On Wed, Jan 12, 2011 at 10:26 PM, Marcus D. Leech <mle...@ripnet.com> wrote: > On 01/12/2011 10:01 PM, Brian Padalino wrote: >> >> Altera Cyclone IV EP4CGX15 FPGA, Analog Devices AD9861 MxFE, USB2 >> microcontroller (for reprogramming the FPGA) in an ExpressCard/34 >> format. The FPGA has a hard PCIe 1.1 x1 lane with a hard IP core for >> PCIe connectivity. The PCIe interface has an extremely low latency >> and pretty high throughput - ~200MB/sec full duplex (after overhead >> and whatnot). The FPGA would be mostly empty since the PCIe core is >> hard. If the F169 package is used, it should be compatible with up to >> a EP4CGX30 which would give 80 18x18 multipliers and over 1Mbit of >> embedded memory. The ExpressCard format can fit into desktop PC's >> with simple and cheap adapters, or into laptops which have ExpressCard >> slots. >> >> ExpressCard has both an x1 PCIe connection as well as a USB 2.0 >> connection. I imagine a small USB 2.0 micro used for FPGA >> configuration and, possibly, a secondary way for samples to enter/exit >> the FPGA for different use cases (similar to the original USRP). But >> the main purpose would be for reconfiguration of the FPGA. >> >> Frequency synthesis can be an optional part of the assembly. I >> imagine a relatively inexpensive VCTCXO (2ppm accuracy?) along with an >> Si5338 clock synthesis chip. The idea, though, is to be completely >> optional for those who really want it. Otherwise, the FPGA PLL's can >> probably be good enough for most people. >> >> >> > There are a couple of downsides to a PCIe implementation that I can > think of: > > o not all host platforms are going to have PCIe slots > o it's noisy in there!
Agreed on PCIe, though I think less platforms have USB3. When speaking of noise at baseband (2V driving 50Ohms), assuming you have a little can over the analog bits, is the noise that high? Brian _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio