Cable Modem, How to get Internet from TV cable

please i need help in designing Cable modem operates on catv cable & using DOCSIS protocal , i'm starting from scratch so i need any info u can provide..
Thanks .....

very ambitious project to design your own cable modem ...

but in the end when you have tweaked all hardware and everything is working perfectly ... you attach it to you cable network and have no internet because you need an IP lease for your modem with a identification number which is unknown to the operator ...

what a disappointment!

thanks for your Reply radiohead

but what if i already got IP do u think the problem would be in the MAC address (physical) ?

any1 can help ?
attached intro to cable modem design if any1 interested