# I Bit rate, bit interval vs frequency, time period

1. Mar 7, 2016

### Geek007

can we use frequency and time period terms for digital signals or we have to use bit rate and bit interval terms for digital signal. in simple words,

2. Mar 7, 2016

### Drakkith

Staff Emeritus
Well, my cable modem tells me it operates on a certain frequency, so I assume we can use frequency in at least a few situations.

3. Mar 7, 2016

### Staff: Mentor

You can see the difference between the digital bitstream and the modulated analog waveform here: https://en.wikipedia.org/wiki/Modulation

You can have a primitive baseband bitstream, and then you will refer to bit rates and bit intervals. But when you modulate an analog carrier with the digital data in order to be able to transmit many signals at the same time (like in different channel frequencies), then you refer to the analog waveform's frequency and wavelength. Does that make sense?

4. Mar 7, 2016

### Anand Sivaram

It depends which layer you are looking at. In the digital layer, it is bit rate. But, when you go down to the physical layer, then the bits are transmitted over, voltage, phase, frequency etc. There parameters like frequency, time period etc. are used.
Take a look at https://en.wikipedia.org/wiki/Modulation#Digital_modulation_methods