how this circuit works?

[wanchope]

Hi, all,
I found one circuit for multiple antenna detection.
But I do not understand how it works. Can anyone help to explain?
How V1 and V2 behave when the current source's current increase?

Thanks.

 

[Fom]

I think it is current level detector.
When current I1 reach some level, V2 is changed from high to liow.
When current I1 will reach more higher level then V1 is also changed from high to low.
It is like overcurrent / short current detectors.

 

[gevy]

It is current detector. What is direction of current?

 

[wanchope]

Thanks.
But how exactly the change of state happens? Can you provide some operation conditions for the 3 BJTs?

regards
Wanchope