This page provides some in-depth information
about the design of the Digimit 2002's digital synthesizer/modulator.
I have not yet prepared a paper which describes the whole FPGA core
of the Digimit 2002, nor its block diagram. Sorry, it should be available
soon. Some detailed description of the first digital SSB
modulator I have designed during this last Summer and which has been partially
reused in the Digimit 2002 can be found here. The paper
describes a fixed frequency, 9 MHz output, digital SSB/CW exciter based
on an FPGA implementation of a digital Weaver modulator.
A very good on-line paper which introduces to FPGA-based CORDICs
can be found here.
Those who are interested in CIC filters/interpolators/decimators
and have access to IEEE Transactions library should give a look to E.B. Hogenhauer's
paper "An economical class of digital filters for decimation and interpolation",
IEEE Trans. on Acoustic, Speech and Signal Processing, ASSP-29(2), 1981,
pp. 155-162. Ehm... Ehm I haven't read it yet :-).
A good recent introduction on the applications of programmable logic
in Amateur Radio can be found in John B. Stephensen's paper "Software-Defined
Hardware for Software-Defined Radios", QEX, Sept/Oct 2002 issue, pp. 41-50.
John, KD6OZH, introduces to ATMEL's SoCs (aka FPSLIC), FPGA-based SDRs and
other. The Digimit 2002 itself is a "System on a Chip". It
features two 8 bits RISC microcontrollers which are integrated in its programmable
logic core and to which I added all the I/O peripherals I needed. The microcontroller
core used in the Digimit 2002 is Xilinx's Picoblaze and
was formerly known as KCPSM, in name of his creator Ken Chapman
(G7CSJ). (Thanks for your kind support, Ken)
If you have any other useful link to Internet resources regarding
these arguments, feel free to suggest them me.
