Bird call in Prahran

Hello everyone!

We're trying to identify a bird which we here always in the morning and at dawn. The call is very similar to a currawong but it's more like ga-ga-gaaa where the last one is long and goes up to a pretty high pitch. We couldn't spot it as it's always dark when it's singing but it must be living close by (Melbourne, Prahran).

Thanks for your help!

Matthias&Anna