Merge bits in EFM

CD, DVD and (Ultra HD) Blu-ray Writers
#1

I understand the need for merge bits in EFM.

BUT.

Are these merge bits ALWAYS present (between every word, wheter needed or not) or are they inserted into the bitstream only when needed (i.e the adjacent words would form an illegal bitpattern).

Anybody who knows why 3 bits are inserted. After all; 2 merge bits should be enough to guarantee at least a 3T signal in the RF output in all situations.

#2

> Are these merge bits ALWAYS present (between every word, wheter needed
> or not) or are they inserted into the bitstream only when needed (i.e
> the adjacent words would form an illegal bitpattern).

Always.

> Anybody who knows why 3 bits are inserted. After all; 2 merge bits should
> be enough to guarantee at least a 3T signal in the RF output in all situations.

The third bit is used to minimize the DSV. It is still not perfect though since
one can still force 3 null merging bits and no DSV correction with sequences of
well chosen data.

#3

Ahhh I see! Thank you for your kind reply. :bow:

#4

Ahhh I see! Thank you for your kind reply. :bow: