Hi..=20

I am currently using a radio module in my latest PIC project. =
(RADIOMETRIX) BIM if anybody is interested.. However I have a natural =
aversion to paying for things I think I can build myself, i.e their =
Radio Packet Controller. As this is basically a PIC I want to see if I =
can make something similar myself.=20

If anybody is interested the datasheet for this part is at address =
http://www.radiometrix.co.uk/products/rpcsheet.htm
if you are doing anything to do with radio and you need some concepts =
about clock recovery etc explaining simply it`s pretty good, however =
obviously there are no technical details as they want to make money =
selling it!

Anyway down to my question. Basically I am transmitting as Manchester =
encoded data. What I need to do at the receiving end is recover the =
clock so that I know where to sample from. This is exactly what the =
radiometrix module does in software. However that looks a little bit =
beyond my skills at present so I am looking for some suggestions. I have =
been trying to put a PLL circuit together with a 4046 chip but I am =
having trouble selecting the correct resistors/capacitors. Help greatly =
appreciated in that area, I need to lock to a 2khz edge so I figured =
with 16x oversamping I need a centre point of 32khz and a fairly narrow =
loop filter bandwidth.=20

Alternatively if somebody could point me in the direction of some =
existing code that is similar I could attempt to do it in software.=20


This is common stuff and I am sure that other people will need to do it =
so if we can get a solution together I will gladly put up a webpage, =
circuit diagrams, layouts etc.

Thanks in advance for any help given. =20

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