Sunday, 30 March 2014

SDR Front End

Work on developing the Arduino SDR continues with the rationalization of the front end into a plug-in module...

This little unit combines the quadrature clock generator section of my DDS shield, as implemented on a brace of 7474's and the switching Tayloe mixer, built around the 74CBT3253. These surface mount goodies, which add up to the same kind of front end seen on "Softrock"-type SDR systems, are mounted on a little PCB about 3 * 5 cm...

The new board makes it easy to build up the front end of a software defined radio using "building bricks" plugged into a solderless breadboard, as in the case below, which includes one of my standard plug-in 40m bandpass filters, a DDS module for clock generation and the new board...

I'm taking this path away from the DDS Shield used previously, in preparation for some experiments with the Si570 - which will be required to get the x4 clock rates required to achieve coverage of higher HF bands.

Here's the entire Arduino SDR receiver with the new front-end module...

Cleaning up the layout (with the new module) seems to have brought about an attendant clean up of the noise performance of the receiver - but that's just a subjective impression and may be no more than wishful thinking!

...-.- de m0xpd 


  1. Am having ZERO success here trying to do the same thing! Any change you can email me the schematic? antonywatts at me dot com

  2. By the way have you looked at LTC6904 as a clock?