Tuesday, February 21, 2006

HPSDR Progress Report - 02-21-2006

LTC2208 Mercury Board:
The HPSDR project is now broken down into various sub-projects. The most important is the Mercury board which contains the LTC2208 130 MSPS ADC. The Mercury board will also contain a FPGA to do the DDC (Digital Down Conversion) function. There will probably be an option to install a Cypress FX2 USB2 microcontroller to make the board stand alone for certain applications. Otherwise the FPGA will connect to the Atlas bus. If you are not sure what Atlas is then see the Xylo list archives.

I have a few LTC 2208 evaluation boards coming from Linear Technology. They should arrive this week. I want to compare the LVDS board to the CMOS board to see if there are any advantages of using the LVDS mode for the 1-70 MHz range.

Initially I think I will program the on board FPGA so that the 130 MSPS from the LTC2208 are downsampled to <= 250 kSPS. The 250kSPS then can be processed in the same way that we process the data from the soundcard. PowerSDR can then be modified to be used with the Mercury board.

DttSP#:
After reviewing the roadmap that Flex Radio has published for the future version of PowerSDR I have decided that it does not appear to meet my needs for the HPSDR project. I am starting work on a library based on DttSP called DttSP# (DttSPSharpened). It will be a C# wrapper around DttSP where the creation of radio objects are handled by C# and the low level functions are delegated to DttSP. There will probably be an alternate constructor for each object that will implement the equivalent DttSP function in C# so performance can be compared. DttSP# will be target Mono on both Linux and Windows.

Friday, February 03, 2006

Linear Technology LTC2208

I have settled on the Linear Technology LTC2208 16 bit, 130 MSPS ADC for the HPSDR project. The LTC2208 has some unique features that put it ahead of offerings from Analog Devices.

Here is the datasheet:

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1155,C1001,C1150,P13693,D9659

of particular interest is the PGA, randomizer and dithering features.

We completed our move into our new home last weekend. We are getting settled in and soon I will start on the Mercury board - which is based on the LTC2208.