developmentfpgakits
I intend to purchase an FPGA, development kit and I have looked at both the Xilinx and Digilent website. Both seem to have good development kits.
I have never worked with FPGA's before but have some experience working with microcontrollers.
I see that the entry level Spartan 6 boards are on a par in terms of price with the Spartan 3A/AN boards. I've not compared the features.
From your experience what development kit would you suggest Spartan3A/AN or Spartan6?
I would not use an FPGA.
You mention you have no experience with FPGA's, and yet you are interested in doing digital signal processing on an FPGA... numerical manipulation + signal processing are difficult enough to get right on a computer/DSP/microprocessor, where the programming tools are conventional programming. It seems to me that using a digital signal processing project for a first FPGA project is likely a recipe for frustration.
If you want to learn FPGAs, try doing something more suited to the development tools, like state machines or communications packet processing.
For a DSP project like what you've described, I'd recommend a DSP or a Cypress PSOC or an Analog Devices Microconverter (=microcontroller with ADC+DAC builtin) instead.
(full disclosure, which provides some context for my advice: I do not use FPGAs myself. I have used programmable logic = PLDs on rare occasions. My officemate does use FPGAs frequently, and I've seen enough VHDL/Verilog code looking over his shoulder to know that it is well suited for bit manipulations. He is a seasoned engineer with lots of experience with FPGAs; in a recent conversation with him where he was doing some fairly simple math on integers with different bit widths, I told him he needed to do sign-extending on the shorter bit width number in order to subtract it properly, and he got this look on his face, like "oh man, I don't want to have to do sign extension..." Adding and subtracting is not very hard in an FPGA. Beyond addition and subtraction, you really need to know the tools and libraries. And floating-point processing??!?!!??!?!!?)
There are various, but I'll suggest the FriendlyArm Mini2440 with 3.5" Display and Touch Panel. See images bellow of the Sergio Prado's blog:
Best Answer
It looks to me like you still get a lot more to play with at a lower price point with Spartan-3. I found three different Spartan-6 options:
Of note here is that only the Atlys has a lot of on-board common I/O connectors, such as audio, video and keyboard. The LX16 kit has most of the interesting details on a Cypress PSoC instead, though it features a battery that may be interesting.
It boils down to what your intended projects are. With the lower budget Spartan-6 boards, you get an FMC-LPC connector that you can attach your own builds to; the LX16 kit also has a pin header, which is easier to get connectors for.
With the Spartan-3 kits, such as I have, we have a quite varied set of connections of more limited quality, and for major expansion there's the Hirose FX2 connector (again, somewhat unusual).
If your plan is to do video processing, I'd be very tempted to save up the extra money for the Atlys. It doesn't have very many expansion pins, but it has multiple on-board HDMI ports.