January 2026 | Updated September 2026, 1 week ago
Digital Communication playlist.
youtube.com/watch?v=Z-LPxkwv3fE&list=PLFxhgwM1F4ywI9EGow6kY-cwEwrMtRiJr
For access to this presentation materials, membership is required: I need the Material PPT
Sent me an email to Technologies.Discussion@gmail.com
If you need the whole playlist material, send me email and we discuss.
Give me some time to response. Thanks.
Bit Rate (Rb)
What it is: The number of bits (binary 1s and 0s) transmitted or processed per second.
Unit: Bits per second (bps), with common multiples like kbps, Mbps, Gbps.
Key Point: It's the fundamental measure of raw information capacity. It's what you usually see advertised as internet "speed" (e.g., 100 Mbps).
Meaning: Counts binary digits (0s and 1s), regardless of how they are grouped or modulated.
Information transfer rate bit rate
Digital signal represent by ‘0’ or ‘1’
1 0 1 0 0 1 0 0 1 1 0 1 in 1 Second
Example: If 12 bits of information are sent every second, then
Information transfer rate = 12 bits / 1s = 12 bps (in 1 sec, 12 bits can tx)
Unit of information transfer rate : bits / second or bps
What it is: The number of symbols (or signal changes) transmitted per second.
Unit: Symbols per second (sps). Also known as Baud.
Key Point: A symbol is a distinct state of the communication channel (e.g., a voltage level, a phase shift, a frequency). Each symbol can represent one or more bits.
Formula:
𝑅_𝑠="Number of symbols transmitted" /"time (s)"
Relation to bit rate:
𝑅_𝑏=𝑅_𝑠×〖𝑙𝑜𝑔〗_2 (𝑀)
where 𝑀= number of distinct symbols.
Example:
QPSK has 𝑀=4 symbols → each symbol carries 2 bits
If symbol rate = 1,000 baud → bit rate = 2,000 bps
Channel Rate (Gross Bit Rate)
What it is: The total number of bits (data + all overhead) physically transmitted on the communication channel per second. It is essentially the raw Bit Rate as seen by the physical layer.
Unit: Bits per second (bps).
Key Point: This is the speed you would measure on the "wire" with an oscilloscope. It includes everything—user data, headers, error correction, framing bits, etc.
Relationship: Data Rate = Channel Rate - Overhead Rate.
Simple Analogy: The total number of letters (both message letters and service letters for addresses/checks) being pushed through the pipe per second.
Meaning:This is the actual load on the channel and is constrained by bandwidth and noise.
Example:If:
Data rate = 5 Mbps
FEC adds 25% redundancy
Then:Channel rate = 6.25 Mbps
Data Rate (Throughput)
What it is: The number of useful, user data bits (excluding overhead) is delivered
Unit: Bits per second (bps).
Key Point: This is the effective speed you experience. It is always lower than the raw Bit Rate because it subtracts all the non-data bits used for:
Protocol Headers (Ethernet, IP, TCP)
Error Correction Codes (FEC)
Preamble/Synchronization bits
Retransmissions due to errors
Simple Analogy: The number of meaningful words (from the original message) you receive per second, after removing envelope addresses.
Key Takeaway
Symbol rate → how fast signal elements change
Bit rate → how fast bits are sent
Channel rate → how fast the physical channel is actually used
Data rate → how fast useful information is delivered
Symbol Rate: The radio changes its phase/amplitude to create new symbols. Let's say the Symbol Rate = 1 Million symbols/sec (1 Mbaud).
Bits per Symbol: 256-QAM encodes 8 bits into each symbol (since 2^8 = 256).
Bit Rate / Channel Rate: Raw physical layer speed = 1 Mbaud × 8 bits/symbol = 8 Mbps on the channel. This is the Channel Rate.
Overhead: This 8 Mbps stream includes Wi-Fi preamble, MAC addresses, error correction (FEC), and retries.
Data Rate: After removing all that overhead, your actual file transfer speed (throughput) might only be ~6 Mbps. This is the Data Rate you care about.
