sampling rate, data rate and bandwidth

Question

I'm new to digital communication. How are the terms data rate and sampling rate related to the term "bandwidth" . Am I missing something here?.Can someone explain me in detail?

thanks in advance, phani tej

Answer 1

Data rate is the speed at which bytes (or chunks of data) are sent down a channel.

The bandwidth is how fast the bits that make up that data are transmitted.

Sampling rate is the frequency at which an incoming signal is read to measure its shape.

Take for example a typical 9600 baud serial connection.

The bandwidth is 9600 bits per second. Each byte, though, has extra bits with it (start, stop, parity, etc). So for a typical 8N1 format there's 10 bits used for every 8 bits sent.

So the data rate for 9600 baud would be 960 bytes per second.

The sampling rate would be the rate the receiver looks at the signal to see if it's a 1 or a 0 - typically at least 2x the bandwidth (see Nyquist-Shannon sampling theorem), so 19.2kHz.

Answer 2

Sampling rate (as defined by here is related to the process of constructing a digital representation of an analogue value: -

T is the the period between samples hence the sampling rate is 1/T

Date rate: Say for instance each point on the above waveform was sampled with a 16 bit ADC, at a rate of 1,000 times per second. If the ADC outputted serial data the basic payload data rate would be 16,000 bits per second. There may be other bits added by the ADC that make the overall data rate higher. That's an example of data rate linked to sampling rate.

Regarding bandwidth, this refers usually to a channel's capacity to send data.