preamble synchronisation pocsag

Hello,

I am about to tackle the decoding of pager (POCSAG) signals for a radio receiver.
I know the POCSAG data consists of 576 bits for the preamble and then a synchronisation codeword.

I imagine that I will use the 576 bit preamble to synchronise my processors clock with. Is there any fancy algorithms required for this? I would think its as easy as checking for a change in state of the data and adjusting the processor clock to trigger an interrupt that indicates the next bit has arrived. If this is the purpose of the preamble then what on earth is the synchronisation codeword used for?

Before any one tells me that the preamble is used for AGC, I ask , do pagers often use AGC? I thought FM receivers such as pagers only cared about the phase of the signal and did not care about the magnitude like AM receivers do.

Can anyone recommend any information I should be reading?

Thankyou

AGC present in all radio receivers whose dynamic range is not controlled by ADC itself.
FM uses constant envelope but this magnitude of envelop will change depend on the distance between the Tx and Rx.
So AGC will reside.
In FM AGC control level is decided with preamble RSSI.


Regards,