Digital Communication playlist.
youtube.com/watch?v=Z-LPxkwv3fE&list=PLFxhgwM1F4ywI9EGow6kY-cwEwrMtRiJr
For access to this presentation materials, membership is required: I need the Material PPT
Sent me an email to Technologies.Discussion@gmail.com
If you need the whole playlist material, send me email and we discuss.
Give me some time to response. Thanks.
Bit Rate (Rb)
What it is: The number of bits (binary 1s and 0s) transmitted or processed per second.
Unit: Bits per second (bps), with common multiples like kbps, Mbps, Gbps.
Key Point: It's the fundamental measure of raw information capacity. It's what you usually see advertised as internet "speed" (e.g., 100 Mbps).
Meaning: Counts binary digits (0s and 1s), regardless of how they are grouped or modulated.
Information transfer rate bit rate
Digital signal represent by ‘0’ or ‘1’
1 0 1 0 0 1 0 0 1 1 0 1 in 1 Second
Example: If 12 bits of information are sent every second, then
Information transfer rate = 12 bits / 1s = 12 bps (in 1 sec, 12 bits can tx)
Unit of information transfer rate : bits / second or bps
What it is: The number of symbols (or signal changes) transmitted per second.
Unit: Symbols per second (sps). Also known as Baud.
Key Point: A symbol is a distinct state of the communication channel (e.g., a voltage level, a phase shift, a frequency). Each symbol can represent one or more bits.
Formula:
𝑅_𝑠="Number of symbols transmitted" /"time (s)"
Relation to bit rate:
𝑅_𝑏=𝑅_𝑠×〖𝑙𝑜𝑔〗_2 (𝑀)
where 𝑀= number of distinct symbols.
Example:
QPSK has 𝑀=4 symbols → each symbol carries 2 bits
If symbol rate = 1,000 baud → bit rate = 2,000 bps
Channel Rate (Gross Bit Rate)
What it is: The total number of bits (data + all overhead) physically transmitted on the communication channel per second. It is essentially the raw Bit Rate as seen by the physical layer.
Unit: Bits per second (bps).
Key Point: This is the speed you would measure on the "wire" with an oscilloscope. It includes everything—user data, headers, error correction, framing bits, etc.
Relationship: Data Rate = Channel Rate - Overhead Rate.
Simple Analogy: The total number of letters (both message letters and service letters for addresses/checks) being pushed through the pipe per second.
Meaning:This is the actual load on the channel and is constrained by bandwidth and noise.
Example:If:
Data rate = 5 Mbps
FEC adds 25% redundancy
Then:Channel rate = 6.25 Mbps
Data Rate (Throughput)
What it is: The number of useful, user data bits (excluding overhead) is delivered
Unit: Bits per second (bps).
Key Point: This is the effective speed you experience. It is always lower than the raw Bit Rate because it subtracts all the non-data bits used for:
Protocol Headers (Ethernet, IP, TCP)
Error Correction Codes (FEC)
Preamble/Synchronization bits
Retransmissions due to errors
Simple Analogy: The number of meaningful words (from the original message) you receive per second, after removing envelope addresses.
Key Takeaway
Symbol rate → how fast signal elements change
Bit rate → how fast bits are sent
Channel rate → how fast the physical channel is actually used
Data rate → how fast useful information is delivered
Symbol Rate: The radio changes its phase/amplitude to create new symbols. Let's say the Symbol Rate = 1 Million symbols/sec (1 Mbaud).
Bits per Symbol: 256-QAM encodes 8 bits into each symbol (since 2^8 = 256).
Bit Rate / Channel Rate: Raw physical layer speed = 1 Mbaud × 8 bits/symbol = 8 Mbps on the channel. This is the Channel Rate.
Overhead: This 8 Mbps stream includes Wi-Fi preamble, MAC addresses, error correction (FEC), and retries.
Data Rate: After removing all that overhead, your actual file transfer speed (throughput) might only be ~6 Mbps. This is the Data Rate you care about.
