What is the importance of synchronized waves in interference?

[bgq]

It is mentioned that the conditions of interference is that the waves should be coherent and synchronized.
What is the meaning of synchronized waves?

Thanks in advance.

 

[Bobbywhy]

1b. SynchronizedWave Sources. Interference of two waves is generally only useful if the waves have the same frequency and hence a constant phase difference. This will happen if the two different waves come from sources that are “synchronized" so they emit crests at the same time, troughs at the same time, etc.

www.physnet.org/modules/pdf_modules/m230.pdf

 

[bgq]

1b. SynchronizedWave Sources. Interference of two waves is generally only useful if the waves have the same frequency and hence a constant phase difference. This will happen if the two different waves come from sources that are “synchronized" so they emit crests at the same time, troughs at the same time, etc.

www.physnet.org/modules/pdf_modules/m230.pdf

OK, thank you very much.