How to make this trance "wobbling" bass

[Alvy]

Hi everybody!

I have been trying with no much success in making a bass which has been used on a few tracks, for example in this one at 3:05
https://www.youtube.com/watch?v=dtHtPE6BCO0

How to make that wobbling effect?
Thanks everybody in advance, I always think there are many true geniuses here!!

[chk071]

Sine wave with pitch modulation, an octave up and down i think.

[Passing Bye]

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