Yes, I am quite aware that noise and jitter are a problem with the GPSDO prototypes built on these cheap breadboards, if you check the previous scope captures I have posted, the noise is quite obvious.
In this development phase of the STM32 GPSDO project, they have proven (just) good enough for testing various circuit ideas and allowing me to write the frequency measurement algorithms and test them.
At some point I'll probably start soldering things on a perforated board (which I already have), but I am not quite there yet.
Some ideas I still want to test and have some fun with, on this latest breadboard prototype:
- Committing calibration and configuration parameters and data to the MCU flash using the EEPROM emulation library for the STM32.
- Expanding flash using a separate SPI memory chip to log days/months of data (yet another optional module...).
- More tests of Erik's version of Lars' TIC.
- The picDIV.
- 1PPS from OCXO+picDIV, synchronized to UTC.
- Measuring the power consumption of the STM32 GPSDO.
The really tedious part of all this experimentation is wiring everything...
![Cry :'(](https://www.eevblog.com/forum/Smileys/default/xcry.gif.pagespeed.ic.tehjCtKixU.png)
(The picture below is for you, JBG)