[![enter image description here][1]][1]I have used a TRIAC and an MOC3021 opto-coupler connected to a PIC16F887A to simulate a a full wave rectifier. 
I am now to design the same using an SCR h-Bridge. 
My question is, in order to trigger the SCRs, do i need 4 separate triggers for each SCR? or could i use two trigger pulses, one for each pair of the SCRs?
I would appreciate any advice. am fairly new to the field.
Thanks.
The following is the layout of the circuit.
Specs:220VAC, 60 Hz.
Load 1Kohms.
These were provided by my senior supervisor.

  [1]: https://i.sstatic.net/IWVWY.png