[hpsdr] Mercury

[Philip Covington]

Hi Phil,

Mercury:
If we go with the AD6636, by using a couple of 74LVC16374
<http://www.nxp.com/pip/74LVC16374ADL.html>
16 bit D FFs, we can either route the ADC input to the AD6636 or
straight to the FPGA on the Mercury board.  That way we can support
radio mode with the AD6636 and spec/oscope mode in the FPGA.  To use
the board just as a scope or spectrum analyzer the AD6636 would not
have to be populated on the board.  It would also allow
experimentation with DDC in the FPGA with a fallback to the AD6636
otherwise.

The IDT72V293 <http://www.idt.com/?genID=72V293> looks like a good
candidate for a FIFO.  I think we'd be better off with an external
FIFO than just SRAM.  What do you think?

Do you have recommendations for the rf front end and filters or does
that need to wait until the first alpha board?

73 de Phil N8VB