tag:blogger.com,1999:blog-9071048343455395511.post6872275915565453153..comments2024-03-24T22:03:31.205+00:00Comments on Roger G3XBM's (Mainly) Amateur Radio Blog: Stable, simple, stand-alone, 8.970kHz source?Roger G3XBMhttp://www.blogger.com/profile/13673890140751539870noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-9071048343455395511.post-53773777187625758042010-10-28T12:25:27.183+01:002010-10-28T12:25:27.183+01:00Hi, This is David - WB4ONA...
I Agree with LY2SS....Hi, This is David - WB4ONA...<br /><br />I Agree with LY2SS. Use a crystal clocked AVR running DDS sine wave firmware.<br /><br />Below is a link to a project that does this. The code is simple once you understand the basics of how a DDS works (download app notes for Analog Devices).<br /><br />Don't use a PIC uC; use an AVR. Typically most PICs use four clock cycles per instruction. The RISC AVR's typically use 1 clock per instruction. A four-times improvement in speed for this application (I continue to scratch my head when I see sooo many people using lame PIC processors).<br /><br />An AVR clocked at 20MIPS will make a nice DDS that can work through 100kHz with sub-sub-Hertz tuning, that's with an 8-bit R2R A/D. Optimally, you should program this DDS stuff in assembler and optimize the number of clock cycles used.<br /><br />http://www.electronics-lab.com/blog/?p=6273<br /><br />Best 73's...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9071048343455395511.post-4787424395492958962010-10-27T17:28:21.806+01:002010-10-27T17:28:21.806+01:00atmega/attiny (arduino) clocked from xtal, with so...atmega/attiny (arduino) clocked from xtal, with some custom code? One can even get sinusoidal signal if needed.LY2SShttps://www.blogger.com/profile/16647751066268814831noreply@blogger.comtag:blogger.com,1999:blog-9071048343455395511.post-46973164895094631572010-10-26T19:22:29.454+01:002010-10-26T19:22:29.454+01:00Thanks Jan. Rik OR7T has also suggested this appro...Thanks Jan. Rik OR7T has also suggested this approach which looks a simple low cost way of doing the job.Roger G3XBMhttps://www.blogger.com/profile/13673890140751539870noreply@blogger.comtag:blogger.com,1999:blog-9071048343455395511.post-75870187443212662392010-10-26T18:47:57.539+01:002010-10-26T18:47:57.539+01:00Idea : use a 27.555MHz 3rd overtone Xtal (oscillat...Idea : use a 27.555MHz 3rd overtone Xtal (oscillating on 9MHz) and divide by 1024 should provide you with 8969.7Hz<br /><br />Close enough?<br /><br />A bit further away : 27.000MHz 3rd overtone (more common) should provide 8789.1Hz<br /><br />73 de Jan PA9QVJan, OZ9QVhttps://www.blogger.com/profile/03992431305032081854noreply@blogger.com