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Technical Topics => The RF Workbench => Topic started by: redhat on September 23, 2017, 2107 UTC

Title: GPS discipline a cheap Ebay DDS module
Post by: redhat on September 23, 2017, 2107 UTC

A neat idea I came across today.  Instead of disciplining the reference oscillator, just measure its drift and update the DDS frequency!  Generate any frequency from 10Hz-30MHz with precision of better than 1 Hz.

Uses (mostly) off the shelf hardware.  You do have to build a divide by 32 prescaler for the DDS clock.

PDF http://www.knology.net/~gmarcus/VFO/GPS_Sig_Gen_v1_1.pdf (http://www.knology.net/~gmarcus/VFO/GPS_Sig_Gen_v1_1.pdf)

Arduino code http://www.knology.net/~gmarcus/VFO/AD9850_gps_vfo_v1.ino (http://www.knology.net/~gmarcus/VFO/AD9850_gps_vfo_v1.ino)

+-RH

Title: Re: GPS discipline a cheap Ebay DDS module
Post by: ChrisSmolinski on September 23, 2017, 2131 UTC

Interesting, thanks for sharing. I just (and mean just, it arrived today) got an Arduino to play with. So far I've read a membrane keypad and sent text to an LCD display. I've got a rotary encoder on the way, I understand knobs are retro and in fashion again.