New C version software

Finally finished a new version of the software this time using an 18F525 running at 40Mhz (10MHz crystal with HSPLL engaged). The software is now in a mixture of C and assmebler and allows FM at 19.5KHz and upped the wobbulator updates to 39000 per second.

The new software is available at http://authorityfile.co.uk/NBSC/Home/OtherStuff

Here's a few pictures of it being used in anger to map the properties of the 10.7MHz input filter of my log-detector (an SA614 RSSI output with 2x 10.7MHz cermic filters).

They're interesting in that they show the harmonics generated by the DDS-60 daughterboard. These appear to be much better than the claimed 40dB down at about 55dB down - though this is just those that fall in the 10.7MHz region.

The traces are all with 10dB per division.

0-60MHz

0-20MHz

10-12MHz

The slight sparkling on the pictures is due to the fact that the scan doesn't progress linearly but is a set of stepped frequencies. This isn't a problem but shows up noticably on a photo. However, a slower scan rate gives less "sparkly" pictures but I had to run these at 50Hz otherwise my shaky hands made the pictures blurred!

Dom