Good day to all. I'm working on another project where I need to generate POCSAG data. This is an add-on to an existing project. What I am wondering is if I need to have crystal accuracy for the baud rate. The reason I ask is that the POCSAG specification has a very long preamble (minimum 576 alternating 1's & 0's), followed by up to 8 frames of data, each with their own synchronization word. The care that the writers of the spec have given to ensuring that the UART in the receiver can accurately synchronize to the incoming data rate makes me wonder if the pagers can tolerate a 0.5% or even a 1% error in data rate (baud rate). I can test against some real pagers but I'd rather hear it from someone who has expertise in the area. The last thing I want to have happen is for it to work fine in my lab, then have it fail in the field. The reason I ask is that the existing project has a PIC with enough spare I/O and code space to stuff the POCSAG protocol into - but its using its internal RC oscillator. The board layout is not conducive to hacking a crystal or resonator into. SO: if someone tells me that the POCSAG protocol is specifically designed to tolerate baud rate errors, I'll try it. On the other hand, if I'm told that POCSAG will NOT tolerate baud rate errors, I'll plan to design up a little daughter board with its own PIC and crystal and such. Many thanks! dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist