E1 and DS1

E1 and DS1 are the basic structures which carry speech signals with them. The difference between them is the frame format and the data rate.

DS1

DS1 is a 24 byte frame which carries speech signals. 24 bytes represent 24 channels which means 24 different voice signals are sent in the same frame.

For management and control purposes 1 bit called framing bit is added to it.

So, in total ((24x8)+1) bits are available in a DS1 frame.

The data rate of DS1 frame is calculated with the time period.

DS1 signals are used in PDH standards.

E1

E1 is a 32-bit frame structure which carries speech signals. The difference between DS1 and E1 is the data rate and the frame structure. E1 has higher data rate than DS1.

Here, among the 32 bytes of the frame only 30 of them are used for transmission of voice signals. Remaining 2 are used for synchronisation and signalling purposes.

The zeroth byte is used for synchronisation and 16th byte is used for signalling.

As of now, the byte pattern of synchronisation and signalling frames are not discussed as there is no need to remember those. We will go through that when the implementation techniques are being discussed.

I am happy to hear your suggestion, doubts and ideas.